Heavy Metals and Hypertension: How Saunas Can Help

Heavy metal exposure from the environment, food, and water is considered a nearly unavoidable occurrence; a process that slowly develops and worsens over a lifetime.¹ Metals such as mercury, lead, arsenic, and cadmium have been identified within individuals, of which there is no known biological benefit. Of particular note; said elements are likely progenitors of carcinogens, and they exhibit a palette of toxic effects upon the endocrine, nervous, renal, immunological, musculoskeletal, and cardiovascular systems.¹⁽¹⁾ As such, the following will consider how sweating/sauna use might help reduce toxic heavy metal burden, and facilitate improvements in cardiovascular health.

Sweating is a process characterized by an increase in thermal load; the body activates heat loss processes which includes amplified circulation along the skin ultimately leading to sweating.¹⁽²⁾ Consistent thermal load induces blood flow to the skin, which increases from a baseline of 5–10%, to as high as 60–70% of the cardiac output.¹⁽²⁾ Peak sweating occurs within approximately 15 minutes, and water losses may be as high as 2 L/h, especially among individuals who habitually sweat.¹⁽²⁾ Having briefly considered the physiological mechanisms behind sweating, the following will explore the application of said process and its relationship to heavy metal release from the body.

Heavy metals, such as cadmium, in sweat was examined in six studies according to Sears et al1¹⁽⁷⁾ with concentrations ranging from <0.5– 10 μg/L to 0.36–35.8 μg/L. Interestingly, the researchers postulated that sweat could be an important route for excretion of cadmium, especially when an individual was exposed to high levels.¹⁽⁷⁾ Such a submission was supported by observation and measurement; total daily excretion of cadmium was higher in sweat than in urine and peak cadmium concentrations observed in sweat was 35.8 μg/L.¹⁽⁷⁾ Ultimately, such knowledge builds a case to implement sweating as a modality for cadmium/heavy metal reduction.

Sweating, especially via sauna use, has been associated with improved cardiovascular markers; Sauna bathing may have various health benefits to include a reduced cardiovascular risk.² Furthermore, Zaccardi et al^2(1120) noted that regular sauna bathing could be a protective factor against the development of cardiovascular diseases (CVDs). Of particular interest was that individuals who repored 4 to 7 sauna sessions/week had a significantly reduced risk of fatal CVD events when compared to participants with 1 sauna session/week.^2(1120) The following will consider potential mechanisms behind such favorable changes behind cardiovascular improvements.

Zaccardi et al^2(1123) stated that repeated sauna sessions improve vascular endothelial function in patients at high CVD risk; such alternations indicate an efficacious role of thermal therapy on said endothelium. Furthermore, sauna therapy also positively affects the autonomic nervous system. For example, a typical Finnish sauna session is characterized by warming up in the sauna with subsequent cooling and relaxation. Zaccardi et al^2(1123) suggested such a protocol could modulate the autonomic system helping explain the effects on blood pressure reduction. Finally, increased heart rates (i.e., 150 beats per min +) during sauna use increases vasodilatation and function of the vasculature; benefits that are associated with low and moderate intensity physical exercise training.^2(1125)

Heavy metal exposure from the environment, food, and water is considered a nearly unavoidable occurrence; a process that slowly develops and worsens over a lifetime. Such exposure has been associated with disease progression to include unfavorable changes in cardiac function. However, sweating, especially through the use of saunas, facilitates the excretion of heavy metals (i.e., cadmium) as well as inducing favorable changes in cardiac function, to include reductions in blood pressure. Ultimately, sauna therapy is a non-invasive, simple, and cost-effective means of helping mitigate the downstream effects of heavy metal exposure and hypertension.

References

1. Sears ME, Kerr KJ Bray RI. Arsenic, cadmium, lead, and mercury in sweat: A systematic review. J Environ Public Health. 2012. doi:10.1155/2012/184745.
2. Zaccardi F, Laukkanen T, Willeit P, et al. Sauna bathing and incident hypertension: A prospective study. Am J Hypertens. 2017;30(11):1120-1125. doi:https://doi-org.libproxy.bridgeport.edu/10.1093/ajh/hpx102.

-Michael McIsaac