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The Power of NO

Antioxidants protect NO synthase, the enzyme that produces the artery-relaxing signal, nitric oxide. This may explain why those who eat especially antioxidant-rich plant foods have improved flow-mediated dilation of the brachial arteries.

January 30, 2012 |
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Supplementary Info

Sources Cited


Images thanks to Benjah-bmm27 via Wikimedia Commons, and European Atherosclerosis Society.


Our understanding of nitric oxide has come a long way since it was named "molecule of the year" in 1992 and won some folks a Nobel Prize in '98. But it's a key biological messenger within the body and its message is: "open sesame". It's released by the lining of our arteries to tell the muscle fibers within the walls  of our arteries to relax, so our arteries open up and let the blood flow.

That's why when people are having a heart attack, they're giving nitroglycerine, which your body converts to nitric oxide to open up our arteries. In fact that's how Viagra works: it boosts nitric oxide signaling, which leads to dilation of the penile arteries.

The ED we really need to be concerned about, though, is endothelial dysfunction: dysfunction of the lining of all our arteries, considered a first step toward atherosclerosis, our leading cause of death.

Here's what happens: NO, nitric oxide, is produced by an enzyme called NO synthase. If you have a lot of free radicals in your body, though, they come in and not only gobble up the NO -- they hijack this enzyme -- they hijack NO synthase, take it over, and have it instead start making more free radicals.

So our arteries become dysfunctional. They don't relax when they should. And that can contribute to the hardening of our arteries.

If, however, we flood our body with antioxidants by eating healthy foods, it should quench those free radicals and let NO get back to its job.

So recently, for the first time ever, researchers studied the effects of eating high antioxidant foods on NO activity. We saw what choosing higher antioxidant plant foods did to inflammation. What effect does it have on our arterial function?

You can hook people up to a device that measures the dilation of their arteries and blood flow through ultrasound. In the study, people started eating their normal miserable diet, then switched to an even more miserable diet, and their arterial dilation capacity dropped, though not significantly.

They started out eating a pretty crappy diet to begin with, but which they then let people get back to, so then their NO activity came back to baseline. Then they had these people eat the higher antioxidant foods, like berries, and within  a period of just two weeks, a significant jump in their arteries' ability to relax and dilate normally.

This is where they should have been in the first place, or even higher. This study suggests that choosing antioxidant-rich plant foods can improve blood flow to all parts of our bodies.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is transcript contributed by Bruce A. Hamilton.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. Be sure to check out all the other videos on antioxidants and don't miss the videos on heart disease. And there are 1,449 subjects covered in the rest of my videos–please feel free to explore them!

For more context, check out my associated blog posts:  Antioxidants in a Pinch: Dried Herbs and Spices and Hibiscus Tea: The Best Beverage?

  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. Be sure to check out all the other videos on antioxidants and don’t miss the videos on heart disease. And there are 1,449 subjects covered in the rest of my videos–please feel free to explore them!

  • BPC

    Fascinating study on flow mediated dilation…perhaps the effects of higher antioxidant consumption by vegetarians (compared to omnivores) may also explain some of the heart health benefits of vegetarianism reported by Dean Ornish’s lab. Given the vastly higher antioxidant content of plant foods compared to animal foods, I wonder if higher antioxidant intake may better explain heart health benefits of vegetarianism than reduced cholesterol/saturated fat intake. I look forward to future videos on this topic!

  • Jubilee

    I stumbled across the
    so called 80 10 10 diet on

    Can you tell me if this diet is great and healthy? Or do people following it risk malnutrition?

  • tree

    yeah choclate has antioxidants!!!

  • Kman

    Could you please do some videos on Whey Protein? I am interested in if they :
    contain any bad chemical residues
    have any cognitive benefits
    have any anti-cancer benefits
    have any satiety or weight loss benefits
    and anything else related to health and illness. Thanks for the great work you do.

    I tried clicking on your Ask the Doctor link but it seems to be broken.

  • Christo Okulian

    Hi Doc, hi Toxins,

    Am crazily addicted w/ health knowledge from doctor Greger and his crew.

    please kindly help me, are there any correlation between arterial elasticity w/ heart beat rate and VO2max ? please kindly provide the literature study, thx much.

  • Caveat M. Tor

    Given that ED drugs work by raising NO levels, and there is now apparently a regimen of daily low-dose Cialis for ED patients, might this regimen be beneficial for an adult male who is physically active, not suffering from ED, but at risk of cardiovascular disease due to age, sex, familial risk, and past diet?

  • Cynthia Chabra

    Dr Esselstyn said on Forks over Knives the Extended Interviews that recent studies now show the same effect on endothelial cells from olive oil, palm oil and soybean oil as from animal fat. Can you address that please?

  • Derrek

    What about BPA tomato paste in cans? I bought some and don’t know if I should eat it or not. I’ll have to buy organic in the future.

    Also would about conventional strawberries, grapes, celery and blueberries? I can’t always afford organic. Should I avoid them then? I’m in college and am broke.

    • Thea

      Derrek: Dr. Greger has a great blog post where he puts pesticide consumption into perspective. :

      “A new study calculated that if half the U.S. population ate just one more serving of conventional fruits and vegetables, 20,000 cases of cancer could be prevented. At the same time the added pesticide consumption could cause up to 10 extra cancer cases. So by eating conventional produce we may get a tiny bump in cancer risk, but that’s more than compensated by the dramatic drop in risk that accompanies whole food plant consumption. Even if all we had to eat was the most contaminated produce the benefits would far outweigh any risks.”


      I translate this bit of info into: Eat organic when you can, but don’t stress about it when you can’t.

      Happily, there is a way to take this advice a step further to minimize your risks without completely depleting the pocketbook. Every year, the Environmental Working Group actually measures pesticide levels in fruits and veggies–after those fruits and veggies have been prepared in the way people would normally eat them. (For example, peeling a banana or washing first.) If you scroll down on the following page, you will see a list for the “Dirty Dozen” and the “Clean Fifteen”.

      I bring your attention to these lists because I think they are very helpful for people who can’t afford to eat organic for everything. You could use these lists to help you decide when it is worth putting down money for organic and when it might be safer to buy non-organic.

  • Lizzi

    Are there any new ideas about how to HELP HAND AND FINGER PAIN?
    I am in a very painful situation with my hands. How can I reverse this and is Aleve safe to take? I do not want drugs, but am Vegetarian with severe hand pain. Thanks for any light we can shed on this~ What foods could help pain?