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Cancer, Interrupted: Garlic & Flavonoids

Garlic and flavonoid phytonutrients found in fruits, vegetables, greens, and grains appear to protect against DNA damage induced by mutagenic chemicals found in cooked meat.

January 28, 2013 |
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Supplementary Info

Sources Cited


Images thanks to Paul-W and / Flickr, Evan-Amos, Ranveig, and Amada44 Ekko via Wikimedia Commons, and University of Leeds Computational Biophysics Group


What about garlic? Remember this study in which it won out as #1 anticancer vegetable? Well, let's see what it can do. This  is what's called a comet assay, currently the standard technique for the evaluation of DNA damage. What you're seeing is the DNA of a single cell, the normal breast cell, as visualized under a fluorescence microscope. It's in an electric field trying to pull the negatively charged DNA to the right, but the DNA is all supercoiled together. But you add a carcinogen like PhIP that literally breaks up our DNA, you can see the chopped up pieces breaking away and flowing out into kind of a comet tail. But what if you add the same amount of carcinogen but also add some garlic phytonutrients? You get some damage, some DNA breakage, but now as much as before. Which kind of garlic would be expected to work the best? Garlic or elephant garlic, the so-called “garlic for people who don't like garlic”. And the answer appears to be garlic, garlic. What about flavonoid phytonutrients,  found in fruits, vegetable, leaves, and grains? Do they have a protective effect on the meat-mutagen induced DNA damage?  They took white blood cells from healthy individuals and colon cancer patients and exposed them to increasing doses of cooked meat carcinogens, IQ—found mostly in fried bacon and baked fish and PhIP, found mostly in fried fish, bacon, and chicken [animal pics] and then continued to pump in that meat mutagen at the highest level but started adding some plant phytonutrients, quercitin, found in foods like apples, red onions, and berries (raspberries), and Rutin, found in citrus, buckwheat, and asparagus. They used the comet assay again, measuring how much DNA was broken off into the tail. And as you can see, as the concentration of meat mutagens increases so does the DNA damage, but then even when the highest dose continues, adding plant phytonutrients starts to bring the damage down. That happened in both healthy individuals, and cancer patients. But I want you to notice something else. Even at a zero concentration of cooked meat chemicals there was more DNA damage present in the white blood cells circulating in cancer patients. And they didn't have blood cancer, they had colon cancer.  Even though the cancer was just in their colon, their whole body was affected by the disease state, their whole body was under increased oxidative stress, inflicting significantly higher DNA damage. Or maybe the DNA damage came first and it's one of reasons they have cancer. Either way, they experiences less reduction of induced DNA damage, ''"suggesting that higher concentration of flavonoids will be required to achieve a protective effect. So cancer patients need even more fruits and vegetables to reduce the damage done by carcinogens.

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 Jonathan Hodgson.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

The prior garlic video I mentioned is #1 Anticancer Vegetable (one of the most popular videos on the site!). Make sure to also watch its "prequel" Veggies vs. Cancer. Other foods that may protect DNA include kiwifruit (Kiwifruit and DNA Repair), cruciferous vegetables (DNA Protection from Broccoli), green tea (see my last video Cancer, Interrupted: Green Tea), and plants in general (Repairing DNA Damage).

Garlic beat out elephant garlic, but what about Carrots vs. Baby Carrots? Or raisins vs. currants?

Should garlic be raw or cooked? See How can I preserve the anti-cancer effects of cooked garlic?

Which foods have the most flavonoids? See my cheat sheet to the USDA nutrient database.

Which foods have the most antioxidants? See my video series starting with Antioxidant Content of 3,139 Foods.

What other dietary changes should we consider after a cancer diagnosis? See:

Please also check out my associated blog posts for more context:  Foods That May Block Cancer Formation and Tarragon Toxicity?

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

  • Andrew

    Yet another reason I wish I weren’t allergic to garlic.

  • Mack

    Were can I see this list of the top 100 flavonoid phytonutrients in printed form so that I can examine it more carefully? I see that the despised banana that I so love, made it on the list, but not before beer. Maybe I should come up with a recipe for a beer-banana smoothie! And funny that plums are higher up than their concentrated form: prunes.

  • Julianna

    like to have a list of the top 100 flavonolds too…..

  • gilesset

    That list of the top flavanoid nutrients is quite astounding: Apple juice ahead of apples? Milk chocolate ahead of spinach? Filtered coffee over black tea which is over green tea? This isn’t what you’ve been telling us……….

    • Shane Jackson

      Maybe you are confusing flavanoids with anti-oxidant profiles?

  • Thinkabouddit

    I cited this site to support a vegan argument, and the response I got is as follows:

    “[. . . ] really ? it’s a website sponsored by the medical association !, he scours the nutritional literature to bring you the most up to date food facts, hahhaahhaha, who’s all the research sponsored by? hahahhahaha”

    May I have an answer for this? Thanks.

    • WholeFoodChomper

      I’d refer the individual to the NF “About” page (I see nothing about a medical association sponsorship, the site is brought about by the “Jesse & Julie Rasch Foundation in partnership with Michael Greger M.D”). As for how the research studies are funded/sponsored, one can determine how each study was/is funded by looking at each respective study cited (which can be done by linking to the studies via the “Sources Cited” tab available with each video).

      • HemoDynamic, M.D.

        What she said too! Let them “Chomp” on that!

    • HemoDynamic, M.D. is not a website sponsored by a “Medical Association”. It is supported by donations only. In fact that is why Dr. Greger had to decrease the videos from 5 a week to 3 a week because of the lack of donations.
      The research he scours is the research that everyone has access to and if they have questions let them look up the answers. But your response should be your health. It’s a waste of time, breath and effort to have an argument with close minded people. So continue to reward yourself with the fact you are the heathiest you can be, by following a Whole Food Plant Based lifestyle.

      I still haven’t seen one patient that has come into my practice having reversed their Coronary Disease, Autoimmune Disorders, Diabetes, Chronic Pain, High Blood Pressure, High Cholesterol, or Insomnia (I could go on all day!) eating meat and dairy. And you know what–It I Never Will.

      But I have seen thousands reverse those problems, get off their medications and elevate their quality of life by following a plant based lifestyle.

      In Health

      • Mary Irving

        I personally did (reverse diabetes) and know friends now off of cholesterol medication by eating paleo….so no dairy, but plenty of meat.

      • Shane Jackson

        Just donated a small amount and will do so every couple of months as I give 99% of the blame to Dr. Greger from turning me into a vegan from a 20+ year meatatarian where the majority of my veggies came from salsa and the occasional Chinese take out night.

        • HemoDynamic, M.D.

          Thank you so much!!!!! That is very generous of you. As well this website and the efforts of Dr. G have changed my life so profoundly that words cannot describe the depth of gratitude I feel towards all those that have made Nutrition a success!!!

      • Thinkabouddit

        Thank you, Hemo. Another question has come up. People wonder if it’s the meat and dairy or if it’s the way it’s produced, with chemicals, hormones, etc. They wonder if in the China Study the results were based on animals raised with pesticides, etc. and if eating animal products from animals raised without chemicals, etc., would be healthy.

        • HemoDynamic, M.D.

          Have you been following the current Videos from Dr. Greger regarding Heterocyclic Amines?

          Have them read the China Study themselves and review the data themselves and ask them why Medicare pays for teaching a plant based diet and not a Paleo, or Atkins or South Beach or Whatever Dr. Oz is selling this week for reversing heart disease.

          And bottom line if they want to eat meat let them.
          “When the student is ready, the teacher will appear.” Buddha

          • bvgrannie

            The Teacher did appear….then moved to So.Cal. :P Redding is better for your footprint

  • HemoDynamic, M.D.

    As one professor told me one time when he was getting a cup of Java in the cafeteria, “Juice of the Gods”. Well it’s clear that Garlic is the Herb of the Gods!
    Anyone for Garlic Coffee?

  • Thrivalista

    I, too, would love to have that list of 100 foods highest in flavanoids, please. Link?

  • Thrivalista

    Ok, I typed them in to save offline, and thought I’d share. Hope that’s ok.

    Black Elderberry
    Black Chokeberry (=aronia)
    Black Currant
    High bush Blueberry
    Globe Artichoke heads
    Coffee, filter [sic]
    Lowbush blueberry
    Sweet cherry
    Red raspberry
    Flaxseed meal
    Dark chocolate
    Chestnut (!) J
    Black tea
    Green tea
    Pure apple juice
    Whole grain rye bread
    Red wine
    Soy Yogurt
    Cocoa powder
    Pure pomegranate juice
    Soy flour
    Black grape
    Black olive
    Pure grapefruit juice
    Pure blood orange juice
    Milk chocolate
    Pecan nut
    Red Currant
    Soy, tempeh
    Soy, tofu
    Green olive
    Black bean
    Red Onion
    Green grape
    White bean
    Chocolate beverage
    Roasted soybean
    Soy milk
    Red Chicory
    Soy meat
    Whole grain rye flour
    Pure Pummelo juice
    Green chicory
    Yellow Onion
    Whole grain wheat flour
    White wine
    Rose wine
    Dark beer
    Extra virgin olive oil
    Soybean sprout
    Pure lemon juice
    Red lettuce
    Soy cheese
    Green bean
    Curly endive
    Peanut, roasted, de-hulled
    Rapeseed (canola) oil
    Endive (escarole)
    Green lettuce
    White onion
    Refined oat flour
    Refined wheat flour
    Sweet green pepper

    Hope that helps!

  • Rossman1

    Dr. Greger! I love your work, you devote so much time and energy in order for people to ״see the light”, I did, through this site, and I would like to thank you from the bottom of my heart!

    I have a question re garlic, is it still so powerful if it is cooked?

  • Jessica

    Dr. G – Any truth to the folk wisdom that eating garlic makes you less attractive to mosquitoes? My kiddo is a virtual mosquito-magnet and the bites swell up into huge welts. I’d love to do something beyond dousing her with repellent in the morning and giving her baking soda baths at night. Thanks!


    egg including yolk ok, if I have hi cholestrol, and high triclerides? My doctor says yes, eat as many (hard boiled eggs as u want) he says you don’t get high cholestrol from eggs.. that people that alter the eggs, gives you high cholestrol…..I can’t find any evidence to support his remark. Please answer this for me. My surgeon, said no stay away from the yolk, my dr. said that dr. is a surgeon, he doesn’t know about the latest reach on egg yolks….who is right?

    • WholeFoodChomper

      Oh goodness, if I were you, I’d find a new primary care physician–STAT! I think the answer you need is right here on this site. Just do a search for “eggs” (and “medical education” while you are at it), and you will see what the latest scientific evidence has to say on the topic.

  • Akinom

    what about black garlic? aka fermented garlic how does that compare to regular garlic for anti-cancer effects ?

  • Andrew

    Guys, I would like your feedback on this. I struggle to believe the following video (and many more like them)… but then i struggle to understand how there could be so many opposing views? Are these opinions or facts? Is there some element of twisted truth?

    • JacquieRN

      Hi Andrew, thank you for posting the video. It can be a struggle to find the best information to make our best choices. I watched the video and looked through Andreas Moritz’s website.

      1. He states that “Ayurvedic medicine is the oldest form of medicine doesn’t recommend garlic at all…” However, it seems this may not be the stance for all practitioners. if you do a simple google search you will find many like this:

      2. Although he says “some studies show that” – I didn’t see any references to actual studies/research.