A single 30-minute sauna session sends white blood cells soaring, according to a Finnish study

A study from the University of Eastern Finland found that a single 30-minute sauna session raises the number of white blood cells in the blood. These are the cells that defend the body against infections.

The work was published this year in the scientific journal Temperature and was shared again this week on ScienceDaily.

How it was done

51 adults took part, 27 women and 24 men, with an average age of 50.

Each of them spent 30 minutes in a sauna at about 73 degrees Celsius. Halfway through the session they took a brief cold shower. The scientists drew their blood several times.

What they found

- Every type of white blood cell increased, including neutrophils and lymphocytes. - The effect was short: about 30 minutes after leaving, levels returned to normal. - Cytokines, molecules the immune system uses to communicate, barely changed on average.

The authors believe the heat moves white blood cells that were in the tissues into the bloodstream. They would not be new cells.

Scientists from two Finnish universities took part in the study: the University of Eastern Finland and the University of Turku.

What is still unknown

The researchers warn that they only measured one session and its immediate effects. It cannot be concluded that the sauna protects against disease or that it has lasting effects.

Also, because there was a cold shower, it is not known how much of the effect is due to the heat alone.

If you have heart or blood pressure problems, check with your doctor before using a sauna.