Certain supplements consumed in order to increase muscle mass – creatine, hormones – are believed to be associated with an increased risk of testicular cancer.
Taking supplements to increase muscle mass is not without risk. The finding seems obvious concerning steroids and anabolics, banned in many states. But it also seems to hold true for legal and common-use products, like creatine.
An excess risk of 65%
Researchers at Brown University in the United States have established a link between the consumption of two supplements (creatine, androstenedione) and the development of testicular cancer. Their work involves nearly 900 American men (including 356 with testicular cancer) and has been published in the journal British Journal of Cancer.
The scientists thus questioned the subjects of the study on their consumption of supplements to promote muscle mass gain. In order to avoid bias, the researchers reviewed several factors that could influence the results (tobacco and alcohol consumption, physical activity, family history of cancer, etc.).
However, according to their observations, men who consumed these supplements would have a 65% more risk of developing testicular cancer. By consumption, researchers mean using one or more supplements at least once a week for at least four consecutive weeks.
Polyconsumption: risk increased by 177%
This risk is closely linked to the intensity, nature and duration of consumption. Indeed, within the cohort, the use of supplements for at least three years was found to be at the origin of an excess risk of 156%. The fact of starting young also seems to influence the results: having consumed supplements before 25 years raises this increased risk to 121%.
But the riskiest of uses would be one that combines different types of supplements. However, it often happens that consumers take several substances at the same time, in order to improve their performance. Within the cohort, polyconsumption was associated with an excess risk of 177%.
“These results are important, because to date, few modifiable risk factors for testicular cancer have been identified”, explain the authors, while acknowledging that if the association seems proven, the causal link remains to be established. This is the first epidemiological study on the relationship between “muscle supplements” and testicular cancer.
ANSES is alarmed
If these results remain to be confirmed, they nevertheless raise questions about creatine, a product that circulates freely in France. The study does not provide any evidence to establish the excess risk specific to this product, but its authors find that people who do not use it are less at risk.
These conclusions join those of a report of the French Food Safety Agency (formerly Afssa, now Anses), dated 2001. At the time, the Agency had to take a position on this product, which would be consumed by one in two Olympic sportsmen. The authors of the report concluded that the product was ineffective for long efforts, and that it was potentially toxic, taken in high doses and for several years.
They then called for the greatest caution. “The application of this precautionary principle to creatine supplements, pending further studies, would lead to not authorizing the prescription or the placing on the market and therefore henceforth in banning it, by justifying this refusal by appropriate information to users ”, we can read in their opinion.
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