Soy Protein Myths – Will It Turn You Into a Woman?

While vegetarians have no doubt soy protein is a quality supplement which may go head to head with ever popular whey protein, many bodybuilders still avoid it choosing whey, egg protein or casein instead.

soy protein feminizing man
Does Soy Protein really feminizes man?

There are a lot of myths surrounding soy protein which is much more popular among female bodybuilders than male ones. Those myths are often kept alive through bro science and huge number of misleading articles available on bodybuilding forums and amateur blogs.


To some degree negative opinions on soy are unjustified and prevent some bodybuilders from using it. Our article fights these negative stereotypes and clarifies few things. So here we go – the most popular soy protein myths debunked.

Soy Protein Estrogen Myth

The most popular myth is based on believe that soy protein reduces testosterone levels. Even worse, some still believe that it actually increases female hormone estrogen slowly changing mescaline guy into woman.

First of all soy DOES NOT contain estrogen. It contains isoflavones classified as plan estrogens but those are different from hormone estrogens. Isoflaovenes possesses weak estrogenic activity and has been shown to act in animal models as an antiestrogen.


Soy Increases Cancer Risk Myth

According to this study there is no proof of soy being related to increased cancer risk. 65% of studied animals fed with soy not only did not show signs of increased cancer risk but actually shown protective results. There is no yet proof for protective effect of soy rich diet but such studies are on their way.

It is worth mentioning that population of countries where soybean are important part of diet (such as China and other Asian countries) got significantly lower cancer ratio than Western population.

Soy Protein Causes Man Breasts Myth

soy protein man breasts
There is no evidence soy protein gives you man breasts

Gynecomastia, because that’s the medical name for man boobs, is related to hormones and obesity. There is no medical evidence of soy protein causing man breast enlargement.
Studies has been made on group of children who were fed soybeans formula due to intolerance to regular formula. Those kids did not show any signs of gynecomastia.


Soy Protein Comes From GMO Soybeans Myth

While some soy protein supplements in fact come from genetically modified soybeans many are free of GMO. When shopping for your soy protein simply get one which is clearly labelled as non-GMO.
Unfortunately it is true that most of soybeans are GMO. According to stats even 90% of soybeans in countries such as United States are genetically modified. This is probably the biggest concern related to soy consumption.

Soy Protein Causes Erectile Dysfunction Myth

There is only one known case study where soy is to be blamed for erectile dysfunction. 19 year old male who was studied by doctors had other health problems which could contribute to the problem.

It is highly important not to consume soy in some incredible quantities. This is where potential erectile problems may occur.


While soy is not as dangerous as some want you to think, there are some issues related to soy intake which still need further studies.

The real problem is many studies showing positive effects of soy intake have been sponsored or started by companies which directly profit from selling soy supplements. Independent studies on side effects are rare.


We cannot give you any guarantees as for safety of soy products but as always – reasonable, limited use should keep you on the safe side.

  • Paul Christopher

    Soy has been proven to increase feminizing affects, Why would doctors recommend it to transgender patients?. You are a fool to believe this article, the mainstream will continue the lies about soy but the transgender community swear by soy.

    I cut soy completely, which is very hard because they put it in everything. My test levels increased and energy levels went down for a week but then came back with a vengeance.

    I also noticed the gyno issue i have had since childhood is gone and yes even as a competing bodybuilder, I still had a gyno issue.

    I recommend males to stay away from soy in all forms.

  • Lala T.

    Straight up lies in this article.