In light of the many questions received following my recent American Heart Association Keynote address and cooking demo; I’ve decided to re-share this post.
With the ongoing red meat controversy and so many shrugs of the shoulder saying “it’s the nitrates;” when in fact it may be the choice of meat, processing, other additives, etc., here’s some food for thought
NO 2 Bacon?
A Commentary in 5 Easy Slices
Bacon: The Good, the Bad, and the Crispy
In my previous book, The Fallacy of The Calorie: Why The Modern Western Diet is Killing Us and How to Stop It, as well as my latest publication, The Food Shaman, I discuss in depth the role and importance of fat in a healthful diet. This also includes a discussion about the role of different proteins, including red meat, in the pursuit of health and wellness and all things scrumptious. In defiance of the conventional wisdom, the data continues to define a neutral and in some cases potentially positive health benefit for those that consume fresh red meat. However, there seems to be a clear association with respect to consumption of highly processed foods, especially heavily processed red meat products, and the development of certain disabilities and diseases.
But what about the gray areas?
What about something like…bacon?
Pork bacon is cured and in fact is defined by the USDA as “the cured belly of a swine carcass.” In other countries, other parts of the pig are used; for example Canadian bacon comes from the pork loin. For those more deeply interested in the aged but divinely delicious, including how to make your own, I suggest Michael Rhulman’s enjoyable and definitive tome on the topic; Charcuterie
Commercially produced meats like bacon undergo extensive processing and are often subject to a number of artificial preservatives, flavorings and modifiers. With an ingredient list that reads like an inorganic chemistry textbook and a shelf life longer than your mother’s memory, these industrial forms clearly march to a processed beat.
But what about the home spun versions?
What about a slab of pork belly from an organically raised, free pasture, heritage breed?
This porcine portion requires only the addition of salt, herbs, spices and a touch of curing salt to transform it into one of the most crisp-i-licious concoctions ever to cross the palate. Curing salt is a slightly pink mixture of salt that contains sodium nitrite at a concentration of 6.25%. This correlates to concentration of only about 120 parts per million.
But the amount of nitrite we consume is substantially less. This is because during the curing process, most of this nitrite will be converted to nitric oxide. The nitric oxide then binds to the iron in the meat giving cured foods like bacon their pinkish hue. The remaining amount of nitrite is estimated to be only about 10 parts per million. This curing process, by the way eliminates pesky little inconveniences, like botulism and listeria.
Nitrates, Nitrites and NO, NO, NO!
For years the conventional wisdom has blamed any ill health effects from bacon at the feet of the nitrites and nitrates, such as the aforementioned sodium nitrite, that are added during the preservation process.
But what are these compounds and what is the truth behind this porcine puzzle and the “no artificial nitrates/nitrites added” bacon bluster?
Both nitrites and nitrates in this setting refer to compounds which contain a nitrogen molecule and two oxygen molecules in the case of nitrites, and three oxygen molecules in the case of nitrates. They occur naturally in many forms throughout the environment, including many of the fresh, wholesome foods we eat (more on that later) and are produced in our own bodies where they are critical for the maintenance of life.
Like many of the food myths that have become conventional wisdom, the story about the detrimental effects of nitrates and nitrites began with animal experiments during the 1970s.
The original research that started the row was performed under the direction of Dr. Newberne at MIT at the request of the FDA. This in turn was generated from public concern over possible carcinogenic effects of nitrates and nitrates. Previously for hundreds, if not thousands of years, nitrates and nitrites had been valued as a healthful adjunct; dating back to at least 2200 BC where the addition to meat preservation was in the form of naturally occurring saltpeter (potassium nitrate).
The modern concern over the carcinogenicity of nitrites centered on the development of lymphatic cancer in a strain of rats as demonstrated in Dr. Newberne’s study done in the mid-1970s. However, a more careful analysis in 1978 by an outside review found that than the original MIT study was flawed. In 1980, a final report from the intra-agency Ad Hoc Working Group (IAWG) consisting of scientists from the FDA, USDA, and NIH was issued on August 15 which failed to confirm the carcinogenicity of nitrite.
When the original pathology slides were reevaluated by a committee consisting of members from fifteen different universities; they found a “reduction of incidence [of lymphomas] to approximately 1% among treated and control groups. This rate of lymphoma incidence is similar to that usually seen spontaneously in Sprague-Dawley rats.” One of the reasons for the discrepancy may have been, as later determined by an investigation under the auspices of the Government Accounting Office (GAO), that “a major portion of his pathological diagnoses was done by students not Dr. Newberne himself.” The final report stated unequivocally that nitrite is not a carcinogen at the doses studied.
These findings were reconfirmed in a 1981 review of nitrites, nitrates, and human cancer risk performed by National Academy of Sciences. Today more than fifty additional studies and reviews have failed to demonstrate a link between nitrites, nitrates, and the risk of developing cancer.
NO, NO, NO!
The reason may have to do with the important biological role of nitric oxide. Nitric oxide is a molecule consisting of a nitrogen molecule and an oxygen molecules; NO. It was named the molecule of the year 1992. For discovering its potent an important biological effects as a cardiovascular signaling molecule; Robert F. Furchgott, Louis Ignarro, and Ferid Murad were awarded the Nobel Prize in 1998.
A biological pathway known as the nitrate-nitrite-nitric oxide pathway increases the available levels of nitric oxide. This exogenous pathway utilizes dietary nitrate and nitrites. Which of course, makes one wonder that if the only source of ingested nitrates and nitrites were artificial additives from Dow Chemical, how come there was a biological pathway already in place to put this to good use. Well, it turns out that most of the nitrates and nitrites that we consume come from plants!
And not just any plants. The leafy greens that are all too lacking in the modern Western diet and which are part of healthful diets across the globe are major sources of nitrates and nitrites that fuel this commanding need for such a physiologic powerhouse. Arugula, bok choy, spinach, lettuce, Swiss chard, celery, red beet roots, Chinese cabbage, radish, endive, mustard leaf, and fennel are a few of the vegetables that furnish the raw materials for our bodies to produce nitric oxide (NO).
But there is an important intermediate step. For us to produce our needed nitric oxide via this mechanism, we need minions. Specifically, we need the right combination of bacteria in our gut (including oral) microbiome [an important topic covered in my latest book, The Fallacy of the Calorie] for this reaction to occur. Eating foods rich in nitrates and nitrites has been shown to reduce the blood pressure and to inhibit platelet aggregation (the reason for the daily aspirin therapy in heart patients) and deliver other beneficial vasoprotective effects via just such a mechanism.
And the primary source of such foods within our diet is vegetables. Depending on the composition, it is estimated that less than 5 to 10% of all dietary nitrites come from such cured meats as bacon. Interestingly, the nitrites and nitrates that we consume from plants are actually the results of the symbiotic relationship between plants and nitrogen fixing bacteria.
It is these bacteria that provide the nitrites and nitrates that we gobble when we eat the greens. Studies suggest that on average 93% of the nitrites consumed each day come from vegetables. Despite being the source of such high nitrate and nitrite concentrations, the opinion of the Scientific Panel on Contaminants in the Food chain on a request from the European Commission to perform a scientific risk assessment on nitrate in vegetables, concluded that “Overall, the estimated exposures to nitrate from vegetables are unlikely to result in appreciable health risks, therefore the recognised [sic] beneficial effects of consumption of vegetables prevail.” In other words, like your Momma told you, shut up and eat your veggies.
The Great Pretenders, Natural and Uncured
If dietary nitrates and nitrites are primarily derived from consuming vegetables and potentially yield health benefits –aren’t we all constantly berated to consume more vegetables, particularly leafy greens – then do we need to be paying exorbitant amounts of money for “natural,” “uncured,” or “no artificial nitrite/nitrate added” bacon?
The answer to that query would be “NO, NO, NO.” Starting with quality ingredients and adding the small amount of sodium nitrite required to eliminate the risk of botulinum poisoning and Listeria infection does not corrupt the endeavor.
The commercial products touting their “natural” or “no added nitrites” label are not a superior solution. These overpriced products are often treated and cured by using a “natural” source of NO2 or NO3 such as celery or beet juice along with salt, often in the form of sea salts. These products have been shown to have similar characteristics as traditionally cured meats; in fact this replicates many of the curing methods for various meat products prior to 1926.
By law, since they do not add sodium nitrite they must be labeled “uncured” although in fact they are cured using the same chemistry that occurs when you add sodium nitrite to your pork bellies. While you may be paying a whole lot more for their product, a nitrate or nitrite by any other name is chemically the same. In fact, if dietary nitrites and nitrates caused cancers or other ill health effects; vegetarians and vegans would be dropping like flies.
The reason they don’t is that in addition to the bulk of nitrates and some nitrites coming from vegetables, 70-97% of our total nitrite exposure comes from our own saliva. And the nitrate in the food and water (yes, water is a source of nitrate accounting for up to 21% of our daily nitrate intake) we ingest is then converted to nitrite by our gut microbiome (approximately 5%–10% of the total) and our own enzymes. A total of about 25-45% of the total nitrate ingested is converted to nitrite. The rest is excreted in the urine with about 60-70% of ingested nitrate being excreted within 24 hours.
The nitrite (NO2) is then quickly absorbed into the systemic circulation where it can be converted to nitric oxide (NO). The average half-life of NO2 once absorbed is only one to five minutes before it is converted to NO.
This NO is identical to the NO produced by the endogenous pathway via the metabolism of L-arginine by nitric oxide synthase (the nitric oxide synthase (NOS) pathway). This is the same L-arginine added and sold as a supplement to increase your body’s levels of NO; also known as the endothelium-derived relaxing factor, or EDRF, for better health. A molecule by any other name…..The NO is then used by the body, recycled via enterosalivary circulation or excreted as a nitrite or nitrate.
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. 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 preventing erectile dysfunction among many others.
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!
 (St. Hilaire, 2014) page 48
 (St. Hilaire, 2014) page 51
 (Lundberg, Weitzberg, & Gladwin, 2008)
 (Hezel & Weitzberg, 2013)
 (Webb, et al., 2008)
 (European Food Safety Aurthority, 2008)
 (European Food Safety Aurthority, 2008)
 (Sullivan, 2011)
 (Agency for Toxic Substances and Disease Registry; HHS, 2013)
 (Sullivan, 2011)
 (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 .