Bodybuilding supplements may cause testicular cancer, study finds

Chuck Bednar for redOrbit.com – @BednarChuck

Men who turn to supplements in order to build muscle mass may unwittingly be increasing the risk that they will develop testicular cancer, especially if they started doing so before the age of 25, used more than one product or took supplements for at least three years.

Those findings are based on a new British Journal of Cancer study which found that males who reported using pills and powders containing muscle-building substances such as androstenedione or creatine reported a significantly higher likelihood of developing the disease.

Building on research linking supplements to testes damage

Senior author Tongzhang Zheng, a professor of epidemiology at Brown University who led the study while at Yale, and his colleagues discovered that the associated testicular germ cell cancer risk was especially high in those who used the substances early, often or with other products.

The relationship was “strong” in users who started using supplements by the age of 25, used the products for a long period of time or took multiple substances to build muscle, the authors said. They wrote that their paper is the first analytical epidemiological study to probe the potential link between bodybuilding supplements and testicular cancer, adding that it was inspired by growing evidence that at least some ingredients of these products could damage the testes.

Supplement use increase testicular cancer risk by 65 percent

Zheng’s team conducted in-depth interviews of nearly 900 men from the states of Massachusetts and Connecticut, including 356 that had been diagnosed with testicular germ cell cancer and 513 who had not. The men were asked about their supplement use, as well as several potential factors such as smoking, drinking, exercise habits, prior injury to the region and family history.

After accounting for all of those other factors, as well as age and other demographics, the authors found that men who used supplements at least once per week for four consecutive weeks or more had a 65-percent increased risk of developing testicular cancer than those who did not.

In men who used more than one kind of supplement, the risk spiked by 177-percent (a 2.77 odds ratio), while those odds ratios were 2.56 among males who used supplements for three years or more, and 2.21 for men who started using supplements at age 25 or younger. While the study has found a link between supplements and testicular cancer, future large-scale epidemiologic studies and lab experiments would be required to establish a causal relationship, the authors said.

So what type of products are the most dangerous?

“Some degree of caution is warranted when interpreting the exact types of [muscle-building supplements] associated with the elevated risks in our study since this is the first analytical epidemiological study investigated the issue,” Professor Zheng told redOrbit via email.

That said, he explained that there are “potential mechanisms for a potential link. For example, creatine, after it is converted to production of methylamine and formaldehyde, could create cross-linked proteins and DNA, and formaldehyde has been demonstrated to cause autophagy in testicular tissues in a dose-dependent manner as well as a variety of reproductive toxicities.”

Similarly, some have suggested that urinary creatine could be used as a potential marker of testicular damage, and androstenedione in high quantities has been shown to result in androgenic or estrogenic effects in humans, including possible development of testicular atrophy, he added. As for the age-related link, he said that testes are more sensitive carcinogens in the younger age, and that testicular cancer increases rapidly after puberty and peaks around age 35.

Unfortunately, Zheng told redOrbit that he “doubts” that the study will have much of an impact when it comes to dissuading people about using these products. “People still smoke tobacco while so much evidence linking smoking increases human diseases including cancers, and with warning signs on tobacco product packages,” he said, “but we want both the FDA and consumers know that there exists a potential link for using the products and human health.”

On a side note…this is all we thought about when writing this article:

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