Do Creatine Supplements Cause Testicular Cancer?

You’ve probably heard by now about the new research that came out suggesting CREATINE SUPPLEMENTS CAUSE TESTICULAR CANCER! If you didn’t know, creatine is a supplement commonly used by athletes with the hopes of supporting more rapid energy production – often for high-intensity sprint-based sports. To athletes currently taking creatine, before you to start to panic and fear the worst, let’s take a look at this study.

To keep this summary brief, this study analyzed questionnaires conducted with 356 testicular germ cell cancer (TGCC) subjects and 513 controls from Connecticut and Massachusetts. TGCC is the most common form of tumor-causing malignancy in men 15-39 years of age.

The following were assessed on the questionnaire:

  • Age
  • Race (White vs. Others)
  • Years of education (≤ or > 12 years)
  • Tobacco smoking (Never vs. Ever)
  • Alcohol drinking (Never vs. Ever)
  • Height at reference date
  • Undescended testes or cryptorchidism (No vs. Yes vs. Missing)
    • Cryptorchidism: abnormally developed testicles, which is a risk factor for TGCC development
  • Family history of TGCC (Yes vs. No)
  • Injury to testes or groin that prevented normal activities for at least 5 minutes (Yes vs. No vs. Missing)
  • Vigorous exercise or sports activities in the last 2 years (No vs. ≤ 12 hours per month vs. > 12 hours per month vs. Missing)
  • MBS-use (Never vs. Ever)
    • Age at first use (Never vs. ≥ 25 years vs. < 25 years)
    • Number of types of MBS used (Never vs. 1 type vs. ≥ 2 types)
    • Duration of use (Never vs. ≤ 12 months vs. 13-35 months vs. ≥ 36 months)
      • Note: Muscle Building Supplements (MBS) use was defined as ≥ 1x per week for ≥ 4 consecutive weeks.

This study suggests that MBS (with creatine and androstenedione as participating ingredients) increased TGCC risk especially in early users, those using ≥ 2 types of MBS, and subjects with longer term use of MBS. The authors note that in MBS, often there are “natural” ingredients including artificial hormones and banned substances. They also highlight, as found in previous international studies, ~15% of commercial non-hormonal supplements includes undisclosed anabolic androgenic steroids, which has been associated with testicular cancer in rats.

Although the questionnaire assessed major risk factors to TGCC development, one must consider the alternative gaps and further questions that need to be answered in this study:

  • Medication use – what medications (prescribed and unprescribed) were individuals on/previously on?
  • Environmental exposure to cancer-causing chemicals (e.g. occupation could potentially play a large role in cancer risk, previous locations subjects have travelled to, or lived in)
  • Dietary assessment – high intakes of processed foods, low vegetable/fruit/fiber intake, poor dietary balance. Although there hasn’t been any direct studies tying nutrition’s impact on testicular cancer, diet has certainly been associated with risk increases of breast, prostate, stomach and colon cancer risk.
  • Although exercise participation was assessed, assessing whether an individual participated in vigorous exercise in the last 2 years does not equate to regular exercise participation. Exercise consistency makes a big difference!
  • Presence of other undeclared ingredients found in the MBS taken by subjects (potential cancer-causing ingredients found in MBS). What about interactions of mixing multiple MBS and other dietary supplements?
  • Do note that in this study, a subject is considered to be a MBS user if they have used a MBS of “≥ 1x per week for ≥ 4 consecutive weeks.” In the grand scheme of things, this isolated 4 week block use of a MBS certainly cannot be isolated as the root cause of TGCC risk, especially in a subject’s 15-39 years of life.
  • Creatine – there are many forms of creatine. Which forms were potentially found in the ingredients consumed by participants? In our practice, we ensure athletes are consuming only the monohydrate form, as this form has been the most researched. As well, we work to ensure the creatine monohydrates our athletes supplement with are either NSF or Informed-Choice tested. Learn about the importance of third-party tested supplements here.

As you can see, this study certainly highlights the potential risks of taking MBS! The supplement industry as we have mentioned before is shady business. BUT, to directly blame creatine as a perpetrator for the development of TGCC is bit farfetched with the gaps identified. Keep in mind, cancer and tumour growth, along with many disease conditions, are multifactorial in nature.

As always, we like to remind our athletes, if you’re looking to elevate your performance to the next level, FOOD FIRST! Build that foundation. Without a strong nutrition foundation for performance, adding supplements to a shaky foundation will never result in the performance benefits you are looking for!

The Research:

Li, N., Hauser, R., Holford, T., Zhu, Y., Zhang, Y., Bassig, B. A., . . . Zheng, T. (2015). Muscle-building supplement use and increased risk of testicular germ cell cancer in men from connecticut and massachusetts. British Journal of Cancer, 112 Suppl, 1247. doi:10.1038/bjc.2015.26