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.
narrative – nitrogen nutrition
Lauren Learns How Meat Is Made
Cape Town, 1930
Dear Lauren,
I write to you many years after I penned my letter to you from Denmark which I called Lauren Learns the Nitrogen Cycle. There have been so many advances in our understanding since I wrote to you that I feel obliged, many years later, to add some thoughts about the role of nitrogen in human nutrition. Where you and Tristan are putting all my letters together in a book format, I want to ask you to place this between my letter about the discovery of the nitrogen cycle and the letter I also wrote from Denmark about how protein was discovered. This letter is an elegant introduction to the concepts of protein and amino acids and the central role of nitrogen in all of it which will make the letter from Denmark about how it was all discovered all the more meaningful.
So, here I deal with protein and how meat is created. Scientists call it protein synthesis, but it is just a fact way of saying the same thing. The element without which protein will not exist is nitrogen and I begin the discussion here and how nitrogen seems to disappear in the human body. The fact is that it is used to create meat! Build muscle! Replace and repair collagen which is nothing but a specialised protein.
This leads me into the briefest consideration of the building block of proteins namely amino acids, the ones that are produced by our bodies and those that we can only get from what we eat. Generally, our nutrition helps even in our creation of the vitamins which our bodies make ourselves which we term non-essential amino acids. Vitamin C, for example, is very important in our body’s production of collagen. Vitamin C does not form collagen, but without it, the synthesis of collagen in our bodies is not effective.
I consider of collagen and its formation generally as it has become a vital protein for my later work. I return by showing the cycle of nitrogen in nature but focusing on its role in protein. I end with the absolutely fascinating way that animals use grass to feed bacteria so that they can use the proteins created by bacteria to break down into amino acids to in turn create meat.
Nitrogen In Respiration
Let me take you back to the letter I sent you so many years ago when I was living in Denmark. (Chapter 12.07.1: Lauren Learns the Nitrogen Cycle) I return to my thoughts on the work of Antoine Lavoisier in the late 1700s related to nitrogen and respiration. Remember the letter that we quoted in the last correspondence that Lavoisier wrote Joseph Blackon on 19 November 1790 from which he concluded that “Nitrogen is absolutely useless in the act of respiration, and it appears from the lung in the same quantity and quality that it has entered it.“
In the experiments, they had their test subjects exercise in a closed container. They measured for oxygen and carbon dioxide. They also measured the amount of nitrogen ingested during a meal before the experiments started and then, after exercise, the urine and stools were tested to see how much nitrogen was retained in the body or “lost” through the urine and stools.
The experiment was undertaken 18 years after the discovery of nitrogen. It is regarded by many as the first metabolic experiment with nitrogen. The experiments appear (D. McKie, personal communication, 1962) to have been based on studies made by Fourcroy in the late 1780s, using gasometric methods that were published in 1791 by Séguin. They did not find any correlation between nitrogen and respiration. Some researchers of the time still claimed that some nitrogen is lost from the body during respiration. Today, most will simply subscribe to Lavoisier’s view that gaseous nitrogen plays no part in the nitrogen metabolism of the mammalian organism. (Munro and Allison, 1964) They believed that the balance of nitrogen ingested and that which was not recovered in stools or urine was probably lost through what they called “insensible perspiration.” (Carpenter, 2003) These you know from my previous communication, but what is fundamental is to understand what happened to the nitrogen that was unaccounted for. It turned out that nitrogen was used up, not in respiration, but within the complex set of chemical reactions that occur within the human body to sustain life which we call metabolism.
It’s now understood that this “lost” nitrogen is utilized by the body for various metabolic processes, including the biological process by which cells build proteins. You see, when we eat the proteins of animals, the animal proteins do not become part of the human body. Instead, our bodies break the proteins we ingest from animal and plant sources down into smaller components called amino acids during digestion. Amino acids are organic compounds that serve as the building blocks of proteins. Once broken down, these amino acids are then used by the body to create its own proteins, tailored to its specific needs. This creation process involves arranging the amino acids in specific sequences determined by the body’s genetic instructions.
The new proteins and other vital compounds like neurotransmitters (serotonin, dopamine), nitric oxide, creatine, glutathione, and hormones (insulin, growth hormone). Excess amino acids undergo deamination.
Deamination is a metabolic process in which the amino group (NH2) is removed from amino acids, the building blocks of proteins. This removal is critical as it allows the amino acid to be used for energy or converted into other compounds. So, what happens to the amino group (NH2)? The body uses it to produce ammonia which is the end product of deamination.
Ammonia is a toxic compound. In a remarkable biochemical adaptation, mammals convert ammonia into urea in the liver, which is then excreted by the kidneys, maintaining nitrogen balance and detoxifying the body. Deamination is therefore essential in regulating nitrogen levels in the body and plays a key role in overall metabolism.
Why is Protein Important in Nutrition
The proteins we ingest, essential for life, are broken down in our bodies into the tiny building blocks of proteins called amino acids. I referred to this a few times now. Our bodies can create their own amino acids. We don’t need to get through what we eat. We call them non-essential amino acids.
In human nutrition, amino acids are categorized into essential and nonessential types. Essential amino acids cannot be synthesized by the body and must be obtained through diet. In contrast, nonessential amino acids can be produced by the body. Animal proteins, such as meat, are valued for their complete protein profile, containing all essential amino acids in sufficient quantities. This completeness is vital for the body to synthesize its own proteins, a process where these amino acids are assembled into specific sequences based on genetic instructions, enabling the body to perform various functions like muscle repair and enzyme production. They are used for a variety of important functions. For instance, some are involved in supporting the immune system, aiding in wound healing, and providing energy for the body. Others play a role in neurotransmitter production, which is crucial for brain function and mood regulation. Essentially, these amino acids contribute to maintaining the overall health and proper functioning of our bodies, even though we don’t need to obtain them directly from our diet.
There are, however amino acids that the body can not produce and the only way we can get it is by eating protein. The earliest humans ate meat. Meat is the only source we have that contains all the essential amino acids we need but can’t create ourselves. Meat not only contains all the essential amino acids, but it also contains them in sufficient quantities. This completeness is vital for the body to synthesize or build its own proteins, a process where these amino acids are assembled into specific sequences based on genetic instructions, enabling the body to perform various functions like muscle repair and enzyme production. The body uses the building blocks of the animal protein to build its own proteins but when it builds its own protein, it does so according to the blueprint of its own DNA and not according to the blueprint of the animal’s DNA.
The essential amino acids are key in muscle building and repair, others are important for maintaining healthy skin and hair, and some play a role in the proper functioning of the digestive and nervous systems. Essential amino acids are integral to producing hormones and enzymes that regulate bodily functions. The essential amino acids are Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine.
It would be a mistake to think that diet plays no role in the production of non-essential amino acids. It aids the production of these amino acids indirectly by providing the raw materials and what scientists refer to as co-factors necessary for their synthesis. Even in non-essential amino acids, meat is a key food source in that it supplies the body with amino acids that can be modified to produce non-essential ones. It is, however not only meat. Beans, for example, do not contain all the essential amino acids in sufficient quantities. Like most plant-based proteins, beans, are typically low in one or more essential amino acids. For beans, the limiting amino acid is often methionine. However, beans, like meat, it is a source of what the body needs as raw materials and co-factors to produce non-essential amino acids.
Certain vitamins and minerals found in fruits and vegetables are vital co-factors in enzymatic reactions that create these amino acids. Foods rich in carbohydrates, like grains, also contribute energy that supports these metabolic processes. The non-essential amino acids the human body produces include Alanine, Asparagine, Aspartic acid, Glutamic acid, Serine, and others.
The Vitamin C Example and Collagen
A good example of a famous vitamin is Vitamin C. It acts as a cofactor for the production of collagen. A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme’s activity as a catalyst. Vitamin C is essential for the hydroxylation of proline and lysine, amino acids that are integral which is important for collagen synthesis. Collagen, in turn, is a key structural protein in the body, vital for the health of skin, tendons, ligaments, and bones. Without sufficient Vitamin C, collagen synthesis is impaired, leading to weakened connective tissues and potential health issues like scurvy. Vitamin C also acts as a cofactor in other enzymatic reactions, aiding in the overall metabolism and synthesis of amino acids.
Collagen Synthesis and Insights from Vegetarianism
One of the interesting amino acids from the standpoint of meat science is hydroxyproline. It is an amino acid, but it’s not one of the twenty standard amino acids directly coded for by DNA in protein synthesis. Instead, hydroxyproline is formed post-translationally, meaning it is created through the modification of another amino acid, proline after it has been incorporated into a protein. This modification is facilitated by the presence of Vitamin C and is crucial in the stability and structure of collagen.
In our discussion above about Vitamin C, we said that Vitamin C is essential for the hydroxylation of proline and lysine. Hydroxylation is a chemical process where a hydroxyl group (-OH) is added to a molecule. In the context of collagen synthesis, this process involves the modification of certain amino acids, specifically lysine and proline, after they have been incorporated into the collagen protein. Vitamin C acts as a cofactor in this reaction, facilitating the addition of the hydroxyl group. This hydroxylation is crucial for the stability and strength of the collagen triple helix structure, which is essential for the functional integrity of tissues like skin, tendons, and ligaments.
Animal-based foods, particularly meat, are prime sources of lysine, proline, and glycine, the trio of amino acids fundamental to collagen structure. Lysine, being an essential amino acid, must be obtained through the diet as the body is incapable of producing it. Conversely, proline and glycine are non-essential, with the body able to synthesize them. Animal tissues, notably skin and tendons, are abundant in collagen, hence providing a rich source of these amino acids. Additionally, these tissues vary in their fat and water content, with tendons typically being higher in collagen and water, but lower in fat. Consumption of animal skin and tendons contributes to these critical amino acids, supporting the body’s collagen synthesis. In this process, the body breaks down the ingested collagen and then uses the amino acids to construct its own collagen, following the unique blueprint provided by its DNA.
An incident while living in Lagos highlighted the role of these amino acids in our own collagen production when I had the opportunity to consider a scenario where collagen production in the human body had to be encouraged through the intake of these amino acids from plants and not meat. My next-door neighbour, diagnosed with gout, was advised by his doctor to increase his collagen intake. However, he is a vegetarian and consuming animal-derived products like skin and tendons wasn’t an option for him. I had the opportunity to consider what options he has from a purely vegetable and fruit perspective.
I knew that it was important that he obtained enough lysine, an essential amino acid, from plant sources. Beans, lentils, and peas, part of the legume family, are rich in lysine. Soybeans and their derivatives, such as tofu and tempeh, also provide a substantial amount of this amino acid. Additionally, proline had to be added which even though it is a non-essential amino acid, is directly present in vegetables like asparagus, cabbage, and spinach.
While glycine, another non-essential amino acid, is more prevalent in animal sources, it is also directly found in plant foods, including legumes, spinach, kale, cauliflower, cabbage, pumpkin, banana, kiwi, and soy products. Although non-essential, meaning the body can synthesize it, including these plants in his diet would help ensure adequate glycine levels. Coupled with Vitamin C-rich fruits and vegetables, vital for collagen synthesis, these foods would enable him to maintain sufficient collagen production without relying on meat
Vegetarianism can completely replace the consumption of meat. This has been demonstrated abundantly, yet, notice the gymnastics required to replace collagen in our diets. This incident illustrates the value of meat as a source of food and underscores the fact that humans evolved in the first place to consume meat.
When we consume collagen from animal products like tendons or skin our bodies don’t utilize the intact collagen or its hydroxyproline directly. Instead, the collagen is digested and broken down into its constituent amino acids. This includes hydroxyproline, which, along with other amino acids, is absorbed and can be utilized by the body in various metabolic processes. For synthesizing its own collagen, the body primarily uses amino acids sourced from the diet, arranged according to its genetic blueprint. While hydroxyproline from dietary collagen is not directly used in new collagen synthesis, the amino acids resulting from its breakdown contribute to the body’s amino acid pool, which is used for synthesizing proteins, including collagen.
From Amino Acids and Proteins, Back to Nitrogen
We have had the most amazing rabbit trail discussion about how our bodies create protein from the protein we ingest. It does not break the food down completely to a molecular level but retains the most basic building block of proteins namely amino acids. Our focus has, however not been amino acids, but nitrogen.
Amino acids cannot exist without nitrogen. Nitrogen is a fundamental component of amino acids, which are the building blocks of proteins. The basic structure of an amino acid includes an amino group (-NH2) and a carboxylic acid group (-COOH), with the amino group-containing nitrogen. Without nitrogen, proteins will be impossible. We can say it like this: The presence of nitrogen in the amino group is not just a component; it’s essential for forming the peptide bonds that link amino acids together into proteins. Without nitrogen, the very structure that defines amino acids and allows them to function as the precursors of proteins would be incomplete, rendering the formation of proteins impossible.
Nitrogen is the only element that can fulfil the unique function it has in amino acids and proteins. Nitrogen is unique in its ability to form the particular chemical structures and bonds required in amino acids, the building blocks of proteins. Each element has its own distinct properties based on its atomic structure, and these properties define its interactions and the types of molecules it can form. Nitrogen’s specific chemical properties make it indispensable for protein synthesis.
Let’s look at the nitrogen cycle again but this time follow it from the atmosphere into the human body and back into the atmosphere.
- Nitrogen Fixation: Nitrogen gas (N2) in the atmosphere is converted into ammonia (NH3) by certain bacteria in the soil and these days also by industrial processes. Some of these bacteria live in a symbiotic relationship with legume plants, fixing nitrogen directly from the air into a form the plants can use.
- Nitrogen Uptake by Plants: Plants absorb nitrogen primarily in the form of ammonium (NH4+) or nitrate (NO3–) from the soil. This nitrogen is then incorporated into plant tissues as amino acids, the building blocks of proteins, and other nitrogenous compounds like nucleotides and chlorophyll.
- Consumption by Animals: When animals eat plants, they consume the plant proteins, breaking them down into amino acids. These amino acids are then used to build animal proteins and other nitrogen-containing compounds in their bodies.
- Human Consumption: Humans, by consuming plant or animal matter, ingest these proteins. In the human body, dietary proteins are digested into amino acids, which are then used for synthesizing human proteins required for various bodily functions, following the body’s genetic instructions.
- Return to the Environment: Nitrogen compounds in the bodies of living organisms are eventually returned to the soil through waste or decomposition, where they can be converted back into nitrogen gas or used by other plants, thus continuing the nitrogen cycle.
I mentioned something above almost in passing when I spoke about nitrogen in plants and animals. The creation of proteins is only one of the functions of proteins in animals and in certain plants. Nitrogen’s role in both plants and animals extends far beyond protein synthesis, impacting various crucial biological functions. In plants, nitrogen is integral to the formation of nucleic acids, including DNA and RNA, vital for genetic processes. It’s also a key component of chlorophyll, the molecule enabling photosynthesis, which is central to plant growth and energy production. Nitrogen significantly influences plant development, affecting everything from leaf growth to fruit and flower production. In animals, nitrogen is similarly vital in the composition of nucleic acids, facilitating cell division and the transmission of genetic information. Additionally, many neurotransmitters, the chemicals responsible for nerve signal transmission, and numerous hormones regulating physiological processes, contain nitrogen. This makes nitrogen an indispensable element, playing a pivotal role in the life processes of both plants and animals.
Now, a question follows if in human digestion, we can use proteins from plants, other than from amino acids to create proteins and fascinatingly the answer is “No”! For humans and all herbivores to utilize nitrogen from plants for protein synthesis, it must be in the form of amino acids. Plants contain proteins composed of amino acids, just like animal proteins. When we consume plant-based foods, our bodies digest these proteins and break them down into individual amino acids. These amino acids are then absorbed and used to synthesize new proteins in the human body. This process is essential, especially for obtaining essential amino acids that the body cannot synthesize and must be sourced from the diet, whether from plant or animal proteins.
Where do cows get the amino acids from to create meat which is what protein synthesis is.
In simpler terms, cows use the protein made by bacteria in their stomachs to create their own muscle tissue or meat. When cows eat grass, the bacteria in their rumen (a part of their stomach) break down the grass. These bacteria not only help in digesting the grass but also create their own proteins. When these bacteria die, they become a source of protein for the cow. The cow then absorbs these bacterial proteins and uses them, along with other nutrients, to build its own body tissues, including the muscle that we refer to as meat. This process is a key reason why cows, which eat primarily grass, can grow and maintain their muscle mass.
Amino acids are then made (synthesized) by plants and bacteria. Humans can also make some amino acids which, as we mentioned above, we call non-essential amino acids. Plants and bacteria produce all the amino acids they need including the essential amino acids. From a human perspective, plants and many bacteria are capable of producing all the amino acids, both essential and non-essential. Many bacteria have the biochemical pathways to synthesize all amino acids. Some bacteria, particularly those involved in nitrogen fixation, play a crucial role in converting atmospheric nitrogen into forms that can be used to synthesize amino acids.
Many plant proteins do contain all the essential amino acids, but often in lower amounts compared to animal proteins. While it’s true that animal proteins such as meat, dairy, and eggs typically contain all the essential amino acids in adequate proportions, making them “complete” proteins, there are also plant-based sources that are complete as well.
For example, quinoa, buckwheat, and soy are plant-based proteins that contain all nine essential amino acids in sufficient amounts. However, most other plant proteins are considered “incomplete” as they are low in one or more of these amino acids. This doesn’t mean they are inferior; it simply means that a varied plant-based diet, combining different sources of plant proteins, can provide all the essential amino acids needed by the body.
This concept is known as protein complementation, where different plant-based foods are eaten throughout the day (not necessarily in one meal) to provide a full profile of essential amino acids. For example, rice and beans, when eaten together, complement each other to provide a balance of essential amino acids.
Meat, on the other hand, has all essential amino acids in high quantities from a human perspective. It provides a complete protein, meaning it contains all nine essential amino acids in proportions that align well with human nutritional needs. Additionally, meat also contains non-essential amino acids.
The high-quality protein found in meat is easily digestible and includes a balance of amino acids that is very similar to what is needed in the human body, making it a highly efficient source for protein synthesis and muscle maintenance. This is one reason why animal-based proteins like meat are often preferred in diets where muscle building or repair is a priority, such as for athletes or in certain medical conditions.
As always, there are lots more to discuss and discover. One of the biggest advances has been in the understanding that nitrogen is far more important in human physiology than only its role in proteins and ammonia. Other nitrogen species like nitrate, nitrite and nitric oxide are essential to making the human body work. One of the biggest over the years has been the vilification of some of these species of nitrogen such as nitrite. Unravelling the truth of the matter is a major theme in my letters.
It was amazing talking to you on the telephone this evening. It makes me realise how much I appreciate discussing these matters with you. The high level of interest you and your brother have in these matters is one of the greatest joys of my life. I cannot wait to spend more time with you and discuss these matters in greater detail in person!
Tons of love,
Your dad.
(c) eben van tonder
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