Muscle Building Supplements Linked to Testicular Cancer

Supplements containing creatine or androstenedione significantly increase disease risk.

Supplements containing creatine or androstenedione significantly increase disease risk.

Popular muscle-building supplements significantly increase the risk of developing testicular cancer, a recent study indicates.

Published in the British Journal of Cancer, the study found that pills and powders with creatine or androstenedione is associated with a high testicular germ cell cancer risk, especially in men who started using the supplements prior to 25 years of age, men who use multiple supplements, and men who used them for more than 3 years.

"The observed relationship was strong," senior author Tongzhang Zheng said in a press release. "If you used at earlier age, you had a higher risk. If you used them longer, you had a higher risk. If you used multiple types, you had a higher risk."

The incidence of testicular cancer increased from 3.7 cases in 100,000 men in 1975 to 5.9 cases per 100,000 men in 2011 due to reasons that remain unclear.

"Testicular cancer is a very mysterious cancer," Zheng said. "None of the factors we've suspected can explain the increase."

The current study is the first analytical epidemiological evaluation of the potential link between supplements and testicular cancer following mounting evidence indicating at least some supplement ingredients may damage the testes, the authors wrote.

"Our study found that supplement use was related to a higher risk of developing testicular cancer. These results are important because there are few identified modifiable risk factors for testicular cancer," main research collaborator Russ Hauser said in a press release.

The researchers interviewed approximately 900 men, with 356 men having been diagnosed with testicular germ cell cancer and 513 men who had not. The researchers questioned the men on their supplement use and a wide variety of other risk factors, including smoking, drinking, fitness habits, family history of testicular cancer, and prior injury to the testes or groin.

Supplement use was defined as consuming 1 or more supplements at least once a week for 4 consecutive weeks or more. After accounting for possible confounders, age, race, and other demographics, the results showed men who used supplements had a 65% greater risk of having developed testicular cancer compared with men who did not use supplements.

Furthermore, there was a 177% greater risk in men who used more than one kind of supplement. Men who used supplements three years or longer and men who started using supplements at 25 years or younger also had a significantly higher risk of developing the disease.

"Considering the magnitude of the association and the observed dose-response trends, muscle-building supplements use may be an important and modifiable exposure that could have important scientific and clinical importance for preventing testicular germ cell cancer development if this association is confirmed by future studies," the authors wrote in the study.