Sunlight, UV-radiation, vitamin D and skin cancer: how much sunlight do we need?
Vtamin D is the sunshine vitamin for good reason. During exposure to sunlight, the utraviolet B photons enter the skin and photolyze 7-dehydrocholesterol to previtamin D3 which in turn is isomerized by the body's temperature to vitamin D3. Most humans have depended on sun for their vitamin D requirement. Skin pigment, sunscreen use, aging, time of day, season and latitude dramatically affect previtamin D3 synthesis. Vitamin D deficiency was thought to have been conquered, but it is now recognized that more than 50% of the world's population is at risk for vitamin D deficiency. This deficiency is in part due to the inadequate fortification of foods with vitamin D and the misconception that a healthy diet contains an adequate amount of vitamin D. Vitamin D deficiency causes growth retardation and rickets in children and will precipitate and exacerbate osteopenia, osteoporosis and increase risk of fracture in adults. The vitamin D deficiency has been associated pandemic with other serious consequences including increased risk of common cancers, autoimmune diseases, infectious diseases and cardiovascular disease. There needs to be a renewed appreciation of the beneficial effect of moderate sunlight for providing all humans with their vitamin D requirement for health.
Holick
Michael F
MF
Department of Medicine, Section of Endocrinology, Nutrition and Diabetes, Vitamin D, Skin and Bone Research Laboratory, Boston University Medical Center, 715 Albany Street, M-1 013, Boston, MA 02118, USA. mfholick@bu.edu
D006801:Humans; D012878:Skin Neoplasms / Q000209:etiology / Q000517:prevention & control*; D013472:Sunlight / Q000009:adverse effects*; D014466:Ultraviolet Rays / Q000009:adverse effects; D014807:Vitamin D / Q000096:biosynthesis*; D014808:Vitamin D Deficiency / Q000517:prevention & control; D014815:Vitamins / Q000096:biosynthesis
D014815:Vitamins; D014807:Vitamin D