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Kiwifruit and DNA Repair

Plant-based diets help prevent cancer not only by blocking DNA damage but by increasing our DNA repair enzymes’ ability to repair any damage that gets by our first line of antioxidant defense.

July 18, 2012 |
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Acknowledgements

Thanks to Moriori and LadyofHats via Wikimedia Commons.

Transcript

In 2003 a landmark study was published in the journal Carcinogenesis. Now we've known "plant –based diets rich in fruit and vegetables can preveent development of several chronic age-related diseases, including cancer, but why? "”consumption of fruits and vegetables is associated with decreased risk of cancer, but why? The “mechanism behind this protective effect is not clear. We know “These foods are rich in antioxidants, which are capable of decreasing oxidative damage to DNA and thus might prevent mutation and cancer,” but what about the second line of defense against oxidative DNA damage, DNA repair. We’re going to get some DNA damage in our world no matter how healthy our diets, so its critical to find ways to upregulate our DNA repair enzymes to better assist with stitching our DNA back together.
    So, how about we give people some kiwifruits on and off for a few weeks and see what happens. Why kiwifruits? Because it was funded by the “”International Kiwifruit Organization. You got to get funding from somewhere.
First, what happened to the level of DNA damage. Each symbol represents the DNA damage measured in one person. So day zero, no kiwifruit, the "WO" means without kiwifruitm and you can see they start out all over the map. Maybe some were smokers, or sat in traffic, who knows. But then here they go on 1 kiwi a day, then they go back to zero, then 2 a day, then zero, then 3 a day. It wasn’t completely consistent on every day for every person, but you can kind of get a sense that the weeks without the kiwifruits DNA damage tended to go up. And indeed that’s what the statistical analysis showed. Significantly less DNA damage on the days they were eating kiwifruits.
Note that it didn’t seem to matter how many kiwis they were eating, though. They seemed to get the same benefit whether they were eating 1 or 3.
Kiwifruits have antioxidants, so no wonder there was less DNA damage, but once you already have DNA damage can kiwifruit help with the restoration? So this was our first line of defense, the antioxidants in plant foods. Now on to our second defense line of defense, DNA repair. This is measuring DNA repair rates. Level of DNA repair off kiwis, on kiwis, off kiwis, on kiwis, off kiwis, on kiwis,.
Now although it appears the 3 kiwis did better, than 1 or 2 statistically all 3 kiwi doses appeared pretty much the same, suggesting there’s some sort of plateau effect. Maybe there’s just some phytonutrient in kiwis that boosts this DNA repair enzyme system and it’s really just a matter of whether we have it in your bloodstream or not, rather than how much of it is there.
What would be interesting is if you added a different fruit or vegetable on top of the kiwi, with a whole different portfolio of phytonutrients; would they complement one another or would it just be a plateau across the board. We didn’t find out until recently….
 (we’ll look at this study in tomorrow’s video)

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 Serena

To help out on the site please email volunteer@nutritionfacts.org

Dr. Michael Greger

Doctor's Note

This is the second video of a three-part series about the latest discoveries on kiwi fruit. See also yesterday's NutritionFacts.org video-of-the-day Kiwifruit for Irritable Bowel Syndrome. Other ways to protect one's DNA include eating broccoli, avoiding bacon, not overdoing stevia, and eating a plant-based diet in general. See Repairing DNA Damage and Research Into Reversing Aging.  In tomorrow's video Plant-Based Diets and Cellular Stress Defenses we'll see if we can break through that kiwi ceiling! In the meanwhile, there are lots (and I mean lots) of other videos to peruse.

Check out my associated blog posts for more context:  Kiwi Fruit for Irritable Bowel SyndromeEating Green to Prevent CancerHow Tumors Use Meat to Grow, and Foods That May Block Cancer Formation

  • Michael Greger M.D.

    This is the second video of a three-part series about the latest discoveries on kiwi fruit. See also yesterday’s NutritionFacts.org video-of-the-day Kiwifruit for Irritable Bowel Syndrome. Other ways to protect one’s DNA include eating broccoli, avoiding bacon, not overdoing stevia, and eating a plant-based diet in general. See Repairing DNA Damage and Research Into Reversing Aging.  In tomorrow’s video Plant-Based Diets and Cellular Stress Defenses we’ll see if we can break through that kiwi ceiling! In the meanwhile, there are lots (and I mean lots) of other videos to peruse.

    • HemoDynamic, M.D.

      Dr G is spending just another day at the office exploiting plants and their ability to heal.
      ;-}

  • TimX

    Is this effect unique to kiwi fruit? Could the same thing happen with red delicious apples, or kale or any number of other plant-based food? (btw, I’m logged in to your site but the comment system asks for yet another login, not even offering the same credentials as the site)

    • HemoDynamic, M.D.

      TimX
      You need to set up a Disqus account or each time you comment you will be asked for your email and username.

  • Myjolina

    Do you recommend eating the skin of the kiwi?

    • Dspollock

       I do eat the skin of the kiwi. Following a tip in another on-line forum, I use a vegetable scrubber to scrub the hairs off the skin, slice off the two ends and then simply slice the rest of the kiwi to eat. Earlier research has shown that often, the layer just below the skin is rich in nutrients.

      • Troy

         I don’t bother removing the hairs, but I get organic for fruits I eat the skin of.  The skin is tasty :)

  • Valnaples

    heh, kiwi were 3 for $1 the other day…bought 6…who says eating healthy is too expensive??? (^_^)

  • Eli

    Damnit! Whats with the cliffhanger?

  • Matt

    Were the kiwis organic or conventional? And do you think it matters which? Any research on the effects of organic vs conventional?  Also, what were their diets like aside from including 1 – 3 kiwis a day? 

    • Thea

       I remember one video on this site which shows measurements of chemical’s in kid’s urine before, during and after eating organic.  That study doesn’t directly address whether the chemicals interfere with DNA repair, but I thought you might be interested in learning about the video if you didn’t know of it already. 

      There may even be more studies concerning organic vs not on this site.  I just can’t keep it all in my head.

      Note that I constantly have the same kinds of questions that you do.  You have company in wanting to know the effects of conventional produce on our health.

  • http://twitter.com/garyyuen गरिष्ठ

    Bet amla works better.

  • Wickedchicken

    That is so interesting that 1 is as good as 3. I rarely eat kiwi, but I will think about adding them (well, 1!). Of course with studies like for example the antioxidant value of all vegetables against cancer, that you so nicely presented, we are spoiled! We get to know all the veg in comparison! So really while a kiwi might be good, is an orange more effective? Are berries more protective? Is 1 apple twice as repair-inducing. I am now used to being spoiled with answers so I need to know it all! LOL! You are spoiling us!! Thank you for all your hard work

  • http://www.facebook.com/JustLoveGardening Alan Saul

     http://www.nsedreams.com/pwp/splash.jsp?pwpID=ASW9345983&textCacheLocale=en-AU

  • http://www.facebook.com/JustLoveGardening Alan Saul

     http://www.nsedreams.com/pwp/splash.jsp?pwpID=ASW9345983&textCacheLocale=en-AU

  • udi

    Dr. Greger. Generally speaking, is DNA repair a good thing for someone who already has cancer? The reason for my question is that i’ve been told that cancer is damaged DNA that the body doesn’t recognize as such.