Potential Health Risks of Sunscreen - Sunscreen and Vitamin D

Sunscreen and Vitamin D

The use of sunscreen with a sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin. A recent study has shown that more Australians and New Zealanders are vitamin D deficient than previously thought. Ironically, there are indications that vitamin D deficiency may lead to skin cancer. To avoid vitamin D deficiency, vitamin supplements can be taken. Adequate amounts of vitamin D₃ can be made in the skin after only ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen in white people (those with darker skins require up to six times longer in the sun). This applies in sunlight when the UV index is greater than 3, which occurs daily within the tropics and during the spring and summer seasons in temperate regions. With sunscreen, the required exposure would be longer: if 95% of vitamin D production is inhibited, then it proceeds at only 5%, or 1/20th, the normal rate, and it would take 20 times as long—200 to 300 minutes (3-1/3 to 5 hours), twice a week—of sun exposure to the face, arms, hands, or back for adequate vitamin D to be made in the skin. Obviously, the required time would decrease with increased body exposure area, as when wearing a swimsuit on a beach, a very common setting where sunscreen is used. By this math, it is apparent that vacationers who spend hours on the beach each day with sunscreen on may make more vitamin D in a week of vacation than they do during a typical week in their lives with no sunscreen, if they spend most of their non-vacationing time inside houses, offices, and other buildings where they get almost no sun exposure. Also, it is worth noting that with longer exposure to UVB rays, equilibrium is achieved in the skin, and the vitamin simply degrades as fast as it is generated. Vitamin D overdose is nearly impossible from natural sources, including food sources.