Food is an essential part of our daily lives. It is necessary to sustain ourselves and lead healthy lives. Some of us may take it for grunted and forget how privileged we are not to feel starved. However, despite our efforts to maintain healthiness through our food choices, have we ever asked what is in the food we consume? Is it just nutrients?

In recent years, there has been growing concern about the presence of nitrosamines in our food supply and their potential link to cancer. Nitrosamines are a class of chemical compounds that are formed when certain foods and additives react with nitrogen-based compounds, such as amines or amides, under certain conditions. This process, known as nitrosation, can take place during food processing, storage or cooking, particularly when certain conditions are met, such as high heat, low pH and the presence of precursors. While the research on the topic is still evolving, there is evidence to suggest that exposure to nitrosamines may increase the risk of developing certain types of cancer.

Sources of nitrosamines

Nitrosamines can be found in a variety of food sources, with some common examples including processed meats, such as bacon, as well as smoked and cured fish. They can also be present in some dairy products, beer and even in certain vegetables and fruits that contain naturally occurring nitrate and nitrite compounds. Additionally, nitrosamines can form during food processing and cooking processes, particularly when high heat and certain ingredients are involved. Some common examples include:

• Processed meats: Bacon, sausage, hot dogs, ham and other cured or smoked meats are known to contain nitrosamines. Nitrite salts, used as preservatives in processed meats, can react with amines present in the meat, leading to nitrosamine formation.
• Smoked and cured fish: Similar to processed meats, nitrosamines can form in smoked and cured fish products due to the smoking and curing processes.
• Dairy products: Some cheese and milk products may contain nitrosamines, as they can be formed during the fermentation process or due to contamination.
• Beer: Nitrosamines can be formed during the malting and brewing process of beer, particularly when malt is dried using indirect-fired kilns.
• Vegetables and fruits: Certain vegetables and fruits, such as spinach, lettuce and beets, contain naturally occurring nitrate and nitrite compounds. Under certain conditions, these compounds can react with amines in the stomach to form nitrosamines.

Although nitrosamines can be harmful to our health in various ways, particularly due to their carcinogenic properties, they do have some beneficial uses. They have antimicrobial properties, which can help prevent the growth of harmful bacteria in processed meats. Additionally, nitrosamines can contribute to the characteristic flavours and colours of certain foods, such as smoked meats and fish.          

The health risks nitrosamines pose to one's health

Nitrosamines are carcinogenic and are consequently linked to an increased risk of developing certain types of cancer, such as gastric, oesophageal, colorectal and bladder cancer since they can interact with our DNA causing mutations and cellular damage. This is believed to be the primary mechanism through which these chemicals cause cancer. Additionally, nitrosamines may encourage cancer development by promoting cell proliferation together with the growth and survival of cancer cells through their interactions with cellular signalling pathways and the production of reactive oxygen species. Furthermore, nitrosamines can be metabolised in the body to form reactive compounds, such as alkylating agents, that can bind to DNA, leading to genetic alterations and potential cancerous changes. Likewise, nitrosamines may also promote the growth and progression of existing cancer cells through various mechanisms.

These chemicals aren't only carcinogenic but may also cause liver and kidney damage as was depicted in some animal studies.

What can be done

Due to the potential health risks associated with nitrosamines, regulatory bodies around the world have implemented measures to minimise exposure to these compounds. For example, the United States Food and Drug Administration (FDA) has set limits on the levels of nitrosamines in various food products, particularly in processed meats. The European Union has also established regulations to control nitrosamine formation during food production and has set maximum limits for specific nitrosamines in various food categories.

While efforts are being made to minimise nitrosamine formation and exposure, consumers can take certain steps to reduce their intake. Choosing fresh, unprocessed foods and avoiding processed meats can help lower nitrosamine consumption. Additionally, proper storage and cooking methods, such as avoiding overcooking or charring, can help reduce nitrosamine formation.

While further research is still needed to fully understand the extent of the cancer risks associated with nitrosamines and to explore additional sources and preventive strategies, ongoing surveillance and monitoring of nitrosamine levels in food products are essential to ensure public safety and guide regulatory actions. Furthermore, educating consumers about the potential risks and encouraging the consumption of fresh, unprocessed foods is of paramount importance.

Alternatives to nitrosamines

In the food industry, alternatives to nitrosamines are being explored to reduce the cancer risks. Some potential alternatives include:

• Natural antioxidants: The addition of natural antioxidants, such as ascorbic acid (vitamin C) or alpha-tocopherol (vitamin E), can inhibit nitrosamine formation.
• Alternative curing methods: Novel curing techniques, like the use of natural brine mixtures or plant-derived compounds, are being investigated as alternatives to traditional nitrite-based curing processes.
• Modified Food Processing: Optimising processing conditions, such as temperature, pH, and the use of additives, can minimise nitrosamine formation

Conclusion

Understanding the scientific intricacies of nitrosamines provides valuable insights into their potential risks and impact on health. As seen throughout this article various processes that one may overlook can lead to the formation of these chemicals. Thus, implementing regulatory measures, exploring alternative additives, modifying food processing techniques and educating the public are essential in minimising nitrosamine exposure.

Renald Blundell is a biochemist and biotechnologist with a special interest in Natural and Alternative Medicine. He is a professor at the Faculty of Medicine and Surgery, University of Malta

Emma Camilleri is currently a medical student at the University of Malta