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Blog. Soy and Man Boobs

They say “what goes around, comes around,” and nothing could fit this old cliché better than supposed causes of man boobs. Whether people are talking about hops, lavender or marijuana, articles trying to connect these kinds of plants with gynecomastia surface on a fairly regular basis. We spend time on and with our own man boob patients discussing the possibilities.

This time it’s “soy = man boobs.” So said a fan to Australian celebrity Osher Gunsberg recently, according to a down-under edition of the U.K.-based Daily Mail. We were glad to see Gunsberg debunk the claim: “That’s not true, and there’s science to refute that.”

Claims and Counterclaims

Soy and man boobs has been a topic of conversation in the gynecomastia community for years. PubMed, a database of the National Institutes of health, summarized a case of man boobs connected with soy in 2008. A man suddenly developed gynecomastia after drinking three quarts of soymilk daily, and the man boobs disappeared when he stopped. The article’s authors, two doctors based in Fort Sam Houston, Texas, concluded that soy was the culprit in this case.

The PubMed database also contains information on a 2004 study in Italy of 34 children raised on soymilk. Researchers found that “none of the boys presented gynecomastia,” and concluded that long-term soymilk feeding does not cause hormonal disruptions.

What’s a guy to think?!

Phytoestrogens at the Heart of the Matter

To help out our man boob patients and others we talk with, we’ve written about this topic several times. (You can read about soy and other plants in our blog archives.) At the heart of the argument are compounds called phytoestrogens, or literally, “plant-based estrogens.” Many foods we consume regularly contain phytoestrogens, including a variety of fruits, vegetables, grains, herbs, and drinks.

A few years ago we discovered a paper published at Tulane University that’s very helpful in understanding phytoestrogens. According to Tulane, these chemicals “mimic or interact with hormone signals in animals,” and, “In general, phytoestrogens are weaker than the natural estrogen hormones (such as estradiol) found in humans and animals or the very potent synthetic estrogens used in birth control pills and other drugs.”

Therein lies the reason these so-called causes of gynecomastia surface over and over in the media. Because phytoestrogens can have estrogen-like effects in humans (albeit a weak one), and because man boobs can be triggered by hormonal imbalances, it makes a certain amount of sense to read headlines like “Man Boobs from Hoppy Beer.”

Understanding Phytoestrogens and Gynecomastia

The key to sorting out the real story is what Tulane has to say about the effect of phytoestrogens being weaker than natural and synthetic estrogen. So, can beer rich in hops cause man boobs? No, we think not. However, if you are a brewer and handle and consume hops daily, it might be possible.

Does marijuana cause moobs? So far there’s no scientific proof. But there is plenty of anecdotal evidence that the phytoestrogens in marijuana can trigger breast growth in regular users, and most gynecomastia surgeons discourage consumption.

What about soy, then? When our gyno patients ask about foods and botanicals containing plant-based estrogens— like soy, lavender, tea tree oil and others— we counsel caution and moderation. Is it likely that the use of these items will cause breast growth? No. Is it possible? Maybe with heavy use. Moderation or avoidance is the safest plan.

Balance is Key

The Tulane paper notes that phytoestrogens offer potential health benefits. Many foods rich in these compounds— such as soy, flax and sunflower seeds, some nuts and many others— are thought to help women with some of the unwanted effects of menopause like hot flashes and osteoporosis. It has also been suggested that phytoestrogens may play a role in protecting against cancer. More study is needed to prove these theories.

What shouldn’t get lost in a discussion of phytoestrogens are the benefits of the foods that contain them. It goes without saying that a diet rich in vegetables, fruits, nuts, and grains is healthy for humans, and the more variety the better. As for the phytoestrogens found in many of these foods, Tulane says, “when consumed as part of an ordinary diet, phytoestrogens are considered safe and possibly beneficial.”

We always strive to add to our knowledge about the causes of man boobs, and we’re constantly on the lookout for new ideas and research. But, our most important focus is on our patients with man boobs and whether male breast reduction surgery makes sense for each one. Yes, the cause of their condition is interesting to consider, but at the end of the day, we want to help banish the problem if it’s the right step.

Contact us if we can help you.


Dr. Elliot William Jacobs is a board-certified aesthetic plastic surgeon who specializes in FTM top surgery, gynecomastia surgery, revision gynecomastia surgery and male breast reduction. He is a native of New York and has over 40 years of experience in his field. Dr. Jacobs is a highly respected and sought-after surgeon who is known for his skill, experience, and compassion. Whether you are interested in gynecomastia for the first time, or are looking to correct a gynecomastia you aren’t happy with, Dr. Jacobs can deliver amazing results.


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