Frequent sauna bathing reduces the risk of elevated blood pressure and is linked to a lower risk of pulmonary diseases, according to an extensive follow-up population-based study carried out at the University of Eastern Finland. The risk of developing elevated blood pressure was nearly 50% lower among men who had a sauna 4-7 times a week compared to men who had a sauna only once a week.
The same researchers have previously shown that frequent sauna bathing reduces the risk of sudden cardiac death, and cardiovascular and all-cause mortality. Elevated blood pressure is documented to be one of the most important risk factors of cardiovascular diseases. According to the research group, underlying protective mechanisms may include the beneficial effects of regular sauna bathing on blood pressure.
The Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) involved 1,621 middle-aged men living in the eastern part of Finland. Study participants without elevated blood pressure of over 140/90 mmHg or with diagnosed hypertension at the study baseline were included in this long-term follow-up study. Based on their sauna bathing habits, men were divided into three sauna frequency groups: those taking a sauna once a week, 2-3 times a week, or 4-7 times a week. During an average follow-up of 22 years, 15.5% of the men developed clinically defined hypertension. The risk of hypertension was 24% decreased among men with a sauna frequency of 2-3 times a week, and 46% lowered among men who had a sauna 4-7 times a week.
Sauna bathing may decrease systemic blood pressure through different biological mechanisms. During sauna bathing, the body temperature may rise up to 2°C degrees, causing vessels vasodilation. Regular sauna bathing improves endothelial function – the function of the inside layer of blood vessels, which has beneficial effects on systemic blood pressure. Sweating, in turn, removes fluid from the body, which is a contributing factor to decreased blood pressure levels. Additionally, sauna bathing may also lower systemic blood pressure due to overall relaxation of the body and mind.
A recent analysis of the same study also revealed that those taking a sauna frequently have a lower risk of pulmonary diseases.
Background: Sauna bathing is associated with reduced cardiovascular risk, but the mechanisms underlying this beneficial effect are not entirely understood. We aimed to assess the relationship between sauna bathing and risk of incident hypertension.
Methods: Frequency of sauna bathing was ascertained using questionnaires in the Kuopio Ischemic Heart Disease Study, a prospective cohort study conducted in Eastern Finland that comprised a population-based sample of 1,621 men aged 42 to 60 years without hypertension at baseline. The incidence of hypertension was defined as a physician diagnosis of hypertension, systolic blood pressure (SBP) >140 mm Hg, diastolic blood pressure >90 mm Hg, or use of antihypertensive medication.
Results: During a median follow-up of 24.7 years, 251 incident cases (15.5%) were recorded. In Cox regression analysis adjusted for baseline age, smoking, body mass index, and SBP; compared to participants reporting 1 sauna session per week, the hazard ratio for incident hypertension in participants reporting 2 to 3 sessions and 4 to 7 sessions was 0.76 (95% confidence interval: 0.57–1.02) and 0.54 (0.32–0.91), respectively. The corresponding hazard ratios were similar after further adjustment for glucose, creatinine, alcohol consumption, heart rate, family history of hypertension, socioeconomic status, and cardiorespiratory fitness: 0.83 (95% confidence interval: 0.59–1.18) and 0.53 (0.28–0.98), respectively.
Conclusions: Regular sauna bathing is associated with reduced risk of hypertension, which may be a mechanism underlying the decreased cardiovascular risk associated with sauna use. Further epidemiological and experimental studies could help elucidate the effects of sauna bathing on cardiovascular function.
Francesco Zaccardi, Tanjaniina Laukkanen, Peter Willeit, Setor K Kunutsor, Jussi Kauhanen, Jari A Laukkanen