The Sunshine Paradox: A Systematic Review and Meta-Analysis of Vitamin D Deficiency Burden and Modifiable Risk Factors in Libya

Abstract

Hypovitaminosis D is an escalating global health concern, yet high-power baseline mapping of its epidemiological burden across North Africa remains limited. Despite Libya’s abundant solar irradiance, localized studies suggest widespread vitamin D depletion. This study systematically pooled nationwide prevalence, clinical stratifications, temporal trends, and publication bias for vitamin D deficiency in Libya. A random-effects systematic meta-analysis pooled data from 20 observational studies across Western, Eastern, and Southern Libya, including 7,167 participants. Deficiency was defined as serum 25-hydroxyvitamin D [25(OH)D] <20 ng/mL. Between-study heterogeneity was explored using univariable and multivariable random-effects meta-regression. Publication bias was assessed with Egger’s regression, Begg’s rank correlation, and trim-and-fill analysis. The pooled national prevalence of vitamin D deficiency was 71.07% (95% CI: 64.91%–76.81%), with substantial heterogeneity (I² = 96.2%; Cochran’s Q = 502.14; P < 0.0001). Pregnant women showed the highest subgroup prevalence at 80.02% (95% CI: 74.88%–84.31%), while the Southern desert region had the highest regional burden at 75.14% (95% CI: 71.05%–78.83%). Univariable meta-regression identified a significant temporal decline in prevalence (β = -0.041; P = 0.029). The multivariable model explained 24.15% of between-study variance. Bias testing showed no significant funnel plot asymmetry. The findings confirm a Libyan “Mediterranean solar paradox,” where abundant sunlight does not ensure adequate vitamin D status. National prevention should prioritize food fortification, antenatal and pediatric supplementation, and standardized diagnostic assays.