US EPA

694296 

Journal Article 

Review 

Sunlight, UV-radiation, vitamin D and skin cancer: How much sunlight do we need 

Holick, M 

2008 

Yes 

Advances in Experimental Medicine and Biology
ISSN: 0065-2598 

624 

1-15 

English 

18348443 

10.1007/978-0-387-77574-6_1 

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.