Are Nitrates Pollutants or Nutrients?

Are Nitrates Pollutants or Nutrients?
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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, with their nitrite-forming nitrates, to our diet can be helpful.

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We know cured meat increases cancer risk—childhood leukemia, for example—yet, higher intake of vegetables is associated with a reduced risk. How can nitrites be bad in meat, but good when they originate in our own mouth 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 of Alzheimer’s, 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 the vice president of the Fertilizer Institute, so how do we know it’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; is 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, not the nitrites themselves. The nitrosamines are what cause the cancers. The only reason we’re concerned about nitrites is that, under certain circumstances, they can turn into nitrosamines, and other N-nitroso compounds.

And the only reason we’re worried about the nitrates is that they form nitrites, which, again, under certain circumstances, can form nitrosamines. The nitrites themselves are fine—in fact, amazing. That’s what all the new beets and blood pressure evidence I showed points to. And the nitrates turn into nitrites, which turn into nitric oxide, which helps our arteries and athletic performance. So as long as nitrites turn into NO [nitric oxide], 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 in the absence of plants. Phytonutrients—like caffeic acid, found in all plants, blocks nitrosamine formation. 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, you add nitrites to meat, and nitrosamines preform in the meat before it even makes it into our mouths. It’s not so much that we’re eating the nitrites added to the meat, but eating the nitrosamines that form in the meat when they add nitrites to it. 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.

Please consider volunteering to help out on the site.

Image thanks to Rebecca Sims / Flickr

We know cured meat increases cancer risk—childhood leukemia, for example—yet, higher intake of vegetables is associated with a reduced risk. How can nitrites be bad in meat, but good when they originate in our own mouth 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 of Alzheimer’s, 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 the vice president of the Fertilizer Institute, so how do we know it’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; is 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, not the nitrites themselves. The nitrosamines are what cause the cancers. The only reason we’re concerned about nitrites is that, under certain circumstances, they can turn into nitrosamines, and other N-nitroso compounds.

And the only reason we’re worried about the nitrates is that they form nitrites, which, again, under certain circumstances, can form nitrosamines. The nitrites themselves are fine—in fact, amazing. That’s what all the new beets and blood pressure evidence I showed points to. And the nitrates turn into nitrites, which turn into nitric oxide, which helps our arteries and athletic performance. So as long as nitrites turn into NO [nitric oxide], 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 in the absence of plants. Phytonutrients—like caffeic acid, found in all plants, blocks nitrosamine formation. 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, you add nitrites to meat, and nitrosamines preform in the meat before it even makes it into our mouths. It’s not so much that we’re eating the nitrites added to the meat, but eating the nitrosamines that form in the meat when they add nitrites to it. 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.

Please consider volunteering to help out on the site.

Image thanks to Rebecca Sims / Flickr

Doctor's Note

If you just arrived right in the middle of this story, for the benefits of vegetable nitrates I allude to, see Doping With Beet JuiceOut of the Lab Onto the Track; and Vegetables Rate by Nitrate. For the problems associated with nitrites added to meat, see Bacon and Botulism, and When Nitrites Go Bad. Which meats have the most nitrite? Find out in Prevention is Better than Cured Meat. Which veggies have the most nitrate? See Vegetables Rate by Nitrate, and all my other other videos on phytonutrients and what they can do. Good places to start include The Power of NOPhytochemicals: The Nutrition Facts Missing From the Label; and Convergence of Evidence.

For more context, check out my associated blog post: Using Greens to Improve Athletic Performance.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

28 responses to “Are Nitrates Pollutants or Nutrients?

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  1. 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!

    1. We will see that when vitamin c is added to processed meat, the nitrosamines are amplified significantly. From this I can assume that when consumed with plant foods the nitrosamines are more harmful. this is my assumption, I don’t know if Dr. Greger has other information.

  2. Wow–bravo on this whole beet juice-mitochondrial efficiency-nitrosamine series. It’s easy to see that you love teaching this stuff, and you’re good at it. You do an excellent job at conveying an engaging story, complete with history, biochemistry, puzzle-solving. Thank you, Dr. Greger.

  3. Very interesting! So nitrites in wine are ok because they’re consumed with grapes? Or are there other reasons to be concerned?

  4. Chris Kresser Lac has been confusing commom men with his data. I gave your present link to him. But I would also aprreciate you comments on this statement he made in his article he posted on face book  ” When it comes to food, vegetables are the primary source of nitrites. On average, about 93% of nitrites we get from food come from vegetables. It may shock you to learn that one serving of arugula, two servings of butter lettuce, and four servings of celery or beets all have more nitrite than 467 hot dogs. (2) And your own saliva has more nitrites than all of them! So before you eliminate cured meats from your diet, you might want to address your celery intake. And try not to swallow so frequently.” he is very cheeky.

        1. Indeed, Nitrates are swallowed, circulated back through to the saliva where bacteria convert the nitrates into nitrites and then again swallowed to convert into nitric oxide.

            1. Dr. Gregar, what about prepared meats that do not use nitrites? A friend of mine buys cold cuts from Menonites and says that they do not use any preservatives. What is your opinion about these “organic” prepared meats?

    1. So then, should one eat leafy greens or greens without any fats, such as nuts, oily seeds, avocado, salad dressing, cheese? I interpret this study to suggest that the fats therein not only negate the effect of vitamin C on inhibiting nitrosamine formation, but instead promote nitrosamine formation.

  5. I am wondering about the organic vs nonorganic difference – organic vegetables have far less nitrates in them. Do they have enough to be effective?

  6. forgive me if I have missed it. If I eat a diet that has typical amounts of meat/animal products AND take a high nitrate beet supplement IS my danger of nitrosamines increased?

  7. Is it okay to heat veggies containing high amounts of nitrates. There are a few internet sources that suggest doing so gives said veggies, like spinach and chard, carcinogenic properties? If so, does the cooking method matter (i.e., is microwaving dangerous)?

  8. I’m very confused because I’ve been reading a book called: world without cancer: the story of vitamin b17 (originally written in 1970’s) and in it he says that b17 is a nitriloside which is found only in certain seeds & few other plant foods. (B17 is used in some countries as part of nutritional cancer therapies). So, has the word nitrilosides been changed to nitrates or what??? Has vitamin b17 been found in all sorts of plant foods since the 70’s and is now called nitrates?? If yes, I have been consuming way too much b17 cause ive been vegan & i bought specific seeds to consume to make sure i get this vitamin…can someone clear this up for me?? Thanks.

    1. Lsmith,
      Thank you for your question. Nitriloside has nothing to do with nitrates. Nitrates are involved in forming Nitric oxide which acts as a vasodilator and thus improves athletic performance and lowers blood pressure. Check out the following link for some videos on evidence-based information to prevent cancer.

    1. Hi, Daniel. This is a very interesting study. Thanks for sharing it! I would like to study this issue in greater detail, but my first inclination is to say that it is best to eat nitrate-rich vegetables without fat, or at least with less than 10% fat. The study used a specific lipid concoction, and it is possible that not all lipids would have the same effect, but at this point we don’t know.

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