All dietary supplements come with inherent risks because they remain largely unregulated by the FDA. That means the various pills and powders on the market don’t have to back up any of their health claims, and they can even include ingredients never tested on humans. Some products are labeled incorrectly, failing to disclose certain substances or claiming ingredients that are actually absent. That doesn’t mean every nutritional supplement will damage your health, but it does mean that all of these products have the potential to do some amount of harm. In fact, a study published in the British Journal of Cancer uncovered a significant link between muscle-building supplements and testicular cancer.
Researchers focused on a range of muscle-building supplements, citing the sharp surge in their use as well as previous studies linking certain ingredients to testicular damage. One study, for example, linked large quantities of creatine to increased production of formaldehyde, a substance that caused testicular damage in rats in a separate study. In 2005, researchers found a high prevalence of performance-enhancing supplement use among people diagnosed with testicular cancer.