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A medical marijuana user lights up a joint.

John Lehmann/John Lehmann/Globe and Mail

There's no delicate way to put this: If you smoke pot and you're a man, the habit may be giving you man boobs.

A Detroit plastic surgeon, Anthony Youn, is highlighting the uncomfortable idea in a column written for CNN, saying he has seen (and smelled) the phenomenon in his office.

The medical term for men developing breasts is gynecomastia. Youn writes that it's a condition that affects 33 to 41 per cent of men between the ages of 25 and 45. He says it's even more common during puberty, affecting about 60 per cent of 14-year-old boys. It also shows up in older men - about 55 to 60 per cent of men aged 50 and older, he writes.

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As Youn handily explains: "Gynecomastia is caused by a hormone imbalance between testosterone and estrogen. When the ratio between testosterone and estrogen tips in favor of estrogen, the body responds by creating excessive breast tissue. Hence, man boobs."

Youn refers to animals studies that found a link between the active ingredient in marijuana, Δ9-tetrahydrocannabinol, or THC, and a decrease in testosterone levels, a reduction of testicular size and abnormalities in the form and function of sperm.

But in that research, scientists suggested a link to gynecomastia was only "plausible," not proven.

"In humans, the effects of marijuana on testosterone and estrogen levels aren't as clear. Lower testosterone levels have been reported in chronic marijuana users compared to non-users, but not all studies support this," he writes.

Apparently the condition can go away over time, but in 2012, 23,000 Americans underwent plastic surgery to treat gynecomastia.

In his field, he says, "the majority of plastic surgeons I've consulted with routinely inquire with their gynecomastia patients about cannabis use and recommend they stop smoking pot immediately."

Youn thinks this legalization of pot in some states might help solidify the link.

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"If a true link between smoking pot and gynecomastia does exist, then we should expect to see a spike in gynecomastia treatments in those states which have legalized marijuana," he writes.

Until then, he's offering the world a bit of free advice: "So for now, if you have moobs, it's probably best to put out that joint."

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About the Author

Tralee Pearce has been a reporter at The Globe and Mail since 1999, starting as a writer in the paper’s Style section. She joined the new Life section for its launch in 2007. She covers parenting and family issues for the daily section. More


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