Using a meta-analytical method, researchers for a study sought to answer critical issues about the efficacy of vitamin D fortification and supplementation in children. In a preliminary search, 2,341 studies were located in MEDLINE, PubMed, Embase, Cochrane Library, and Google Scholar. About 31 studies were chosen after evaluating the titles and abstracts.

Significant increases in circulation 25-hydroxy vitamin D (25(OH)D) concentrations were detected in both groups that received vitamin D supplements (mean difference [MD] 28.7, 95% CI 22.5–34.9) and vitamin D-fortified meals (MD 20.29, 95% CI 13.3–27.2). The meta-regression analysis demonstrated a significant relationship between participant age (B -1.4, 95% CI 2.8, 0.02, P=0.047) and vitamin D dosage (B 0.007, 95% CI 0.003, 0.01, P<0.001) and blood 25(OH)D concentrations. After adjusting for age, baseline serum 25(OH)D, and latitude, the research revealed that serum 25(OH)D concentration increased by 0.7 nmol/L for every 100 IU of vitamin D consumption, which was significantly less than the stated quantity in adults.

Overall, the data suggest that in a mass vitamin D fortification program, children’s circulatory 25(OH)D concentration-response may be lower than in adults, and vitamin D supplementation may be required in the demographic.