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.
Breast cancer can take decades to develop, so “early” detection via mammogram may be too late. The breast cancer you may feel one day as a lump in the shower, may have started 20 years ago. We now suspect that all the epithelial cancers: breast, colon, lung, pancreas, prostate, ovarian—the ones that cause the vast majority of cancer deaths—take up to 20 years or more to manifest. By the time it’s picked up it may have already been growing, maturing, scheming for years, acquiring hundreds of new survival-of-the-fittest mutations to grow even quicker and better undermine our immune system. Early detection may in effect be really, really late detection.
People are considered “healthy” until they show symptoms, so if we’ve been harboring a malignancy for 20 years we may feel all right, but we haven’t been. Thus, many people who do the right thing and improve their diet in hopes of preventing cancer may, at that very moment, be treating it as well. In this way, cancer prevention and treatment may sometimes be the same thing.
What new developments are there are in the battle against breast cancer? Well, most breast tumors are estrogen receptor positive, meaning they respond to estrogen; estrogen makes them grow. The problem for tumors in postmenopausal women is that there isn’t much estrogen around—unless of course you take it in a drug like Premarin (so-named because it’s made from pregnant mare urine). Premarin appears to increase the risk of breast cancer (as well as strokes, heart attacks, and blood clots). Unfortunately, the plant-based bioidentical hormone replacement therapies don’t appear any safer (see my 4-min. video Plant-Based Bioidentical Hormones).
Thankfully millions of women stopped taking Premarin in 2002, and we saw a nice dip in breast cancer rates. Unfortunately, those rates have since stagnated. Hundreds of thousands of American women continue to get the dreaded diagnosis every year. So what next?
Well, with no estrogen around, many breast tumors devise a nefarious plan—they’ll just make their own! Seventy percent of breast cancer cells synthesize estrogen themselves using an enzyme called aromatase. In response, drug companies have produced a number of aromatase inhibitor drugs that are used as chemotherapy agents. Of course by the time you’re on chemo it can be too late, so researchers started screening hundreds of natural dietary components in hopes of finding something that targets this enzyme.
To do this you need a lot of human tissue. Where are you going to get it from? To study skin, for example, researchers use discarded human foreskins from circumcision. They’re just being thrown away–might as well use them! Where are you going to get discarded female tissue? Placentas. They got a bunch of women to donate their placentas after giving birth to further this critical line of research.
After years of searching, they found seven vegetables with significant anti-aromatase activity. You can see the graph in my video Vegetables Versus Breast Cancer. Bell peppers, broccoli, carrots, celery, green onions, and spinach dropped aromatase activity by about 20%, but mushrooms forced down the estrogen-producing enzyme more than 60%.
Which mushroom worked best? Woodear, crimini, oyster, Italian brown, enoki, button, stuffing, shiitake, chanterelle, or Portobello mushrooms? Don’t even try to guess—you won’t get it! Check out my 2-min video Breast Cancer Prevention: Which Mushroom Is Best? for the answer.
-Michael Greger, M.D.