More summer sun accounts for 38% of vit D in blood in Italy Mar 2010
J Steroid Biochem Mol Biol. 2010 Mar 15. [Epub ahead of print]
Sun exposure questionnaire predicts circulating 25-hydroxyvitamin D concentrations in Caucasian hospital workers in southern Italy.
Hanwell H, Vieth R, Cole D, Scillitani A, Modoni S, Frusciante V, Ritrovato G, Chiodini I, Minisola S, Carnevale V.
Department of Nutritional Sciences, University of Toronto and Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Canada M5G 1X5.
INTRODUCTION: Recent sun exposure should correlate with circulating 25-hydroxyvitamin D [25(OH)D] due to ultraviolet B (UVB)-catalyzed cutaneous synthesis of vitamin D. 
METHODS: A sun exposure score was calculated for healthy adults using a recall questionnaire assessing daily Time in Sun (<5min; 5-30min; >30min) and Skin Exposure (face/hands; face/hands and arms; face/hands and legs; and "bathing suit") for 1 week in each of the winter and summer (n=47 and 23, respectively; n=18 participated in both). Concentrations of 25(OH)D were measured by DiaSorin RIA on end-of-week sera. 
RESULTS: Mean serum 25(OH)D was higher in summer than winter (58.6+/-16.5 vs. 38.8+/-29.0 nmol/L, respectively, P=0.003 unpaired). The calculated Sun Exposure Score correlated strongly with serum 25(OH)D during summer (Spearman's rho=0.59, P=0.003); based on the Pearson coefficient of determination, summer Sun Exposure Score explained 38% of the variability in summer serum 25(OH)D. The Sun Exposure Score did not correlate with 25(OH)D in the winter (rho=0.19, P=0.210). The summer correlation was largely explained by the Time In Sun (rho =0.58, P=0.004) rather than area of Skin Exposed (rho=0.10, P=0.660). Although there was a correlation between winter and summer Sun Exposure Scores (rho=0.63, P=0.005), there was no summer vs winter correlation in serum 25(OH)D (rho=0.08, P=0.76). 
CONCLUSION: This simple 1-week sun exposure recall questionnaire predicted summer serum 25(OH)D concentrations, accounting for 38% of the variability in 25(OH)D among healthy Italian adults. Copyright © 2010. Published by Elsevier Ltd.
PMID: 20298782 [PubMed - as supplied by publisher]