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Sun exposure questionnaire predicts circulating 25-hydroxyvitamin D concentrations in Caucasian hospital workers in
H E C Hanwell1, R Vieth, D E C Cole
1Department of Nutritional Sciences, University of Toronto, Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5. heather.hanwell@gmail.com
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 (<5 min, 5-30 min, >30 min) 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 nmol/L 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.
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