It has been common knowledge for a few decades now that the nitrates and nitrites added to processed meats such as bacon, ham, hot dogs, sausages, salami and other “cold meats” as preservatives and colour enhancers are not healthy. These chemicals are a substantial part of the reason that processed meats are linked with cancers of the colon, stomach, esophagus, rectum, pancreas, lung, prostate, testes, kidney and bladder (1). In 2015, the World Health Organization concluded that for every 50 grams of processed meat eaten daily, the risk for colorectal cancer increases by 18% (2). The hazards associated with processed meats affect cardiovascular health as well. A 2010 study found 42% higher risk of heart disease from eating processed meat compared to not eating processed meat (3).
Interestingly, it is not only processed meats that expose us to nitrates. They are also present naturally in water and soil and are ubiquitous in many of the plant-sourced foods that we eat. Celery, beets and their greens, rhubarb, cabbage, lettuce, spinach, endive, fennel, cilantro, arugula and parsley are especially rich in nitrates (4). So this might leave you wondering if you should be worried about eating these foods. The answer is a definite “No”. In fact, nitrate-rich plant-derived foods are very nutritious. Many studies have determined that nitrates from plants are associated with lower blood pressure and significant reductions in the risk of cardiovascular disease (5,6) and many other chronic conditions (14,17).
The Nitty Gritty on Nitrates and Nitrites
Nitrates and nitrites themselves are not injurious. On the contrary, nitrites are extremely beneficial for the health of blood vessels (37). Problems begin with the reaction that occurs between a nitrite and an amine group from a protein (perhaps from the meat that contains the nitrite) which produces a nitroso compound called nitrosamine (9). Nitrosamines are known carcinogens and are the main cancer-causing agent in cigarettes (8).
Nitrates are dealt with in two ways by the body and circumstances dictate the direction that their transformation will take. The most crucial variable here is the source from which the nitrates came because the human body treats nitrates from plants very differently than it treats nitrates from meats.
Nitrates derived from plants are converted into nitrites by bacteria present in the saliva of the mouth and a portion of these nitrites will then be transformed into a health-giving gas called nitric oxide. None of these nitrites will be converted into nitroso compounds. (37,7).
Nitrates derived from processed meats are also turned into nitrites in the mouth. However, these nitrites do not go on to become nitric oxide. Instead, some of them will be metabolized in the stomach or the large intestine into nitrosamines (9).
Why is the source of the nitrite so important?
Plants contain a wide variety of nutrients within their structures that are favourable to human health. Phytonutrients are a powerful example of these valuable substances. Phytonutrients such as Vitamin C and E, phenolic compounds and others contained in complex mixtures of plant extracts severely inhibit and even prevent altogether the transformation of nitrites into nitrosamines (10).
Processed meats, on the other hand, do not contain any phytonutrients at all. Phytonutrients are beneficial compounds produced only by plants. Compounding this major deficiency is the heme iron in meat that accelerates the formation of nitroso compounds from nitrite in the gastrointestinal tract (11). Furthermore, the nitrates and nitrites added to meat as preservatives can create nitrosamines in the meat even before it is ingested (12,13).
The Valuable Consequences of the Production of Nitric Oxide from Nitrites
The innermost lining of our blood vessels is called the endothelium. If you could closely examine the endothelium and its function you would be amazed. It is only one cell thick. In fact, if laid end to end, the 1.2 trillion endothelial cells from one human being would wrap four times around the world! The endothelium was once thought to be simply an inert lining of blood vessels but it is now considered to be much more than that. Indeed, the endothelium is now deemed the largest endocrine organ of the human body. (Endocrine organs are hormone releasing organs such as the pancreas, the thyroid and the adrenal glands.) Ongoing research continues to reveal the far-reaching positive influences that the endothelium has on human health (14).
The most vital function of the endothelium is its production of a gas molecule called nitric oxide. Nitric oxide is responsible for relaxing the smooth muscle in blood vessel walls to dilate (open up) the blood vessels when nerve and chemical signals from the body call for more blood. Nitric oxide also acts to prevent stickiness between all the different cells that make up the blood in order to keep the blood flowing smoothly (15) and to inhibit inflammation and plaque build-up in blood vessels (16). In this way nitric oxide lowers blood pressure and contributes to lower risks of cardiovascular disease (5,6). Nitric oxide is why nitroglycerin works to dilate coronary arteries and relieve angina pain – our body converts the nitroglycerin to nitric oxide. It’s even why Viagra (sildenafil) works. The drug increases blood flow to the penis through the production of nitric oxide, encouraging an erection. Dysfunction of the endothelium is directly involved with the development of heart disease as well as peripheral vascular disease, stroke, venous thrombosis (blood clots), tumor growth, diabetes, chronic kidney failure, non-alcoholic liver disease and erectile dysfunction (14,17).
In addition, many studies show that dietary nitrates from vegetables can enhance physical performance in intense exercise. Though the exact mechanism has not yet been determined, nitrates seem to increase the efficiency of the mitochondria, the energy-producing part of cells (18), and also may encourage greater uptake of glucose by muscles and prolong muscle excitability (19). These nitrate studies used beetroot juice and diets rich in vegetables as the nitrate sources.
Nitric oxide is of prime importance to human health. This is an element that we definitely want to encourage in our bodies.
The Destructive Consequences of the Production of Nitrosamines from Nitrites
It is generally agreed among researchers and health professionals that processed meat is a cause of cancer. The exact mechanism is still unclear but it is thought to be due to the combination of nitrosamine, heme iron and free radical formation resulting in DNA damage that promotes the formation of tumors (20,21,22,23,24,25,26).
There are many cancer-promoting factors present in processed meat. Some of these are (27,28,29,30);
1 The presence of high levels of fat that may promote carcinogenesis through insulin resistance or fecal bile acids
2 The presence of heme iron that can not only accelerate nitrosamine production, but also promote cancers through increased cell growth in body tissues and oxidative stress (inflammation)
3 The presence of carcinogenic nitroso compounds such as nitrosamine, either preformed in the meat or produced in the body from nitrites which originated from meat
4 The high temperatures at which processed meats are often cooked which can produced heterocyclic amines and polycyclic aromatic hydrocarbons, known cancer-producing compounds
The threat from processed meat intake does not stop at cancer. High consumption of these products is also associated with increased early death from all causes (31,32). Other research has discovered higher risks of cardiovascular disease and type-2 diabetes with consumption of processed meat compared to eating unprocessed meat (33). Additionally, investigations have shown that nitrosamines play a role in the development of Alzheimer’s Disease, non-alcoholic steatohepatitis (NASH) and type-2 diabetes (34).
Nitrosamines are a danger to human health and an element that we definitely do not want to encourage in our bodies.
Why not just add phytonutrients to processed meat to prevent the formation of nitrosamines?
You can be sure that processed meat producers have thought of this angle. They’ve experimented with adding Vitamin C to processed meats but the added phytonutrient is simply not successful in reducing the production of nitroso compounds. Quite the opposite actually. In the presence of the fat that is an integral part of meat, the addition of phytonutrients not only does not prevent the production of nitroso compounds, it multiplies their formation by up to 140 times (35).
What about “uncured” processed meats?
When it comes to processed meats, uncured does not mean the absence of nitrates or nitrites. A vegetable source of nitrates/nitrites, usually celery powder, is been added to so-called “uncured” meats to cure the product. Puzzlingly, celery powder is allowable as an organic ingredient even though the celery itself is not required to be organic. Note that non-organic celery is notoriously high in concentrated pesticides and fertilizers. Also the celery is significantly processed during its production for use in processed meats. Additionally, the chemical composition of nitrates/nitrites from celery is exactly the same as that of the synthetic chemicals. The amounts used are similar as well (36).
What about the health effects from celery-cured meats? There is no evidence that nitrates/nitrites from celery have biological effects that are any different than those from synthetic nitrates/nitrites (36).
Keep in mind that there are two sides to nitrates.
For best health, emphasize the beneficial “Dr. Jekyll” nitrates that dwell in plants and avoid the damaging “Mr. Hyde” nitrates that lurk in processed meats.
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