Sauna and heart health: a study that included women
A later Finnish study added women to the sauna research, and found a similar pattern linking frequent sauna use with fewer fatal heart events. Here’s what it can tell us, and how it relates to the earlier study of men alone.
The short version
Researchers followed 1,688 men and women in eastern Finland, in a later examination of the KIHD study that unlike the 2015 heart-health cohort also enrolled women, for a median of 15 years. People who reported more frequent sauna use had lower rates of fatal cardiovascular disease than people who went once a week. Adding sauna habits to a standard risk calculator improved its accuracy, but only slightly. The study cannot show that sauna caused the difference: participants chose their own habits, and only 181 cardiovascular deaths were recorded.
Keep in mind
An association, not proof of cause and effect. The 15-year follow-up recorded only 181 cardiovascular deaths, and the risk-prediction improvement was small.
What they found
During follow-up, 181 people died of cardiovascular disease. People who reported four to seven sauna sessions a week had a lower rate of cardiovascular death than people who reported one session a week: a hazard ratio of 0.23 (95% confidence interval 0.08 to 0.65) after adjustment.
The pattern held for both men and women in the analysis.
Adding sauna frequency to a standard cardiovascular risk calculator changed its accuracy (a measure called the C-index) by 0.0091: a small but statistically significant shift, not a meaningfully more accurate personal prediction.
What this means for your practice
This adds women to a body of evidence that had previously only looked at men, which matters. It does not tell you how often to use a sauna: the frequencies above are comparison groups, not a recommended routine.
This does not establish a sauna routine to follow, or show that a KUUME ritual has these effects.
Methods and limitations
What the researchers did
Researchers analyzed a later examination of the Kuopio Ischaemic Heart Disease (KIHD) study that, unlike the 2,315 men in our 2015 heart-health article, also enrolled women: 1,688 people aged 53 to 74, just over half of them women. They were followed for a median of 15.0 years through Finnish health registers.
As in the earlier study, this is observational: nobody was asked to change their sauna habits. The researchers compared people who reported different sauna frequencies, for instance four to seven sessions a week against one.
The analysis adjusted for standard cardiovascular risk factors, and the researchers also tested whether adding sauna frequency to a conventional risk calculator changed how well it predicted future cardiovascular deaths.
How much can this tell us?
This is a separate, more recent KIHD examination from the 2,315 men in our 2015 article: it recruited older participants (53 to 74, against 42 to 60) and, importantly, included women for the first time in this line of research.
The wide confidence interval (0.08 to 0.65) and the relatively small number of deaths (181) mean the exact size of the association is uncertain. As with the 2015 study, people who used the sauna often may have differed in other ways the statistics could not fully capture.
The improvement in risk prediction was real but small. It does not mean sauna frequency should replace or outweigh blood pressure, cholesterol or smoking status in judging someone’s heart risk.
What makes it useful
- Extends the KIHD sauna research to women for the first time
- 1,688 people followed for a median of 15 years
- Adjusted for established cardiovascular risk factors
What limits it
- Observational: an association, not proof of cause
- Only 181 cardiovascular deaths, so estimates are imprecise
- Risk-prediction improvement was small in absolute terms
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular sauna means fewer deaths from heart disease. Some support
Low certaintyLarge effectIllness and death
Heart-disease death, men and women 77% fewer
Likely 35% to 92%
Fewer cases than the comparison group. The bar is the best estimate, the band behind it the likely range.
From the same participant group as 7 other articles in The Study, so we count them as one group of people.
Read the original
Laukkanen T, Kunutsor SK, Khan H, Willeit P, Zaccardi F, Laukkanen JA. Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study. BMC Med. 2018;16(1):219.
DOI 10.1186/s12916-018-1198-0