Evidence Matters

Saunas and Stroke: Bake your Way to Health?

BACKGROUND AND PURPOSE:

Sauna bathing has been a tradition in Finland for thousands of years
There is evidence to support a positive association between sauna bathing and reduced risk for cardiovascular disease (CVD), dementia, hypertension and all-cause mortality
Kunutsor et al. (Neurology, 2018) hypothesize that based on the association with decreased blood pressure, sauna bathing may be associated with decreased risk for stroke

Prospective cohort study of men and women
Participants: No prior history of stroke, middle-aged men and women
Patients reported their baseline habits of sauna bathing and stratified accordingly
Traditional Finnish sauna
- Relative humidity between 10% to 20% which can be increased by throwing water on the hot rocks of the sauna heater
- Temperature is lower at floor level
Three sauna bathing frequency groups were defined:
- 1 session per week
- 2-3 sessions per week
- 4-7 sessions per week
Hazard ratio (HR) and 95% CI were estimated for incident stroke, taking into account
- Age | Sex | Cardiovascular risk factors | Physical activity | Socioeconomic status

1,628 subjects were included in the study
- Age Range: 53-74 years; mean age: 62.7 years
- 51.6% female; 48.4% male
Median follow up of 14.9 years, with 155 incident stroke events recorded
Compared with participants who had one sauna bathing session per week, the age- and sex-adjusted HR (95% CI) for stroke was 0.39 (0.18–0.83) for participants who had 4–7 sauna sessions per week
HR unchanged even after adjusting for multiple CVD risk factors (BMI, smoking, systolic BP, LDL-C, alcohol consumption, type 2 diabetes, use of hypertensive/aspirin/lipid-lowering therapy)
Association was similar for ischemic stroke but modest for hemorrhagic stroke, which could be attributed to the low event rate (n = 34)

In the first prospective study on this topic, middle-aged women and men who sauna frequently have an approximately 60% reduced risk of new-onset stroke over 15 year follow up
Appears to be an independent association
Authors suggest that underlying “mechanisms include reduction in systemic blood pressure, stimulation of the immune system, positive alteration of the autonomic nervous system, positive effects on circulating lipid profiles, reduction in oxidative stress/arterial stiffness/carotid intima media thickness and peripheral vascular resistance”
The above mechanisms may also include the previous findings related to the protective effect related to memory diseases such as dementia

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