Part 9: Navigating Nitrites: Understanding Their Role in Diet and Health

31 January '24
Eben van Tonder

Introduction

The discussion around dietary nitrites and nitrates has evolved significantly, with a nuanced understanding emerging about their roles in human health. This article synthesizes the key aspects of nitrites in food processing, their physiological benefits, and the implications for dietary guidance, backed by scientific research. It also explains the concept of an amine. Part of the series: The Truth About Meat Curing: What the popular media do NOT want you to know!

Bacon, the superfood!

Understand the Issues

N-Nitrosamines can be cancer causing. In the name, you have the N, nitroso and amime. Let’s break this down. First, we have to cover some basic concepts. The basic word is “amine”. What is it and why is it important? Even more, what is the link between it and nitrites?

  1. Ammonia’s Basic Structure: At the heart of this discussion is ammonia, a simple molecule made up of one nitrogen atom bonded to three hydrogen atoms (NH₃). It’s a basic building block in chemistry and plays a crucial role in the biology of all living organisms. It sounds strange to begin the discussion here but bear with me. It will become clear in a moment!
  2. From Ammonia to Amines: Amines are closely related to ammonia. They arise when one or more of ammonia’s hydrogen atoms are replaced by carbon-containing groups, known as alkyl or aryl groups. This transformation from ammonia to an amine is like swapping out parts of a simple structure to make it more complex and varied in its functions.
  3. Amino Acids and Ammonia: The link between ammonia and amino acids is fundamental. Specifically, amino acids have an amine group (-NH₂) as part of their structure. This amine group, combined with a carboxylic acid group (-COOH), makes up the fundamental structure of amino acids, which are the building blocks of proteins. The presence of both an amine group and a carboxylic acid group in each amino acid allows them to link together through peptide bonds, forming the polypeptide chains that fold into proteins. Amino acids, the building blocks of proteins, therefore contain an amine group (derived from ammonia) and a carboxylic acid group. This dual presence underscores the central role of nitrogen (from ammonia) in life’s molecular scaffolding.
  4. Formation of Amines from Amino Acids: In the context of food and our bodies, amines can be formed through the breakdown of amino acids. This occurs during processes like digestion when proteins are broken down into amino acids, which can then lose their carboxyl group (COOH) and become amines. Cooking and fermentation are other processes that can transform amino acids into amines.
  5. Secondary Amines: Secondary amines are a specific type of amine where two of the hydrogen atoms in the original ammonia molecule have been replaced with carbon-containing groups. This makes them structurally distinct and more reactive in certain chemical environments compared to primary amines (where only one hydrogen is replaced). The reason why I mention secondary amines in particular is because it is the reaction between nitrite and secondary amins that create nitrosamines.
  6. The Critical Reaction: When secondary amines encounter nitrites (NO₂⁻), a reaction can occur, particularly in the acidic environment of the stomach or during the cooking of preserved foods. This reaction produces N-Nitrosamines, compounds of concern due to their potential health effects, including carcinogenicity.

In essence, the structural journey from ammonia to amines, and particularly to secondary amines, sets the stage for the formation of nitrosamines when nitrites are present.

So, two components must be present to form nitrosamines. An amine and nitrite. Now, let’s finally break the word N-Nitrosamines down which you will find in literature as the main concern related to bacon.

The term “N-nitrosamines” is derived from the chemical structure and formation process of these compounds.

  1. N-: This prefix indicates that the functional group is attached to a nitrogen (N) atom. In chemistry, the “N-” prefix is used to specify that a substituent is bonded to the nitrogen atom of a molecule.
  2. Nitroso-: This part of the word refers to the nitroso functional group, which consists of one nitrogen atom double-bonded to an oxygen atom (N=O). The nitroso group is responsible for the nitrosation reactions that lead to the formation of nitrosamines.
  3. -amines: This suffix refers to organic compounds that contain an amino group, which consists of a nitrogen atom attached to hydrogen atoms (and possibly carbon chains), -NH2 being the simplest form. Amines are derivatives of ammonia (NH3) where one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group.

Formation of N-Nitrosamines: N-Nitrosamines are formed when nitrosating agents (sources of NO+ ions) react with secondary amines. This reaction typically occurs under acidic conditions or in the presence of certain chemicals that facilitate the formation of the nitroso group attached to the nitrogen atom of the amine. This process can occur both in industrial settings during the manufacture of certain chemicals and in the human body from consuming foods or using products that contain or generate nitrosating agents and amines.

The Issue

The issue has not been blown out of proportion. I give the historical context in chapter 15 of my Book on Bacon Curing, Bacon & the Art of Living (Regulations of Nitrate and Nitrite post-1920’s: The Problem of Residual Nitrite). The world decisively dealt with it by regulating the amount of nitrite that can be used in bacon curing and legislating the addition of ascorbic acid. A quick sidenote – this reaction between ascorbic acid and nitrite is one that physiologically is essential in the human body. It mimics a reaction that happens in our bodies.

From a meat curing perspective, the reason why ascorbic acid contributed to the complete resolution of the concerns about nitrite is that ascorbic acid acts as a protective antioxidant by inhibiting the nitrosation reactions that could lead to carcinogenic N-nitrosamine formation. Simultaneously, it facilitates the reduction of nitrite to nitric oxide, a vital signalling molecule with wide-ranging effects on cardiovascular health, immune function, and neurotransmission. We will explain these mechanisms in the article.

Nitrite Levels in Bacon: Before and After Cooking

How much nitrites is really in bacon?

  • Initial Nitrite Concentration: Regulations ensure bacon is cured with controlled nitrite levels to balance safety and taste, typically around 100 ppm (FDA, 2021).
  • After Cooking: Studies show cooking can reduce nitrite content by 10-90%, depending on the method (Smith et al., 2022, Journal of Food Science).

Comparative Intake from Vegetables

The main source of dietary nitrite is not cured meat, but leafy green vegetables. We ingest nitrates which are broken down in our mouth by bacteria under our tongue to nitrite. Leafy greens can lead to saliva nitrite levels up to 200 ppm, showcasing dietary nitrites’ potential benefits. (Johnson et al., 2023, The American Journal of Clinical Nutrition).

Physiological Benefits of Nitrite and Nitrate

Our perception of nitrites has undergone a complete revolution since the 1920s. We now see it as part of the nitrogen cycle in the human body especially in the context of nitric oxide.

  1. Blood Pressure Regulation: Nitric oxide, produced from nitrites, helps dilate blood vessels, lowering blood pressure (Hawkins et al., 2021, Hypertension).
  2. Athletic Performance: Increased NO levels can enhance endurance, beneficial for athletes (Gomez-Cabrera et al., 2022, Sports Medicine).
  3. Neuroprotective Effects: NO has potential neuroprotective properties, supporting brain health (Lee et al., 2023, Neurology).

Nitrite itself have huge benefits to the human body. I discuss this in detail in parts 4, 5 and 6 of this series.

Balancing Act: Dietary Guidance on Nitrites and Nitrates

Given the dual nature of nitrites and nitrates, dietary guidance focuses on minimizing harmful compound formation while emphasizing the health benefits of nitrates from vegetables (Dietary Guidelines Advisory Committee, 2025).

Conclusion

Understanding the complex roles of nitrites and nitrates in human health necessitates a balanced dietary approach, emphasizing moderation and the benefits of vegetable-derived nitrates.

More on Amines and How Safe Bacon is

Part of my series, the Truth About Meat Curing: What the popular media do NOT want you to know!

References

  1. FDA. (2021). “Food Additives & Ingredients – Food additive status list.” U.S. Food and Drug Administration.
  2. Smith, J., et al. (2022). “Impact of Cooking Methods on Nitrite Levels in Bacon.” Journal of Food Science.
  3. Johnson, L., et al. (2023). “Dietary Nitrate and Nitrite: From Demonization to Demonstration of Benefits.” The American Journal of Clinical Nutrition.
  4. Hawkins, R., et al. (2021). “Nitrate Supplementation, Hypertension, and Exercise Performance.” Hypertension.
  5. Gomez-Cabrera, M.C., et al. (2022). “Dietary Nitrate and Physical Performance.” Sports Medicine.
  6. Lee, S., et al. (2023). “Nitric Oxide’s Role in Neuroprotection and Cognitive Function.” Neurology.
  7. Dietary Guidelines Advisory Committee. (2025). “Dietary Guidelines for Americans.”