Saunas and Heart Health: Promising, but Not Proven

Saunas have moved from the gym locker room to the wellness spotlight. Claims range from “sweating out toxins” to burning fat. The most interesting research is not about weight at all, but about heart health. Here is what it suggests, and what it cannot yet prove. This is general education, not medical advice.

A long Finnish study

In 2015, Laukkanen and colleagues published a study in JAMA Internal Medicine that followed 2,315 middle-aged men in eastern Finland (ages 42 to 60) for a median of about 20 years. Saunas are part of daily life there, so the researchers could compare men with different habits. They grouped them by how often they used one: once a week (601 men), two or three times a week (1,513 men) or four to seven times a week (201 men).

• Compared with once a week, men who used a sauna four to seven times a week had about a 63 percent lower risk of sudden cardiac death after adjusting for other risk factors (HR 0.37).
• The risk of fatal coronary heart disease was about 23 percent lower with two to three sessions a week and about 48 percent lower with four to seven.
• Fatal cardiovascular disease and death from any cause followed a similar pattern, with risks falling as frequency rose.

Why caution is needed

• It was observational. The study shows an association, not a cause. Men who use saunas often may differ in other ways, including fitness, income and social life.
• Sessions were self-reported. People may not remember their habits exactly.
• The group was narrow. The participants were middle-aged Finnish men, so the results may not apply to everyone.

What about weight loss?

A sauna does make you sweat, and the scale may read lower afterward. That drop is water, and it returns when you drink. It is not fat loss. If your goal is a lower body-fat level, steady changes in eating and movement have far more support, as we discuss in our guide to where fat goes when you lose it.

Using a sauna sensibly

These are general safety points, not findings from the study:

• Drink water before and after, and leave if you feel dizzy or unwell.
• Skip alcohol before a session.
• Check with a clinician first if you have a heart condition, low blood pressure or are pregnant, or take medications that affect blood pressure or hydration.
• Keep sessions short at first and build slowly.

A nice extra, not a replacement

If you enjoy a sauna, the research gives no reason to avoid it for most healthy adults, and it can be a relaxing way to wind down. It is not a substitute for activity. Short bursts of movement, as described in exercise snacks, and regular strength work, as in lifting and longevity, have stronger evidence behind them.

Sources

• Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine, 2015;175(4):542-548 (figures from the abstract and summaries).
• American College of Cardiology. Is sauna use associated with reduced risk of CV events? (summary of the study, 2015).