A systematic review and meta-analysis of circulating 25-hydroxyvitamin D concentration and vitamin D status worldwide

Vitamin D deficiency is a public health concern; however, data on its global prevalence are limited. We reported pooled mean circulating 25-hydroxyvitamin D (25(OH)D) concentration and estimated the prevalence of concentration according to commonly reported thresholds for general, healthy populations worldwide.

We searched MEDLINE, Embase, Web of Science, Global Index Medicus and grey literature sites. We included cross-sectional and cohort studies published since 2011 that reported circulating 25(OH)D concentration in general, healthy populations of all ages. Using random-effects meta-analysis, we pooled data on circulating 25(OH)D concentration and prevalence estimates according to thresholds by continent, country, latitude, sex, adults/children, season, assay, and study quality. PROSPERO registration: CRD42021242466.

Eligible publications (n = 586) included 2 370 136 eligible participants across 102 countries. The pooled mean (95% confidence interval [CI]) overall circulating 25(OH)D concentration was 53.9 (52.6-55.1) nmol/L (529 publications; 1 412 281 participants). The pooled prevalence of concentration < 30, < 50, and < 75 nmol/L was 18, 47, and 75%, respectively (403 studies; 1 508 830 participants).

Low vitamin D status is prevalent across general, healthy populations worldwide. Governments, health organizations and policy makers could use these findings to identify regions in need of public health strategies for improving vitamin D status.