Some plant foods especially root vegetables contain higher concentration of nitrate naturally and so processed meats also contain nitrate or its reduced form nitrite. Nitrates or nitrites can become either vital health beneficial compound or cancer forming agent. So what is it, are nitrates in food healthy or harmful? Should you take nitrate containing vegetables and meat?
Are nitrates in food healthy or harmful cancer forming agent?
What is nitrate? (1, 2)
Nitrate is a compound on nitrogen and oxygen with chemical formula as NO3-. Nitrates are relatively less active and can be turned into more active form nitrites(NO2-). Bacteria in mouth play the major rule in converting nitrates into nitrites also some enzymes to an extent.Human body also produces large amount of nitrates and excreted in saliva.
Nitrates can be reduced to nitrites by bacteria in mouth as well as in gastrointestinal tract.
Nitrites further convert to either nitric oxide(NO) or N-nitrosamines. From intense research it clears that nitric oxide(NO) has many vital beneficiary rules from the aspect of human health, including regulation of cardiovascular function, cellular energy, immune function, neurotransmission, and more. We will come in details shortly in our next article.
On the other hand, N-nitrosamines is carcinogenic i.e. can promote cancers.
So, should you eat vegetables or meat containing nitrate or nitrite?
To find the answer we are going through the following research findings.
Nitrate or nitrite in meat or meat product
Nitrates or nitrites are frequently used for preservation of processed meat like ham, bacon, sausage, hot dogs and other form and also prevent growth of bacteria. Nitrites give a smoked taste, a pinkish color in the meat. (3)Nitrites added to meat may oxidize to nitrates and also nitrates may reduce to nitrites by microorganism. (4)
Many organisations warn about usage of nitrate or nitrite in processing of meat as potential threat to health. Research suggests that high consumption of processed meat may increase the risk of stomach cancer.(5)
A population based cohort study published in The BMJ in 2017, informed nitrate/nitrite from processed meat has been associated with increased risks of different cancers.(6)
Nitrate in vegetables
Usually root vegetables and leafy green vegetables that grows near to the soil including beets, carrots, radishes, turnips, lettuce, rocket, spinach, cabbage, celery and some others contains higher amount of nitrates. However nitrate concentration may vary with the soil of cultivation.
In opposite to nitrate or nitrite in meats or meat products, dietary nitrate of some root and green leafy vegetable is now to be an important source of nitric oxide, via the nitrate-nitrite-Nitric oxide pathway. Dietary nitrate appears to be an essential component of ‘healthy diets’, including DASH diet to lower blood pressure and the Mediterranean diet, with its potential to lower cardiovascular risk. Apart from improving vascular function and lowering high blood pressure dietary nitrates of vegetables also offer health beneficial effects including improve mitochondrial efficiency, performance and some other.(7)
You can also read about best high blood pressure lowering foods.
Research suggests that nitrates in vegetables contribute to the beneficial health effects including protection against cardiovascular disease and type-2 diabetes.(8)
Beets contains higher concentration of dietary nitrate and has many health beneficial rules including lowering high blood pressure. You can read more about this with this link.
Why nitrate or nitrite in meat or meat product can become carcinogenic and nitrate in vegetables has robust health beneficial effects (Why two opposing movements of nitrate?)
Overall what we have observed that what make it different from conversion of nitrite to carcinogenic nitrosamine is presence of protein in meat with nitrite.
Prof. Gunter Kuhnle, Professor of food and nutritional sciences at the University of Reading, U.K., explains the difference as “When you eat nitrates, they are converted to nitrites by bacteria in your mouth. Once the nitrites reach the stomach’s acid, they can turn into either nitric oxide or N-nitroso compounds. N-nitroso compounds like nitrosamines are carcinogenic. What makes processed meats so ideal for forming N-nitroso compounds is that they have a combination of nitrite and proteins from the meat. And the meat’s heme seems to help convert them into N-nitroso compounds.”
On the other hand vitamin C and polyphenols in vegetables inhibit the process of nitrosamine formation.(9, 10)
World Health Organization’s International Agency for Research on Cancer (IARC) concluded that vitamin C or other antioxidants inhibit the process of formation of carcinogenic N-nitrosamines in the stomach.(11)
You can read more about antioxidant and free radical health damage and premature aging.
Bottom line:
The above analysis our attempt to bring out a picture of whether nitrates in food are healthy or harmful based upon recent research findings. In near future, we aspect more well researched studies to find out the whole mechanism.
We have mentioned earlier also that excessive consumption of even a healthy food goes against the nature. Intake of high dietary nitrite is associated with an increased risk of adult glioma and thyroid cancer-as informed by Cancer Therapy Advisor. (12)
Nitric oxide bioavailability is essential for vascular health as well as lowering blood pressure and other health issues. Oral bacteria play a key role in bioactivation of nitrate by first reducing it to the more active nitrite. Antibacterial mouthwash destroys bacteria in mouth and reduces conversion of nitrates to nitrites. And thus lowers the biological effects of dietary nitrate. Hence this raises potential public health related questions of using mouthwash.(13,14)
Disclaimer: Information provided here are generalized information for informational and entertainment purpose only, not intended to provide one to one health consultation or replace practice of a qualified practitioner. Different people may have different health condition and may have different reaction to the same food. Hence it has been advised to consult with health care provider before application of any of above information Source and references:
Source and references: 1.Nitrate transport in salivary glands with implications for NO homeostasis, Bioavailability of sodium nitrite from an aqueous solution in healthy adults,Hunault CC, van Velzen AG, Sips AJ, Schothorst RC, Meulenbelt J., Toxicol Lett. 2009 Oct 8;190(1):48-53. 3.Green Alternatives to Nitrates and Nitrites in Meat-based Products-A Review,Gassara F, Kouassi AP, Brar SK, Belkacemi K., Crit Rev Food Sci Nutr. 2016 Oct 2;56(13):2133-48 4.The use and control of nitrate and nitrite for the processing of meat products,Karl-OttoHonikel,Meat Science,Volume 78, Issues 1–2, January– February 2008, Pages 68-76 5.Processed meat consumption, dietary nitrosamines and stomach cancer risk in a cohort of Swedish women,Larsson SC, Bergkvist L, Wolk A, Int J Cancer. 2006 Aug 15;119(4):915-9 6.Mortality from different causes associated with meat, heme iron, nitrates, and nitrites in the NIH-AARP, Diet and Health Study: population based cohort study,Arash Etemadi, research fellow, Rashmi Sinha, senior investigator,Mary H Ward, senior investigator, Barry I Graubard, senior investigator, Maki Inoue-Choi, staff scientist, Sanford M Dawsey, senior investigator, Christian C Abnet, senior investigator,BMJ 2017; 357 7.It is rocket science - why dietary nitrate is hard to 'beet'! Part II: further mechanisms and therapeutic potential of the nitrate-nitrite-NO pathway,Mills CE, Khatri J, Maskell P, Odongerel C, Webb AJ,Br J Clin Pharmacol. 2017 Jan;83(1):140-151 8.Roles of dietary inorganic nitrate in cardiovascular health and disease,Formation and occurrence of nitrosamines in food,Scanlan RA.,Cancer Res. 1983 May;43(5 Suppl):2435s-2440s 11. https://monographs.iarc.fr/wp-content/uploads/2018/06/mono94-1.pdf 12.https://www.cancertherapyadvisor.com/fact-sheets/cancer-dietary- nitrates-nitrites-risk-fact-sheet/article/784074/ 13.The increase in plasma nitrite after a dietary nitrate load is markedly attenuated by an antibacterial mouthwash,Govoni M, Jansson EA, Weitzberg E, Lundberg JO., Nitric Oxide. 2008 Dec;19(4):333-7 14.A stepwise reduction in plasma and salivary nitrite with increasing strengths of mouthwash following a dietary nitrate load, Woessner M, Smoliga JM, Tarzia B, Stabler T, Van Bruggen M, Allen JD, Nitric Oxide. 2016 Apr 1;54:1-7
