Kiwifruit and DNA Repair

“Kiwifruit & DNA Repair” In 2003, a landmark study was published in the
journal Carcinogenesis. Now, we’ve known “(p)lant-based diets rich in fruits and vegetables can prevent development of
several chronic age-related diseases, including cancer.” But why? Well, the mechanism behind this
protective effect is not clear. We know whole plant foods
are rich in antioxidants, which are capable of decreasing
oxidative damage to DNA, and thus might prevent
mutation and cancer. But what about our 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 it’s critical to find ways to
upregulate our DNA repair enzymes, to better assist with stitching
our DNA back together again. 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 kiwifruit. And you can see they start
out all over the map, right? Maybe some were smokers,
or sat in traffic, who knows. But then, here they go, on one kiwi a day, then they go back to zero, then two a day, then zero, then three kiwis a day. Now, it wasn’t completely consistent
on every day for every person, but you can kind of get a sense that the times without the kiwifruits,
DNA damage tended to go up. And indeed, that’s what the
statistical analysis found: 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 one or three. Kiwifruits have antioxidants, so no wonder there was less DNA damage. But once you already have DNA damage, can kiwifruit help with DNA restoration? So, this is our first
line of defense, right? The antioxidants in plant foods. Now on to our second line of defense, DNA repair. This is measuring DNA repair rates. Level of DNA repair off kiwis, on kiwis, off kiwis, on two kiwis, off two kiwis, on three. Now, although it appears the three
kiwis did better than one or two, statistically all three 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 just really a matter of whether
or not you have it in your bloodstream, 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. And we’ll look at that
study in tomorrow’s video.


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