Though breast cancer is the most common cancer among women around the world, the rate in some areas of the world, such as Asia, is up to six-fold lower than in North America. Maybe it's the green tea and soy?
As I show in my 3-min. video Why Do Asian Women Have Less Breast Cancer?, if anything, green tea may only drop risk by about a third. Soy works better, but only, it appears, if you start young. Soy intake throughout the lifecycle is associated with decreased breast cancer risk, but the strongest, most consistent effect is for childhood intake, cutting the risk of later breast cancer by as much as half. If you don't start consuming soy until your teens or adulthood, though, then soy is only associated with about a 25% drop in breast cancer risk. I have another video on Breast Cancer Survival and Soy, though it may be possible to overdo it.
Combined, green tea and soy consumption would only account for maybe for a two-fold difference in breast cancer risk--not 6-fold, so researchers looked into what else Asian women were eating. In my last post Mushrooms For Breast Cancer Prevention I presented evidence that plain, cheap, widely available white mushrooms appear able to outsmart breast cancer cells that try to make their own estrogen. That was based on placental tissue samples, though. Check out my 2-min video Breast Cancer vs. Mushrooms to see mushrooms stacked up against the real thing.
Given the intriguing mushroom experiments, researchers asked a thousand breast cancer patients how many mushrooms they ate. Then they asked the same question to a thousand healthy women who they tried to match to the cancer patients as closely as possible--same age, height, weight, exercise, smoking status, etc. Based on those answers they calculated that women who averaged at least a certain daily serving size of mushrooms appeared to drop their odds of getting breast cancer 64%! What was that average serving size? Half of a mushroom a day.
Who eats half a mushroom? Well, that was averaged over a month. So compared to women who didn't regularly eat any mushrooms, those who ate just 15 a month appeared to dramatically lower their risk of breast cancer. Similar protection was found for dried mushrooms.
Combining mushroom consumption with green tea--sipping a half teabag's worth of green tea every day along with eating that half a mushroom--was associated with nearly a 90% drop in breast cancer odds.
Green tea may also help account for the Asian Paradox. Which type is best? See Antimutagenic Activity of Green Versus White Tea. And what may be the best way to prepare it? See Cold Steeping Green Tea.
-Michael Greger, M.D.