Potential Risks of Branched-Chain Amino Acid Supplements on Male Fertility

A recent research study published in the journal Zygote highlights a concerning link between commonly used supplements by male bodybuilders and athletes—branched-chain amino acids (BCAAs)—and reduced fertility. The study reveals that BCAAs, which include leucine, isoleucine, and valine, may negatively influence reproductive health, particularly impacting sperm quality and concentration.

The research, conducted on male mice, demonstrated that high intake of BCAAs led to significant declines in sperm count and fertility rates. Notably, valine appeared to have a particularly strong detrimental effect among the amino acids tested. These findings suggest that excessive consumption of BCAA-rich foods, such as meat and dairy products, or supplementation with BCAA products, could potentially impair human male reproductive functions.

The authors, Roya Kamali from the Royan Institute and Joël R. Drevet from Clermont Auvergne University, emphasized the importance of further investigation to verify these results in humans. Given that many young men involved in bodybuilding and athletic pursuits frequently use BCAA supplements to enhance muscle growth, there is a growing concern that such practices may have unintended effects on fertility.

This research might also help explain the broader decline in male fertility observed globally over recent decades, often linked to environmental and dietary factors. Experts urge caution regarding the widespread, unrestricted use of dietary supplements, especially among reproductive-aged men for whom fertility preservation is crucial.

Further studies are necessary to determine whether these findings in animal models translate directly to humans. Nonetheless, this research advocates for increased awareness and potential reevaluation of the safety of BCAA supplementation in young men seeking to optimize muscle development.

Source: https://medicalxpress.com/news/2025-05-chain-amino-acids-supplements-male.html