You already know that wearing sunscreen can prevent a nasty burn.

Now it turns out that blocking ultraviolet light has an additional benefit you probably don’t know about.

Sunscreen may protect your blood vessels.

As with many biological functions, nitric oxide (NO) is a key player in what happens. NO is a powerful vasodilator—it helps blood vessels open wider.

Vasodilation of the tiny vessels near the surface of your skin is critical to your survival because it helps regulate your body temperature, which protects you from heat stress.

When sunlight hits the skin, the ultraviolet rays disrupt NO production on your skin.  

In theory, scientists felt that because more sun leads to less NO, sunlight might be bad for your blood vessels.

A recent study at the University of Pennsylvania tested the idea and found what happens to blood vessels near the surface when skin is exposed to ultraviolet radiation from the sun.  Test subjects had one arm left bare—no sunscreen. The other arm was treated with sunscreen; then the two arms received the same sun exposure.

On the bare arms, vasodilation was impaired. Vasodilation worked efficiently on the arms that were covered with sunscreen.

In addition to sunscreen, some subjects’ arms were doused with moisture to mimic sweat. The results were the same. But the interesting thing was when no sunscreen was present, sweat alone had some protective properties. Not as much as sunscreen, however.

Researchers used an SPF 50 sunscreen in the experiment and considered that was the bare minimum needed to protect vasodilation.  SPF’s over 50 probably do not have any greater ability to block ultraviolet rays.

Dr. S. Tony Wolf, who led the study, says, “People who experience repeated and/or prolonged exposure to the sun -- those who work or exercise outdoors, tourists, etc. -- should consider using sunscreen, not only to protect against skin cancer but also against reductions in skin vascular function."

Now you have at least four good reasons for sunscreen—you won’t burn, your skin will stay younger looking, you will lower your chances of skin cancer, and you will protect your blood vessels.