Transcript: Which Fruit Fights Cancer Better?
There are many ways to compare the healthfulness of different foods. One can compare nutrient content, for example. So if you were interested in antioxidants you might compare vitamin C levels. If you did that with our two most popular fruits, apples and bananas, based on vitamin C content bananas would appear twice as healthy, 10 mg in a banana compared to only 5mg in an apple. But vitamin C is just one of thousands of different phytonutrients in fruits and vegetables. Turns out the vitamin C in apples accounts for less than 1% of an apple's total antioxidant activity.
Here's the total antioxidant content of a red delicious apple. Here's how much the vitamin C in the apple contributes. You can hardly even see it. Even though there's only about 5mg of vitamin C in a small apple, it has the antioxidant equivalent of 1500 mg of vitamin C. I've reviewed before how taking that much vitamin C straight in a supplement may actually have a pro-oxidant effect and cause DNA damage, but you can get three times that antioxidant power eating an apple, without the adverse effects.
Of course there's more than just vitamin C in bananas too. In fact I was surprised to see this study out of Harvard suggesting that not only blueberries and strawberries, but bananas was a significant source of anthocyanins, the red/blue/violet phytonutrients found in berries. Maybe I underestimated bananas. They are after all, technically berries.
Still, I'm looking three fruits and I'm seeing some anthocyanins here and here, but not seeing much red, blue, or violet here. Now wild bananas are a different story. There's anthocyanins in blue, purple, orange red, red purple, and pink purple bananas, but none in yellow… So the Harvard researchers were challenged on it and they said look, we just took values from the USDA, and it turns out USDA apparently made a mistake. No anthocyanins in bananas, and despite twice the vitamin C, bananas were beat out by apples in terms of overall antioxidant power. But that's just measuring the ability of these fruits to quench an oxidation reaction in a test tube. It would be nice to measure actual biological activity. For example in this apple study, they also measured the ability of apple extracts, from both peeled and unpeeled apples, to suppress the growth of human cancer cells growing in a petri dish compared to control. Wouldn't it be great to be able to compare that kind of superpower between different fruits. Well, now we can.
Here is a graph of cancer cell proliferation versus increasing concentrations of the 11 most common fruits eaten in the United States. They decided to use liver cancer for this study. If you drip water on these cancer cells as a control, nothing happens they start out powering away at 100% growth and they keep powering away at 100% growth. And pineapples, pears, and oranges don't do much better. Peaches start pulling away from the pack. At high peach concentrations, cancer cell proliferation drops about 10%, but bananas and grapefruits work about 4 times better, dropping cancer growth rates by about 40%. Red grapes, strawberries and apples do even better, cutting cancer cell growth up to half at only half the dose, but these two fruits are the winners, causing a dramatic drop in cancer proliferation at just tiny doses, lemons, and, cranberries. So if you look at the effective dose required to suppress liver cancer cell proliferation, apples are more powerful than bananas, but cranberries win the day. And there was no effective dose listed for orange, pear, and pineapple since they didn't appear to affect the cancer cell growth at all.
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.
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