Sauna Science Addendum: Cedar Seeded Side-Effects
Shortcut to regular sauna bathing’s effects on male fertility metrics
Friendly disclaimer: I am not a licensed medical professional, so nothing in this post is medical advice in any way, shape, or form. You are responsible for conducting your own research, consulting your doctor, and making your own choices.
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In the recent Sauna Science Shortcut, we dove deep into some of the commonly touted physical, cognitive, and health benefits of sauna use, including improved endurance (I, II, III), reduced muscle atrophy (IV), and decreased cardiovascular and all-cause mortality (V). Today, we’ll touch on sauna bathing’s less often discussed impacts on male fertility metrics.
Dating as far back as the early 2000’s, reviews on sauna literature have mentioned how regular sauna bathing disrupts normal spermatogenesis – the production and development of sperm. (VI, VII, VIII) In particular, testes typically function 2-3 ℃ below core body temperature, creating an intuitive potential conflict between sauna bathing and testicular processes. (VI, IX)
For this reason, in 2013, Garolla and colleagues conducted a 9-month long experiment to test how regular sauna-use affects male hormones and several sperm metrics. The study consisted of 10 male subjects with an average age of ~33 years old who had no sauna exposure in the previous year completing two 15-minute sauna sessions at 176-194 ℉ per week for 3 months, followed by 6 months of no sauna bathing. Notably, the authors did not find any statistically significant changes in follicle-stimulating hormone, luteinizing hormone, testosterone, estradiol, inhibin-B, or sex hormone-binding globulin across the study period; however, they found a 65.2% relative reduction in sperm concentration (sperm per mL of semen), 58.3% relative reduction in sperm count (sperm per ejaculate), and 37.8% relative reduction in percentage of, “progressive motile,” sperm at the end of the 3-month sauna-bathing phase. (IX) Interestingly, all three of these parameters returned to baseline levels following 6 months without sauna bathing. (IX)
So, from a zoomed-in perspective, the data showing halvings of sperm concentration and count may be important for males to consider if they’re actively attempting to have children – especially males with naturally low sperm metrics. However, considering that the subjects from Garolla and colleagues’ study sustained sperm concentrations and counts significantly greater than what are viewed as low levels even after their large decreases, paired with the return of their sperm metrics to baseline levels following 6 months of zero sauna use, this may not be a huge concern from a zoomed-out perspective. (IX, XI) Also, despite their prominent sauna culture, Finnish men maintain high sperm counts (X) and healthy fertility (VII) compared to men from other nations. On the other hand, for males seeking to avoid impregnating a female partner for any reason, regular sauna bathing may have potential as an adjuvant to typical contraceptives – one more potential reason to hop into the heat.