Vitamin D deficiency is common among adults in Wallonia (Belgium, 51°30' North): findings from the Nutrition, Environment and Cardio-Vascular Health study

Data on the vitamin D status of the population of Wallonia (Belgium, 51°30' North) are scarce. This study was carried out to estimate vitamin D deficiency, identify potential determinants, and analyze their relationship with vitamin D supplementation. We tested the hypothesis that vitamin D deficiency is common in the general population, particularly among subjects without supplementation. Vitamin D deficiency was defined as a serum level of 25-hydroxyvitamin D (25(OH)D) concentration less than 50nmol/L. Data were analyzed from 915 participants of the Nutrition, Environment and Cardio-Vascular Health cross-sectional survey. The median (interquartile range) 25(OH)D level was 53.1 (37.8-69.9) nmol/L, and 44.7% of the subjects were vitamin D deficient. Subjects without vitamin D supplementation were more concerned by vitamin D deficiency than those with supplementation (odds ratio [OR], 3.35; P < .0001). From a multivariate standpoint, the potential determinants of vitamin D deficiency among subjects without vitamin D supplementation were season, specifically spring and winter (OR, 7.36 and 6.44, respectively), obesity (OR, 2.19), low household income (OR, 1.73), and lack of solarium use (OR, 1.79). For subjects with supplementation, the only determinant observed for vitamin D deficiency was obesity (OR, 5.00). This work evidenced the high prevalence of 25(OH)D deficiency in the general population, especially among nonsupplemented subjects with obesity, low household income, and/or lack of light. Vitamin D supplementation looks effective in our population, especially via a stabilization of vitamin D coverage throughout the seasons. The best dietary strategy to achieve optimal 25(OH)D concentrations all year round in the general population requires more research.