Many people were left alarmed this week by some very confronting study results which made the claim that users of muscle building supplements ran a significantly increased risk of developing testicular cancer.
This study was an overwhelming success in terms of generating attention grabbing headlines, but when we take a closer look at the actual findings, it becomes clear that these eyecatching are not successful in describing the realistic risk to people who use legal supplements in a safe way to enhance their physique and performance.
The researchers conducted their study on a group of nearly 900 young men from the United States. Just over one third of these participants had been diagnosed with a type of cancer called testicular germ line cancer (TGCC). TGCC is a very important area of research, because it is the most common cancer in young men, and the incidence has risen in the last few decades for reasons that doctors have been unable to explain.
The study participants were asked about a large number of factors that the researchers believed may have an influence on the development of this type of cancer. Along with supplement use, this included things like groin injury, a history of undescended testes, and alcohol and tobacco use.
They questions about supplement use were somewhat specific, and included the type of supplements used, the frequency of use, the length of time supplements were used for, and the age at which the participant first used supplements.
When the researchers looked at the data and took into account the effect of other factors that influenced the development of TGCC (for example, white males were more likely to develop cancer), there was an observable correlation between use of muscle building supplements and the development of cancer. Overall, they calculated a 65% greater chance of developing TGCC for all supplement users. This was even higher for men who used more than one type of supplement, people who used supplements before the age of 25, or people who had been supplementing for three years or more. Sounds scary, right?
If you stop reading there, this does make a pretty compelling argument for throwing your protein in the bin, but we don't really get the full story from this statistic alone. We need to look at the way the study was carried out to determine what this conclusions actually means.
The first issue worth looking at in detail is what the authors of the study have considered to be a 'supplement'. The paper mentions that thirty different types of muscle building supplement were mentioned by participants in their interviews, which the researchers then classed these into three groups – androstenedione and androstenedione boosters, creatine, and protein, based on the ingredients listed on the label.
You might have already spotted something that seems a little odd – androstenedione is a hormone precursor which is illegal in Australia because it is classed as an anabolic steroid. Furthermore, androstenedione has already been linked to the development of serious illness, including testicular cancer (2). On the other hand, creatine and protein supplements have been subject to hundreds of well-designed safety and efficacy studies and have repeatedly been found safe for the vast majority of people to use.
Androstenedione was sold over the counter legally in the US until 2004 which means that there is a high likelihood that a number of participants in this study would have reported the use of this steroid prohormone. Additionally, It is important to note the difference between androstenedione itself, a prohormone which is introduced from an external source, and a legal male hormone booster like Elemental Nutrition Massive Muscle Fuel or BSc Triandrobol, which maximises the body's own production of testosterone using ingredients like amino acids and botanical extracts. We know that these types of supplement have very different effects on health.
Other commentators have raised issue with the reliability of using company-declared supplement ingredient lists to determine what was in each product the participants used. There have been a number of recent instances where seemingly legal supplements have been adulterated with illegal and potentially dangerous ingredients. This is a factor which has the potential to confound results (3).
It is also important to look at the way in which the data has been presented. Saying that supplement users have a 65% greater risk of contracting testicular cancer sounds huge, and the 177% greater risk cited by the authors for people using more than one supplement is quite frightening.
Knowing the sort of numbers we are looking at helps keep this study in perspective. The paper states that the 2011 incidence of testicular cancer is 5.9 out of every 100,000 men between 15 and 49, or a 0.0059% chance, which rises to 0.0097%, or 9.7 out of 100,000 men with supplement use. There's no doubt that this is a significant increase which should be investigated further so we can one day work out how to reverse it, but it is important to note that the actual number of men contracting this disease is still very small. This study is not saying that supplement users have sealed their fate, rather it has determined a small correlation in risk which needs to be further explored.
What must be very strongly emphasised in these results is the difference between cause and correlation. This study shows a correlation between supplement use and testicular cancer, but it does not directly show that any of these supplements cause cancer. There are many factors which the authors have not considered in this preliminary research. What this study does do is raise the need for further research. We would particularly like to see some research that looks at the relative risks of each type of supplement.
Until then, there is a wealth of well conducted research showing that supplements like creatine and protein are safe and effective. We believe that people using legal muscle building supplements in a responsible way have very little to worry about.
(1) N Li, R Hauser, T Holford, Y Zhu, Y Zhang, B A Bassig, S Honig, C Chen, P Boyle, M Dai, S M Schwartz, P Morey, H Sayward, Z Hu, H Shen, P Gomeryand T Zheng. Muscle-building supplement use and increased risk of testicular germ cell cancer in men from Connecticut and Massachusetts. British Journal of Cancer 112, 1247-1250
(2) Androstenedione. Compound Summary. Pubchem Open Chemistry Database. http://pubchem.ncbi.nlm.nih.gov/compound/androstenedione#section=Drug-and-Medication-Information. Accessed April 15 2015.
(3) Do muscle building supplements cause testicular cancer? A deeper look at the latest study on MBS usage and testicular cancer. Examine.com. http://examine.com/blog/do-muscle-building-supplements-cause-testicular-cancer-a-deeper-look-at-the-latest-study-on-mbs-usage-and-testicular-cancer/?utm_source=Examine.com+Insiders&utm_campaign=ee6592ba37-MBS_testicular_cancer4_14_2015&utm_medium=email&utm_term=0_e4d662cb1b-ee6592ba37-69988545&goal=0_e4d662cb1b-ee6592ba37-69988545&mc_cid=ee6592ba37&mc_eid=6f47605109. Accessed 15 April 2015.