The adverse effects of solar ultraviolet radiation on the skin are well documented, especially in fair-skinned people. These can be ameliorated by photoprotection strategies advocated by many public health bodies and typically include sun avoidance,
sunscreen use and clothing. The UVB waveband which is the main cause of all adverse effects investigated in the laboratory to date is also the waveband for
vitamin D photosynthesis which is the only established benefit of solar exposure. This is especially important because solar UVB is the main source of
vitamin D for most people. There is increasing evidence that
vitamin D plays a much greater role in human health than was previously thought. This has given rise to concerns that photoprotection, especially
sunscreen use, could adversely affect
vitamin D status and human health. Furthermore, it is stated that people with heavily pigmented skins often have poor
vitamin D status because of photoprotection by
melanin. In this paper we review the effect of photoprotection strategies and pigmentation on
vitamin D status. Clothing can clearly be very effective at inhibiting
vitamin D synthesis.
Sunscreens are effective in theory and some limited human studies support this. However, most studies show little or no effect and the most likely reason for this is that
sunscreens have not been applied in the manner that was used to determine their labelled index of protection against
sunburn. This could change in the future if public health campaigns and the
sunscreen industry are successful in encouraging the public to apply
sunscreens more liberally and/or use much higher levels of labelled protection. The role of
melanin on
vitamin D status is not clear and requires further investigation.