(Reuters Health) - People who visit the sauna frequently may be less likely to develop heart and lung diseases or to get the flu than those who rarely go, a research review suggests.

FILE PHOTO: A view of a sauna in Gdynia November 27, 2011. REUTERS/Peter Andrews

Past studies on the health benefits of saunas have yielded mixed results because they focused on many different types of sauna and were too small or brief to assess long-term health outcomes from routine use, the authors note in Mayo Clinic Proceedings.

In the current study, researchers examined only the type of sauna typically used in Finland, where saunas are engrained in daily life for many adults. These saunas usually have temperatures of 80 to 100 degrees Celsius (176 to 212 degrees Fahrenheit) and very dry air, with relative humidity of about 10 to 20 percent.

When they looked at research focused on Finnish saunas, the study team found routine use associated with a lower risk of many common chronic health problems as well as a lower risk of premature death from all causes.

“Beyond pleasure and relaxation, evidence suggests that sauna bathing has several health benefits, which include reduction in the risk of vascular diseases such as high blood pressure, cardiovascular disease (CVD), stroke and memory diseases,” said lead author Dr. Jari Laukkanen of the University of Jyvaskyla in Finland.

“Sauna is also related to a lower risk of pulmonary diseases including asthma, pneumonia and chronic obstructive pulmonary disease,” Laukkanen said by email.

One study in the current analysis, for example, found that going to the sauna at least four times a week was associated with a roughly 50 percent lower risk of death from cardiovascular disease or coronary heart disease. This study included 2,315 people and also linked regular sauna use to a 40 percent lower risk of premature death from all causes.

Another study in the analysis compared the effects of using the sauna for 19 minutes versus 11 minutes. In this study, longer sauna sessions were linked to a 17 percent lower risk of premature death from all causes, as well as a 36 percent lower chance of death from heart disease.

In a third study in the analysis, with 1,621 participants, using the sauna at least four times weekly was tied to a 47 percent lower risk of developing high blood pressure than going once weekly.

Yet another study linked at least four weekly sauna visits with about 66 percent lower risk of dementia and Alzheimer’s disease than going just once a week.

Two other studies found going to the sauna at least four times a week associated with a 41 percent lower risk of respiratory diseases and a 37 percent lower chance of pneumonia than going once weekly.

The review wasn’t a controlled experiment designed to prove whether or how regular sauna visits might directly reduce the risk of developing or dying from common health problems. The researchers also did not pool and analyze data to examine the risk of certain outcomes across multiple smaller studies.

Still, it’s possible that regular sauna bathing helps reduce blood pressure, inflammation, oxidative stress, circulation of bad cholesterol and stiffness in the arteries, the authors note.

“When the body is exposed to the heat, blood vessels in the skin dilate (become wider) to bring blood from the inside of the body to the skin surface where heat can be exchanged with the environment,” said Daniel Gagnon of the University of Montreal, who wasn’t involved in the study.

“This response causes the heart to beat faster which in turn increases the circulation of blood throughout the body,” Gagnon said by email. “Increased blood circulation is generally beneficial for blood vessel health, and this could be one reason why sauna bathing is associated with so many health benefits, especially those related to heart and blood vessel diseases.”

Risks of sauna use include dizziness and dangerously low blood pressure, especially with longer sessions.

SOURCE: bit.ly/2MbKoqe Mayo Clinic Proceedings, online July 31, 2018.