New Approach to Develop Optimized Sunscreens that Enable Cutaneous Vitamin D Formation with Minimal Erythema Risk

Sunscreens protect the skin against erythemal radiation (E-er). But at the same time they reduce the effective radiation dose (E-VD) responsible for the formation of previtamin D in the skin. The paper describes a calculation method for optimizing the ratio E-VD/E-er behind sunscreens e.g. with SPF 5, 15 and 30 respectively. Taking into account that a majority of people in industrialized countries suffer from a shortage in vitamin D even in summer time, the ratio E-vd/E-er is a new and important criterion for the quality of sunscreens. Furthermore the exposure time t(vd) needed per day for forming the equivalent of the recommended amount of 2000 IU of vitamin D per day for skin type 2 is estimated when sunscreens with different filter compositions are used. In vitro experiments show a significant increase of the conversion of 7-dehydrocholesterol (7-DHC) to previtamin D when exposed to artificial solar radiation behind an experimental sunscreen optimized for previtamin D production compared to a commercial sunscreen having the same SPF.