Should we be concerned about nitrites or nitrates in bacon? Meat retailers are experiencing a downturn in demand for bacon due to resistance from people who are concerned about health risks of eating meat. Let’s examine this.
The plant based lobby is working hard to discredit animal based foods despite our ancestors regularly eating meat or fish, often as the only food consumed. The dominance of these animal and fish based diets over thousands of years have been confirmed by isotope testing of human remains (Richard’s M.P. et al. 2009) and are still the basis of a number of traditional diets for groups such as the Masai, Inuit, Hadza and Tokelau Islanders. These groups, eating traditional diets, do not apparently suffer from the cancers common amongst people eating a modern diet. It is revealing to note that as these people migrate to a more western diet, their health declines. The Australian aborigines and Pima Indians of Arizona are well documented examples of this change from predominantly meat based diets to western diets and their resulting health issues.
In 1906-12, American doctor and anthropologist, Vilhjalmur Stefansson, lived with the Inuit in Northern Canada for about 5 years eating their nearly 100% animal based diet of fish, caribou, whale, seal and other smaller animals without any significant health issues. He recorded their good health and longevity and noted in his diaries and books that he very rarely observed any cancer.
Dietary comparison is difficult due to the number of confounding factors. For example, vegetarians and vegans are often very particular about what they eat meaning that a study finding benefits from their diet may be unable to establish if the benefit came from eating vegetables or from avoiding sugar, alcohol, processed foods or refined grains. In addition, meat eaters as a group often include people who are less concerned about their diet, seldom exercise, consume alcohol frequently and eat lots of processed food, all of which can contribute to poor health.
Colon cancer is sometimes linked to meat consumption and there are studies about this. However, a UK study (Tim Key, 2022) examined data on 63,550 men and women aged 20 to 89 recruited throughout the UK during the 1990s. They obtained the cancer incidence figures from national cancer registries. They concluded: “Within the study, the incidence of all cancers combined was lower (11%) among vegetarians than among meat eaters, but the incidence of colorectal cancer was higher in vegetarians (39%) than in meat eaters.”
One of the concerns raised about eating bacon is the presence of Nitrates and Nitrites initially present in the meat and added for the curing process, to preserve the meat, extend the shelf life, and to keep it looking red and delicious. They suppress the bacteria that causes Botulism in meat and, without them, the meat can look grey and unappealing.
Nitrates (NO3) are relatively stable and, therefore, in small quantities they are unlikely to change and cause harm, however bacteria and enzymes in the mouth will convert them to nitrites. The nitrites are then converted by stomach acid to Nitric Oxide (NO). This is beneficial.
Nitrites (NO2) which come into contact with protein are converted to nitric oxide which is very beneficial for the body and is a natural anti-bacterial. This helps lower blood pressure, helps people with angina, and relaxes artery walls, assisting with blood circulation and is the active compound in Viagra. Nitrites are not stable and in the 1970’s it was suggested that heating them can create Nitrosamines which can be carcinogenic. The good news is that these nitrosamines are heat-labile, ie: altered or destroyed by high heat (Am J Clin Nutr. - 2009).
Curiously people are less concerned about nitrates and nitrites in vegetables, which is where 80% of the ingested nitrates and nitrites come from, according to the above study. Beetroot greens and juice are touted as health foods because of the abundant nitrites which convert into Nitric Oxide when eaten. Celery for example, is very high in nitrites, can be ground into a powder and used as a replacement preservative in processed meats. When this is done the meat, must by (US) law, be labelled as “uncured”.
There is no difference in the action of the nitrites regardless of the source. The craziness is that (in USA) when the nitrite comes from sodium (or potassium) nitrite, it’s regulated (allowable levels vary by product). There are no limits for nitrite from celery powder, which means that bacon labeled as “uncured” may actually contain higher levels of nitrites. It turns out that almost all meat labelled “uncured” has been treated with vegetable based nitrites.
Nitrites are also present in drinking water and naturally occur in saliva, where they function as an anti-bacterial with, for example, the ability to kill salmonella. Nitrite in saliva increases gastric mucosal blood flow and mucus thickness helping digestion. This action removes toxins, and helps with acid buffering by supporting bicarbonate production downstream of the stomach.
The summary of one study claimed: “These results indicate that dietary nitrate may serve important gastro-protective functions”.
In a study (N P Sen, et al. 1980) the nitrosamine levels detected in both cured and uncured meat products (both cooked and uncooked) were very low and were degraded and destroyed by cooking at high heat and, therefore, would not be expected to occur in fried foods at significant levels.
Like most dietary substances there are upper limits. Excess nitrate (NO3) which has no taste or smell, can affect how our blood carries oxygen. Nitrates can turn hemoglobin (the protein in blood that carries oxygen) into methemoglobin . High levels can turn skin to a bluish or gray color and cause more serious health effects like weakness, excess heart rate, fatigue, and dizziness. This is sometimes referred to as “blue baby syndrome” as babies are particularly vulnerable. In some US farm areas warnings are issued when nitrate levels get too high in drinking water.
In New Zealand, if nitrate (NO3) levels in drinking water exceed 50 mg/L, then it must be treated. Boiling or disinfectant has zero impact on this. Generally only private bore water would have this problem with rain water unlikely to be affected and community supply water regularly tested for this.
One study (Dubrow et al. 2010) examined 545,000 participants of which 585 were diagnosed with Glioma, (Brain Tumors). They were testing the hypothesis that Nitrosamines derived from dietary Nitrites (NO2) elevated the risk of brain tumors. Their conclusions stated:
“We found no significant trends in glioma risk for consumption of processed or red meat, nitrate, or vitamin C or E. We found significant positive (not good) trends for nitrite intake from plant sources and, unexpectedly, for fruit and vegetable intake. Further work is needed on early life diet, adult intake of nitrite from plant sources, and adult intake of fruit and vegetables in relation to adult glioma risk”. “We observed an unexpected finding of increasing glioma risk with increasing intake of fruit and vegetables. ~~~ which may be due to pesticide residues consumed with fruit and vegetables”
What about the fat in bacon? The fats in bacon are about 50% monounsaturated and a large part of those is oleic acid. This is the same fatty acid present in olive oil and is generally considered “heart-healthy”. The remaining fat in bacon is 40% saturated and 10% polyunsaturated, accompanied by some cholesterol. Dietary cholesterol was a concern in the past, but scientists now agree that it has very minor effects on cholesterol levels in your blood, while the Sydney Diet Health study showed us that saturated fat is healthy.
Maybe bacon does not need to be avoided?
Seek professional medical advice before making dietary changes, particularly if you have underlying health problems.
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Good health, George Elder, Diet Researcher, Dip. Nutrition.