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| While it is wise to avoid burning or excess tanning from solar or indoor ultraviolet radiation, it should be realized that solar UVB radiation (290-315nm wavelength) is the primary source of vitamin D for most people. Dietary sources are generally inadequate, and supplements have to be used carefully. As for melanoma and other skin cancer, a couple of points should be made. First, while ultraviolet radiation generates free radicals that can do damage, dietary antioxidants and skin pigmentation are nature's way of fighting free radicals. Second, occupational exposure to ultraviolet radiation is associated with reduced risk of melanoma [Kennedy et al., Leiden Skin Cancer Study. The influence of painful sunburns and lifetime sun exposure on the risk of actinic keratoses, seborrheic warts, melanocytic nevi, atypical nevi, and skin cancer. J Invest Dermatol. 2003 Jun;120(6): pp. 1087-93]. Usually 10-15 minutes exposure of hands, arms and face two to three times per week (depending on one's skin sensitivity) is enough to satisfy the body's vitamin D requirement. Use of sunscreen markedly diminishes the manufacture of vitamin D in the skin, as does window glass, clothing and air pollution. The fairer your skin color, the more vitamin D you make. As adults age, their ability to make vitamin D through the skin decreases. The health benefits of UVB through production of vitamin D are considerable, with more benefits being recognized at a rapid pace. It has been estimated that half of those with multiple sclerosis in the U.S. would not have MS if they had as much UVB exposure as those living in the southern states. Directions Mid-day summer sun is the best source of UVB, since minimal exposure times are required, and the UVB to UVA (315-400nm) ratio is highest. If using sunscreen, it might be advisable to go into the sun for 10-15 minutes without sunscreen to generate a day's worth of vitamin D. |
| Cancer, General Osteoporosis - Osteopenia Ovarian Cancer Vitamin D Requirement |