Nitrites- A health plus?
Nitrogen is the most abundant chemical element in the earth’s atmosphere. It is critical in the construction of innumerable biomolecules such as amino acids, vitamins, hormones, enzymes and nucleotides and therefore is indispensable in the physiology of living organisms. Without nitrogen there is no life as we know it.
In fact, there is a well described nitrogen cycle; in which nitrogen is constantly exchanged between plants, animals and the inorganic environment. In summation, since nitrogen is utilized naturally in our bodies and also comes from our foods; not only is it safe, but it is an integral part of human biology. According to the National Research Council, there is no evidence for nitrite or nitrate carcinogenicity.
The concern over nitrates and nitrites is that they could lead to the formation of N-nitrosamine compounds. These compounds have been shown to be carcinogenic. The singular concern is for the formation of N-nitroso compounds (NOCs) and their formation in the stomach or within the food itself. Such NOCs have been shown carcinogenic in animals when exposed to high levels. Whether these compounds form in humans in normal dietary conditions in large enough amounts to pose a health risk, however, has not been established. In fact, as it turns out, the pH of our gastric juices doesn’t support nitrosamine formation and there are other substances in our body that inhibit their formation (like ascorbic acid).
Nitrites and nitrates can combine with natural amines from proteins to form various NOCs. However, the concentrations of nitrosamines in bacon have been studied and have been determined to be at undetectable levels, according to the USDA. In addition, the very act of frying bacon does more than imbue it with crunchy goodness; it volatizes many of these nitrosamines. For any residual compounds that persist, it seems that their absorption can be blocked by the addition of ascorbic acid or ascorbate.[i] It just so happens that our stomach and upper GI tract excretes copious amounts of just such a compound every time we eat. It is almost as if we were born into such a friable, golden brown delight.
At the same time as the warnings began to take on a Henny Penny tone, potential health benefits from nitrites began to slowly seep to the surface. As multiple studies have shown over the last several decades, dietary nitrites demonstrate multiple healthful functions. Researchers at the University of Aberdeen observed that oxides of nitrogen are formed in the acidic stomach after swallowing salivary nitrites. As far back as 1994, Dr. Jon Lundberg, M.D., Ph.D., of the Karolinska Institutet in Stockholm, and Dr. Nigel Benjamin of Peninsula Medical School in Exeter, England, independently noted that the human stomach holds large amounts of these compounds like nitric oxide.
These chemicals provide for us a natural antimicrobial barrier. They have potent antimicrobial action against a wide range of gastrointestinal pathogens, such as Yersinia enterocolitica, Salmonella enteritidis, S. typhimurium, Shigella sonnei, E. coli O157:H7, Helicobacter pylori, and Candida albicans.
Interestingly, research has shown that after we eat gastric pH rises; in other words the stomach becomes less acidic. The antibacterial actions of the gastric juices increases with nitrate concentrations, and after eating the stomach fluids are not very good protection against food borne pathogens unless nitrite is present. Therefore nitrites appear to have a biological function to help protect us against stomach infections and foodborne illnesses. It would have been very important in the times before food safety to eat your veg with your meats, poultry and fish! Also it has been observed that that cavity-causing bacteria die in high-nitrite environments. Which of course makes sense, because you can’t gum perfectly prepared bacon!
Nitrites are being studied for many potential pharmacological roles in various medical treatments, including in hypertension, heart attacks and sickle cell. They are being studied as an adjunctive therapy for intubated patients; because they cannot swallow their saliva and therefore lack the potentially protective effects. Such therapy may help in the treatment of ischemia-reperfusion injury, gastric ulcers, cerebral vasospasms, and in neonatal pulmonary hypertension. Nitric oxide which is in part produced from consumption of dietary nitrites is involved in vasodilation, platelet aggregation, enzyme regulation, antioxidant activity, iron regulation, immune response, metabolic regulation, apoptosis, and erectile dysfunction among many others.[ii]
As Dr. Ferric Fang, M.D., professor of laboratory medicine and microbiology at the University of Washington in Seattle has noted, “We’ve gone from considering all of these things to be toxic and carcinogenic to realizing that [nitrites are] playing a fundamental homeostatic role. They’re a normal, natural part of a healthy body and not chemicals to fear.” A study in the Journal of Food Protection put it another way: “Since 93% of ingested nitrite comes from normal metabolic sources, if nitrite caused cancers or was a reproductive toxicant, it would imply that humans have a major design flaw.” Dr. Nathan Bryanm Ph.D., from the Institute of Molecular Medicine at the University of Texas in Houston added, “The public perception is that nitrite/nitrate are carcinogens but they are not…Many studies implicating nitrite and nitrate in cancer are based on very weak epidemiological data. If nitrite and nitrate were harmful to us, then we would not be advised to eat green leafy vegetables or swallow our own saliva, which is enriched in nitrate.”
As always, the medical truism that the poison is in the dose; applies. While anything, even water-yes water- in excess can be toxic; to consume a toxic level of nitrite would require eating 278 to 556 pounds of bacon in a single meal. So this year make your porking personal; don’t just bring home the bacon-make it!
[i] (Sullivan, 2011)
[ii] (Sullivan, 2011)
Agency for Toxic Substances and Disease Registry; HHS. (2013). Nitrate/Nitrite Toxicity. ATSDR Case Studies in Environmental Medicine, 1-130.
European Food Safety Aurthority. (2008). Nitrate in vegetables: Scientific Opinion of the Panel on Contaminants in the Food chain (Question No EFSA-Q-2006-071). The EFSA Journal , 689:1-79.
Hezel, .. M., & Weitzberg, E. (2013). The oral microbiome and nitric oxide homoeostasis. Oral Diseases, 1:7-16 DOI: 10.1111/odi.12157.
Lundberg, J. O., Weitzberg, E., & Gladwin, M. T. (2008). The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nature Reviews Drug Discovery , 7, 156-167;| doi:10.1038/nrd2466.
St. Hilaire, C. (2014, December 26). An Anatomy of Risk Assessment: Scientific and Extra-Scientific Components in the Assessment of Scientific Data on Cancer Risks; Nitrites. Retrieved from The National Academic Press: http://books.nap.edu/openbook.php?record_id=776&page=43
Sullivan, G. A. (2011). Naturally cured meats: Quality, safety, and chemistry. Retrieved from Iowa State University: http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=3179&context=etd
Webb, A. J., Patel, N., Loukogeorgakis, S., Okorie, M., Aboud, Z., Misra, S., . . . Ahluwalia, A. (2008). Acute Blood Pressure Lowering, Vasoprotective, and Antiplatelet Properties of Dietary Nitrate via Bioconversion to Nitrite. Hypertension, 51:784-790 doi: 10.1161/HYPERTENSIONAHA.107.103523 .