The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial.

摘要: Sunscreens absorb ultraviolet B (UVB) and it is a major concern that sunscreen use may lead to vitamin D deficiency.To investigate the relation between amount of applied serum level in humans after UVB exposure under controlled conditions.Thirty-seven healthy volunteers with fair skin types were randomized receive an inorganic sun protection factor (SPF) 8 0 mg cm(-2) , 0.5 1 1.5 or 2 thickness on upper body, approximately 25% body area. Participants irradiated fixed dose 3 standard erythema doses 20 min application. This procedure was repeated four times 2- 3-day interval. Blood samples drawn before first irradiation days last determine expressed as 25-hydroxyvitamin D(3) [25(OH)D].The increased exponential manner decreasing layer response exposure. For all thicknesses sunscreen, 25(OH)D significantly (P<0.05), except for group treated which increase not statistically significant (P=0.16).Vitamin production increases exponentially when thinner layers than recommended are (<2 ). When SPF advised by World Health Organization used, be abolished. Re-evaluation sun-protection strategies could warranted.