The Most Potent Phytoestrogen (Plant Estrogen) is in Beer

Why do alcoholic men develop man boobs, and other feminine traits? Well, we know estrogens produce feminization, and our liver clears estrogens from the body. And so, the original theory was alcohol-induced liver damage leading to the retention of excess estrogens. The problem was that when they measured estrogen levels, they were not elevated. And even those with cirrhosis of the liver appeared to clear estrogens from the body normally. And also, men’s testicles started shrinking, even before serious liver disease developed.

So, alternative explanations were considered. Well, if it’s not due to estrogens produced endogenously, meaning within the body, maybe alcoholics are being exposed to exogenous estrogenic substances from dietary sources—maybe from phytoestrogens in the plants that alcoholic beverages are made from.

The discovery that plants could contain hormonal compounds was made back in 1951 by two Australian chemists charged with finding out the cause of an epidemic of infertility in sheep, that was ravaging their nation’s wool industry. It took them ten years, but they finally figured out the cause—a compound present in a type of clover called genistein, the same phytoestrogen found in soybeans.

Online, you can read about the dreaded clover disease on scare-mongering websites, but you’ll note they never talk about the difference in dose. To get as much as the sheep were getting from clover, you’d have to drink more than a thousand cartons of soy milk a day, eat 8,000 soy burgers, or about 800 pounds of tofu a day.

This is not to say you can’t overdo it. There are two case reports in the medical literature on feminizing effects associated with eating as few as 14 to 20 servings of soy foods a day. But at reasonable doses, or even considerably higher than the one or two servings a day Asian men eat, soy phytoestrogens do not exert feminizing effects on men.

So, anyways, back in 1951, we realized plant compounds could be estrogenic. Aha, two German researchers realized, maybe that’s why women who handle hops start menstruating. And indeed, they found estrogenic activity in hops, which is the bittering agent used to make beer. They found trace amounts of the soy phytoestrogens, but in such tiny quantities that beer would not be expected to have an estrogenic effect.

But then in 1999, a potent phytoestrogen called 8-prenylnaringenin was discovered in hops—in fact, the most potent phytoestrogen found to date; 50 times more potent than the genistein in soy, an obvious explanation for the menstrual disturbances in female hop workers in the past. Now that we have machines to pick our hops, our only exposure is likely via beer consumption, but the levels in beer were found to be so low, they shouldn’t cause any concern.

But then in 2001, a study on a hops-containing dietary supplement for “breast enhancement” raised the concern that another phytoestrogen in hops, called isoxanthohumol, might be biotransformed by our liver into the more potent 8-PN—which would greatly augment the estrogenic effects of hops. But this was a study done on mice. Thankfully, a study using human estrogen receptors found no such liver transformation.

And so, all seemed fine, until 2005. See, the liver is not the only transformation site inside the human body. The human colon contains trillions of microorganisms with enormous metabolic potential. It’s like a whole separate organ within our body, with a hundred livers’ worth of metabolizing power. So, let’s effectively mix some beer with some poop, and see what happens.

And indeed, up to a 90% conversion was achieved. Up until then, the concentration of 8-PN in beer was considered too low to affect human health. However, these results show that the activity of the intestinal microbial community could more than tenfold increase the exposure concentration. This can explain why you can detect 8-PN in the urine of beer-drinkers for days—because their gut bacteria keep churning it out. Obviously, the amount of straight 8-PN in beer is not the only source of estrogen effects, given this conversion.

So, a decade ago, the question remained, might drinking too much beer cause estrogenic effects and feminize men? I’ll give you the ten-year update in my next video.

Doctor’s Note

Check out the thrilling conclusion in my next video: What are the Effects of the Hops Phytoestrogen in Beer?

Previous phytoestrogen videos include:

What about GMO soy? See GMO Soy and Breast Cancer.

Menstrual health videos include:

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In health,
Michael Greger, M.D.

Michael Greger, M.D., is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United

Preventing Breast Cancer with Flax Seeds

Flaxseeds prevent breast cancerI’ve previously discussed the role of dietary lignans in the reduction of breast cancer risk and improvement in breast cancer survival, based on studies that showed that women with breast cancer who ate the most lignans appeared to live longer (Flaxseeds & Breast Cancer Survival: Epidemiological Evidence and Flaxseeds & Breast Cancer Survival: Clinical Evidence). However, lignans are found throughout the plant kingdom—in seeds, whole grains, vegetables, fruits, berries—so how do we know lignans aren’t merely a marker for the intake of unrefined plant foods? For example, those who eat lots of plants—vegetarians—have about eight times the lignan intake than omnivores.

In a petri dish, lignans have been shown to both have direct anticancer growth activity against human breast cancer cells and to prevent cancer cell migration. But it wasn’t until 2005 that it was put to the test in people. Researchers from the University of Toronto conducted a randomized double-blind placebo-controlled clinical trial (as seen in my video, Can Flax Seeds Help Prevent Breast Cancer?) of flaxseeds, the world’s most concentrated source of lignans, in breast cancer patients. The researchers found that flax appears to have the potential to reduce human breast tumor growth in just a matter of weeks. Therefore, I started recommending ground flax seeds to breast cancer patients.

Can lignans also help prevent breast cancer in the first place? High lignan intake is associated with reduced breast cancer risk, but again lignan intake may just be saying an indicator of high plant food intake in general. So researchers from the University of Kansas gave women at high risk for breast cancer a teaspoon of ground flaxseeds a day for a year, and found on average a drop in precancerous changes in the breast.

What about women who regularly eat flax seeds? Outside of an experimental setting, there just weren’t a lot of women eating flax seeds regularly to study—until now. Matching 3,000 women with breast cancer to 3,000 women without, a study published in Cancer Causes and Control found that consumption of flaxseed (and of flax bread) was associated with a 20–30 percent reduction in breast cancer risk. The researchers note that, as flaxseeds are packed with lignans, only a small daily serving of flaxseed is required to attain the level of lignan intake associated with a reduction in breast cancer risk. Researchers concluded: “As it appears that most women do not consume flaxseed and that small amounts may be associated with reduced breast cancer risk, interventions to increase the prevalence of flaxseed consumption might be considered.”

The latest review summarizes the association between flax and decreased risk of breast cancer, better mental health, and lower mortality among breast cancer patients. The only other study of flax and brain health I’m aware of was an exploration of 100 commonly used drugs and supplements on cognition in older adults, which found that flax is one of the few things that appears to help.

How else may flaxseeds aid in preventing and treating breast cancer? There’s an inflammatory molecule called interleukin-1, which may help tumors feed, grow, and invade. Our bodies therefore produce an interkeukin-1 receptor antagonist, binding to the IL-1 receptor and blocking the action of IL-1. The activity of this protective inhibitor can be boosted with the drug tamoxifen—or by eating flax seed. In premenopausal women, the proinflammatory profile of interleukin-1 can be counteracted by a dietary addition of a few spoonfuls of ground flax. One month of flax may be able to increase the anti-inflammatory inhibitor levels by over 50 percent, better even than the drug.

Yes, having one’s ovaries removed may reduce breast cancer risk as much as 60 percent, but at the cost of severe side-effects. The drug tamoxifen may reduce the incidence of breast cancer by more than 40 percent, but may induce other severe side effects such as uterine cancer and blood clots. That’s why less toxic (even safe!) breast cancer preventive strategies such as dietary modifications need to be developed. These lignan phytoestrogens in flaxseeds may be one successful route given the data showing reduced breast cancer risk and improved overall survival.

Lignans are not a magic bullet to prevent breast cancer—we can’t just sprinkle some flax on your bacon cheeseburger—but as a part of a healthy diet and life-style, they might help to reduce breast cancer risk in the general population.

Flaxseeds may also help fight hormone-mediated cancers in men. See Flaxseed vs. Prostate Cancer and Was It the Flaxseed, Fat Restriction, or Both?

What else can these puppies do? See:

I have another 100+ videos on breast cancer if you want to become an expert and help take care of yourself and/or the women in your life. Here’s a few recent ones to get you started:

In health,
Michael Greger, M.D.

ger, M.D., is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous “meat defamation” trial. Currently Dr. Greger proudly serves as the Director of Public Health and Animal Agriculture at the Humane Society of the United States.

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