Vitamin D insufficiency in a sunny environment: A demographic and seasonal analysis

Background: Hypovitaminosis D has been shown to be extremely common in various regions around the world, mostly at high latitudes. Israel is characterized by certain features - cultural (e.g., ethnic isolates) and geographic (e.g., sunny climate) - that have been identified for their possible association with vitamin D status. Objectives: To conduct an ecological study on a representative sample of the population of Israel, testing vitamin D status across age groups, genders, ethnic groups, and seasons. Methods: We obtained serum samples from 195 healthy Israeli volunteers representing a broad demographic spectrum. Serum concentrations of 25(OH)D were measured with the commercial kit Liaison 25(OH)D Assay (DiaSorin, Italy). Results: The mean vitamin D level for the entire cohort was surprisingly low (22.9 ± 10.1 ng/ml), with 149 subjects (78%) suffering from vitamin D insufficiency (< 30 ng/ml). Vitamin D status was better in infants than in older age groups. Differences by gender were significant only in the infant age group (i.e., vitamin D status was worse among females) and were not prominent across older ages. Israelis of Ashkenazi origin had higher vitamin D mean levels than those of Sephardic origin, who, in turn, had higher vitamin D levels than Arab subjects (31.4 ± 12, 24.1 ± 10, and 17.6 ± 9 ng/ml respectively). With regard to season, there were no differences between the samples collected in winter and the samples collected in summer. Conclusions: The results suggest that hypovitaminosis D is common across all ages, genders and seasons in Israel, a country characterized by a sunny Mediterranean climate. Specific ethnic groups may be at especially high risk.