This is probably a conversation I do not want to have. After all, the link between cancer and nitrates is well-established, isn’t it? So why do I keep reading about studies that show the benefits of dietary nitrates. Well, further investigation finds that once again, well-established facts are not so well established. And the nitrate issue is just one example of this. So what is the real truth about nitrates?
Most people may assume nitrates are only found in processed or cured meats. The truth is that plant-based foods such as beets, celery, cabbage and other leafy greens account for 80% of the dietary intake of nitrates. And it is the consumption of these foods where research is looking for health benefits. Let’s face it – no one is going to research a hot dog for its health benefits.
So here is where it gets interesting. Nitrates are converted to nitrite by bacteria is our saliva and then is further converted to nitric oxide (NO) when mixed with our stomach acid. Nitric oxide is a potent vasodilator and has been linked to lowering blood pressure and increasing the response of the immune system. It also helps with sleep, lowering inflammation, assists gastric motility and improves our sense of smell. Nitric oxide can also be oxidized by enzymes and converted back to nitrite in the body which has been linked aiding athletic performance
One study found that beetroot juice, high in nitrates, reduces the expenditure of oxygen and increased endurance in athletes when consumed over a six day period. Blood levels of nitrite were considerably higher on days 4-6 and systolic blood pressure was lower. So just to be clear, as the nitrate/nitrite thing gets confusing, they consumed nitrates in the beet juice but it was nitrite by the time it got into their blood.
So what is the issue? Nitrates and nitrites may bind with amino acids and form nitrosamines, which may be carcinogenic and has been linked to stomach cancer. There is not a lot of conclusive evidence for this as the original study that made this claim, did not stand up to peer-review and subsequent studies have not been able to confirm that nitrosamines are carcinogenic. But let’s say for the sake of argument that it is true, other studies have found that vitamin C and vitamin E can block the production of nitrosamines. Once again we need to look at the meal and not just the food, although cabbage is a good source of Vitamin C. For beets and celery and other nitrate-rich foods, planning them as part of meal with vitamin E-rich foods and vitamin C-rich foods will solve any potential problems.
But here is where it gets interesting, at least to me. Looking at the process of fermentation has found that fermenting beets, cabbage and other plant-based foods lowers nitrates and nitrites and increase nitric oxide. Furthermore, there seems to be a relation between good bacteria, bad bacteria and nitrosamines. Some study information has linked nitrosamine production to bad bacteria and several studies have shown that good bacteria can de-activate them by breaking them down. How great is that? It shows that nature gave us a lot to work with so as long as we consume nutrient-rich food and look after our gut health, we do not seem to have to worry about nitrates and can benefit form them instead.
And there is more good news. Another study found that beet juice increased blood flow to the brain in older people. Twelve 70-year old participants consumed a low or high nitrate breakfast, after a 10 hour fast, for four days. The high nitrate breakfast included 16 ounces of beet juice. The rest of the day, they consumed foods that complied with their assigned diets. One hour after eating breakfast, an MRI recorded their blood flow to the brain. The tests show that the subjects that consumed the high nitrate breakfast not only had greater blood flow to the brain but specifically, better flow to the white matter of the frontal lobe. Degeneration of this area leads to dementia and other cognitive functions. Increasing blood flow to this area would be helpful for preventing dementia. And that is something we should all want to know.
So start consuming those nitrates and if you want to ferment them first for the best benefit, eat plenty of sauerkraut, kimchi and beet kvass.
Tip: Be sure to buy unpasteurized sauerkraut or kimchi to get the beneficial bacteria.
- Acute effect of a high nitrate diet on brain perfusion in older adults, Tennille D. Presley, Ashley R. Morgan, Erika Bechtold, William Clodfelter, Robin W. Dove, Janine M. Jennings, Robert A. Kraft, S. Bruce King, Paul J. Laurienti, W. Jack Rejeski.. Nitric Oxide, 2010; DOI: 10.1016/j.niox.2010.10.002
- The inhibition of bacterially mediated N-nitrosation by vitamin C: relevance to the inhibition of endogenous N-nitrosation in the achlorhydric stomach, C.W. Mackerness, S.A. Leach, M.H. Thompson and M.J. Hill, Carcinogenesis (1989) 10 (2): 397-399.
- Ingestion of Nitrate and Nitrite and Risk of Stomach Cancer in the NIH-AARP Diet and Health Study
- Ward, Mary H.1; Kilfoy, Briseis1; Sinha, Rashmi1; Hollenbeck, A. R.2; Schatzkin, Arthur1; Cross, Amanda1, Epidemiology: January 2011 – Volume 22 – Issue 1 – pp S107-S108
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- Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans Bailey SJ, Winyard P, Vanhatalo A, et al.. J Appl Physiol. 2009;107:1144-1155.
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- White cabbage fermentation improves ascorbigen content, antioxidant and nitric oxide production inhibitory activity in LPS-induced macrophages C. Martinez-Villaluenga et al, LWT – Food Science and Technology, Volume 46, Issue 1, April 2012, Pages 77–83
- Degradation of N-nitrosamines by intestinal bacteria, I.R. Rowland, P Grasso, Applied Microbiology, 02/1975; 29(1):7-12.