New research suggests muscle-building supplements containing creatine or androstenedione could raise men's risk of testicular cancer.
The findings also showed testicular germ cell cancer risk was significantly elevated in men who started using these supplements before the age of 25, Brown University reported.
"The observed relationship was strong," said study senior author Tongzhang Zheng. "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."
This was the first analytical epidemiological study to look at the link between supplements and testicular cancer.
"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," said Russ Hauser, professor of environmental health science at Harvard T.H. Chan School of Public Health and a main collaborator of the research.
To make their findings the researchers conducted detailed interviews of 900 men from Massachusetts and Connecticut, 356 of whom had been diagnosed with testicular germ cell cancer. After taking other risk factors into account, the data showed men who used supplements were 65 percent more likely to develop testicular cancer. "Use" was classified as consuming one or more supplements per week for a period of at least four weeks. The odds increased to a 177 percent increased risk in men who used more than one type of supplement, and they were even higher in those who used them for three years or longer.
"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 concluded in the study.
The findings were published in a recent edition of the British Journal of Cancer.
