[Vitamin D and UV protection].

A high percentage of people present with reduced vitamin D3 levels. Reduced vitamin D3 levels have to be supplemented. Oral supplementation can be performed easily and without significant side effects. Because vitamin D3 can be produced in the skin via ultraviolet B (UVB) irradiation, it is possible to elevate reduced vitamin D3 levels by UVB exposure. However, UVB, which is classified as a complete carcinogen, induces skin cancer. Therefore, UVB irradiation should not be utilized to stimulate vitamin D3 synthesis. Sun protection, especially wearing of clothes and seeking shade and appropriate use of sunscreens, correlates with reduced D3 levels. A risk-benefit calculation shows that oral supplementation of vitamin D3 is preferred to UVB/sun expsure to increase serum vitamin D3 levels.