Effect of different dress style on vitamin D level in healthy young Orthodox and ultra-Orthodox students in Israel

Summary Ultra-orthodox Jewish lifestyle, which encourages modest dress and indoor scholarly activity, represents a risk factor for vitamin-D deficiency. Our study in healthy young males from higher education religious institutions located in the same geographical area showed frequent and severe vitamin D deficiency, strongly correlated with the degree of sun exposure. However, PTH level was usually normal. Introduction Ultra-orthodox Jewish lifestyle encourages modest dress and indoor scholarly activity. As such, it represents a risk factor for vitamin-D deficiency, a worldwide problem previously underestimated in sunny countries. Our aim was to characterize the vitamin-D status of religious Jewish males according to sun exposure and outdoor activity, and study the correlation between serum 25-hydroxyvitamin D (25(OH) D) and PTH level. Methods Seventy-four young adult males were recruited from three Jewish higher education institutions (Yeshiva) in Jerusalem. Yeshiva-A ultra-Orthodox students (aged 20.1± 0.6) wear traditional clothing, live in dormitories and stay mostly indoor. Yeshiva-B ultra-Orthodox students (aged 33.0±4.2) dress similarly but have regular outdoor activities. Yeshiva-C religious students (aged 19±2.0) participate in a mixed army/Yeshiva program. Weekly outdoor activity time and degree of sun exposure were estimated by questionnaire. Results 25(OH)D was 8.9±3.6, 10.2±5.7 and 21.7± 10.4 ng/ml (mean±SD) in Yeshiva A, B and C. 25(OH)D was correlated with degree of sun exposure (r=0.54, p< 0.0001) and inversely correlated with PTH (r=-0.3, p= 0.01). Levels below 20 ng/ml were considered as vitamin D deficiency. PTH was normal in 87% of vitamin D-deficient subjects from Yeshiva-A and Yeshiva-C (mean age 20), compared to 52% of Yeshiva-B students (mean age 33). Bone mineral density studied in a random subset (n=14) of vitamin D-deficient subjects showed Z-scores of -1.5±1.0, -1.8±0.8, -2.1±0.4 in femoral neck, spine and radius. Conclusions Severe vitamin-D deficiency is extremely prevalent in ultra-Orthodox males. Despite rare secondary hyperparathyroidism, they represent an important previously unrecognized high-risk group for metabolic bone disease.