The findings don't mean you should become a baked couch potato. They instead hint at a new way you can reduce your risk of heart disease. It seems to help people at risk of heart disease: those who have high blood pressure or high cholesterol levels, those with diabetes, or those who smoke. It also seems to help people who already have heart problems.
"We have seen many patients with severe heart failure whose clinical symptoms improved dramatically by repeated sauna therapy," lead study author Chuwa Tei, MD, tells WebMD.
Tei says the research team has evidence that repeated sauna treatment improves the blood vessel and heart function of patients with chronic heart failure. "The effect of sauna is similar to exercise for patients with coronary risk factors," Tei says, adding that the advantage of sauna compared to exercise also is applicable to patients with walking disturbances or to patients who can't exercise because of heart failure.
The dry sauna used in this "thermal therapy" is not as hot as the saunas normally used in Japan and in Europe, warns Tei, who leads the internal medicine department at Japan's Kagoshima University. The treatment uses a sauna set at 140 degrees Fahrenheit (60(C), whereas saunas in gyms and hotels often are set at 175-210 degrees Fahrenheit (80-100(C). Tei advises patients to use the low-heat sauna for 15 minutes a day, three to five times per week. After the sauna, patients rest under blankets for 30 minutes.
In a study appearing in the current issue of the Journal of the American College of Cardiology, Tei and co-workers gave this sauna treatment to 25 men ranging in age from 25 to 51. Three of the men had diabetes; eight had high blood pressure; eight had high cholesterol levels; and 15 were smokers. They also gave the treatment to 10 men who did not have risk factors for heart disease.
The at-risk men had worse blood vessel function than the normal men. Two weeks of daily sauna treatment didn't change the blood vessel function of the normal men -- but it helped most of the at-risk men.
"What I was surprised at ... is that only two weeks of repeated once-a-day sauna treatment significantly improved [the blood vessel] function -- about 40% -- of patients with coronary risk factors," Tei says.
Emory University cardiologist Randy Patterson, MD, reviewed Tei's study for WebMD. He says that it is unlikely that moderate sauna heat could harm the vast majority of heart patients and that it could help many.
"It looks like a pretty safe thing to do: 140 degrees is not really too hot," Patterson says. "If you had somebody teetering on the edge of a heart attack, there might be some danger. But this dilates the arteries, and that makes it easier for the heart to pump. Even people with heart failure wouldn't be hurt. Of course, if someone gets chest pain every time they exercise, this is not the thing."
Patterson says heart patients who think they may want to try saunas should start slowly and that they should ask their doctor's advice before they begin.
So would he recommend it?
"It is something that should be explored more, and I wouldn't mind recommending it to a patient," he says.