Phytonutrients such as vitamin C prevent the formation of nitrosamines from nitrites, which explains why adding nitrite preservatives to processed meat can be harmful, but adding more vegetables and their nitrite-forming nitrates to our diet can be helpful.
Image thanks to Rebecca Sims
We know cured meat increase cancer risk— childhood leukemia, for example—yet higher intake of vegetables are associated with a reduced risk . How can nitrites be bad in meat, but good when they originate in our own stomach from all the nitrates we get from green leafy vegetables?
Well, one possibility could be that nitrates are not good, — and such a case has been made, blaming the rise in Alzheimers, diabetes, Parkinson’s, and the kitchen sink on not only the rise in fast food and processed meat, but also the use of nitrate-containing fertilizers on our crops. Now this was dismissed as an unsupportable conclusion, but by a vice president of the Fertilizer Institute, so how do we know that’s not just a load of bull? And speaking of manure, organic producers in fact brag that their vegetables are significantly lower in nitrates.
So nitrates in plants, it just a matter of too much of a good thing? Are nitrates in foods harmful or healthy?
Before our heads explode, let’s go back to the basics: the facts of the case. The nitrosamines are the carcinogens. The nirtosamines are what cause the cancers. The only reason we’re concerned about nitrites, is that under certain circumstances then can form nitrosamines. And the only reason we’re worried about nitrates is that they form nitrites, which, again, under certain cirumstances can form nitrosamines. The nitrites themselves are fine— in fact amazing—that what all the new beet juice and blood pressure evidence I showed points to. — The nitrates turn into nitrites which turns into nitric oxide, which helps are arteries and athletic performance. So as long as nitrites turn into N.O.; we're good. It's only when they turn into nitrosamines that they cause trouble.
So the answer to the riddle—finally—lies in the circumstances in which nitrites form nitrosamines. And that circumstance is the absence of phytonutrients. —Phytonutrients like caffeic acid found in all plants, ferulic acid, ascorbic acid—vitamin C, and others. So, nitrates plus plant foods, no problem, but is there any vitamin C in meat? No. So nitrosamines preform in the meat before it even make it into our mouths. It’s not so much that we’re eating the nitrites added to the meat, but the nitrosamines formed in the meat when they added the nitrites in the first place. Nitrites in the absence of plants turn into carcinogenic nitrosamines.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Dianne Moore.
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If you just arrived right in the middle of this story, for the benefits of vegetable nitrates I allude to, see Doping With Beet Juice, Out of the Lab and Onto the Track, and Vegetables Rate by Nitrate. For the problems associated with nitrites added to meat, see yesterday’s video and When Nitrites Go Bad. Which meats have the most nitrite? Find out in tomorrow's video-of-the-day. Which veggies have the most nitrate? See Vegetables Rate by Nitrate. There are 48 other videos on what phytonutrients can do. Good places to start include The Power of No, Phytonutrients: The Nutrition Facts Missing From the Label, and Convergence of Evidence. And there are hundreds of other videos on more than a thousand subjects here at NutritionFacts.org—enjoy!
For some context, please check out my associated blog post, Using Greens to Improve Athletic Performance.