Sun & Skin News

Ask the Expert: What Is a Solar Callus?

By Skin Cancer Foundation • November 8, 2023

Q: I’ve heard online health coaches talk about building up a solar callus to help your body produce vitamin D. Is it ever OK to expose your skin to the sun without sun protection?

Ramzi Saad, MD: First, there is no such thing as a “solar callus” or “sun callus.” These are made-up terms not recognized in the medical field. You cannot build up a tolerance for sun exposure. Further, there is no such thing as a safe or healthy tan. In fact, ultraviolet (UV) radiation from the sun is a proven human carcinogen. A tan or sunburn is a sign of DNA injury to your skin, not a pass to skip sun protection in the future. Sun damage is also cumulative. So even a few minutes of intentional, unprotected exposure every day can increase your risk of skin cancer and premature skin aging.

Vitamin D is an important nutrient that contributes to bone health and helps the immune system function. It’s true that you can obtain a limited amount of vitamin D from the sun’s UV rays. Still, more research is needed on how much vitamin D the body can produce, the level of vitamin D necessary and vitamin D’s importance in overall health. However, the relationship between UV exposure and skin cancer is well documented and significant. The risks of unprotected sun exposure far outweigh any benefits.

The Skin Cancer Foundation recommends getting your vitamin D through foods, such as oily fish, egg yolks and fortified dairy products. If your diet is lacking in vitamin D, talk to your doctor about taking a supplement to safely boost your level of this nutrient.

About the Expert: Ramzi W. Saad, MD, is a board-certified dermatologist practicing in Plymouth, Massachusetts. He is a fellow of the American Academy of Dermatology, a member of the Massachusetts Academy of Dermatology, a member of the Massachusetts Medical Society and a member of The Skin Cancer Foundation’s Amonette Circle.

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