Sunlight, ultraviolet radiation, vitamin D and skin cancer: how much sunlight do we need?

Adv Exp Med Biol. 2014;810:1-16.

Abstract

Vitamin D is the sunshine vitamin for good reason. During exposure to sunlight, the UV 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 13 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aging / metabolism*
  • Bone Diseases, Metabolic / metabolism
  • Bone Diseases, Metabolic / prevention & control
  • Cholecalciferol / analogs & derivatives
  • Cholecalciferol / metabolism
  • Dehydrocholesterols / metabolism
  • Humans
  • Osteoporosis / metabolism
  • Osteoporosis / prevention & control
  • Photolysis
  • Rickets / metabolism
  • Rickets / prevention & control
  • Skin / drug effects
  • Skin / metabolism
  • Skin / radiation effects
  • Skin Neoplasms / metabolism*
  • Skin Neoplasms / prevention & control
  • Skin Pigmentation / radiation effects
  • Sunlight
  • Sunscreening Agents / adverse effects
  • Ultraviolet Rays
  • Vitamin D / administration & dosage
  • Vitamin D / metabolism*
  • Vitamin D Deficiency / diet therapy
  • Vitamin D Deficiency / metabolism*

Substances

  • Dehydrocholesterols
  • Sunscreening Agents
  • Vitamin D
  • Cholecalciferol
  • 7-dehydrocholesterol
  • previtamin D(3)