What one research group’s sauna review can tell us
A wide-ranging review from the Kuopio research group summarizes their own studies alongside others’ trials on sauna and cardiovascular, brain and respiratory health. It is a useful map, written by the same team behind much of the evidence it covers.
Worth knowing: Searched MEDLINE and EMBASE through 24 February 2018: a snapshot of the evidence at that time, not an up-to-date answer, and written by the same research group behind much of the KIHD evidence it summarizes.
The short version
This 2018 narrative review, by the same Finnish and UK researchers behind many of the underlying studies, brings together evidence on sauna bathing and cardiovascular disease, dementia, respiratory disease, arthritis and headache, searching MEDLINE and EMBASE through February 2018. It proposes possible biological mechanisms and reports generally favorable associations across these outcomes. But much of that evidence comes from the authors’ own Kuopio cohort, already covered in our other articles, so this review is not independent confirmation of those findings: it is the same team summarizing its own body of work.
Keep in mind
Written by the same small group of researchers whose own Kuopio cohort studies make up much of the evidence it reviews, including our heart, dementia, fitness and respiratory articles. Not independent confirmation of those findings.
What they found
The review reports generally favorable associations between sauna bathing and each of these outcomes, and proposes biological mechanisms, including effects on blood-vessel function, arterial stiffness, the nervous system and blood lipids, that could plausibly connect sauna heat exposure to them.
Much of the cardiovascular, dementia and respiratory-disease evidence it discusses is the same Kuopio cohort data covered in our other articles on this site. The review does not present new data of its own; it summarizes work already published elsewhere, a meaningful share of it by the same authors.
The authors describe the mechanisms as “postulated” rather than established, and note areas of continuing uncertainty. That is a more cautious framing than the review’s confident title suggests.
What this means for your practice
This is a helpful starting map of what one influential research group has found and argued, not a settled verdict on sauna and health. Treat each outcome it discusses with the same care as the specific study behind it.
This does not establish a sauna routine to follow, and it is not evidence for the effects of any particular KUUME ritual.
Methods and limitations
What the researchers did
The same three researchers who lead the Kuopio Ischaemic Heart Disease (KIHD) sauna studies (the source for our heart-health, dementia, fitness and respiratory-disease articles) searched MEDLINE and EMBASE from each database’s inception through 24 February 2018 for research on sauna bathing and health.
This is a narrative review: the authors describe and summarize studies they judged relevant, rather than following a systematic, pre-registered protocol with a formal risk-of-bias score for every study, the way our review of 40 dry-sauna studies does.
It draws on observational studies (including their own KIHD cohort analyses), randomized trials and non-randomized trials, covering cardiovascular disease, blood pressure, dementia, respiratory disease, arthritis, headache and other outcomes.
How much can this tell us?
A review by the researchers most responsible for the underlying studies is a useful map of one research group’s body of work, but it is not independent confirmation of that work. The same limitations that apply to the individual KIHD studies apply here too: observational design, Finnish men only, self-reported sauna habits.
Unlike a systematic review with a bias assessment for each included study, this is a narrative synthesis: the authors chose what to include and how to frame it. That does not make it wrong, but it is a different, less independently checkable kind of evidence than our review of 40 dry-sauna studies by other authors.
It is also a snapshot: the literature search ran through February 2018, so more recent research is not part of it.
What makes it useful
- Written by researchers deeply familiar with this literature
- Covers cardiovascular, neurological, respiratory and other outcomes in one place
- Mechanisms are framed as proposed, not established
What limits it
- Narrative, not systematic: no formal risk-of-bias score per study
- Written by the same team behind much of the evidence it reviews
- Not independent confirmation of the KIHD findings it discusses
- A snapshot of the literature through February 2018
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular sauna helps you live longer. Some support
Low certaintySmall effectIllness and death
Your heart rate rises and blood pressure dips in the sauna. Well supported
High certaintyLarge effectBody signals
Sauna can stand in for exercise. Not supported
Low certaintyNo effect foundIllness and death
Read the original
Laukkanen JA, Laukkanen T, Kunutsor SK. Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence. Mayo Clin Proc. 2018;93(8):1111-1121.
DOI 10.1016/j.mayocp.2018.04.008 · PubMed 30077204