Branched-chain amino acids supplements may harm male bodybuilders’ fertility

A new study published in Zygote reveals that common over-the-counter supplements popular with male bodybuilders and athletes may impact their fertility. This study comes amid a global decline in male fertility.

In this study, branched-chain amino acids (BCAAs) clearly impacted the reproductive function of male mice, causing significant changes in sperm concentration and a decline in fertility. The study pointed out that among BCAAs, valine in particular had a powerful effect on male reproductive function, although all BCAAs showed negative effects.

This preliminary research suggests that it could also have an impact on human fertility. Men who consume large amounts of animal proteins (whether from meat or dairy products), known to be rich in BCAAs, particularly leucine (Leu), isoleucine (Ile), and valine (Val), as well as men who take BCAA supplements, may be harming their sperm quality. In this regard, bodybuilders, who increasingly use BCAA supplements to build muscle mass, are particularly at risk.

Author Roya Kamali, from the Royan Institute, said that the link between BCAA supplements and declining male fertility warrants further investigation as “the unrestricted use of dietary supplements for bodybuilding by athletes and consumers in general could be a public health concern.

“In bodybuilders in particular, given that the vast majority of these consumers are young men of reproductive age, it is important to study in more detail the impact of such a choice on their ability to have children.”

Co-author Joël R. Drevet, from Clermont Auvergne University, said that if the data obtained from an animal model could be confirmed in humans, it could help explain the global decline in male fertility recorded in recent decades, for which environmental factors, including diet, are suggested as major culprits.