A Systematic Review and Meta-Analysis of Vitamin D Status of Apparently Healthy Adults in Worldwide Regions.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies
PubMed 42210828 · doi:10.3923/pjbs.2026.160.170
What was done
Authors searched PubMed, Web of Science, ScienceDirect, and Google Scholar for English-language observational studies published between 2013 and 2024 reporting plasma 25-hydroxyvitamin D [25(OH)D] status in apparently healthy adults. Heterogeneity was assessed using Cochran's Q and I² statistics. Due to significant heterogeneity, a random-effects meta-analysis was used to estimate pooled prevalence across 56 studies representing 30 countries and 394,548 participants.
What was found
The pooled global prevalence of vitamin D deficiency was 55% (95% CI: 49.0% to 60.0%) with considerable heterogeneity (p < 0.001; I² = 100%). Subgroup analysis showed the highest deficiency prevalence in the Middle East (62%; 95% CI: 54% to 70%), followed by Asia (54%; 95% CI: 39% to 69%), Africa (43%; 95% CI: 24% to 63%), and Europe (43%; 95% CI: 23% to 63%). Weighted mean 25(OH)D levels ranged from 8.4 ± 0.5 ng/mL to 37.7 ± 10.8 ng/mL, with an overall mean of 20.14 ± 6.7 ng/mL. Recalculated regional weighted means were lowest in the Middle East (17.8 ng/mL), followed by Asia (20.4 ng/mL), Europe (26.8 ng/mL), Other regions (28.0 ng/mL), and Africa (29.2 ng/mL, influenced by one high outlier study).
Why it matters
This review provides an aggregated worldwide estimate indicating that over half of healthy adults are vitamin D deficient, with substantial regional disparities concentrated in the Middle East and Asia.
Limits
Between-study heterogeneity was complete (I² = 100%), weakening the reliability of pooled summary estimates. The abstract does not specify the numerical cutoff value used to define vitamin D deficiency across the included studies. The search excluded non-English literature and pre-2013 publications. Confounding variables such as season, assay method, skin pigmentation, and supplement use were not standardized in the reported pooled estimates.
Cited by
- supports Vitamin D is clinically deficient in a high percentage of the population and subclinically low in the vast majority.