Heterosexual men are united in their admiration for large, shapely breasts, except when they grow on their own chest. As bizarre as it may sound, it is perfectly possible for men to grow breasts like woman, in a condition known medically as gynecomastia and colloquially as man boobs or moobs. Straight out of men’s nightmares, gynecomastic can be caused by a medley of medical conditions and lifestyle problems. And going by the results of a new study, man boobs can also be caused by harmless things like essential oils, namely lavender and tea tree oil.

In 2007, a study published in The New England Journal of Medicine, said that young boys who applied products containing lavender and tea tree oil developed breasts. And even more suspiciously, when they discontinued the use of these products, their breasts reduced.

The research team from National Institute of Environmental Health Sciences believe that chemicals found in these essential oils can trigger growth of male breasts. These chemicals are said to cause growth of man boobs by increasing the production of the female hormone oestrogen and reducing the male hormone testosterone.

Lavender and tea tree oils are present in a wide variety of cosmetics and toiletries, many of which are used even by men. Scientists who conducted the research believe that these chemicals are present in over 65 essential oils in total. This means, men have to be extra careful while using anything that contains these oils, which include soaps, creams, perfumes, shampoos, conditioners, hair gels and other styling products. But that’s not all. Apart from essential oils, many everyday things can also trigger an oestrogen boost in men and cause man boobs. Here are five man boob-causing things men should stay away from.

1 Soy products

Soy is prized for its many health benefits and most importantly for its rich protein content. But it’s also a rather contentious food because it is known for its phytoestrogens, substances that act like the female hormone oestrogen when it is consumed. Although it’s not very well documented, a 2008 study published in Endocrine Practice reported a case of a 60-year-old man who had male breasts, erectile dysfunction and decreased libido after having 3 quarts of soy milk every day. After he discontinued, he stopped experiencing those problems.

2 Beer

You’ve heard of the beer belly, but what about beer breasts? A potent phytoestrogen, 8-prenylnaringen (8-PN) is present in the hop flowers used as a flavouring and a stabilising agent in beer. Studies show that hops have a powerful hormonal activity that may cause excessive oestrogen in the male body. But the good thing is that the levels are low. So unless you are drinking beer like water, it shouldn’t cause much concern. It has to be noted that alcohol consumption can cause cirrhosis of the liver, leading to gynecomastia as a side effect.

3 Men’s grooming products

Men’s cosmetics and grooming products like perfume, lotions, hair gels, etc. may contain the aforementioned essential oils. It’s already established that daily exposure to these chemicals may mess with the hormonal activity and cause gynecomastia.

4 Marijuana or weed

Weed proponents can wax eloquent about the benefits of weed. But they can’t deny that it also has some undesirable side effects, one of which is possibly gynecomastia. Animal studies indicate that an active ingredient in marijuana can cause a dip in testosterone levels, leading to a possible increase in man boobs. But although studies haven’t been able to conclusively tie marijuana usage to gynecomastia, it is widely believed that smoking weed could cause man boobs.

5 Plastic water bottles

That plastic bottle from which you sip water every day could be causing your man boobs. The BPA from your plastic bottle is a known endocrine disrupter. If you use a plastic bottle to store your drinking water, chances are that BPA may leach into it. Once ingested, BPA acts like oestrogen in your system, causing hormonal problems and gynecomastia. Note that BPA is also present in other household products such as canned food. So the best way to ensure your body stays BPA free is to reduce your dependence on canned food and bottled water.

While external factors do contribute towards gynecomastia, men should know that moobs could also be a result of underlying health problems. If you are struggling with the problem, it's best to seek medical help. And luckily, most cases can be corrected with the right treatment.

(The above story first appeared on LatestLY on Mar 19, 2018 12:56 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).