Solar ultraviolet B radiation and photoproduction of vitamin D3 in central and southern areas of argentina

摘要: The incidence of nutritional rickets in the southern part Argentina is 8-12 times higher than rest country. Winter 25(OH)D serum levels normal population areas are lower central and northern areas. To elucidate these differences, we compared photoconversion provitamin D3 (7-DHC) to previtamin two cities: Ushuaia (latitude 55 degrees S) Buenos Aires (34 S). Ampules containing 7-DHC were exposed sunlight one day middle each month either from 10:30 a.m. 2:30 p.m. or 8:00 5:00 percentages photoproducts formed determined by high performance liquid chromatography (HPLC). Previous studies have proved that this a valid model assess "in vitro" photoproduction vitamin human skin. Previtamin + less (p < 0.02) those found during all seasons: summer, (X +/- SEM) 6.4 0.8% vs. 13.2 1.8%; autumn, 1.2 0.7% 6.3 1.3%; winter, 0.8 3.6 0.7%; spring, 3.4 0.5% 9.1 1.1%. produced similar for latitude when ampules We conclude there prolonged "vitamin D winter" which cutaneous synthesis absent, leading values contributing rickets.