title: Contributions of sunlight and diet to vitamin D status.
abstract: Vitamin D is made in the skin using ultraviolet radiation of specific low wavelength, 290-315 nm (UVB). For many parts of the world there is a period when there is insufficient intensity of UVB to make vitamin D, which is reflected by a clear seasonal variation in vitamin D status. Sun avoidance practices, melanin in pigmented skin, and sun protection creams (sunscreen), if used properly, can dramatically reduce vitamin D synthesis. Few foods naturally contain vitamin D, although some countries fortify foods with vitamin D. Regulatory mechanisms in the skin mean there is no danger of vitamin D toxicity through sunlight synthesis. Although oral vitamin D is potentially toxic with high-dose supplements, there is a wide safety margin. Long-term safety data covering a range of potential adverse outcomes are limited.
authors.affiliation: Musculoskeletal Research, Health Sciences Building, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK. h.macdonald@abdn.ac.uk
authors.forename: Helen M
authors.initials: HM
authors.lastname: Macdonald
mesh_terms: D004032:Diet; D006801:Humans; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage* / Q000097:blood; D014808:Vitamin D Deficiency / Q000517:prevention & control
chemical_list: D014807:Vitamin D