Saunas have become commonplace in wellness spaces.
Better heart health and detox are the top.
1. Better Heart Health:
So here is what we actually know, from a purely biological perspective:
Source: Kunutsor et al, 2024
CRF = Cardio Respiratory Fitness/VO2 Max, the higher the better
A light cardio might add +3 or +7 mL/kg/min of fitness to VO2 Max over time.
In this study, sauna adds 0.3 mL/kg/min (3% of the minimum) with 1.22 mL/kg/min for 2-3 sauna sessions/week in the longer-term analysis.
So not much (3% of barely nothing). But there is no dose-response relationship (when the sauna stops, fitness doesn’t decrease), meaning that it might just be that sauna is just correlated to exercise (which is good for you).
2. Detoxification:
Ni = Nickel, needed in tiny amounts in body, but toxic in higher concentrations.
Pb = Lead, no safe level, accumulates over time
Cu = toxic only at high levels
As = Arsenic, carcinogenic. Chronic exposure is the concern
Hg = Mercury, strong neurotoxin
Results: this paper showed that exercise-induced sweating expels higher concentrations of toxins than a sauna would.
Source: Kuan et al. 2022
What do these concentrations mean? Well 57.3 µg/L is not significant. Tens of hundreds of µg are expelled through urine and other bodily methods.
In another paper covering Lead (Pb) specifically:
Source: Thompson. 1974
Conversion: µg/L in 7mL of sweat to µg
(4.9 µg/L in sauna * 0.007L) / 264 µg (urine and faeces) =
0.013% of lead excreted in sauna
This number is tiny tiny, so these “detox” effects are minimal.
And since alcohol freely diffuses across membranes (there is no reservoir to be drained), the amount lost through sweat in the sauna is barely anything. It may just make people feel flushed.
At the end of the day
If sauna makes you feel good, relaxed, and gets your heart-rate up a little bit then by all means do it.
The psychological effects of it are great,
Source: Kerhart, L., & Stackeová. 2024
But if you’re looking for miracle effects on the body such as a healthier heart or detox.. you’re out of luck.
Sauna is a helpful, healthy ritual that can make people feel better, which in turn has great effects on overall health.
Works Cited:
Kuan, W.-H.; Chen, Y.-L.;
Liu, C.-L. Excretion of Ni, Pb, Cu, As,
and Hg in Sweat under Two Sweating
Conditions. Int. J. Environ. Res. Public
Health 2022, 19, 4323. https://
doi.org/10.3390/ijerph19074323
Kunutsor, S. K., Isiozor, N. M., Kurl, S., & Laukkanen, J. A. (2024). Enhancing cardiorespiratory fitness through sauna bathing: Insights from the Kuopio Ischemic Heart Disease prospective study. Journal of Cardiopulmonary Rehabilitation and Prevention, 44(4), 241–249. https://doi.org/10.1097/HCR.0000000000000876
Kerhart, L., & Stackeová, D. (2024). Psychological benefits of sauna ceremonies in the context of wellness. Acta Salus Vitae, 12(2).
Thompson, J. A. (1974). Balance between intake and output of lead in normal individuals. British Journal of Industrial Medicine, 31(4), 266–271. https://doi.org/10.1136/oem.31.4.266
TheWhyLab 