Sunlight and Artificial Ultraviolet B Radiation

Vitamin D Deficiency

Michael F. Holick, M.D., Ph.D

Sunlight and Artificial Ultraviolet B Radiation

Sensible sun exposure can provide an adequate amount of vitamin D3, which is stored in body fat and released during the winter, when vitamin D3 cannot be produced.7,15,85,108-110

Exposure of arms and legs for 5 to 30 minutes (depending on time of day, season, latitude, and skin pigmentation) between the hours of 10 a.m. and 3 p.m. twice a week is often adequate.2,7,108-110

Exposure to one minimal erythemal dose while wearing only a bathing suit is equivalent to ingestion of approximately 20,000 IU of vitamin D2.1,2,7,85

The skin has a great capacity to make vitamin D3, even in the elderly, to reduce the risk of fracture.109-111

Most tanning beds  emit 2 to 6% ultraviolet B radiation and are a recommended source of vitamin D3 when used in moderation.111-113,115

Tanners had robust levels of 25-hydroxyvitamin D (approximately 45 ng/ml [112 nmol/L) at the end of the winter and higher bone density as compared with nontanners (with levels of approximately 18 ng/ml [45 nmol/L).112

For patients with fat malabsorption, exposure to a tanning bed for 30 to 50% of the time recommended for tanning (with sunscreen on the face) is an excellent means of treating and preventing vitamin D deficiency (Table 3).113 This reduces the risk of skin cancers associated with ultraviolet B radiation.

Link to the full paper