There’s no evidence that IPAs are giving you man boobs. A provocatively titled article claiming the exact opposite made the rounds on social media a few days ago, but there is no evidence to back up this claim. Here are the facts.
As with any plant, hops contain a wide variety of chemical compounds. One of these compounds — 8-prenylnaringenin (8-PN) — is a phytoestrogen. A phytoestrogen is a plant compound (hence the prefix “phyto”) that binds to estrogen receptors. Specifically, 8-PN has been shown to bind tightly to estrogen receptors in rat uterus. Hops also contain isoxanthohumol, which can be converted to 8-PN in the intestines.
8-PN is a potent phytoestrogen, one of the strongest detected to date, but it’s concentration in beer varies from undetectable to very low levels. (One study found 20 micrograms per liter as the highest concentration.) In the few papers that have been published on the topic, none show a direct link between beer consumption and male breast development (or female breast development). One study claimed that 8-PN levels in beer might reach a level that could result in human biological activity, but two others claimed this was unlikely.
Phytoestrogens in hops may have some effects on humans. It’s been suggested that female workers at hop plants may develop irregularities in their menstrual cycles, but this hasn’t been proven. It’s too early to tell, but the fact that 8-PN is a potent phytoestrogen may have consequences for people who are directly exposed to lots of hops. It could even have some effects on heavy consumers of very hoppy beers, but this is not likely and has yet to be shown.
An explicit link between IPAs (or other beers) and male breast development has never been documented. The same goes for hops from beer consumption and impotence, another claim made in the article. Heavy beer consumption may lead to males having more adipose around their chests because beer contains a fair amount of Calories. However, actual male breast development (gynecomastia) is different from simply being fat. Gynecomastia involves hormone-induced changes in breast tissue, usually leading to a layer of firm tissue developing behind the areola. More adipose tissue forming beneath the skin across the whole breast, as in weight gain, is not by itself gynecomastia. Likewise, high sustained levels of alcohol consumption can cause impotence. There’s no evidence that hops are the culprit.
That whole idea that IPAs give you man boobs rests on the idea that 8-PN is a phytoestrogen (which it is), but completely ignores that fact that the dosage required to cause problems in humans is unknown. And, there are more likely reasons for “man boobs” (fat) than a hop compound that can’t even be detected in many beers. In addition, lots of plants contain phytoestrogens and the amount we consume of these plants far outweighs the relatively tiny amounts of hop compounds in beer. (In a homebrewed IPA, you are talking about a few ounces of hops in 5 gallons (19 L) of liquid, and most of the plant material is left behind in the kettle.)
The presence of 8-PN in hops is interesting, and deserving of further study, but the idea that drinking IPA gives you man boobs is completely unfounded. The current evidence is scarce, but levels of 8-PN in beer appear to be too low to cause a problem.
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