Frequent sauna use can weaken sperm count

Men who spent 15 minutes in a sauna twice a week for three months saw an immediate drop in their sperm count after every sauna session, and levels didn't return to normal until after six months, finds new research in the journal Human Reproduction.

In order to produce healthy sperm, the testicles need to be kept at a temperature that's about two degrees less than your core temp (98.6°F), which is why they hang down away from your body. But any condition that chronically increases their temperature has a negative effect on sperm production, said study author Andrea Garolla, MD, of the University of Padova in Italy.

While sauna time didn't affect men's sperm long-term, the researcher still advises against it - along with prolonged exposure to other heat sources that could overheat your fluid, like a hot tub or even your laptop.

Here's a tip: Eating just 75 grams of walnuts a day - roughly a handful - can improve the quality of your semen, according to a report in Biology of Reproduction.