Most Men Taking Bodybuilding Supplements Don’t Know They Can Harm Fertility

Bodybuilders are largely unaware that the protein supplements they use to bulk up might harm their fertility, a new study shows.

Four out of five male gym enthusiasts (79%) said they use protein supplements as part of their fitness plan, the poll found.

But only 14% had considered how those supplements — which contain high levels of the female hormone estrogen — might impact their fertility, researchers found.

“Too much female hormone can cause problems with the amount and quality of sperm that a man can produce,” explained lead researcher Meurig Gallagher, an assistant professor studying infertility at the University of Birmingham in the U.K.

Men taking these protein supplements also might be unintentionally dosing themselves with steroids, Gallagher added.

“Many protein supplements that can be bought have been found to be contaminated by anabolic steroids, which can cause reduced sperm count, shrunken testicles and erectile dysfunction, amongst other things,” Gallagher said.

For this study, Gallagher and his colleagues surveyed 152 avid gym-goers. They found that more than half (52%) of male participants had thought about their fertility prior to being asked.

“We found that men are genuinely curious about their fertility when prompted, but that they don’t think about it on their own – likely because societally people still think of fertility as a ‘female issue’ and [incorrectly] believe that men’s fertility doesn’t change throughout their lifetimes,” researcher Jackson Brown, a professor in reproductive biology at Birmingham, said in a university news release.

About 28% of male respondents said the benefits of gym routines and supplements were more important to them than fertility, while 38% disagreed.

The findings were published recently in the journal Reproductive BioMedicine Online.

“Infertility is a problem of increasing concern, affecting 1 in 6 people worldwide, according to the World Health Organization,” Gallagher said. “Globally, there is limited understanding of the fact that men contribute to half of these cases of infertility.”

“While people were aware of the problems associated with anabolic steroid use, very few understood that gym protein supplementation can have negative effects,” Gallagher added.

Brown stressed that the findings don’t mean bodybuilders should abandon the gym.

“It’s important that people don’t see this as a reason not to be healthy or get exercise — but people should try and educate themselves about any form of supplementation they take, whether that is protein, vitamins or anything else,” he noted.

More information

Harvard Medical School has more about the health risks of protein powders.

SOURCE: University of Birmingham, news release, Nov. 29, 2023