PROVIDENCE, R.I., April 13 (UPI) -- Many young men and women looking to sculpt their bodies rely on a variety of supplements to build and tone muscle mass. But for men, a brawnier physique may come at a steep cost. New research suggests the consumption of supplements like creatine or androstenedione may boost the risk of testicular cancer.
The correlation was confirmed by a team of scientists at Yale University who interviewed more than 900 men about their workout regiment and history of supplement use. More than 350 of the men, all from Massachusetts and Connecticut, had been diagnosed with testicular germ cell cancer. In addition to divulging diet and exercise details, study participants also answered questions about smoking and drinking habits, family history of testicular cancer and groin injury history.
The data showed that men who used supplements at least once a week for four consecutive weeks were 65 percent more likely to have been diagnosed with testicular cancer.
For men who used more than one kind of muscle-building supplement, the risk of developing testicular cancer was 177 percent greater. Consuming supplements for three years or longer resulted in a 156 percent risk increase.
"The observed relationship was strong," explained study leader Tongzhang Zheng, who carried out the researcher at Yale before moving to Brown University's School of Public Health as an epidemiology professor. "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."
Testicular cancer rates have been rising over the last several decades, and researchers haven't been able to pinpoint why. This latest study -- published this week in the British Journal of Cancer -- offers clues.
"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," Zheng and his colleagues concluded.
But the study only suggests correlation, not causation. Additional lab experiments are necessary to confirm whether or not -- and if so, how -- these supplements encourage testicular cancer.