Part 5. Nitrite – the Misunderstood Compound

by Eben van Tonder
1 September 2022

Part 5 in our series, The Truth About Meat Curing: What the popular media do NOT want you to know!

Introduction

The accusation is widespread in the media, sensation-seeking documentaries and celebrity chefs alike that nitrite, derived from ammonia, nitrate (Salpeter) or added in the form of sodium nitrite in meat curing is tantamount to poisoning consumers and inviting cancer into your lives. I am a meat curing professional. My interest in the truth about nitrites is in the first place to be certain that I am not engaged in an action where harmful products are produced. To state this slightly differently, what steps can I take to ensure the safest possible product is made available?

The issue of nitrites is complex and to develop even a rudimentary understanding of all the issues requires that we work through a lot of technical information. Despite this, the basic evaluation is simple and well within the grasp of the general public. Here I desire to share with you what I discovered about this remarkable compound!

It is part of a short series I’ve put together on the matter entitled, The Truth About Meat Curing: What the popular media do NOT want you to know! After preliminary discussions, we now place the spotlight squarely on nitrite. We discover that instead of poison, even though this is true in large dosages and under certain conditions, it is a vitally important compound for the normal functioning of our bodies. That the sources are mostly from vegetables and not cured meat, and that any possible harmful effect is removed through the simultaneous consumption of vitamins A, C, E, etc.

What I discovered is that an entirely different (and positive) world exists related to nitrites generally and dietary nitrites in particular. The evidence is clear, overwhelming and available to anybody with an honest interest in the matter that nitrites are beneficial to human health and essential for the optimal functioning of our bodies. We will discover that there is a seemingly unresolved issue in that while nitrites, in balanced concentrations, have overwhelmingly beneficial results in the human body (may I even call it essential?!), there is seemingly contradictory information which shows that nitrites are involved, under certain conditions in the generation of N-Nitrosamines which can be cancer-causing. Parallel to this is the indication of many studies that there seems to be a relationship between the consumption of cured meats and cancer and even though the exact reason has not been elucidated, it begs the question as to possible reasons for this. How do we deal with this seemingly contradictory information, that n-nitrosamines which are the obvious culprit for any possible link between cured meat and cancer on the one hand come from nitrites and on the other hand, nitrites play an vital part in our general health and the resolution of many common diseases and ailments? Can it be that nitrosamines are not the culprit of what seems to be a link between cancer and cured meat? Can it be that lifestyle or general nutritional habits alter the nature of an important chemical in our bodies from beneficial to harmful and if this is the case, what are those factors? Is it fair to label bacon as possibly cancer-causing? When it comes to the full array of reactive nitrogen species of which nitrite is a part, is it possible to have the one without the other, especially in light of the fact that the curing molecule is nitric oxide, also one of the reactive nitrogen species? Is the statement that curing was done with no nitrite even a sensical one in light of the oxidation of nitric oxide to nitrite and nitrite to nitrate in the curing environment? It begs the question if no nitrite curing which has been the goal of meat scientists for so many years even valid question to ask or is this something that will sell products without any real benefit to the consumer as far as the removal of the real risk of n-nitrosamine formation. This is an extremely timely question as we stand at the dawn of a time when no-nitrite curing will become a reality across the world. The emphasis is about to squarely shift to nitric oxide and in light of this future trend we have to ask, can nitric oxide contribute to nitrosamine formation as is the case with nitrites which would mean that removing nitrites from the curing system has no real benefit as far as nitrosamine formation is concerned.

We have to continue the questioning. If ingesting dietary nitrite has overwhelmingly positive effects on human physiology, should nitrite curing not rather be encouraged and embraced and should ham and bacon not be seen as a superfood instead of something to be avoided? I ask another question which is the focus of my own work and that of a small band of like-minded food professionals and scientists – how do we turn ham, bacon and the cured meats we love into superfoods in such a decisive manner that there can be no argument from any quarter about this status!? These are all valid questions and despite the mammoth task ahead, I will do my best to interact with all these questions in this document. Where I fail, please point it out to me so that I can improve on the document and evolve in my thinking, but please, do it from a position of constructive interaction and partnering with me in seeking the truth!

I will try and deal as honestly as a layman can with these complex questions, believing that I have a sacred responsibility to the consumer to do exactly this and if the evidence points away from what I would like it to say, that I should have the integrity follow the lead of the evidence. My ultimate goal is therefore the TRUTH and not to generate “likes” on social media posts. Anybody with a meaningful contribution or who wants to correct me on any point can contact me at ebenvt@gmail.com or WhatsApp me at +27 71 545 3029.

History of Nitric Oxide and the Close Link between Nitrate, Nitrite and Nitric Oxide.

Nitric oxide (NO) was discovered in 1772. Nitroglycerine (NG), a vasodilator acting via NO production, was synthesized in 1847. The effect of nitroglycerine was studied on healthy volunteers by Constantin Hering in 1849 and it was proven to cause headaches. Later in 1878, nitroglycerine was used by William Murrell for the first time to treat angina. Towards the end of the 19th century, nitroglycerine was established as a remedy for relief of anginal pain.” (Ghasemi, 2011) Angina is a type of chest pain caused by reduced blood flow to the heart. In 1916, Mitchell et al. suggested that body tissues can also produce nitrate and Richard Bodo in 1928 showed a dose-dependent increase of coronary flow in response to sodium nitrite administration. In the 1970s, it was shown that nitrite-containing compounds stimulate guanylate cyclase,” which is an enzyme that converts guanosine triphosphate (GTP) to cyclic guanosine monophosphate (cGMP) and pyrophosphate. An increase of cyclic guanosine monophosphate (cGMP), also caused by the intake of nitrite containing compounds cause vascular relaxation and it is presumed that cGMP activation may occur via the formation of NO. (Ghasemi, 2011)

In 1980, Furchgott and Zawadzki showed that endothelial cells are required for acetylcholine-induced relaxation of the vascular bed which refers to the vascular system or a part thereof, through the endothelium-derived relaxing factor. Even though they could not initially pinpoint what caused the relaxation of the endothelium, scientists knew that such a relaxing factor existed and the race was on to identify it. The endothelium is the thin membrane that lines the inside of the heart and blood vessels. The breakthrough came in 1987 when it was shown that endothelium-derived relaxing factor and NO are the same or almost the same thing. Nitric oxide was the agent responsible for relaxing the endothelium. (Ghasemi, 2011)

In 1992, NO was proclaimed as the molecule of the year and in 1999, Furchgott, Ignarro, and Murad were awarded the Nobel Prize in Physiology or Medicine for studies in the NO field. Due to the proven roles played by NO physiologically and pathologically, research on NO was increased rapidly and at the end of the 20th century, the rate of NO publications was approximately 6,000 papers per year, with currently more than 100,000 references invoking NO listed in PubMed.” (Ghasemi, 2011)

In our earlier discussion of nitric oxide as the curing molecule in bacon, we referred to S. J. Haldane who was the first person to demonstrate that the addition of nitrite to haemoglobin (blood protein) produces a nitric oxide (NO)-heme bond, called iron-nitrosyl-hemoglobin (HbFeIINO). He showed that nitrite is further reduced to nitric oxide (NO) in the presence of muscle myoglobin (muscle protein key in supplying oxygen to the muscle) and forms iron-nitrosyl-myoglobin. It is nitrosylated myoglobin that gives cured meat, including bacon and hot dogs, their distinctive red colour and protects the meat from oxidation and spoiling. Discovering that Nitric Oxide (NO) is a key molecule in human physiology should not have been a surprise to meat scientists. There was, an understanding in meat science since the time of Haldane that the nitrate-nitrite-NO pathway was the curing reactions in meat from saltpetre to nitric oxide. It was later decided to use nitrite directly for reasons elucidated in a previous part of this series, Part 2: The Curing Molecule

When we say that the reduction of nitrite to nitric oxide occurs chemically, we refer to the non-enzymatic reduction of nitrite to nitric oxide. Ghasemi (211) gives us the technical details of this. “NO was found to be synthesized from L-arginine by the enzymes known as NO synthase (NOS) (EC 1.14.13.39) in two separate mono-oxygenation steps; first, L-arginine is converted to N-hydroxyarginine in a reaction requiring one O2 and one NADPH and the presence of tetrahydrobiopterin (BH4) and in the second step, by oxidation of N-hydroxyarginine citrulline and NO are formed. At least three NOS enzyme isoforms including neuronal, inducible, and endothelial (eNOS) have been identified and encoded by different genes.”

This non-enzymatic production of Nitric Oxide was suggested in 1997 by Ghafourifar and Richter. They postulated the “existence of mitochondrial NOS and in 1994, Lundberg and colleagues and Benjamin and colleagues demonstrated NOS-independent NO formation. Non-enzymatic NO production by one-electron reduction of nitrite, a blood and tissue NO reservoir, seems to be found everywhere and greatly accelerated under hypoxic conditions or conditions of low oxygen levels in your body tissues. This finding changes the general belief that nitrate and nitrite are waste products of NO.” (Ghasemi, 2011)

I want to refer as an important sidenote at this point to the work of Vanek (2022) which we will look at in much greater detail in a following discussion since they beautifully elucidates the reason for the importance of Nitric Oxide and how it binds to the meat protein we rely on in meat curing, forming the reddish/ pinkish colour of cured meat and giving muscles its characteristic red colour. The important point is that just as nitric oxide is produced through enzymes and non-enzymatic ways to react with myoglobin, in the same way and hugely important to meat curing is that myoglobin has also been shown to have enzymatic functions and is responsible for the decomposition of bioactive nitric oxide to nitrate. The importance of this point can hardly be over-stated! If we are able to convert L-arginine into Nitric Oxide in other ways besides indigenously through NO synthase (the enzymes responsible for oxidising nitrogen in L-Arginine to nitric oxide), and so cure meat, and should we find that this can be done through bacteria, then we still do not strictly speaking have meat curing with no nitrite present as the nitrate will be converted through bacteria in the meat to nitrite and albeit this being present at very low dosages, there will still be nitrite in the meat that we cured.

Allow me to state it again. If we are able to access L-arginine either through bacteria or enzymes directly (as we do in salt-only-long-term-cured-hams) and as a result of this do not start our curing process with nitrite (as is the case with long-term salt-only cured hams) and we are able to claim that we cure meat with no nitrite salts as we are indeed able to do at the present time, then we can not say that we eliminated nitrite from meat curing because there is the likelihood that some of the NO will be converted to nitrate which will be reduced to nitrite again and we are back at the beginning of the quest for nitrite-free curing. Stated a different way, it would seem that curing without nitrite is not possible. This is the heart of the conundrum of people propagating that meat has been cured with no nitrites in that we are dealing with REACTIVE nitrogen species and where you find the one, you are likely to find the others. Our nitrogen species of interest, when we refer to “we will find the one where we find the others” are nitrate, nitrite and nitric oxide, but as we will see further on, these are by no means the only nitrogen species we will encounter in the human muscle and in meat curing alike.

The extent to which what I suggest above is true, we will have to verify through experimentation. The rest of this document is dedicated to answering the following question: why would we want to eliminate a physiologically important species of nitrogen from our diet in any event!? So, on the one hand, is nitrite free curing a realistic goal and secondly, why would we want to do it? Are there other ways to overcome the health concerns associated with cured meats?

Effects of Nitrite in Human physiology.

– Sources of nitrogen for Human Physiology and the Value of Nitrite

The great discovery of the past few decades is that nitrate and nitrite have a fundamentally important role in our physiology and nitrite in particular, namely to act as a reservoir for nitric oxide (NO) which is a physiologically important molecule. Apart from nitric oxide being generated from the amino acid, L-Arginine, nitric oxide is generated through what is referred to as the nitrate-nitrite-Nitric Oxide pathway which is, as we have said before, exactly the same pathway of bacon curing. So, in order for this mechanism to work, we need a direct source of nitrates or nitrites and nature provided this for us in what we eat. The biggest source is vegetables which account for 60%–80% of the daily nitrate intake in a Western diet. As you will see from the table below, they not only supply us with nitrates but with nitrites directly as well. It has been shown that elevations in the blood plasma nitrite levels can occur by increasing the dietary nitrate intake. (Kobayashi, 2015)

Nitrate, nitrite and nitric oxide are closely linked as the difference between them is one oxygen atom. NO3 (nitrate), NO2 (nitrite) and NO (nitric oxide). Nitrate is reduced to nitrite through bacteria and nitrite to nitric oxide through chemical means (enzyme and non-enzyme driven). NO can be oxidized back to nitrite again and nitrite to nitric oxide. Nitric oxide, in the presence of myoglobin, can be converted directly back to nitrate. As a result of this, where one finds nitrate and bacteria such as in the mouth or digestive tract, you will always find nitrite and nitric oxide and where you have nitric oxide, one can find nitrite and nitrate. This is true in meat curing and true in the human body. “In humans and other mammals, about one-quarter of all circulating inorganic nitrate (NO3), derived from diet or oxidation of endogenous (within the body) nitric oxide (NO), is actively taken up by the salivary glands and excreted in saliva. As a result, salivary nitrate levels are 10–20 times higher than those levels found in our blood. The mechanism behind this massive nitrate accumulation in saliva has remained elusive. The work by Qin et al. reports that the protein sialin can function as an effective nitrate transporter.” (Lundberg, 2012)

With these brief remarks, we are then thrust into the domain of the nitrate-nitrite-NO cycle in the human body. Nitrite is no longer viewed as something to be avoided at all cost, but as a chemical essential for human life and cured meat becomes by far, not the biggest contributor of nitrate and nitrite to our system, but the possibility exists for it to become an important one as we can use the same basic principles that gave us cured meat, reduce the fat and salt and find ways to introduce essential goodness of plant matter and we are confronted with the amazing opportunity to change processed food into a superfood! In this one statement, I seek to address the unfounded negative perception of nitrite, give a clue as to the possible real reason behind the health concerns related to processed meat (fat, salt, phosphates, etc) and give a roadmap for future work by imaginative food scientists in the incorporation of healthy plant matter into the sought after food group, allowing for all the conveniences that make processed-meats a well-loved and very convenient food for our era!

Have a look at the table below which gives the main dietary sources for nitrate and nitrites. Pay close attention to where hot dogs and bacon feature on the list!

Sindelar (2012), as quoted by (Kobayashi, 2015)

Hord (2009) as quoted by (Kobayashi, 2015)

When we ingest nitrates from leafy green vegetables or cured meat, it is absorbed in the upper gastrointestinal tract which comprises the mouth, salivary glands, oesophagus, stomach, and small intestine. The levels in the blood reach the highest level around 30–60 min after the nitrates have been swallowed. Approximately 25% of nitrate absorbed by the body reappears in our mouth through our salivary glands which pump it back into our mouths. Here it is reduced by the bacteria on our tongue from nitrate to nitrite. As it reaches our stomach, a part of the nitrites which we swallow is what we call protonated (adding hydrogen to the nitrite) and nitrous acid is formed which is the form that nitrite takes on when diluted into water (NO2− + H+ → HNO2). This reaction is similar to what happens to nitrite when we dilute it into the curing brine and inject it into meat which is also a more acidic environment like the stomach. Similar to meat curing, the nitrite we ingested now decomposes to form a variety of nitrogen oxides such as Nitric Oxide, the curing molecule, nitrogen dioxides (NO2), and dinitrogen trioxide (N2O3) (2 HNO2 → N2O3 + H2O, N2O3 → NO + NO2). These nitrogen oxides form additional bioactive adducts, such as S-nitrosothiols and N-nitrosamines. S-nitrosothiols sound very intimidating but are not. They are proteins discovered in the 90s and have since been shown to be key in many biochemical processes in our body. Specifically, S-nitrosothiols play a key role in the total system encompassing our heart and blood vessels, for example, the widening of blood vessels as a result of the relaxation of the blood vessel’s muscular walls and preventing thrombosis. N-nitrosamines are known to us by now as formed by the reaction of nitrite with secondary amines which can be cancer-causing.” (Kobayashi, 2015)

The next point requires us to know what gastric mucosa refers to. It is the mucous membrane layer of the stomach, which contains the glands and the gastric pits. Blood flow plays an important role in the protection of normal gastric mucosa and in the protection and healing of damaged mucosa. “Nitric Oxide production in the stomach is greatly enhanced in the presence of micronutrients that naturally occur in plants called dietary polyphenols and vitamin C or ascorbic acid, whereas because of its lower stability and shorter half-life relative to S-nitrosothiols, the released Nitric Oxide in the stomach is thought to locally contribute to increasing the gastric mucosal blood flow and mucous thickness to ensure the normal gastric physiology, and serves as the first-line host defence against harmful bacteria which we swallowed with our food. However, not all the nitrite reacts with H+(escapes the protonation) in the acidic milieu of the stomach and enters the systemic circulation, and then reaches the peripheral organs, including skeletal muscles, where it acts in an endocrine manner (like hormones) to exert NO-like activity. An interesting side note is that because the levels of nitrite in the blood are depends to a large degree on the amount of nitrate in the saliva and its reduction to nitrite, the use of antibacterial mouthwash and frequent spitting of saliva consequently decrease the plasma levels of nitrite.” (Kobayashi, 2015) We just said that Nitric Oxide production in the stomach is greatly enhanced in the presence of micronutrients that naturally occur in plants called dietary polyphenols and vitamin C or ascorbic acid. As we will see later, these substances and in particular vitamin A, C and E plays an important role as “blocking” agents by reacting with the partially digested amino acids called amines, and with secondary amines in particular called N-Nitrosamones denoting a reaction between the amine and nitroso component in nitrite, binding nitrogen and nitrogen (therefore the name, N-Nosotros-amines), blocking the formation of n-nitrosamines. Let me state it again. If we ingest nitrite with vitamins a, c, e, etc., these vitamins react with the secondary amines before nitrite can react with it, therefore blocking nitrosamine formation. This is something to look at on its own and we will not spend much more time on this important point. Here, my goal is to show that nitrite is NOT the harmful cancer-causing entity we believed it was, but turns out to be indispensable for healthy living! We can, therefore, for the moment, suspend the concerns about N-nitrosamine formation but rest assured that we will return to this in great detail! For now, let us continue with our focus on nitrites and the diagram below shows the main way we get nitrates and nitrites into our body.

(Kobayashi, 2015)

“The plasma nitrite which reaches peripheral tissues is stored in various organs. Although there have been few reports dealing with the tissue levels of nitrate/nitrite following dietary nitrate supplementation in humans, animal studies show that dietary nitrate certainly increases the tissue levels of nitrate/nitrite following an increase in the plasma levels of nitrate/nitrite, which accordingly exerts therapeutic efficacy for animal models of various disease conditions. Interestingly, while acute dietary nitrate intake increases the plasma levels of nitrite in rodents and humans, chronic dietary nitrate intake does not always increase the plasma and tissue levels of nitrite but increases the tissue levels of nitrate and S-nitrosylated products. Although the mechanism underlying this finding is yet to be clarified, there might be some redox equilibrium of nitrate-nitrite-NO after chronic dietary nitrate intake, resulting in oxidation or reduction of the tissue nitrite to form nitrate or S-nitrosylated species, respectively. On the other hand, animal models chronically fed a diet deficient in nitrate/nitrite exhibit significantly diminished plasma and tissue levels of nitrate/nitrite, resulting in increased ischemia-reperfusion injuries in the heart and liver compared with the animal models fed a normal diet. Ischaemia-Reperfusion injury (IRI) is defined as the paradoxical exacerbation of cellular dysfunction and death, following the restoration of blood flow to previously ischaemic tissues. Ischemia or ischaemia is a restriction in blood supply to any tissues, muscle group, or organ of the body, causing a shortage of oxygen. These results suggest that dietary nitrate intake is important in the maintenance of steady-state tissue levels of nitrate/nitrite for NO-mediated cytoprotection. Cytoprotection is a process by which chemical compounds provide protection to cells against harmful agents. (Kobayashi, 2015) The key point is the importance of nitrate and nitrate in our diets and the possible harmful effect of nutrition deficiency in these compounds.

“Historically, the fact that nitrate and nitrite are present in human saliva has received little attention, because no one could attribute any kind of function to these anions. However, this lack of interest ceased in the 1970s, when researchers formulated a pathophysiological model for gastric cancer based on the accumulation of nitrate in saliva. Commensal bacteria in the mouth reduce parts of the salivary-derived nitrate to nitrite (NO2), and when swallowed into the acidic stomach, this nitrite yields reactive intermediates that can react with dietary compounds to promote the formation of N-nitrosamines (a versatile class of carcinogens in rodents). With the emergence of this theory, nitrate immediately fell into deep disgrace, and ever since that time, authorities worldwide have put strict regulations on allowable levels of nitrate in our food and drinking water.” (Lundberg, 2012)

In the 1990s, research on nitrate took an unexpected turn when two research groups independently showed that salivary nitrate was a substrate for the formation of NO, and we looked at the development of our understanding of the importance of this molecule in our lives earlier on. It was revealed that NO plays “a key role in virtually every aspect of human physiology, including regulation of cardiovascular function, cellular energetics, immune function, neurotransmission, and more. The newly described alternative means of NO generation from nitrate was fundamentally different from the NO synthase pathway; it did not use arginine as a substrate, and it was independent of NO synthases. After the discovery that nitrate could be a substrate for the formation of a potentially beneficial biological messenger, the interest in nitrate shifted away from only being focused on carcinogenesis, and instead, researchers started to study potential NO-like physiological effects of this anion. From intense research performed during the past 15 y, it is now clear that administration nitrate or nitrite has robust NO-like effects in humans and other mammals. These effects include vasodilation, reduction in blood pressure, protection against experimental ischemia-reperfusion injury, reduction in cellular oxygen consumption, reversal of metabolic syndrome, reduction in oxidative stress, stimulation of mucosal blood flow and mucus formation in the gastrointestinal tract, and more.” We will spend time further on many of these in particular looking at lifestyle diseases.

“Intriguingly, most of these nitrate effects occur at dietary doses easily achievable through a normal diet rich in vegetables. Bioactivation of nitrate requires initial reduction to the more reactive nitrite anion, and this reaction is mainly carried out by commensal bacteria in the oral cavity and to a lesser degree, the tissues by mammalian enzymes. Salivary-derived nitrite is partly reduced to NO in the acidic stomach as described above, but much nitrite also survives gastric passage and enters the systemic circulation, which is evident from the marked nitrite increase in plasma seen after ingestion of nitrate. In blood and tissues, nitrite can undergo additional metabolism to form NO and other bioactive nitrogen oxides, including S-nitrosothiols. A number of enzymes and proteins have been shown to act as nitrite reductases, including deoxygenated haemoglobin, myoglobin, xanthine oxidase, mitochondrial respiratory chain enzymes, and more.” (Lundberg, 2012)

This matter of nitrate-nitrite-Nitric Oxide as the reaction sequence from nitrate in saliva becomes very interesting to us in the meat curing industry for one specific reason. When we surveyed the approach taken by the industry and the US government in particular, we noted in Part 3: Steps to secure the safety of cured meat, of our series that the direct application of nitrite was seen as a way to bypass the first bacteria mediated reduction step of nitrate to nitrite. The reasons given by industry and scientists alike was that it would yield better control in the curing process amongst others, as it relates to the lowest possible dosage of nitrite to effect curing since the dose dependency of the toxicity of nitrites was recognised from very early.

Lundberg (2012) surveyed the work of Qin in identifying sialin as the nitrate transporter to the saliva. This is relevant to curing. Lundberg describes a disorder which leads to ineffective transport of nitrate as follows, “Mutations in the sialin gene cause Salla disease and infantile sialic acid storage disorder, which are serious autosomal recessive lysosomal storage disorders characterized by early physical impairment and mental impairment.”

A fibroblast is a type of cell that contributes to the formation of connective tissue. It secretes collagen proteins that help maintain the structural framework of tissues. “Fibroblasts from patients with infantile sialic acid storage disorder show a lower nitrate transport activity compared with healthy controls. The work by Qin et al. also tested the importance of sialin for nitrate transport in the pig in vivo. Interestingly, adenovirus-dependent expression of a sialin mutant vector (sialinH183R) in the salivary gland decreases NO3 secretion in saliva after ingestion of a nitrate-rich diet compared with control animals.” (Lundberg, 2012)

“Sialin is expressed not only in the salivary glands but also in the brain, heart, lung, kidney, and liver, although seemingly at lower levels. The functional importance of nitrate transport into cells in these tissues would be of interest to study. In this context, it is interesting to note that nitrate metabolism does, indeed, occur in mammalian cells, although to a much lesser degree than in bacteria. The work by Jansson et al. reported on a functional mammalian nitrate reductase in numerous tissues, including liver, kidney, and intestines. Xanthine oxido reductase was identified as the major mammalian nitrate reductase, but the study indicated the presence of other unidentified nitrate reductases as well.” (Lundberg, 2012) The observation that nitrate metabolism occurs in mammalian cells, although to a much lesser degree than in bacteria should not escape our notice. I discussed the matter with a collaborator on key projects, Richard Bosman and we speculated that the reason for the curing in long-term salt-only-dry-cured hams probably has more to do with the relaxing of the muscles as a result of early cell breakdown and the accompanying invasion of bacteria able to oxidize L-arginine than with the endogenous oxidants in the meat. This fact possibly further points to a symbiotic evolution of humans with oral cavity bacteria positioned to fulfil this vital role of reducing nitrate to the more reactive nitrite.

“The work by Qin et al. proposes that sialin functions as the major NO3 uptake system in salivary gland cells; however, a remaining question is how this nitrate is further transported to saliva through the apical portion of the cells. Sialin seems to be a versatile anion transporter that also mediates H+-dependent transport of NO2, aspartate, and glutamate. Previously, antagonism between nitrate, perchlorate, iodine, and thiocyanate for secretion in human saliva was shown, but in the work by Qin et al., these anions are not studied. It will be of interest to study if sialin also transports these anions. Definitive evidence for a functional role of sialin in nitrate transport and systemic nitrite/NO homeostasis in humans is lacking, but with the identification of this protein as an important nitrate transporter, it now seems possible to study this area. One approach could be to study the nitrate–nitrite–NO pathway in genetically engineered mice or perhaps, patients with Salla disease. Are salivary and plasma levels of nitrate/nitrite different in these patients? Do these animals or the patients exhibit any signs of systemic NO deficiency, including increased blood pressure, altered blood flow responses, different cellular energetics, or others? In the case that NO homeostasis is disturbed in Salla disease, would the patients benefit from substitution with nitrite?” (Lundberg, 2012)

This is the relevant question. Look at the possible suggestions. Is it possible to bypass nitrate and the bacterial reduction to nitrite and instead, would a solution be to administer nitrite directly as happens when we ingest nitrate which is transported to the saliva glands and in the mouth, are converted to nitrite, which, in the mouth and in the reducing environment in the stomach is changed to the physiologically vital nitric oxide? Lundberg (2012) puts his finger on the issue when he asks, “By giving nitrite instead of nitrate, one could bypass the initial nitrate transport step that might be disturbed in these patients, and NO and other bioactive nitrogen oxides would form directly from nitrite in blood and tissues.” He points to the fact that this therapeutic approach “was recently successfully tested in another genetic disorder involving a disturbed NO homeostasis.” Homeostasis refers to a self-regulating process by which biological systems maintain stability while adjusting to changing external conditions. “Another approach could be to study the proposed negative consequences of nitrate transport. If salivary nitrate transport promotes nitrosamine formation, which has been believed for a long time, are nitrosamine levels and occurrence of gastric malignancies lower in subjects lacking the transporter?” (Lundberg, 2012)

Huizing reports by 2021 that “plasma-membrane nitrate transport in salivary gland acinar cells, remains enigmatic.” (Huizing, 2021) Our hiatus into this question has, however, not been without reward.

  • We have seen the widespread distribution of nitrate to physiologically vital sites in the body;
  • We glimpsed at the key role of nitrite in the blood plasma, mainly derived from ingested nitrate and nitrates.
  • We see how other scientists in other fields of study came to the same conclusion as food scientists in the early 1900 namely that a direct application of nitrite, bypassing the time and bacteria dependant reduction step of nitrate has beneficial consequences.

In the discussion about possible negative effects of nitrite, one very important point to remember is that our overall natural design favours an adequate intake of nitrites. This can be seen by its presence in our blood. Here, nitrite is reduced to nitric oxide.

Gladwin (2008) that “recently, multiple physiologic studies have surprisingly revealed that nitrite represents a biologic reservoir of NO that can regulate hypoxic vasodilation, cellular respiration, and signalling.” They summarise that “studies suggest a vital role for deoxyhemoglobin- and deoxymyoglobin-dependent nitrite reduction. Biophysical and chemical analysis of the nitrite-deoxyhemoglobin reaction has revealed unexpected chemistries between nitrite and deoxyhemoglobin that may contribute to and facilitate hypoxic NO generation and signalling. The first is that haemoglobin is an allosterically regulated nitrite reductase, such that oxygen binding increases the rate of nitrite conversion to NO, a process termed R-state catalysis. The second chemical property is oxidative denitrosylation, a process by which the NO formed in the deoxyhemoglobin-nitrite reaction that binds to other deoxyhemes can be released due to heme oxidation, releasing free NO. Third, the reaction undergoes a nitrite reductase/anhydrase redox cycle that catalyzes the anaerobic conversion of 2 molecules of nitrite into dinitrogen trioxide (N2O3), an uncharged molecule that may be exported from the erythrocyte. We will review these reactions in the biologic framework of hypoxic signalling in blood and the heart.”

It is interesting that nitric oxide produced in the endothelium is oxidised to nitrite. In this instance, one could say that it “bypasses” the intestinal section where it could react with amino acids to form n-nitrosamines which some of them can cause cancer. Rassaf (2014) states that Nitric Oxide is produced in the body from the amino-acid L-arginine by the NO-synthases (NOSs). Three different NOSs exist: the endothelial NOS (eNOS, NOS III), the inducible NOS (iNOS, NOS II) and the neuronal NOS (nNOS, NOS I). This may be one way that the body uses to “manage” the possible harmful effects of nitrite but there are others as we have already eluded to and will look at in greater detail further on, namely ways to “block” nitrite through ingested vitamins. Still, there is another important mechanism which we will discuss in the future when we focus on n-nitrosamines and ways to mediate its possible harmful effect. Note that making it mandatory to include vitamin C in cured meats has been a strategy employed by the industry and regulated by governments from very early on. I will say a bit more about this at the end of this article.

Let’s return to the endothelial. The endothelial is the largest organ system in the body. I repeat the definition as I realise that these concepts may be new to many of the readers and repetition aids learning! It refers to a single layer of cells, called endothelial cells which lines the inside of all blood vessels (arteries, veins and capillaries). Inductable NOS is expressed after cell activation only and then produces NO for comparatively long periods of time (hours to days) in response to autoimmune and chronically inflammatory diseases in humans and neurodegenerative diseases and heart infarction, during tumour development, after transplantation, during prostheses failure and myositis. (Kröncke, 1998) Neuronal or nNOS relates to the brain. “Brain nNOS exists in particulate and soluble forms and the differential subcellular localization of nNOS may contribute to its diverse functions and has been implicated in modulating physiological functions such as learning, memory, and neurogenesis, as well as being involved in a number of human diseases.” (Zhou, 2009)

Let’s return to Gladwin (2008) who now describes a fascinating cycle of Nitric Oxide in the blood which relies on its conversion to nitrite. As we have seen above, Nitric Oxide is produced in endothelium and then diffuses to adjacent smooth muscle to activate soluble guanylyl cyclase that produces cGMP, and ultimately produces smooth muscle relaxation. Nitric oxide is subject to rapid inactivation reactions with haemoglobin that greatly limit its lifetime in blood, however recent studies suggest that NO formed from endothelial NO synthases is also oxidized by oxygen or plasma ceruloplasmin to form nitrite.  Nitrite transport in blood provides an endocrine (from glands) form of NO that is shuttled from the lungs to the periphery while limiting the exposure of authentic NO to the scavenging red cell environment. Then during the rapid haemoglobin deoxygenation from artery to vein, the nitrite is reduced back to NO. Such a cycle conserves NO in the one-electron oxidation state. In this model, the nitrite pool represents the “live payload,” only one electron away from NO.”

If the body then generates enough Nitric Oxide, is there a requirement for additional dietary intake of nitrate or nitrite? “It has been suggested that the nitrate-nitrite-NO pathway serves as a backup system to ensure sufficient NO generation under hypoxic conditions when NOS may be malfunctioning.” (Ghasemi, 2011)

“It has been shown that 3-day dietary supplementation with sodium nitrate (0.1 mmol/kg/day) could reduce significantly diastolic blood pressure in non-smoking healthy volunteers. Recently, a large cohort study of 52,693 patients from 14 countries with acute coronary syndrome, of whom 20% were on chronic nitrate, demonstrated that chronic nitrate therapy (medication routinely taken at home and started at least 7 days prior to index event) was associated with reduced severity of myocardial injury in response to acute coronary events. The result showed that the proportion of these subjects with ST-segment elevation myocardial infarction was 41% in nitrate-naïve patients compared to only 18% in nitrate users and conversely a higher percent of nitrate users (82%) presented with non-ST-segment elevation acute coronary syndrome compared to 59% in nitrate-naïve patients.” (Ghasemi, 2011)

“Increasing nitrate or nitrate dietary intake provides significant cardioprotection against ischemia-reperfusion (I/R) injury in mice and it has been proposed that nitrite-/nitrate-rich foods may provide protection against cardiovascular conditions characterized by ischemia. It has been suggested that the nitrate-nitrite-NO pathway serves as a backup system to ensure sufficient NO generation under hypoxic conditions when NOS may be malfunctioning.” (Ghasemi, 2011)

“Abundant consumption of fruits and vegetables, especially green leafy vegetables, is associated with lower risk of cardiovascular disease. It has been proposed that inorganic nitrate, which is found in vegetables with a high concentrations, i.e. >2000-3000 mg/nitrate/kg, is the major factor in contributing to the positive health effects of vegetables via bioconversion to nitrite, NO, and nitroso-compounds, NOx intake now being considered as a dietary parameter for assessing cardiovascular risk.” (Ghasemi, 2011)

“Any intervention that increases blood and tissue concentration of nitrite may provide cardioprotection against I/R injury because it serves as a NOS-independent source of NO and reacts with thiols to form S-nitrosothiols. Nitrate-nitrite-NO pathway can be boosted by exogenous administration of nitrate or nitrite and this may have important therapeutic as well as nutritional implications. However, additional studies are required to clarify the protective roles of nitrate, considering the medical status of subjects, concomitant use of inhibitors of endogenous nitrosation (e.g. vitamin C and E), or foods containing high levels of nitrosatable precursors (e.g. fish). Some individuals, including those with high blood pressure and atherosclerosis, may benefit from increased nitrate while those with oesophagal dysplasia should avoid foods with high concentration of nitrate.” (Ghasemi, 2011)

The value of nitrite in the human body, however, goes far beyond only a reservoir of Nitric Oxide. We have eluded time and time again to many of the benefits and we now drill down on some of the different benefits or tahre, its role in resolving some of the negative lifestyle diseases prevalent in our modern era. “Nitrite-induced transnitrosylation in organs might be an alternative in vivo nitrite signalling for the mammalian biology including protection of protein thiols from irreversible oxidation, transcriptional modulation, and posttranslational regulation of most classes of proteins present in all cells, and also that changes in plasma nitrite levels even within the physiological ranges (e.g., postprandial and fasting) can affect tissue levels of S-nitrosothiol and subsequent cellular biology.” (Kobayashi, 2015)

-> Protective Effects of Dietary Nitrate/Nitrite on Lifestyle-Related Diseases

Kobayashi (2015) reviewed nitrites’ protective effect on lifestyle-related diseases. They write: “Lifestyle-related disease is a chronic disease characterized by oxidative and proinflammatory state with reduced NO bioavailability. The cellular redox balance in these patients shifts toward a more oxidizing state which affects a number of protein functions at the transcriptional and posttranslational levels, consequently disrupting the cellular homeostasis. However, increased NO bioavailability can improve the intracellular redox environment by S-nitrosylation-mediated modulation of most classes of proteins present in all cells. Recently, accumulating evidence has suggested that dietary nitrate/nitrite improves the features of lifestyle-related diseases by enhancing NO availability, and thus provides potential options for prevention and therapy for these patients. Based on the recent evidence, the beneficial effects of a diet rich in these components are discussed below, focusing on insulin resistance, hypertension, cardiac ischemia/reperfusion injury, chronic obstructive pulmonary disease (COPD), cancer, and osteoporosis.”

Insulin Resistance

“The insulin receptor shares a signalling pathway with the activation of endothelial NOS (eNOS) to regulate the postprandial blood flow and efficient nutrient disposition to peripheral tissues. Therefore, insulin resistance is always associated with impaired NO availability, suggesting that a reciprocal relationship exists between insulin activation and endothelial function. Insulin resistance is improved by NO at various levels including insulin secretion, mitochondrial function, modulation of inflammation, insulin signalling and glucose uptake. For example, insulin-stimulated NO production has physiological consequences resulting in capillary recruitment and increased blood flow in skeletal muscle, leading to efficient glucose disposal.” (Kobayashi, 2015)

However, the most important mechanism to improve insulin resistance might be at the post-receptor level of insulin signalling. In diabetic states, increased adiposity releases free fatty acids and produces excessive reactive oxygen species (ROS) through a toll-like receptor 4 (TLR4)-mediated mechanism, which activates a number of kinases and phosphatases, and then disrupts the balance of protein phosphorylation/dephosphorylation associated with insulin signalling. The mechanisms underlying the NO-mediated beneficial effects on insulin resistance are as follows: First, NO suppresses the TLR4-mediated inflammation and ROS production by inactivating IkB kinase-β/nuclear factor-κB (IκκB/NF-κβ), the main trigger for the induction of a number of proinflammatory cytokines. Second, Wang et al., indicated that NO mediates the S-nitrosylation of protein-tyrosine phosphatase 1B (PTPB1) and enhances the effects of insulin. Because PTPB1 dephosphorylates the insulin receptor and its substrates, attenuating the insulin effect, its phosphatase activity tends to be suppressed by eNOS-mediated S-nitrosylation. In contrast, when the vascular eNOS activity is impaired, PTPB1 suppresses the downstream signalling to PI3K/Akt, leading to insulin resistance. Therefore, NO might act as a key regulatory mediator for the downstream signalling linking glucose transporter 4 (GLUT4) translocation and glucose uptake. Third, Jiang recently reported that NO-dependent nitrosylation of GLUT4 facilitates GLUT4 translocation to the membrane for glucose uptake, and improves insulin resistance. Fourth, excess nutrients also overproduce superoxide in the mitochondrial respiratory chain, leading to the subsequent formation of ROS. NO can inhibit mitochondrial ROS production through the S-nitrosylation of mitochondrial respiratory chain complex 1 enzyme and by improving the efficiency of oxidative phosphorylation in the mitochondria.” (Kobayashi, 2015)

“Indeed, the therapeutic potential of dietary nitrate/nitrite has been supported by recent studies demonstrating the improvements of insulin resistance in humans and animals as a result of its enhancing the NO availability in plasma and tissues. As mentioned above, insulin resistance always accompanies metabolic and endothelial dysfunction, which leads to hypertension and atherosclerosis. Enhancement of the availability of NO might therefore be a promising strategy for the prevention and treatment of patients with not only insulin resistance but also endothelial dysfunction.” (Kobayashi, 2015)

-> Cardiac Ischemia/Reperfusion Injury

“During heart ischemia, ATP is progressively depleted in cardiac muscle cells, which impairs ion pumps, leads to the accumulation of calcium ions, and consequently damages the cell membrane stability. On reperfusion, the cardiac muscle cells are further injured, because in the mitochondria, ROS are produced in large quantities due to massive electron leaks and the formation of superoxide with the resupplied oxygen, which denatures cytosolic enzymes and destroys cell membranes by lipid peroxidation. ROS-mediated dysfunction of the sarcoplasmic reticulum also induces massive intracellular calcium overload, leading to the opening of the mitochondrial permeability transition pore and causing cell apoptosis or necrosis, depending on the intracellular ATP levels. The availability of vascular NO would thus be expected to be impaired due to the reduced NOS activity in ischemia and subsequent consumption by superoxide during reperfusion, resulting in severe ischemia/reperfusion injury.” (Kobayashi, 2015)

“Nitrite, nitrate, and NO-related compounds (e.g., S-nitrosothiols) are constitutively present in blood and tissues. The nitrite level in cardiac tissue is a couple of times higher than that in plasma due to an unknown form of active transport from blood to tissues or due to the oxidation of endogenously generated-NO to nitrite by ceruloplasmin, and serves as a significant extravascular pool for NO during tissue hypoxia. Carlström et al., showed that dietary nitrate increased the tissue levels of nitrite and S-nitrosothiols in the heart, and attenuated oxidative stress and prevented cardiac injury in Sprague-Dawley rats subjected to unilateral nephrectomy and a high-salt diet. Shiva et al., recently showed that the nitrite stored in the heart and liver via systemic and oral routes augmented the tolerance to ischemia/reperfusion injury in the mouse heart and liver.” (Kobayashi, 2015)

“Although the genetic overexpression of eNOS in mice attenuates myocardial infarction, in general, the protective effects of NO on cardiac ischemia/reperfusion injury depend on the local stock of nitrite and its subsequent reduction to NO at the critical moment when NOS activity is lacking under hypoxic conditions. Indeed, the tissue levels of S-nitrosothiols (NO-mediated signalling molecules) are enhanced through the nitrite reduction due to NOS inhibition, hypoxia, and acidosis, suggesting that the tissue nitrite stores can be regarded as a backup and on-demand NO donor. There are a number of factors that have been demonstrated to reduce nitrite in the tissues, including deoxyhemoglobin, deoxymyoglobin, xanthine oxidoreductase, heme-based enzymes in the mitochondria and acidosis during ischemia. In patients with coronary heart disease, the different consequences of myocardial infarction may depend on the patient’s daily intake of nitrate/nitrite. Indeed, Bryan et al., showed that dietary nitrite (50 mg/L) or nitrate (1 g/L) supplementation in drinking water for seven days maintained higher steady-state levels of nitrite and nitroso compounds, as well as nitrosyl-heme, in mouse cardiac muscle, and these mice exhibited a smaller cardiac infarct size after ischemia/reperfusion injury compared with control mice fed a diet deficient in nitrate/nitrite for seven days. These findings suggest that this protective nitrate/nitrite may be derived at least in part from dietary sources.” (Kobayashi, 2015)

“Shiva et al., demonstrated that the cytoprotective effects of nitrite on ischemia/reperfusion injury are mediated by post-translational S-nitrosylation of complex 1 in the mitochondrial respiratory chain, which consequently inhibits the overall mitochondrial ROS formation and apoptotic events. Another possible cytoprotective effect of nitrite may be mediated by the effects of S-nitrosylation on the intracellular Ca2+ handling, which decreases Ca2+ entry by inhibiting L-type Ca2+ channels and increasing the sarcoendoplasmic reticulum (SR) Ca2+ uptake by activating SR Ca2+ transport ATPase (SERCA2a) [102]. These effects will lead to an attenuation of the increase in cytosolic Ca2+ during ischemia and Ca2+ overload during reperfusion.” (Kobayashi, 2015)

“Intriguingly, recent large-scale epidemiological studies reported the preventive effects of antioxidant supplementations including vitamins E, C, and beta carotene rich in fruits and vegetables on cardiovascular disease, whereas no beneficial effects were shown in other studies, and in some cases, a decrease in cardiovascular protection with these supplementations was observed. On the other hand, a number of epidemiological studies have shown the preventive effects of fruits and vegetables on coronary heart disease. It should be noted that the consumption of an appropriate amount of fruits and vegetables, which might contain balanced doses of nitrate/nitrite and vitamins, might be more effective with regard to health maintenance and improvement than antioxidant supplementation alone.” (Kobayashi, 2015) It is this finding in particular that gives direction to my work with two collaborators Richard Bosman and Dr Jess Goble. Whether we will succeed in our quest, time will tell but we have some impressive early breakthoughs and with solid support of scientists, industry professionals and inventors of new technology which has the potential to unluck the application of these fruits and vegetables to meat, we are hopeful and extremely motivated!

-> Chronic Obstructive Pulmonary Disease (COPD)

“COPD is considered to be a lifestyle-related disease because long-term tobacco smoking and subsequent chronic bronchitis are causally associated with this disease. Varraso et al., recently reported the importance of a healthy diet in multi-interventional programs to prevent COPD. They showed that high intake of whole grains, polyunsaturated fatty acids, nuts, and long chain omega-3 fats, and low intake of red/processed meats, refined grains and sugar-sweetened drinks, were associated with a lower risk of COPD in both women and men.” (Kobayashi, 2015)

“Because cured meats such as bacon, sausage and ham contain high doses of nitrite for preservation, antimicrobial and colour fixation, epidemiological studies have demonstrated that the consumption of cured meats is positively linked to the risk of newly diagnosed COPD. Nitrite generates reactive nitrogen species, which may cause nitrosative damage to the lungs, eventually leading to structural changes like emphysema. This is supported by an animal study in which rats chronically exposed to 2000 and 3000 mg/L of sodium nitrite in their drinking water for two years showed distinct lung emphysema. However, the dose of nitrite used in that study was 250–350 mg/kg/day, which was too high to compare with those achieved in standard human diets.

In fact, cured meats have been reported to generally comprise only 4.8% of the daily nitrite intake, and 93% of the total ingestion of nitrite is derived from saliva, suggesting that cured meats provide minimal contributions to the human intake of nitrite, even if they are frequently consumed. In addition, the recent nitrite levels in processed meats have been approximately 80% lower than those in the mid-1970s in the US. Therefore, discussions encompassing all ingested sources of nitrite should consider whether or not the nitrite derived only from the consumption of cured meats might be responsible for the development of COPD.” (Kobayashi, 2015)

“On the other hand, a number of epidemiological studies have shown the beneficial effects of n-3 fatty acids, vitamins, fruits and vegetables on lung functions and the risk of COPD. Although it may be difficult to isolate the specific effects of these dietary nutrients, as discussed above, the nitrate and nitrite derived from vegetables and fruits are reduced to NO, which is followed by the formation of S-nitrosothiols, rather than the formation of nitrosamines especially in the presence of reducing agents such as vitamin C and E in the stomach. It has been shown that high dietary nitrate intake does not cause the expected elevation of the gastric nitrite concentrations or appreciable changes in the serum nitrite concentrations.” (Kobayashi, 2015) As I stated previously, these findings do not cause the industry to sit back and proclaim, “you see, consumption of cured meat is safe” even though the validation is encouraging – in the case of me and my collaborators it energises us to do even better and work to turn cured meat into a superfood.

“As mentioned above, different from the effects of the direct elevation of nitrite concentration in the plasma, the entero-salivary route of dietary nitrate/nitrite might enhance the availability of NO through the formation of S-nitrosothiols and its transnitrosylation to the other thiol residues of proteins, suggesting that, depending on the tissues and organs, separate metabolic pathways might exist for NO availability in this entero-salivary route. Consistent with this idea, Larsen et al., recently demonstrated that acute intravenous infusion of nitrite enhanced the plasma levels of nitrite, whereas it did not affect the oxygen consumption (VO2) or the resting metabolic rate (RMR) in humans. Instead, dietary nitrate significantly reduced the VO2 and RMR by improving the mitochondrial respiratory chain function and enhancing efficient O2 consumption, suggesting that rather than direct nitrite infusion to enhance the plasma nitrite levels, biologically active nitrogen oxide (including the S-nitrosothiols produced in the stomach) might be an important molecule for the transfer of biological NO activity for cardiopulmonary function [126]. Because COPD is a state of protein-energy malnutrition due to an increased resting metabolic rate and VO2, the effects of dietary nitrate on the reduction of the RMR and VO2 might be advantageous for patients with COPD.” (Kobayashi, 2015)

“Whether the role of NO in COPD is protective or pathogenic depends on the origin and concentration range of NO. NO activity derived from dietary nitrate and constitutive NOS might be protective against COPD largely through the S-nitrosothiol-mediated mechanism including inhibition of the noncholinergic nonadrenergic nerve activity, bronchial smooth muscle relaxation, reduction of airway hyperresponsiveness, downregulation of the proinflammatory activity of T lymphocytes, and antimicrobial defence. However, the deleterious effects of NO on the development of COPD might be derived from iNOS-mediated pro-inflammatory signalling, which is consequently (not causally) reflected by the huge amount of NO in the exhaled air of patients with COPD.” (Kobayashi, 2015)

“Recent human studies have demonstrated that dietary nitrate (beetroot juice containing approximately 200–400 mg of nitrate) improved the exercise performance and reduced blood pressure in COPD patients. However, large-scale epidemiological evidence of the impact of nitrate is still lacking.” (Kobayashi, 2015)

-> Lowering Blood Pressure

An obvious benefit of nitrite is its role as a reservoir of Nitric Oxide which is a key molecule which blood pressure. The blood pressure-lowering and performance-enhancing effects of nitrites have been known for many years. (Keller, 2017) This is due to the fact that the nitrite anion (NO–2) acts as an endogenous nitric oxide source. (Keszler, 2008) Nitrite is reduced to nitric oxide (NO). “One major mechanism of nitrite reduction is the direct reaction between this anion and the ferrous heme group of deoxygenated haemoglobin.” The oxidation reaction of nitrite with oxyhemoglobin (oxyHb) which is formed by the combination of haemoglobin with oxygen, is also well established and generates nitrate and methemoglobin (metHb). (Keszler, 2008)

“Increased consumption of fruits and vegetables is associated with a reduction of the risk of cardiovascular disease. The DASH studies recommended the consumption of diets rich in vegetables and low-fat dairy products to lower blood pressure, and these effects are thought to be attributable to the high calcium, potassium, polyphenols and fiber and low sodium content in these food items. However, vegetable diets containing high nitrate levels increase the plasma levels of nitrate and nitrite, which are the physiological substrates for NO production. Accumulating evidence has recently indicated that the nitrate/nitrite content of the fruits and vegetables could contribute to their cardiovascular health benefits in animals and humans.” (Kobayashi, 2015)

“A number of publications have demonstrated that dietary nitrate reduces blood pressure in humans. Larsen et al., reported that the diastolic blood pressure in healthy volunteers was reduced by dietary sodium nitrate (at a dose of 0.1 mmol/kg body weight per day) corresponding to the amount normally found in 150 to 250 g of a nitrate-rich vegetable, such as spinach, beetroot, or lettuce. Webb et al., studied the blood pressure and flow-mediated dilation of healthy volunteers, and showed that the vasoprotective effects of dietary nitrate (a single dose of 500 mL of beetroot juice containing 45.0 ± 2.6 mmol/L nitrate), were attributable to the activity of nitrite converted from the ingested nitrate [86]. Kapil et al., also showed a similar finding that consuming 250 mL of beetroot juice (5.5 mmol nitrate) enhanced the plasma levels of nitrite and cGMP with a consequent decrease in blood pressure in healthy volunteers, indicating that there was soluble guanylate cyclase-cGMP-mediated vasodilation following a conversion of the nitrite to bioactive NO. They later presented the effects of dietary nitrate on hypertension, and showed the first evidence that daily dietary nitrate supplementation (250 mL of beetroot juice daily) for four weeks reduced the blood pressure, with improvements in the endothelial function and arterial stiffness in patients with hypertension. Because arterial vascular remodelling is the major histological finding associated with ageing, these vascular structural changes represent vascular wall fibrosis with increased collagen deposits and reduced elastin fibers, which result in arterial stiffening and subsequent hypertension in elderly patients. Sindler et al., recently demonstrated that dietary nitrite (50 mg/L in drinking water) was effective in the treatment of vascular ageing in mice, which was evidenced by a reduction of aortic pulse wave velocity and normalization of NO-mediated endothelium-dependent dilation. They showed that these improvements were mediated by reduction of oxidative stress and inflammation, which were linked to mitochondrial biogenesis and health as a result of increased dietary nitrite. These beneficial effects were also evident with dietary nitrate in their study, suggesting that dietary nitrate/nitrite may be useful for the prevention and treatment of chronic age-associated hypertension.” (Kobayashi, 2015)

“In addition, hypertension is also a major cause of ischemic heart and cardiac muscle remodelling, which lead to congestive heart failure. Bhushan et al., reported that dietary nitrite supplementation in drinking water (50 mg/L sodium nitrite, for nine weeks) increased the cardiac nitrite, nitrosothiol, and cGMP levels, which improved the left ventricular function during heart failure in mice with hypertension produced by transverse aortic constriction. They also showed that dietary nitrite improved the cardiac fibrosis associated with pressure-overloaded left ventricular hypertrophy through NO-mediated cytoprotective signalling. Although a number of studies on the acute effects of dietary nitrate have been conducted using animal models and healthy humans, more evidence in patients with hypertension, as well as additional studies on the long-term effects of dietary nitrate, will be needed in the future.” (Kobayashi, 2015)

-> Cancer

“In the stomach, swallowed nitrite is decomposed to form a variety of nitrogen compounds, including N-nitrosoamines. In the 1950s, Magree et al., first reported that N-nitrosodimethylamine caused malignant primary hepatic tumours in rats. After this report, a number of studies followed in relation to the carcinogenic effects of N-nitroso compounds in animal models. In particular, the dietary intake of red and cured meats was found to be associated with an increased risk of certain types of cancer due to the relatively large amounts of nitrite added. However, the methodological aspects have been challenged concerning the high dose of nitrosatable amines, and the physiological difference between animals and humans.” (Kobayashi, 2015)

“In the stomach, the nitrosonium ion (NO+) derived from nitrite can bind to thiol compounds (R-SH) and amines (especially secondary amines: R1-NH-R2), forming S-nitrosothiol and N-nitrosamine, respectively. However, while N-nitrosamine formation occurs even at neutral or basic pH, S-nitrosothiol formation tends to occur only under acidic conditions. In addition, this reaction kinetically occurs much more easily than N-nitrosamine formation, particularly in the presence of vitamins C and E and polyphenols, which are highly present in fruits and vegetables, which also eliminate potent nitrosating agents such as the N2O3 formed from nitrite by decomposing them to NO. This might partly explain why patients with achlorhydria and non-vegetarians eating large amounts of cured meats are at risk of developing gastric cancer.” (Kobayashi, 2015)

“However, this idea appears to be inconsistent with the belief that dietary nitrite is a major cause of cancer. This is because, according to the average nitrate/nitrite intake of adults in the US, most of the daily nitrate intake (around 90%) comes from vegetables, and the nitrite intake is primarily derived from recycled nitrate in the saliva (5.2–8.6 mg/day nitrite), with very little coming from cured meats (0.05–0.6 mg/day nitrite in 50g/day cured meats) and other dietary sources (0–0.7 mg/day nitrite) [136], suggesting that the entero-salivary route may be the more important source of nitrosamine exposure than exogenous intake including cured meats, that is, spitting out saliva all day long might prevent cancer development more effectively than cutting cured meats. However, recent experimental and epidemiological studies could not demonstrate a positive relationship between nitrate consumption and the risk of cancer, and the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives concluded in 2008 that there was no evidence that nitrate was carcinogenic in humans. Consistent with this, recent studies have found no link between dietary nitrate and cancer.” (Kobayashi, 2015)

“Bradbury et al., reported a large-scale study (>500,000 participants) of the associations between fruit, vegetable, or fiber consumption and the risk of cancer at 14 different sites. They showed that there was an inverse association between fruit intake and the risk of upper gastrointestinal tract and lung cancer, as well as an inverse association between fiber intake and liver cancer. The dietary intake of vegetables, as well as fruits and fiber, was inversely associated with the risk of colorectal cancer, suggesting that there is little evidence that vegetable intake is associated with the risk of any of the individual cancer sites reviewed.” (Kobayashi, 2015)

“However, chronic inflammation, including inflammatory bowel disease and Helicobacter pylori-induced gastritis induce inducible NOS (iNOS) and generate large quantities of NO, forming nitrosating and oxidant species such as N2O3 and peroxynitrite, which might cause mutagenesis through deamination, nitration of DNA, or inhibition of the DNA repair system. Depending on the sites and amounts of NO generation, NO might represent a double-edged sword in the sense that it confers both protective and deleterious effects on cancer development.” (Kobayashi, 2015)

“Meta-analyses of primary and secondary cancer prevention trials of dietary antioxidant supplements, such as beta carotene, vitamins A, C, and E, showed a lack of efficacy, and on the contrary, an increased risk of mortality. Although the general role of NO in carcinogenesis is complicated, and many unknown mechanisms remain to be resolved, the dietary nitrate/nitrite (at least that obtained from plant-based foods such as fruits and vegetables) has obvious inhibitory effects on cancer risk by playing some synergistic role with other nutrients in these foods.” (Kobayashi, 2015) It is again findings like these that give direction to our product developments.

-> Osteoporosis

“Lifestyle habits, such as smoking, alcohol intake, little or no exercise, and an inadequate amount of calcium intake all influence the calcium-vitamin D metabolism and bone mineral density, in some cases leading to osteoporosis, particularly in postmenopausal women. The implications of NOS-mediated NO in the regulation of bone cell function have been well described in a number of publications. For example, iNOS-induced NO production following stimulation with proinflammatory cytokines, such as interleukin 1 (IL-1) and tumor necrosis factor-α (TNF-α), inhibits bone resorption and formation, resulting in osteoporosis in patients with inflammatory diseases such as rheumatoid arthritis. On the other hand, eNOS, a constitutive NO synthase, plays an important role in regulating osteoblast activity and bone formation, because eNOS knockout mice exhibit osteoporosis due to defective bone formation, and eNOS gene polymorphisms were reported to be causally linked to osteoporosis in postmenopausal women.” (Kobayashi, 2015)

“In addition, Wimalawansa et al., showed that some of the beneficial effects of estrogen on bone metabolism are mediated through a NO-cGMP-mediated pathway, suggesting that NO donor therapy might provide a promising alternative to estrogen therapy. In this context, it has been shown that organic nitrate NO donors, such as glycerol trinitrate, isosorbide dinitrate and mononitrate all have beneficial effects on experimental and clinical osteoporosis, and a number of epidemiological studies also indicated that a high fruit and vegetable intake appears to have a protective effect against osteoporosis in men and pre- and postmenopausal women. However, few studies have been conducted to evaluate the detailed mechanism by which inorganic nitrate/nitrite prevents osteoporosis at the molecular level, and thus further basic research will be needed for this purpose.” (Kobayashi, 2015)

-> Methemoglobinemia (MetHb)

A negative effect of nitrite in the body relates to its link with methemoglobinemia. It is historically this link which contributed to cast nitrite in a negative light and day plays a dominant role in establishing what the WHO regards as safe levels of ingested nitrites.

“Methemoglobinemia (MetHb) is a blood disorder which the US National Institute of Health defines as occurring when “an abnormal amount of methemoglobin is produced.” They explain that “hemoglobin is the protein in red blood cells (RBCs) that carries and distributes oxygen to the body. Methemoglobin is a form of hemoglobin. Inherited (congenital) methemoglobin occurs when the disorder “is passed down through families.” Our interest is in what is referred to as acquired MetHb which is “more common than inherited forms and occurs in some people after they are exposed to certain chemicals and medicines.” One such chemical is nitrites. (National Libary of medecine) “Elevated levels of nitrite in the blood can trigger the oxidation of hemoglobin, leading to methemoglobinemia.” Keszler (2008) suggests a simplified model of the kinetics involved where the end products of the reaction are methemoglobin (metHb) and nitrate.

The “World Health Organization (WHO) used data based on the risk of methemoglobinemia to set an accept­able daily intake (ADI) for nitrate of 3.7 mg/kg body weight per day, equivalent to 222 mg nitrate per day for a 60-kg adult, and nitrite of 0.07 mg/kg body weight per day, equi­valent to 4.2 mg nitrite per day for a 60-kg adult. (Keller, 2017)

The upper limit represented by the WHO ADI corresponds to the concentration of dietary nitrate that lowers blood pressure in normotensive and hypertensive adults. (Keller, 2017)

Very high concentrations of nitrate in drinking water may cause methemoglobinemia, particularly in infants (blue baby syndrome). “In the 1940s, Comly first reported cases of cyanotic infants who received formula prepared with well water containing a high nitrate content. Based on the subsequent analyses of the infantile cases of methemoglobinemia, the US Environmental Protection Agency (EPA) set a Maximum Contaminant Level (MCL) for nitrate of 44 mg/L (equal to 10 mg/L nitrogen in nitrate). However, it is now thought that methemoglobinemia per se was not caused by nitrate itself, but by faecal bacteria that infected infants and produced NO in their gut. A recent report by Avery has argued that it is unlikely that nitrate causes methemoglobinemia without bacterial contamination, and also that the 40–50 mg/L limit on nitrate in drinking water is not necessary.” (Kobayashi, 2015)

However, there are now legal limits to the concentrations of nitrate and nitrite in both food and drinking water. The WHO showed that the Acceptable Daily Intake for humans (ADI) for nitrate and nitrite were 3.7 and 0.07 mg/kg body weight/day, respectively, which were based on the calculations from the doses of <500 mg of sodium nitrate/kg body weight that were harmless to rats and dogs. The international estimates of nitrate intake from food are 31–185 mg/day in Europe and 40–100 mg/day in the United States. However, the Ministry of Health, Labour and Welfare of Japan reported that the average intake of nitrate in the Japanese population is around 200–300 mg/day, which is one and a half times to two times the ADI. Furthermore, according to a report by Hord, in which the daily nitrate and nitrite intakes were calculated based on the variations using the vegetable and fruit components of the DASH (Dietary Approaches to Stop Hypertension) dietary pattern, the level easily exceeds 1,200 mg/day nitrate. This is more than five-fold higher than the WHO’s ADI of 3.7 mg nitrate/kg body weight/day, and more than two-fold the US Environmental Protection Agency’s level of 7.0 mg nitrate/kg body weight/day for a 60 kg individual. Furthermore, as indicated in Figure 2, approximately 25% of the ingested nitrate is secreted in saliva, and 20% of the secreted nitrate in the saliva is converted to nitrite by commensal bacteria on the tongue, indicating that about 5% of the originally ingested nitrate is swallowed into the stomach. Therefore, for a DASH diet containing 1200 mg nitrate, an individual would be expected to swallow approximately 45 mg of nitrite a day, which easily exceeds the ADI of nitrite. Therefore, a comprehensive reevaluation of the health effects of dietary sources of nitrate/nitrite might be required in the near future.” (Kobayashi, 2015)

– Other International Views on Nitrite/ Nitrate from Dietary Sources besides from the USA and Europe

The Food Standards Australia New Zealand and the European Food Safety Authority concluded that the major sources of estimated nitrate and nitrite exposure, across different population groups, were vegetables and fruits (including juices). Processed meats only accounted for 10% of total dietary exposure to nitrite in the European survey. Consumption and exposure to dietary nitrate and nitrite is not considered an ‘‘appreciable health and safety risk’’, according to the Australian agency. (Keller, 2017)

Given the established vasoprotective, performance-enhancing, blood pressure lowering effects of dietary nitrates in humans, specific recommendations to encourage plant-based, nitrate-rich foods may produce significant public health benefits. (Keller, 2017)

Is vitamin C and E the crucial link that saves bacon’s bacon?

Three important nitrosamines, namely N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and N-nitrosomorpholine (NMOR), are classified as probably carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer (IARC) (IARC 2000). (Erkekoglu, 2010)

Intrinsic antioxidant systems, such as protective enzymatic antioxidants as well as antioxidants available in the human diet, provide an extensive array of protection that counteract potentially injurious oxidizing agents. (Erkekoglu, 2010)

It was found that antioxidants protected the cells against nitrite and nitrosamines. (Erkekoglu, 2010) Dietary antioxidants can be a saviour when exposure to dietary genotoxic/carcinogenic compounds is the case. (Erkekoglu, 2010)

Erkekoglu, 2010 confirmed the DNA damaging effect of nitrosamines as shown in other studies (Robichová et al. 2004b; Arranz et al. 2006; 2007; Garcia et al. 2008a; b). Additionally, they used sodium nitrite to show the genotoxic effects of nitrite alone. They showed that antioxidants supplementation was capable of reducing both tail intensity and tail moment in all of the nitrosamine treatments, particularly in NDMA. They proposed that this may be related to antioxidants’ reduction of CYP2E1 and CYP2A6. They write, “CYP2E1 is responsible for α-hydroxylation of N-alkylnitrosamines with short alkyl chain, whereas cyclic nitrosamines like NPYR, NPIP, and NMOR may be activated by CYP2A6 and by CYP2E1 to a lesser extent (Kamataki et al. 2002). Furthermore, inhibition of CYP450 enzymes may not be the only mechanism underlying the protection of antioxidants. Alternative mechanisms by antioxidants may be as follows: ROS scavenging capacity, the conversion of reactive compounds to less toxic and easily excreted compounds, alteration of cell proliferation, stimulation of DNA-repair induced by nitrosamines, induction of Phase II enzymes, and NAD(P): quinine oxidoreductase activity (Roomi et al. 1998; Chaudière and Ferrari-Iliou 1999; Gamet-Payrastre et al. 2000; Surh et al. 2001; Surh 2002).” (Erkekoglu, 2010)

Conclusion

It is obvious that the overwhelming weight of evidence is that nitrite is not the destructive chemical that it was made out to be and that the negative media frenzy is completely misguided, to put it mildly. The health benefits of nitrate, nitrite and nitric oxide are clear. An obvious path for improving the geneneral healt and nutritional status associated with cured meats is the incorporation of vegetable and plant matter into its formulation. The fact that nitrire-free curing may possibly never be achieved has been raised and warrants further investigation. The next two segments will focus on N-nitrosamines and why the protein myaglobin evolved in such a way that it wants to react with oxygen and nitric oxide.

Want to Know More?

Gladwin, M. T., Kim-Sharipo, D. B.. (2008) The functional nitrite reductase activity of the heme-globins. Review in Translation Hematology, October 1, 2008. Blood (2008) 112 (7): 2636–2647. https://doi.org/10.1182/blood-2008-01-115261

Moncada, Salvador and Higgs, Annie. 1993. The L-Arginine-Nitric Oxide Pathway. New England Journal of Medicine doi: 10.1056/NEJM199312303292706 DO – 10.1056/NEJM199312303292706. Massachusetts Medical Society, https://doi.org/10.1056/NEJM199312303292706

Reference

Erkekoglu P, Baydar T. Evaluation of the protective effect of ascorbic acid on nitrite- and nitrosamine-induced cytotoxicity and genotoxicity in human hepatoma line. Toxicol Mech Methods. 2010 Feb;20(2):45-52. doi: 10.3109/15376510903583711. PMID: 20100056.

Ghasemi A, Zahediasl S. Is nitric oxide a hormone? Iran Biomed J. 2011;15(3):59-65. PMID: 21987110; PMCID: PMC3639748.

Gladwin, M. T. and Kim-Shapiro, D. B.. (2008) The functional nitrite reductase activity of the heme-globins. ASH Publication, Blood. Review in Translational Hematology. Blood (2008) 112 (7): 2636–2647. https://doi.org/10.1182/blood-2008-01-115261

Hlinský, Tomáš, Michal Kumstát, and Petr Vajda. 2020. “Effects of Dietary Nitrates on Time Trial Performance in Athletes with Different Training Status: Systematic Review” Nutrients 12, no. 9: 2734. https://doi.org/10.3390/nu12092734

Hord, N.G.; Tang, Y.; Bryan, N.S. Food sources of nitrates and nitrites: The physiologic context for potential health benefits. Am. J. Clin. Nutr. 2009, 90, 1–10.

Huizing M, Hackbarth ME, Adams DR, Wasserstein M, Patterson MC, Walkley SU, Gahl WA; FSASD Consortium. Free sialic acid storage disorder: Progress and promise. Neurosci Lett. 2021 Jun 11;755:135896. doi: 10.1016/j.neulet.2021.135896. Epub 2021 Apr 20. PMID: 33862140; PMCID: PMC8175077.

Keller, Rosa M. BS; Beaver, Laura PhD, MS; Prater, M. Catherine; Hord, Norman G. PhD, MPH, RD. Dietary Nitrate and Nitrite Concentrations in Food Patterns and Dietary Supplements. Nutrition Today: 9/10 2020 – Volume 55 – Issue 5 – p 218-226, doi: 10.1097/NT.0000000000000253

Keszler A, Piknova B, Schechter AN, Hogg N. The reaction between nitrite and oxyhemoglobin: a mechanistic study. J Biol Chem. 2008 Apr 11;283(15):9615-22. doi: 10.1074/jbc.M705630200. Epub 2008 Jan 17. PMID: 18203719; PMCID: PMC2442280.

Kobayashi, J. (2015) NO-Rich Diet for Lifestyle-Related Diseases, Article in Nutrients, June 2015, DOI: 10.3390/nu7064911

Kröncke KD, Fehsel K, Kolb-Bachofen V. Inducible nitric oxide synthase in human diseases. Clin Exp Immunol. 1998 Aug;113(2):147-56. doi: 10.1046/j.1365-2249.1998.00648.x. PMID: 9717962; PMCID: PMC1905037.

Lundberg JO. Nitrate transport in salivary glands with implications for NO homeostasis. Proc Natl Acad Sci U S A. 2012 Aug 14;109(33):13144-5. doi: 10.1073/pnas.1210412109. Epub 2012 Jul 31. PMID: 22851765; PMCID: PMC3421160.

Rassaf T, Ferdinandy P, Schulz R. Nitrite in organ protection. Br J Pharmacol. 2014 Jan;171(1):1-11. doi: 10.1111/bph.12291. PMID: 23826831; PMCID: PMC3874691.

Sindelar, J.J.; Milkowski, A.L. Human safety controversies surrounding nitrate and nitrite in the diet. Nitric Oxide 2012, 26, 259–266.

Vanek T, Kohli A. Biochemistry, Myoglobin. [Updated 2022 Jul 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK544256/

Zhou L, Zhu DY. Neuronal nitric oxide synthase: structure, subcellular localization, regulation, and clinical implications. Nitric Oxide. 2009 Jun;20(4):223-30. doi: 10.1016/j.niox.2009.03.001. Epub 2009 Mar 17. PMID: 19298861.

Chapter 13.04: Finally – nitrate, nitrite, nitric oxide as valuable molecules and the triumph of nature over foolish strawman positions

Introduction to Bacon & the Art of Living

The story of bacon is set in the late 1800s and early 1900s when most of the important developments in bacon took place. The plotline takes place in the 2000s with each character referring to a real person and actual events. The theme is a kind of “steampunk” where modern mannerisms, speech, clothes and practices are superimposed on a historical setting.  Modern people interact with old historical figures with all the historical and cultural bias that goes with this.


Finally

October 1960

Bacon & the Art of Living

When I say that it was my study of bacon that taught me the essence of the art of living, the reality is that in the first place it taught me to accept who I am in life. As important as my hopes and aspirations are, I am not my ideals and dreams. I am not the most current fad of the ever-changing mental world we live in. I am in the first place the physical being who lives in a physical world, connected to the bountiful earth that brought me forth. Despite the fact that I am in my mental world the centre of the universe, I am not! Life is not the life I live in my brain minus the physical world. It is all one thing and my mental world is only my perception of the real world I live in. In reality, I am nature!

I am Nature

My brain is a very complex physical event and my consciousness, as I define it with my human mind is here today and gone tomorrow. My thoughts, my thinking, is predicated upon my memory and indoctrination (learned information and past experiences). What is fundamental and what bacon taught me is that my connection with the earth itself is not primarily through my brain. The billions upon billions of atoms that form the molecules and the amino acids and bacteria and proteins and synapsis and organs that make up my body by its most basic essence is my connection to nature. My essential nature is my oneness with the universe and the universe is nature. Bacon curing is not a study of any food in that it mimics natural physiological processes essential for life. Nitrogen plays an essential role in it irrespective of the current thinking on the benefits or dangers of its consumption.

My initial resistance against eating bacon was initially not restricted to the question of nitrites. I had to work out for myself if I am comfortable eating other animals. Like the question about nitrogen, the fact that I eat other animals is a fact of my existence as a human being whether it is fashionable to do so or not. We only perceive this as a moral dilemma because we have departed our natural environment and so we think that in the plant kingdom the same predatory behaviour does not exist. If we see all living organisms as essentially the same, we will understand that to arbitrarily choose to eat one group and not another is non-sensical.

The Zambian Revelation

During my second trip to Zambia, I’ve spent days in the forests in the north of the country close to the Kongolese border with a remarkable man, Richard Horton. He looks at the trees and plants and knows every one of them by name. Which one is related to which. The basic characteristic of each individual fruit and flower. The locals call him “Capenta Mabullo,” meaning “The Man who Counts Leaves.” It was through the eyes of Richard and walking the forests of Zambia that I discovered that in the plant kingdom we find the same struggle for life and death as we find in the animal kingdom and the same predatory behaviour of many plant species. Walking with him through the woods becomes the same experience as seeing a lion hunt in the Kruger National Park or crocodiles hunting wildebeest in the great migrations on the Serengeti plains of Kenia.

It is here that I learned that to think that plants are different from mammals or other animals is a view based on our removal from the forests of our youth. Humanity lost its perspective on our essential nature. In the first place, the plants and trees of the forest are just as much alive with struggles and pleasures as the world of animals and insects. Both are living. Both have intellect – yes, not as we would define it in our human-centric worldviews of intellect. Choosing one over the other – to assign intellect and emotions as we understand it arbitrarily to the one group and not the other is supreme foolishness. In the Zambian forests, I have seen plants behaving like animals. They strive and compete; they weep and reach out in joy.

Evaluating the effect of the human intellect on the natural world, I am at a loss to see the benefit of our version of intellect and I fear that if we don’t come to our senses, our time as a species is short and nature will remove the element poised to destroy its world from the universe. Then, again, saying that we evolved intellect for a particular reason beyond simply survival is an assumption I can not make. That our intellect is not superior to that of plants and animals and insects and microbes is clear when we evaluate the effect our intelligence have on the natural world. The most we can say, it seems to me, is that our intellect is different in degree and an effective means to dominate. It manifests in a different way but I fail to see its superiority in quality or the result of its “differentness.” So, at least, it seems to me. Superseding everything is nature and it is nature that dictates that we eat in order to live and as a food source, nature feeds itself from all it brings forth, including humans as part of the world of animals.

I Consume and Will be Consumed – the Same Eternal Sycle for All

Before I could engage the issue of nitrites in meat I had to come to grips with the fact that no matter what I assign to animals and plants – the fact is that I consume both natural “forms” just as I will be consumed by them one day is the natural cycle of everything. The micro-world and insects will feast on my body one day long with plants. The possibility still exists that my initial end may be brought about by an animal if I continue to venture into forests. This does not make the animals or trees or microorganisms or insects immoral. It is life. Nature does not care about my view of morality. Nor yours!

When I transfer my view of emotion, righteousness or morality to non-human living beings (plants, animals, insects, microorganisms), it is supreme foolishness. These are mental constructs that operate solely in the mind-space of humans and within the ambit of human culture. It is natural in the sense that it is from nature (being our natural brains), but what we think and dream up is not a result of nature and is not inherently “natural.” It does not represent nature automatically.

One of the best recent developments in our mental world is the fact that we start to value the animals and plants who share the world with us. Abusing and mistreating them becomes cruel and unnatural. Inflicting suffering on nature for the sake of our own comfort is the most unnatural thing we can do and recognising this is a sign of a maturing understanding. Mistreating our food source becomes physical harm we do to them and mental harm we do to ourselves! However, to assign more to them than what nature intends is unnatural. I consume living beings that I share this world with. It took me years to understand this and it came to me through the understanding of the curing of bacon. I struggled with the fact that I am making my living through the death of other animals. The first lesson I had to learn was that it is unnatural to try and be more natural than nature itself.

The Basic Problem – Our Evolving Culture

As human populations increased and our culture developed we changed our natural habitat. We urbanised and had to design our own food sources. Humans incorporated the preparation of food into our culture and changed it for the sake of distributing it to the cities and towns we started living in. Food, in its most natural form, is best suited for our bodies as this is how we initially evolved. In so doing we did not always understand the implications of what we were doing. One of the most important lessons we had to learn, not just related to additives but also food sources themselves, like red meat, was the issue of “how much.” Including many additives at the wrong inclusion ratio becomes unhealthy and even poisonous. Red meat, for example, must be consumed in moderation. Too much will have serious health consequences. Not just ingredients and types of foods must be carefully considered, but also methods of preparations. Science is invaluable in a continual investigation into these matters so that we can improve our health.

A curious position emerged in particular related to the use of nitrites in foods. Despite the fact that nitrogen is an inherent constituent of animal and plant proteins and despite the essential role it plays in human physiology, there exist among parts of our population a perception that nitrite is one of the key villains in modern food. This group of our population further see the presence of nitrite restricted to cured meat and bacon in particular.

The advice from the WHO that intake of cured meat must be limited as is the case with red meat, alcohol, fatty food, refined carbohydrates and sugars, in particular, is something that every food scientist will agree with. In general, humans per capita consume more food than ever with the accompanying diseases of obesity and the impact on our general health. For some reason, the perception still exists that bacon or possibly cured meat should be singled out. Some go as far as to equate the consumption of these products with cigarette smoking.

Understanding why this is the case and dealing with this issue brought me to the greatest realisation about life namely the value of using nature itself as our guiding principle in the design of our food and our lives. Right at the outset then I can reveal that the greatest lesson I learned from bacon over many years is that if we want to be safe, we must strive to use the ratios and proportions of various compounds naturally found in the human body and in plants. This extends much further than only food. Over the years I have taken these lessons and applied them to every area of my life including things like exercise, water intake and stress. I learned to limit my mental activity during the day by quieting my mind whenever the flurry of mental activities goes out of hand. The blueprint of nature became the essence of my goals.

How I discovered that nitrate and nitrite have key physiological functions in the body and that it is by no means a villain to be avoided at all times in foods came to me through the contemplation of and search for the original location on earth where nitrate curing of meat most probably developed into an art form. I will deal with nitrosamines and the fact that most nitrosamines are cancer-causing in animals, but before I do so, let me start by giving you the chronology of my own discovery that nitrate, nitrite and nitric oxide are three absolutely essential molecules for our existence on earth.

How I discovered the Value of Nitrate, Nitrite and Nitric Oxide to Human Health

It was my search for the original location where meat curing was turned into an art form that made me look at the use of salt in meat preservation which predates the use of nitrogen salts. The general consideration of salt led me to mummification which took me natural deposits of nitrate in the Atacama Desert in South America and the Turfan Depression in the West of China. In searching for supporting evidence of the general development of technology related to nitrates, I happened upon a very clear and effective remedy from this region which used nitrate, a cure so revolutionary that it was only finally understood by science in the 1980s which unlocked the reality of the absolutely key role of nitrate, nitrite and nitric oxide in human physiology. So, in re-capping the progression of my search for the location of the birthplace of nitrate curing of meat, I am actually telling the story of my discovery of the value of nitrite, nitrate and nitric oxide to human existence and health.

The Story at a Glance

My quest started with a consideration of salt which is older than humanity itself. My interest is in its use as a meat preservative. When did this start and how and what are its functional benefits? Most of this has been dealt with in Chapter 12.10: Meat Curing – A Review, but I left an important link out in that discussion namely a realisation that studying mummies and mummification technology through the ages may be a very productive way of searching for the oldest known meat preservation technology and the use of salts at a time before writing was invented. I applied this thinking and did a survey of the oldest mummies on earth which yielded the most startling two results.

atacama-mummy-570x427.jpg

A semi-natural mummy in Chile’s Atacama Desert

The oldest mummies on earth, dating from around 7000 BCE are the Chinchorro mummies from the one place on earth that is at the same time the dryest and is replete with the highest concentration of natural sodium nitrate, the Atacama Desert from Chile and Peru!  What makes this startling is that sodium nitrate has been the curing agent of choice for meat until it was replaced after World War 1 by sodium nitrite. I always thought that the use of sodium nitrate in meat curing became popular due to the cured colour it imparts to meat and that its preserving ability was a secondary application. I also thought that its widespread use was a very recent development that reached a height in Europe at the end of the 1800s.  Following my logic about mummification technology, I was certainly not expecting a date of 7000 BCE for a probable use of sodium nitrate in meat curing.

I turned my attention to Asia from where, in an iconic review article from Binkerd and Kolari (1975), they claim that the use of nitrates in the curing of meat was first used as meat preservative “in the saline deserts of Hither Asia and in coastal areas.” They say that “desert salts contained nitrates and borax as impurities” and the discovery was accidental when they actually thought they use ordinary sea or bay salt (sodium chloride).  I wanted to examine the veracity of their claims.

What I discovered was the most startling possibility, that curing technology was developed into an art form between a particular location in China and another one in Austria. Even more than that, following the mummy trail, I managed to identify one particular geographic location which is a prime candidate for the exact location where the technology of curing was discovered, developed and spread across the rest of Asia and into Europe.  This is an amazing possibility and the fact presented by themselves are startling!

The oldest mummies in China are found in the Taklimakan Desert, in the Tarim Basin. Right here, in the region where the mummies are found, in the Turpan-Hami Basin, massive nitrate ore fields, close in proximity to the Tarim Basin exists.  Nitrate deposits, so massive that it is estimated to be at least 2.5 billion tonnes and comparable in scale to the Atacama Desert super-scale nitrate deposit in Chile.

tarim_32

A Tarim mummy

At the graves near Loulan, one of the bodies were subjected to radiocarbon dating which indicated that she died about 1200 BCE.  In the oldest cemetery so far discovered, the Small River Cemetery, mummies were discovered which carbon tests, done at Beijing University, show to be 3980 years old. This takes the known date for meat preservation, by our logic of linking it with mummification, to almost 4000 years ago in China.

The two areas in the Atacama Desert and the Taklimakan Desert in China share a striking similarity in weather. They are both some of the aridest regions on earth.  A second factor that plaid a role in the natural mummification is rapid freezing due to extreme cold conditions in the winter and then, of course, the very high sodium chloride content of the soil.

I honed in on this region in China for its geographical importance as being on the important Silk Road connecting Asia with the Middle East and Europe. I asked if there is any evidence of the development of sophisticated thinking pertaining to the use of sodium nitrate salt from this particular region.  My reasoning is that if meat curing as an art developed here, that would have been a springboard for the development of related applications.

The results of my enquiry have been nothing less than startling and leave me with little doubt that I have identified one of the exact locations on earth from where the art of curing meat developed and was spread into Europe and back into Asia.  Not that they were the only ones who would have discovered this. I am convinced the ancients in the Atacama Desert would have easily made the same link with meat preservation but it was here, in China’s Western front, on the Silk Road, where a level of sophistication in thought related to the application of sodium nitrate developed that is unrivalled, as far as I am aware off, by any other location on earth.

The first factor in favour of the Tarim Bason for the birthplace of curing technology that was spread into Europe is then the enormous natural deposits of sodium nitrate. Secondly, you have the mummies which are something that observant ancients would have noticed almost immediately. It won’t take you 4000 years to realise that something extraordinary is happening with the corpses. The third fact relates to the level of sophistication in the application of sodium nitrate.

The clue of such sophistication of thought comes to us in the discovery of an ancient medical prescription dating from some time between CE 456 and 536, during the life of the famous Daoist alchemist and physician Toa Hongjing in a cave close to the city of Dunhuang, right in our area of interest.

The text describes the treatment of a condition identified as a case of severe angina, i.e. restricted blood flow due to the narrowing of the cardiac arteries.  The treatment was to place saltpetre (potassium nitrate) under the tongue.

The basic curing pathway that alleviates the condition by the ancient prescription is a reduction of the nitrate through bacteria under the tongue to nitrite and in the tissue, transported there by the blood, the nitrite is converted to nitric oxide.  The role of nitric oxide as a vasodilator was, amazingly, only discovered in 1987 simultaneously by a group of researchers at the Wellcome Research Laboratories in Beckenham led by Professor Salvador Moncada and by a group in the USA led by Professor Louis Ignarro. So momentous was this discovery that the 1998 Nobel Prize in Physiology and Medicine was awarded for the work.  Once nitric oxide was identified as playing a role in physiological processes, it was found to be involved in many processes from inflammation to crying. So, here we have a text, detailing a medical prescription in the 5th and 6th decade of the Christan Era, from China, that has only been fully understood by modern science in 1987!  This by itself is an astounding fact!

It gets even more startling. It turns out that this exact reaction sequence of nitrate ion that is reduced to nitrite through bacterial reduction and changed to nitric oxide, along with the influence of acidity and various reductants on the speed of the process is something that is well known in meat science. Humphrey Davy, in 1812 (cited by Hermann, 1865) was the first one to note the action of nitric oxide upon haemoglobin. On 7 May 1868, Dr Arthur Gamgee from the University of Edinburgh, brother of the famous veterinarian, Professor John Gamgee (who contributed to the attempt to find ways to preserve whole carcasses during a voyage between Australia and Britain), published a groundbreaking article entitled, “On the action of nitrites on the blood.” He observed the colour change brought about by nitrite.  He wrote, “The addition of … nitrites to blood … causes the red colour to return…” Over the next 30 years, it would be discovered that it is indeed nitrites responsible for curing and not the nitrates added as saltpetre.  It was Polenski who first speculated that saltpetre is reduced to nitrite in the curing of meat in 1891 and 1901 Haldane showed that nitrite is further reduced to nitric oxide (NO).  (Fathers of Modern Meat Curing)

Meat curing has been known to follow this exact pathway since 1901. The tantalising possibility, now presents itself that the preserving nature of the salt was recognised from things like the natural mummification in this exact region in China. The salt was applied to meat in which it had an amazing preserving impact as well as, what must have been, a mysterious reddening effect. To the ancients, it probably looked as if the meat was coming to life again. The Chinese alchemists in all likelihood gravitated to this as a possible key component of the elusive elixir of immortality. Finding such an elixir was the goal of Chinese alchemy. They probably applied its preserving power to all kinds of ailments and in a process of trial and error, a treatment for angina must have been especially effective.

Such experimentation takes many centuries and if this was a known cure and part of a medical prescription by CE 400 or CE 500, it means that curing of meat must have been very advanced in terms of it being practised in this region by this time.  From here, in terms of its key position on the Silk Road, the curing technology would have spread across Asia and into Europe.

Mummification – Key to Preservation Technology

The use of salt in embalming is an obvious application of the preserving power of salt to meat. It also seems reasonable to speculate that salt for preserving meat for domestic consumption came first and the application of the technology to mummification was probably a later development. One obvious reason for this is that meat preservation for consumption would have been a daily requirement. An immediate need, for a large group of people. So, many people, over a long time would have been engaged in experiments with various salts and ingredients to determine by a simple process of observation which salts ingredients and combination of factors preserved meat best. Burying the dead and mummification, on the other hand, was a far more infrequent event, with very few people working on solving the problem resulting in a much slower development trajectory. It is far more probable that techniques for meat preservation in general use would have been applied to the preservation of human bodies after death and in the art of mummification.

If one assumes this logic, it becomes an important tool to establish a date by which food preservation with salt was done by a society. The use of salt in embalming leaves us with clear records with precise dates and exactly what was used in meat preservation. If one assumes that meat preservation for general consumption would have predated the use for embalming, we can fix precise dates by what time a society used which salts to preserve meat.

I found support for this reasoning from Valerie Wohl. She writes, “While we do not know exactly how embalming began, it is likely that methods common at the time for preserving meat, fowl or fish probably suggested a clue for early techniques. One might bleed a fish, for example, then preserve it by salting, smoking, sun drying or otherwise heating it to prevent decomposition and store it for a later time. By the time of the very earliest documentation of the process of embalming (in about 500 BCE), it had become a sophisticated technique that had been evolved over hundreds of years.” (Wohl, V.)

The Chinchorro Mummies of the Atacame Desert

This line of reasoning yielded the most surprising results imaginable. Not in my wildest imagination did I think that the oldest mummies and their preservation would be linked, not with sodium chloride, but with what has been the curing salt of choice up until at least 1905, namely sodium nitrate. I have always thought, based on research on the subject, that sodium nitrate was used for preserving meat from the 1600s and reached its height in Europe in the 1700s and 1800s before it was replaced with sodium nitrite from around 1905 and in particular after World War 1. I thought it was used in isolated places around the world where various cultures re-discovered the reddening effect it had on meat, independently and over a long time and that this slowly filtered through to Europe where it gained popularity over time until it became a general practice.  Never did I expect sodium nitrite to have been used for meat preservation since between 5000 and 7000 years BCE and not due to its reddening effect, but for its preserving properties. Let’s look at this case.

It turns out that the oldest mummies on earth are the Chinchorro mummies from the Atacama Desert in Chile and Peru, dating from as early as 7000 BCE. (Guillén, S. E.; 2005) Gypsum, a sulphate mineral, was later used with clay (3000 – 1300 BCE), but mud and clay played an important role from as early as 5000 BCE.

The fascinating link is between this region and sodium nitrate. Nowhere on earth are such large natural deposits of this salt found. The soil here is rich in sodium nitrate salt which is known as Chilean Saltpeter to distinguish it from potassium nitrate or regular saltpetre. A war was fought over these deposits and securing it was a major consideration of Germany going into World War 1. The second important factor is that the Atacama desert is the dryest place on earth. The soil is so rich in saltpetre and it is so dry that mummification occurred naturally, leaving mummies that exist since 7020 BCE.

Two of the most important ingredients in meat preservation namely heat/ drying and saltpetre were present in the mummifications rituals of the Chicharro people of the Atacama Desert since as early as at least 5000 BCE. I do not think that it is too far a stretch to assume that these people knew about the meat preserving ability by drying in combination with their special salts (sodium nitrate).  Even though it is complete conjecture, I am comfortable to say that preserving meat through sodium nitrate salt and drying was probably known since at least 5000 BCE in Chile and parts of Peru. It is then not a stretch to say that this was likely to be known in the other two main regions in the world where saltpetre is found naturally namely in China and India. This is, of course, a fascinating possibility since this particular salt became the curing agent of choice in the 1700s which gave rise to the food category of cured meats and directly resulted in our use of sodium nitrite in meat curing today. This date of between 5000 and 7000 BCE is completely in line with a date proposed by Binkerd and Kolari.

Despite this tantalising possibility, the actual sodium nitrate concentrations at the burial sites in the Atacama Desert has never been studied. The degree of mummification varies tremendously (Aufderheide, A. C.; 2003: 141) which will indicate that various factors have been present in varying degrees.

The Tarim Mummies of China

A date of between 5000 and 7000 BCE is completely in line with a date proposed by Binkerd and Kolari. According to their iconic 1975 review article about the history and use of nitrates and nitrites in the curing of meat, “it appears that meat preservation was first practised in the saline deserts of Hither Asia and in coastal areas. Desert salts contained nitrates and borax as impurities. However, the reddening effect of nitrates was not mentioned until late Roman times.” (Binkerd, E. F. and Kolari O. E.; 1975: 655)  A probable time for this discovery is however not given.

I first thought that what they were talking about was salt preservation generally, but the more I look at events in the Atacama desert, the more I wondered if the particular preserving power of sodium and potassium nitrate was not known from the earliest times and the discovery, focusing on its preserving power and not on its reddening effect on cured meat.

A further elaboration of what Binkerd and Kolari may have been talking about comes to us from a 1977 newspaper article. According to it, the suspicion is that prehistoric nomadic hunters in Western Asia began carrying salt, containing nitrate with them to preserve the hunting catch. (The Indianapolis Star;  1977) The focus was indeed on nitrate and its preserving ability and not just on salt generally. I learned that nitrate deposits occur and precipitate as an efflorescent crust in amongst other the Egyptian and Namibian deserts, the Abu Dhabi sabkhas, and deserts of the Mojave, Death Valley and of course, the Atacama Desert and the Gobi Desert.  (Warren, J. K.;  2016: 1278)

It is, however, the largest desert in China, the Taklimakan Desert of Western China that offers the biggest surprise when I find the oldest examples of natural mummification in China, right in this desert region, replete with natural nitrate deposits. The conditions are almost identical to those of the Atacama desert.

Like the Atacama desert, the Taklimakan Desert is at the same time one of the aridest regions on earth and massive nitrate ore fields exist in the Turpan-Hami Basin, close in proximity to the Tarim Basin, in the Xinjiang province, where the oldest mummies in China was found. The nitrate deposits are so substantial, that an estimated 2.5 billion tons exist, comparable in scale to the Atacama Desert super-scale nitrate deposit in Chile. (Qin, Y., et al; 2012) The mummification happened, as was the case with the mummies of the Atacama Desert between 5000 BCE and 7020 BCE,  spontaneously.

The initial discovery was made in 1939 by the Swedish archaeologist Bergman Folke. A set of tombs were discovered in the Chinese province of Xinjiang, known as the Xiaohe Tombs. For 60 years the tombs were forgotten until in 2000 a researcher, head of the Xinjiang Cultural Relics and Archaeology Institute, found the tombs again. It wasn’t until 2005 that the excavations were complete. (www.ancient-origins.net)

The size of the area is unprecedented. So far there have been 330 tombs found in multiple different layers. The tombs include adults and children as well as 15 intact mummies. About half of the tombs were looted by grave robbers. It is the first time anywhere on Earth that so many mummies have been found.  (www.ancient-origins.net)

“Several bodies have been excavated from graves near Loulan, a site that once bordered a still shrinking lake fed by the Kongi River. Among these is the body of a young female with remarkably well-preserved facial features, whose radiocarbon date indicates that she died she died about 1200 BCE.” Subsequently, more than 500 tombs have been studied.  Dr Wang Bing Hua, director of the Ürümxi’s Archeological Research Institute, attributes the spontaneous mummification to three factors:  arid climate, salty soil and shallow, winter burial. Average salt content of the desert soil near Turpan is about 10g/ L but in the very surface layer, it can be five times greater. At Hami the soil contains layers of gypsum and at Cherchen actual salt blocks are obvious within the soil, especially near the surface.  Most burials are only about a meter below the surface.  (Aufderheide, A. C.; 2003: 268, 269) In the oldest cemetery so far discovered, the Small River Cemetery, mummies were discovered which carbon tests, done at Beijing University, show to be 3,980 years old. This takes the known date for meat preservation, by our logic of linking it with mummification, to almost 4000 years ago in China. The nitrate in Xinjiang Lop Nur exists in two forms: natural sodium nitrate mine and natural potassium nitrate. (en.cnki.com.cn)

The Turpan Basin is a “fault-bounded trough located around and south of the city-oasis of Turpan, in the Xinjiang Autonomous Region in far western China, about 150 kilometres (93 mi) south-east of the regional capital Ürümqi.” “The surrounding mountain ranges are the central Tian Shan in the west, the Bogda Shan in the north-west, the Haerlike Shan in the north-west, and the Jueluotage Shan in the south. Beyond the surrounding mountain ranges lie the Junggar Basin in the north and the Tarim Basin in the south.” (www.revolvy.com)

“Some geographers also use the term Turpan-Hami Basin, which is understood as including the Turpan Depression along with the Hami Depression (located to the east of the Turpan Depression, and to the southwest of the city of Hami) and the Liaodong Uplift separating the two depressions.” (www.revolvy.com)

One of these mummies may hold a further clue to their preservation. She became famous for her “excellent preservation and beauty and it is known as the Beauty of Xiaohe. It is a white person with round eyes, perfect eyelashes, and long hair and has features that are more similar to a European person than a Chinese person.” (www.ancient-origins.net)

According to Elizabeth Wayland Barber, her “beautiful eyelashes finally proves an earlier hypothesis, deduced from little detail at Zaghunluq, that those bodies that mummified had to have died in early winter, flash freezing and gradually freeze-drying over the next few months whereas other bodies decomposed.” She was dismayed at people’s acceptance or refutation of his arguments without dealing with the arguments posed.  In the Beauty of Xiaohe she, at last, had hard evidence. “Eyeballs, being wet, cause rapid decomposition of both themselves and the eyelash-holding eyelids when warm; but by the same token, being wet, cause rapid decomposition of both themselves and the eyelash holding eyelids when warm, but by the same token, being wet, both they and the thin overlaying eyelids will freeze rapidly when being very cold, thus securing the eyelashes in place.  Unlike putrefaction, the gentle process of freeze-drying will not dislodge eyelids.” (Mair, V. H., Hickman, J.;  2014:  35)

It has been known from the earliest times that meat curing could be done only in the winter in the absence of refrigeration. If not, the putrefying and decomposing forces would overtake the preserving action of saltpetre and decomposition would be unstoppable. It is the combination of cold and dry conditions along with the use of sodium nitrate to preserve and ordinary salt (sodium chloride) to aid in drying out the meat, that forms a link between the earliest forms of mummification and modern meat-curing techniques. It seems unreasonable to think that the result of these forces, in combination, would have gone unnoticed. I further suspect that the power of these forces would have been practised in relation to fish, fowls, game and domesticated animals for centuries before they found inclusion in the earliest mummification practices.

The Silk Road

The location of the Turpan-Hami and Tarim Basins are very important. Crossing the Taklimakan Desert is possible at the foot of the mountains surrounding the Turpan-Hami Basin or along its streams such as the Tarim, “that spring from the mountains to enter the desert from its periphery but soon vanish into the sand. As ancient caravans from Eastern China approached Dunhuang at the edge of this segment of what eventually came to be part of the Silk Road to the Mediterranean, the near absence of water in the desert’s centre forced them to make a choice. The southern option skirts the desert along its southern edge at the foot of the steep Kunlun slopes descending from Tibet’s high plateau. Alternatively, the northern route passes through Hami and those communities living along the Kongi and Tarim rivers that lead to Loulan and Lop Nor.  It is along these routes that mummies from the Tarim Basin have been found.”  (Aufderheide, A. C.; 2003: 268, 269)

The caravans on the Silk Road approached Dunhuang, crossing vast sodium and potassium nitrate deposits. If the knowledge of its power was developed in this region and exported to Europe, I am sure that there should be remnants of this ancient knowledge in this city.

“One of the people who has extensively studied the Caucasian mummies of China, Professor Victor Mair of Pennsylvania University, said that he believes that early Europeans long ago spread out in different directions. He believes that some of these peoples travelled west to become the Celts in Britain and Ireland, others went north to become the Germanic tribes, and still, others journeyed east to find their way to Xinjiang. These ancient European settlers are believed to represent some of the earliest human inhabitants of the Tarim Basin, and Mair has stated that from around 1800BCE the earliest mummies to be found here are exclusively Caucasoid or Europoid rather than Chinese in origin.”

The origins of the mummies have been studied extensively using DNA technology.  Writing in the journals BMC Genetics and BMC Biology, Chunxiang Li, an ancient DNA specialist at Jilin University, and colleagues report on their analysis of human remains from the Xiaohe tomb complex also on the eastern edge of the basin.

They conclude that by reconstructing a possible route by which the Tarim Basin was populated, Li and colleagues conclude that “people bearing the south/west Asian components could have first married into pastoralist populations and reached North Xinjiang through the Kazakh steppe following the movement of pastoralist populations, then spread from North Xinjiang southward into the Tarim Basin across the Tianshan Mountains, and intermarried with the earlier inhabitants of the region, giving rise to the later, admixed Xiaohe community.” (Killgrove, K, 2015)

“The populations from the Russian steppe seem to have contributed more genetically to this population than did the populations from the oases of Bactria. “The groups reaching the Tarim Basin through the oasis route,” the researchers note, “may have interacted culturally with earlier populations from the steppe, with limited gene flow, resulting in a small genetic signal of the oasis agriculturalists in the Xiaohe community.””  (Killgrove, K, 2015)

A New York Times article on the origin of these people presents the picture clearly. It reads that “all the men who were analyzed had a Y chromosome that is now mostly found in Eastern Europe, Central Asia and Siberia, but rarely in China. The mitochondrial DNA, which passes down the female line, consisted of a lineage from Siberia and two that are common in Europe. Since both the Y chromosome and the mitochondrial DNA lineages are ancient, Dr Zhou and his team conclude the European and Siberian populations probably intermarried before entering the Tarim Basin some 4,000 years ago.” (Wade, N; 210)

It is however not the origin of these people who interest me as much as their destination and the destination of the traders who passed through this region. The Silk Road that ran through this region reached into the heart of the Middle East and Europe to the West and into the rest of China and India to the East. There is an interesting possibility that comes up and that is if it is possible that the Europeans brought the technology with them. Of course, this is a possibility but then there is the matter of the unique level of sophisticated insight into saltpetre from this exact region. Such a level of understanding of saltpetre did not exist in Europe for many centuries. It seems more likely that the transfer of technology went from Tarim, East, into Europe, rather than the other way round. The next section explains what I mean by this.

Dunhaung

The question is if there is any evidence that anything was done with the nitrate deposits and the clear evidence of its preserving power in the mummification. If this was the region where curing of meat was progressed into the art that we know it as today, is there any evidence of this? Any ancient document or reference, not just from China generally, but linked to this region. These were the actual questions I asked myself as I was searching. This is not a device I employ after the fact for the sake of creating drama.

I knew my general geographic area of focus was the one I show below featuring the Tarim Basin.

IMG_0132[1].PNG

I started plotting the important points.

IMG_0134[1].JPG

Looking at the images above, the saltpetre deposits are the largest at Yuli, marked as NO3-. Loulan is the city where many of the mummies have been found. Dunhuang is a major city before the trip past or across the desert was undertaken on the Silk Road past the Tarim Basin.

I did a search for any reference to saltpetre from the city of Dunhuang which would have been a key trading city in the area and important in terms of its location on the Silk Road. Not in my wildest imagination did I expect to uncover what I found!

It is here, in the Mogao Caves, where a remarkable find was made by the Daoist monk, Wang Yuanlu on 25 June 1900. The mix of religious and secular documents date from the 5th to the early 11th centuries.  One text is of particular interest to us, the Dunhuang Medical Text. “The text has been carefully studied by China’s leading experts in traditional Chinese medical literature and ancient manuscripts. The text is attributed to the famous Daoist alchemist and physician Toa Hongjing (CE 456 – 536).” (Cullen, C, Lo, V.;  2005) There is evidence that it relies on earlier traditions from the Han and Sui Dynasties. “The original was decorated with images of the Three Daoist Lords and the Twelve Constellations, indicating links with Doist traditions.  In Translation, it reads as follows:

Dunhuang Medical Manuscripts 1
Dunhuang Medical Manuscripts 2

(Cullen, C, Lo, V.;  2005)

Until the 1500s this is the only script of its kind that we know off. “The symptoms described by the patient, as described in the Dunhuang manuscript, suggests an advanced case of cardiovascular distress. The colour of the fingernails (cyanosis) indicates ischaemia (lack of oxygen in the tissue) due to restricted blood flow.  Cold hands and feet are additional symptoms of this condition. Also, acute pain suggests that the patient may be suffering from severe angina, i.e. restricted blood flow due to the narrowing of the cardiac arteries.”  (Cullen, C, Lo, V.;  2005)

“Modern treatment for angina is glyceryl trinitrate or isosorbide dinitrate. So, at first glance, there seems to be a similarity in treatment. All three remedies contain the all important nitrate. Salpeter is, however, an inorganic compound that exists as a positively charges potassium cation (K+) and a negatively charged nitrate anion (NO3-). Concerning organic nitrate, such as glyceryl trinitrate, there is a covalent bond or a molecular bond between the nitrate moieties (NO3) where they share electron pairs which form the bond with the rest of the molecule (CH2). Where glyceryl trinitrate relaxes the muscle lining of the artery to relax, enlarging the vessel and so allowing more blood flow, saltpetre by itself will have no effect on the treatment of angina. (Cullen, C, Lo, V.;  2005)

This is however not the full story. The remarkable feature of the Dunhuang text is that the combination of the use of saltpetre, not on its own, but when applied according to the dictates of the text, becomes a remedy for exactly the condition described. “The thing about glyceryl trinitrate is that this too, in itself, is not a vasodilator (relaxing of the arterial lining). It is transformed, probably in the arterial wall, into a chemical species which is the vasodilator. Under very special circumstances, exactly as detailed in the Dunhuang text, the nitrate ion from saltpetre also converts to exactly the same species which is the vasodilator. Despite the fact that glyceryl trinitrate has been in use for over a hundred years, the identity of this species has only been discovered in 1987.” (Cullen, C, Lo, V.;  2005)

“Lining almost all blood vessels on the inside is a layer of cells known as the endothelium. A very important function of the endothelium was first reported in 1890 by Furchgott and Zawadzki. The presence of acetylcholine (a small biologically active molecule) in the bloodstream affects vasodilation and it was generally assumed that acetylcholine acted directly upon vascular muscle. However, this was found not to be the case. Furchgott and Zawadzki showed convincingly that acetylcholine acted, not upon the muscle of the artery, but upon the endothelium and the endothelium produces a “second messenger” which then acts upon the muscles to effect relaxation. This second messenger was christened “the endothelium-derived relaxing factor” (EDRF).” (Cullen, C, Lo, V.;  2005)

During the 1980s, an intense effort was effected to identify the EDRF. It was initially assumed that it would turn out to be a complex molecule like a hormone. This speculation enhanced the surprise when the chemical nature of the molecule was finally determined. It turned out to be a small diatomic molecule called Nitric Oxide (NO).  “That it had a physiological role, in a process as important as vasodilation, came as a complete surprise.” (Cullen, C, Lo, V.;  2005)

“The discovery was made simultaneously by a group at the Wellcome Research Laboratories in Beckenham led by Professor Salvador Moncada and by a group in the USA led by Professor Louis Ignarro. The 1998 Nobel Prize in Physiology and Medicine was awarded for this discovery. Once nitric oxide had been detected in one physiological process it was found to have roles in many others, from inflammation to crying. That it should have remained undetected during a hundred years of intense scrutiny of human physiology is astonishing. Glyceryl trinitrate is a vasodilator because it is transformed by an enzymatic process (possibly by the enzyme xanthine oxidoreductase) into nitric oxide.” (Cullen, C, Lo, V.;  2005)

Let us now return to the Dunhuang text. Is there any way that the inorganic nitrate could be transformed into nitric oxide?  “In a healthy body it is very unlikely, that nitrate which is present in the blood plasma, is converted to nitric oxide. However, there is a species, nitrite (NO2-), very closely related to nitrate (NO3-), for which conversion into nitric oxide is quite possible. Do humans ever convert nitrate into nitrite? Such a conversion can occur in the mouth and it is this aspect of the Dunhuang prescription that is so interesting. The saliva contains many bacteria, some of which contain the enzyme nitrate reductase, which converts nitrate into nitrite.” (Cullen, C, Lo, V.;  2005)

“Experiments on rats have shown that reduction of nitrate to nitrite is confined to a specialised area on the posterior surface of the tongue. If the same applies to humans, the Dunhuang procedure, which specifies that the saltpetre should be placed under the tongue will maximise the conversion of nitrate into nitrite. The retention of saliva as described would also enhance nitrite production.  Unlike nitrate, nitrite is physiologically active.  t is an antiseptic and a vasodilator, although not a powerful one. It has been suggested that animals, particularly cats, lick wounds because of the antiseptic effect of nitrite in the saliva. Although not a powerful vasodilator, there is now direct evidence that rat hearts, when subjected to global ischaemia, generate nitric oxide and that a significant proportion comes from nitrite present in the tissue. Ischaemic tissue is very acidic and the acid affects the conversion of nitrite to NO via the following equilibria:”

reaction of NO2 to NO.png

(Cullen, C, Lo, V.;  2005)

“Calculations, assuming only a modest level of nitrite in ischaemic tissue, show that enough nitric oxide from the above equilibria to activate guanylate cyclase, the enzyme responsible for the initiation of the cascade of reactions which lead, eventually, to vasodilation. So, if nitrite enters the plasma, as a result of administration of sublingual saltpetre, it could generate nitric oxide in ischaemic tissue. Because of the abundance of blood vessels under the tongue sublingual administration of a drug is a good way of getting a drug into the bloodstream and bypassing the stomach. Also, the tongue, in traditional Chinese medical theory, is linked to the function of the heart.” (Cullen, C, Lo, V.;  2005)

“The interaction of saliva and nitrate to generate nitrite before conversion to nitric oxide in ischaemic tissue gives considerable credence to the Dunhuang procedure as a treatment for cardiovascular distress.” (Cullen, C, Lo, V.;  2005)

Here, in the Tarim Basin, we have three things present. One of the world’s largest natural saltpetre deposits. Natural mummification dating back to just over 3000 years ago. From these, the preserving power of these soils would have been evident to all since the mummies existed then already. The longevity of the corpses would have been evident to the ancients. We have a record of very sophisticated use of saltpetre from very early in the Christian Era from this exact region. In fact, some of the most sophisticated use of the salt on record and the exact mechanics is even today mirrored in the act of curing itself which has been until the early 1900’s when the direct addition of sodium nitrite replaced saltpetre as curing agent of choice.

Until that happened, curing was done by the addition of saltpetre which was reduced, through bacterial action to nitrite which diffused into the muscle for the purpose of preservation. The similarity in the curing action and the mechanism relied on, in the utilisation of saltpetre in the Dunhuang Medical Manuscripts is startling, to say the least. Of course, I am not suggesting that the full or even a partial understanding of the mechanism was known to the ancients, but the application did suggest a much more detailed understanding of saltpetre and its efficacy on meat muscles which could easily have originated from the experience with curing! Seeing the preserving power of the salt and the reddening effect of the meat could have led them to an application of the salt for heart conditions even though the reduction steps may not have been fully understood.

This is without a doubt the best possible location from anywhere in the world where the curing of meat could have originated in an art form which would have been preserved and transmitted to successive generations through societies which later became known as guilds. The picture is not of wondering hunters who stumbled upon the salt and early farmers using it for preserving meat – or at least, it could have started like this. But if it happened in this exact region, it soon found itself in the most advanced society on earth of its time with the most sophisticated thinking about chemistry. The Chinese alchemists in all likelihood gravitated to this as a possible key component of the elusive elixir of immortality. Finding such an elixir was the goal of Chinese alchemy.  They probably applied its preserving power to all kinds of ailments and in a process of trial and error, a treatment for angina must have been especially effective.

Here, at a key location on the silk road, the knowledge of curing and the power of saltpetre could easily have been spread through India and China to the East and right into the heart of Europe to the West.

This is a remarkable find!

The Fascinating Link between Turfan and Salzburg

The possibility that the art of meat curing was developed in Turpan and spread around the world is most promising. Despite this not being my main point under discussion here, it is important to note that Europe may also have influenced the community around Turpan. Influences certainly did not only go one way.

A fascinating link has been discovered between the mummies in Turfan and the Austrian city of Salzburg. Victor Mair, a professor of Chinese in the Department of Asian and Middle Eastern Studies at the University of Pennsylvania was committed to trace the ancestry of the mummies. “In Xinjiang, a Chinese colleague had slipped him a . . . gift: a swatch of blue, brown, and white cloth taken from a twelfth-century-bc mummy. The fabric looked like a piece of Celtic plaid. Mair passed it over to Irene Good, a textile expert at the University of Pennsylvania Museum. Good examined it under an electron microscope. The style of weave, known as a “two over two” diagonal twill, bore little resemblance to anything woven by Asian weavers of the day. (Indeed, it would be almost another two millennia before women in central China turned out twill cloth on their looms.) But the weave exactly matched cloth found with the bodies of thirteenth-century-BCE salt miners in Austria. Like the DNA samples, the mysterious plaid pointed straight towards a European homeland.” (Tocharians: The Whites of Ancient China)

This startled me. The thread that ties it all together is salt and meat curing. Is it possible that a mummy found in the region which I believe may have been pivotal in spreading nitrate curing of meat across the world may have some direct or indirect link with the Austrian salt mines? It unlocks the possibility that work done on the use of nitrate salts was influenced by work done in Austria.

In my mind, the fact that nitrate and nitrite did not only have negative effects on human health was discovered by contemplating the possible location where the art of meat curing with nitrate originated. Today students learn this from textbooks but I somehow like the journey of discovery that I took much more.

Villifying Nitrite: A Drama for Fools

After telling the story of my own discovery that nitrate, nitrite and nitric oxide is far from evil molecules, tantamount to poison being added to meat, I return to the primary subject at hand. Is bacon safe to consume? Is the use of nitrate and nitrite in meat curing irresponsible? What about the claims that it causes cancer?

There is no greater illustration of willing enslavement to an incomplete understanding of nature than the drama related to the use of nitrites in meat processing. Humans happened upon a natural phenomenon that special salts containing nitrate change the colour of meat and has the power to preserve it. Since the start of the use of nitrites in meat curing, it was viewed with great suspicion due to its inherent toxicity. Much of Bacon & the Art of Living is dedicated to chronicling the unfolding of the great saga of nitrate and nitrite and the discovery of its essential nature and role in meat curing. There is no need to repeat any of what has been written by me earlier in this work except to point the reader specifically to the following chapters. The first two deal with the initial objection against the use of nitrite in food as a poison. This dilemma was resolved through science and legislation.

Chapter 12.03: The Direct Addition of Nitrites to Curing Brines – the Master Butcher from Prague

Chapter 12.04: The Direct Addition of Nitrites to Curing Brines – The Spoils of War

The use of a substance that is, in high concentrations, poisonous is, after all, nothing new to humans. Alcohol is one of the best examples. Aspirin is another example where, in high dosages, it is dangerous despite its positive benefits at low dosages. Ultra-high dosages of ascorbic acid are equally likely to have adverse effects, cause diarrhoea and nausea. Vinegar is another good example which in moderation is beneficial but consuming too much over a long period of time will have serious detrimental health implications. There are hundreds of other examples we can give. I heard of a well-known speaker in the Uk who addressed a group of meat processing professionals and started his talk by accusing them of poisoning the public through the use of nitrites. Statements like this show a serious lack of understanding not just nitrites but almost every other food ingredient customarily used in food production.

A far more serious issue was discovered in the late 60s and early 70s related to the formation of n-nitrosamines. Nitrosamines are cancer-causing. We have already dealt with the matter in great detail in Chapter 12.06: Regulations of Nitrate and Nitrite post-1920’s: the problem of residual nitrite where we outlined the scientific, industry and government response to the issue.

A friend of mine who is a 3rd generation German Master Butcher tells the story of his grandfather who used to buy nitrites from the pharmacy in the early days and made the most beautiful rich pink bacon. There were no limits on ingoing nitrites in those days and the role of ascorbate was poorly understood and sadly he passed away from colon cancer. This anecdotal account has been subsequently confirmed by countless studies and indeed it is true that at the wrong concentrations, without the use of ascorbate or erythorbate, the high nitrite levels used in curing meat is tantamount to poisoning the consumers. The chapter which I just mentioned deals with the international response to the subject and the combined legislative framework for the use of nitrites in food. The minuscule amounts of nitrites used in bacon curing today along with the use of ascorbate render bacon a safe product to consume in moderation. Of course, the caveat should always be remembered that this should be done in moderation as is the case with any other processed food, red meat, beer, cheese, milk, alcohol, dried milk powder, etc.

What has been said before should settle the issue, but over the years a number of other factors occurred to me which must be added to the discussion to un-vilify nitrite.

Nitrosamines – A Much Broader Issue than Bacon

At the outset, I want to apologise to the reader because the issue becomes wonderfully complex almost right from the start. You don’t have to remember all the terms used and all the intricate connections. I chose an article as the basis for our discussion which broadly introduces you to enough of the important factors so that you will be able to see that the issue with bacon is the same issue with beer, cheese, fish, red meat and many other foods. You will see that it even extends to packaging and food preparation. So, don’t be intimidated by the technical discussion which follows.

I firmly believe that despite the fact that a mammoth amount of work has been done on bacon and cured meat since the 1970s; despite the fact that I am absolutely convinced that based on the preponderance of the latest scientific data on nitrite in meat showing that it is a completely safe food to consume, the responsible producer will continue to work on doing even better by limiting residual nitrite in its products after it has been prepared by the consumer even further so that the consumer will be satisfied that concerns, valid and non-valid are being taken seriously by the producer.

Having said all this, let’s now delve into the issue.

a. What is N-nitrosamines?

Nitroso compounds refer to non-organic compounds containing the NO group. This immediately will get the readers attention because we know that it is NO (nitric oxide) which is responsible for the pinkish/ reddish colour in cured meat. The NO group in nitroso compounds for example directly binds to the metal via the N atom, giving a metal–NO moiety. A nonmetal example is the common reagent nitrosyl chloride (Cl−N=O).

If you combine nitroso with amines, you get nitrosamines or as they are more formally called, N-Nitrosamines. So, the next question is: what is an amine. Amines are compounds and functional groups with a nitrogen atom and a lone pair. Amines are formally derivatives of ammonia (NH3). Nitrosamines then is a group of organic compounds with the chemical structure R2N−N=O, where R is usually an alkyl group. An alkyl group, very simply stated, refers to hydrogen and carbon atoms arranged in a tree structure in which all the carbon-carbon bonds are single. The nitroso group (NO+) binds to a deprotonated amine. The reader with no background in organic chemistry will be able to spot the nitrogen in the three structures below.

The important point for our discussion is that most nitrosamines are carcinogenic in animals.

b. How are they formed in Food?

Look at the three structures of amines represented above. Nitrosamines are formed by the reaction of secondary or tertiary amines with a nitrosating agent, such as nitrite from which nitric oxide and an R-NO group formes. When water is eliminated from a compound, we say that an anhydrate is formed. This describes the formation of NO (nitric oxide) from NO2 (nitrite). So, in food, NO is formed from nitrite in an acidic, aqueous solution. The nitrosating agent is usually then a nitrous anhydride, formed from nitrite in an acidic, aqueous solution. This is, for example, the condition found in our stomachs or in the mouth and if we ingest nitrites, we run the risk of nitrosamine formation after we swallowed the food.

Another culprit for nitrosamine formation is the frying of bacon. Nitrite in combination with fats (lipids) seems to be the nitrosating agent during the frying of bacon. “The formation is related to the relatively high internal temperature of bacon during frying and the relatively low moisture content of bacon as compared to other cured meat products. When bacon is cooked by other methods, particularly in a microwave oven, considerably lower amounts of nitrosamines are found.” (Scanlan, 2003) 

c. Bacon is not the only Product of Concern

From the point just made about the frying temperature of bacon in an environment where there are lipids and low internal water content which leads to nitrosamine formation, it should be a clue to the fact that processing techniques are also responsible for its formation. This was indeed shown and since the late 70s and 80s, it has been known that processing techniques, as well as packaging procedures, are responsible for introducing these carcinogens into food. Hotchkiss (1984) writes that these processing and packaging “procedures include drying foods in direct flame heated air, migration from food contact surfaces and direct addition as contaminants. In addition, other reports of N-nitrosamines in foods have less well defined routes of contamination.”

Hotchkiss (1984) cautions that despite the presence of nitrosamines in food, it is actually “occupational exposures” which may be responsible for “the highest individual exposures (Fine and Rounbeh1er, 1981).” Still, “the largest numbers of people have been exposed to exogenously formed N-nitroso compounds through the diet.”

There are three abbreviations I want to introduce at this point namely NA (N-nitrosamines), NVNA (non-volatile NA) and VNA (volatile nitrosamines where “volatile” refers to those compounds amenable to gas chromatography without derivatization). VNA includes for example “N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosopiperidine (NPIP) and N-nitrosodiethylamine (NDEA), which occurs generally at low levels <5 µg kg−1 but levels up to 20 µg kg−1 has been reported (Hill et al, 1988, Massey et al, 1991). NDEA has been evaluated as the most potent carcinogen among the known meat related VNAs (Peto et al., 1984).” (Herrmann, 2015) NVNA include “the N-nitrosamino acids, e.g. N-nitrosohydroxyproline (NHPRO), N-nitrosoproline (NPRO), N-nitrososarcosine (NSAR), N-nitroso-thiazolidine-4-carboxylic acid (NTCA), N-nitroso-2-methyl-thiazolidine-4-carboxylic acid (NMTCA), generally occur at significantly higher levels than the VNAs, i.e. up to several thousand microgram per kilo (Herrmann et al, 2014a, Massey et al, 1991, Tricker, Kubacki, 1992).” (Herrmann, 2015)

Hotchkiss (1984) continues that “several groups have demonstrated that a number of foods can contain trace quantities of VNA. To date nearly all types of foods have been analyzed for VNA and, hence, some important generalizations can be made. Most importantly is that the use of nitrite as a curing agent is not solely responsible
for the VNA content of foods. Several foods to which nitrite has not been intentionally added have now been shown to contain trace levels of VNAs. Equally significant is that the N-nitrosamine content of foods has decreased as a result of research in this area. He classified the routes and mechanisms by which foods can become contaminated. “The routes of contamination can be divided into 5 groups: Additives; drying processes; migration from contact surfaces; addition of performed NA; and those for which the route is not clearly defined.

Additives

This is the class where cured meats fall in. We are already familiar with the story as we discussed it in Chapter 12.06: Regulations of Nitrate and Nitrite post-1920’s: the problem of residual nitrite. Let’s recap what we said by quoting Hotchkiss (1984). “The suspicion that the use of nitrite in foods might result in the formation of NA stems from an incident in which animals fed nitrite preserved fish meal developed liver necrosis. The causal agent was determined to be NDMA and it was shown that the compound resulted from the nitrosation of the amines in the fish by nitrous
acid formed from nitrite (Ender et a1., 1964). Nitrite is an economically and technically important food additive in the curing process in order to fix color, develop flavor and inhibit toxigenesis by C1. botulinum.” (Hotchkiss, 1984)

“Since the late 1960s, a substantial research effort has resulted in a body of information concerning the occurrence and formation of VNA in cured meats. This has resulted in the knowledge that the addition of nitrite to meat is not, in most cases, sufficient to routinely cause the formation of VNA. In order for cured meats to consistently contain more than 1 μg /kg VNA6 the product must be subjected to temperatures greater than 100 C in a low moisture environment. The only cured product which meets these criteria is bacon. Other cured products only sporadically contain VNA in excess of 0.1 μg /kg (Gray and Randall, 1979). In a recent large survey, only 6 of 152 cooked sausage products had a VNA content greater than 5 μg /kg and only 4 of 91 dry sausages had similar VNA contents. In the same study, however, 11 of 12 dry-cured fried bacons contained VNA, some as high as 280 μg/kg. The fact that fried cured bacon consistently contains detectable VNA has been observed by numerous workers (Scanlan, 1975).” (Hotchkiss, 1984)

“Efforts have been directed at determining the chemical mechanism and precursors to the major VNA, NPYR, found in fried bacon. While several potential precursors to NPYR have been identified, including collagen, ornithine, hydroxyproline, citrulline, putrasine and arginine, it is generally accepted that the major precursor is proline (Gray, 1976). While the free-radical mechanism proposed by Bharucha et a1. (1979) is often cited as the mechanism which best fits observations, the steps of the reaction have not been clearly elucidated. At least two possible routes exist; proline could be nitro sated to form NPRO which is subsequently decarboxylated during frying to NPYR, or proline is first decarboxy1ated to the amine pyrrolidine which is then subsequently nitrosated. Both decarboxylation and nitrosation, regardless of order, must occur during frying because uncooked bacon does not contain NPYR or sufficient preformed NPRO (Hansen et aI, 1977). Nakamura et al. (1976) have suggested that the mechanism is temperature dependent; at temperatures above o 175 C decarboxylation precedes nitrosation and at lower temperatures nitrosation precedes decarboxylation.” (Hotchkiss, 1984)

“In addition to NDMA and NPYR, Kimoto et a1. (1982) and Gray et a1. (1982) each have reported that fried bacon also contains NTHZ. This VNA was likely missed by many researchers due to its long retention time or its on-column decomposition. We have also confirmed this VNA in fried bacon and have further identified the compound in the fried-out fat from bacon. NDMA and NPYR are, under most frying conditions, found in higher concentration in the fried-out fat than in the edible portion. However, in our experiments NTHZ consistently occurs in higher concentrations in the edible portion regardless of the frying conditions. The mutagenicity of NTHZ has been demonstrated (Sekizawa and Shib, 1980) but the compound has not been tested in whole animals for carcinogenicity. The formation of precursors of NTHZ have also not been studied in fried bacon but thiazolidine has been identified as a browning product in a glucose-Cysteamine model system (Mihara and Shibamoto, 1980).” (Hotchkiss, 1984)

“Nitrate may be added to certain cheeses to retard the growth of microorganisms which might cause defects. Concern has been expressed that the nitrate might be reduced to nitrite by reductase containing microflora and that this nitrite could nitrosate amines endogenous to the product. The Danish government has published the results of a large survey of cheeses in which no correlation between the use of nitrate and concentration of VNA in the product could be made (Anon. 1980). Only very small amounts (less than 0.7 μg/kg) were found in any cheese. Sen et al. (1978), however, found 21 of 31 cheeses imported into Canada contained VNA up to 20 μg/kg. These apparent discrepancies with regard to the use of nitrate in cheese have not been resolved.” (Hotchkiss, 1984)

Drying

“In addition to the use of nitrite and nitrate as additives, a second general mechanism by which foods may become contaminated with NA is through the drying of foods in air which has been directly heated in an open flame. The highest levels of VNA resulting from this common method of food processing have been in the kilning of malted barley. Concentrations of NDMA -in the dried malt of over 100 μg/kg have been reported (Hotchkiss et al. 1980; Preussmann et al. 1981). A number of workers have shown that the NDMA in the malt survives the brewing process and can be detected in the resulting beer in concentrations expected from the dilution of the malt (Havery et al. 1981). This widespread contamination was shown to be the result of the formation of oxides of nitrogen in the air as it is heated in the flame. Oxides of nitrogen have been demonstrated to be effective nitrosating agents over a wide pH range (Challis and Kyrtopoulos, 1978).” (Hotchkiss, 1984)

“Scanlan and coworkers have extensively investigated the formation of NDMA in malt. They have demonstrated that the plant alkaloids hordenine and gramine are effective precursors of NDMA in model systems and that it is likely that NVNA may also be present in direct fired kiln dried malt (Mangino et a1. 1981).” (Hotchkiss, 1984)

“The first reports of NDMA in beer indicated average concentrations in the range of 2 to 6 μg/kg (Spiegelhalder et a1. 1981). While these levels seem, at first, low it is possible to consume 1 to 2 kg of beer at a single serving. This represents more NDMA exposure than from any other food source. Spiegelhalder et a1. (1980) have estimated that 64% of a West German’s dietary NDMA came from beer. There is recent evidence, however, that the VNA content of beer has decreased sharply (Mangino et a1. 1981). This decrease is due to the widespread use of sulfur dioxide or indirect heating of the drying gases in the malting industry. The application of sulfur dioxide during the early part of the kilning process may be either by direct injection of gaseous sulfur dioxide or by burning elemental sulfur in the drying air. The inhibition by sulfur dioxide is most likely due to the formation of bisulfite which may react with the nitro sating agent in a redox reaction.” (Hotchkiss, 1984)

“Other foods which are dried in direct flame heated air have also been shown to contain trace amounts of VNA, albeit at lower levels than malt. Most notable is the finding that nonfat dried milk may contain traces of NDMA. Several reports have shown NDMA levels of 0.1 to approximately 5 μg/kg (Libbey et al. 1980; Lakritz and Pensabene, 1981). In a recent nationwide survey of 57 nonfat dried milks conducted by the US Food and Drug Administration, an average NDMA level of 0.6 μg/kg was found with 48 samples being positive (Havery et al. 1981). Apparent NPYR and NPIP were also detected in sub μg/kg concentrations. Because nonfat dry milk is diluted lOx before consumption some have onsidered it not to be a significant problem while others have been concerned because of the widespread use of this product by the young.” (Hotchkiss, 1984)

“Other dried foods have been shown to sporadically contain detectable VNA. Sen and Seaman (1981) analyzed nonfat dry milk, dried soups, and instant coffee and found VNA in all dried milks, 3 of 20 dried soups and 5 of 10 instant coffees, most at levels of less than 1 μg/kg. Perhaps more importantly, 3 of 8 dried infant formulas contained detectable VNA. Fazio and Havery (1981) have observed VNA in soy isolates and concentrates and dried cheeses.” (Hotchkiss, 1984)

Migration

“In addition to formation from direct additives or from the direct flame drying process, recent evidence indicates VNA may enter foods through migration from food contact surfaces. In 1981 Spiegelhalder and Preussmann (1981) reported that a number of rubber products including nursing nipples contained substantial levels of VNA and that these compounds could migrate to water and milk. Later Havery and Fazio (1982) investigated one brand of nipple available in the US. They confirmed the presence of VNA in this product and demonstrated that when inverted nipples were sterilized in milk or formul, migration occurred.” (Hotchkiss, 1984)

“We have investigated the VNA content of 8 types of rubber nipples available in the US from several domestic and foreign manufacturers (Babish et al. 1982). One or more VNA were detected in all nipples tested and when each nipple was boiled for 3 minutes in 150 ml water or incubated 3 hours at 37oC, 6 to 44% migration occurred. Total VNA contents ranged from 42 to 617 μg/nipple (nipple weight is approximately 5 gm) and most nipples contained more than one VNA.” (Hotchkiss, 1984)

“Direct food contact paper and paperboard packaging may also be a source of VNA and nitrosatable amines in foods. Analyses of 34 food packages by GC-TEA revealed 9 to be contaminated with NMOR. Perhaps more importantly, all packaging materials examined had levels of the parent amine morpholine ranging from 98 to 842 μg/kg (Hotchkiss and Vecchio, 1982). Morpholine is easily nitrosated and there is evidence that it may be nitrosated in the stomach to produce the carcinogenic N-nitroso derivative (Mirvish, 1975). Two experiments indicated that both the NMOR and morpholine may migrate to dry foods. First, when a food package was found to contain NMOR and morpholine, the food closest in the package often also contained NMOR and morpho line (Hoffmann et ale 1982). Secondly, when paperboards which contained NMOR and morpho line were incubated at elevated temperatures in closed vessels with dry foods migration could be demonstrated. Further research is needed to determine the extent of the contamination and degree of migration under normal conditions.” (Hotchkiss, 1984)

Direct Addition

“When agricultural chemicals or food additives contain preformed VNA, it is conceivable that a portion of the VNA contaminate could be added to food. For example, meat curing premixes which contained salt, sugar, spices and nitrite and were designed to facilitate the mixing of curing brines were shown to contain relatively high levels of VNA including NPIP (Sen et ale 1974). This VNA resulted from the nitrosation of piperidine ring containing compounds in the spices. The NPIP was then added along with the cure solution to the meat and could be detected in the product.” (Hotchkiss, 1984)

“Certain agricultural chemicals were shown at one time, to contain mg/kg quantities of VNA (Ross et al. 1977). Although current levels have been greatly reduced (Oliver, 1981) it has been demonstrated under laboratory conditions that when these mixtures are applied to food crops, absorption of the VNA either directly through the plant or indirectly through the soil is possible (Khan, 1981). For example, Dean-Raymond and Alexander (1976) have shown that radio labeled NDMA incorporated into soil could be taken up by edible plants. A recent survey of dried waste sludge also indicates most sludges contain small amounts of VNA (Mumma et al. 1982). If sludge is incorporated into soil uptake may be possible. It should be noted that no confirmed report of VNA in foods as a result of the use of pesticides or sludge in actual field use has appeared. On the contrary, Ross et al. (1978) analyzed soil, run off water and edible plant tissue after the application of a commercial herbicide containing NDPA and failed to detect the VNA in any sample. As pointed out by Oliver, (1981) it is difficult to draw conclusions about the VNA contamination of foods based on laboratory experiments.” (Hotchkiss, 1984)

“Another potential source of direct addition of NA to food maybe through the use of processing water which has been deionized by anion exchangers. Kimoto et al. (1980) have shown that NDMA and NDEA at levels of less than 1 μg/kg can be detected in water which has been passed through an anion exchange column. This is a common treatment process in food plants.” (Hotchkiss, 1984)

Miscellaneous

“In addition to the above four mechanisms by which food may become contaminated with small amounts of VNA, other less well defined or uncorroborated contamination processes have been reported. For example, one group of Japanese workers have reported that broiling fish under a gas flame may result in substantial increases in the VNA content of the food (Matsui et al. 1980). The average NDMA content of 20 fish and seafood products increased 3 fold after broiling under a gas flame and one dried squid sample increased in NDMA from 84 to 313 μg /kg. When broiled under an electric element or covered with aluminium foil smaller increases in NDMA content were seen. Presumably, VNA is being formed by a mechanism similar to that occurring in dried foods such as malt and nonfat dried milk. Further work is needed to evaluate this source of dietary NA. Smoking fish has also been reported to result in the nitrosation of the amines associated with fish (Kann et aL 1980).” “Another potential source of direct addition of NA to food maybe through the use of processing water which has been deionized by anion exchangers. Kimoto et al. (1980) have shown that NDMA and NDEA at levels of less than: 1 μg/kg can be detected in water which has been passed through an anion exchange column. This is a common treatment process in food plants.” (Hotchkiss, 1984)

The Occurance and Benefit of Nitrate in Our Diet

So far we have looked at the occurrence of nitrite and the dangers associated with nitrosamines. I deal with it directly because it is the main charge levelled against the curing industry that poison is used to cure the meat. The second, and equally important consideration is the benefit of nitrate in our diets. The reader should be well familiar by now that nitrite is converted through bacteria from nitrate. Such bacteria occurs for example in our mouths and when we ingest nitrate much of these are converted into nitrite. So, in a way, when we talk about nitrate, we also talk about the occurrence of nitrate in our food.

Nitrate has been shown to be beneficial to our health and occurs naturally in, for example in beetroot. It has been credited with a speedy recovery after a strenuous workout, thus enhancing our exercise performance as well as lowering our blood pressure. Nitrates are the active ingredient in medicine for the treatment of angina where blood flow is restricted causing chest pains.

It is reported by the BBC that “only around 5% of nitrates in the average European diet come from cured meat, while more than 80% are from vegetables. Vegetables acquire nitrates and nitrites from the soil they grow in – nitrates are part of natural mineral deposits, while nitrites are formed by soil microorganisms that break down animal matter.” BBC

Uddin (2021) published an extremely helpful list of fruits and vegetables containing nitrate and the mg/kg which they typically contain all of which should be the end of the debate about nitrite in bacon.

Mean concentrations of nitrate in the tested fruits and vegetables.
From: Study of nitrate levels in fruits and vegetables to assess the potential health risks in Bangladesh

The Guiding Power of Nature

My life has been guided by invisible forces from my birth. I believe this force to be nature itself. The biggest thing I have learned is that what I believe is completely irrelevant. Nature does not care for my belief! It is not swayed by it! What IS will prevail, irrespective of my personal belief or even our universal belief as humans. Every step of life was crafted by nature itself in a way that I don’t understand.

I came to realise that my own intellect and our ability as humans to perceive life through the matrix of our minds is not the most important aspect of our lives. I examined the most important mental constructs very carefully and realised that they are all bankrupt. The first quest was to understand God.  I wrote a book about it, The Anatomy of a Sceptic.  This magical time in my life introduced me to the amazing world of the human mind and the gods we create! We first create them and then we worship them just as we do with all our mental constructs. We do the same with concepts such as democracy and the free market system and yes, even with the idea of science! We first created these mental concepts and then we worshipped them.

It was my quest to understand bacon that brought me back to nature and to understand that I exist as a living being, in the first place not in my mind, but in my body as every bodily need and desire and instinct and drive is connected in the first place to nature. I eat to live and I eat that which I share this earth with. My quest to understand the secrets of bacon taught me that life is infinitely interconnected and I am nature itself!

Bacon evolved over millennia in a way that my quest only briefly introduced. Living life excellently means that I re-connect with nature. This is the art of living! It is why so many people who looked deeply into this tell us that the problem is not that we think too little. The problem is often that we think too much and the art of reconnecting with life is to become quiet and to stop thinking! It is that simple.


(c) Eben van Tonder


green-next
green-previous
green-home-icon

(c) eben van tonder

Bacon & the art of living” in book form
Stay in touch

Like our Facebook page and see the next post. Like, share, comment, contribute!

Bacon and the art of living

Promote your Page too


References

Herrmann, S. S., Duedahl-Olesen, L., Christensen, T., Olesen, P.T., Granby, K.. 2015. Dietary exposure to volatile and non-volatile N-nitrosamines from processed meat products in Denmark. Food and Chemical Toxicology, Volume 80,
2015, Pages 137-143, ISSN 0278-6915, https://doi.org/10.1016/j.fct.2015.03.008. (https://www.sciencedirect.com/science/article/pii/S0278691515000873)

Hotchkiss, J. H.. 1984. Sources of N-Nitrosamines Contamination in Foods. Adv Exp Med Biol. 1984;177:287-98. doi: 10.1007/978-1-4684-4790-3_14.

Scanlan, R. A.. 2003. Nitrosamines. Encyclopedia of Food Sciences and Nutrition (Second Edition).

Uddin, R., Thakur, M.U., Uddin, M.Z. et al. Study of nitrate levels in fruits and vegetables to assess the potential health risks in BangladeshSci Rep 11, 4704 (2021). https://doi.org/10.1038/s41598-021-84032-z