OBJECTIVES: This study was conducted to respond certain important questions regarding the efficacy of vitamin D fortification and supplementation in children using a meta-analytical approach. METHODS: MEDLINE, PubMed, Embase, Cochrane Library, and Google Scholar were searched, and 2341 studies were found in a preliminary search. After screening of titles and abstracts, 31 studies were selected. RESULTS: Significant raises in circulating 25(OH)D concentrations were observed in both groups that took vitamin D supplement (MD, 28.7, 95% CI, 22.5 to 34.9) and vitamin D-fortified foods (MD, 20.29, 95% CI, 13.3 to 27.2). The meta-regression revealed a significant association between age of participants (B, -1.4, 95% CI: -2.8, -0.02, p = 0.047) and dose of vitamin D (B, 0.007, 95% CI: 0.003, 0.01, p < 0.001), with the effect on serum 25(OH)D concentrations. The analysis showed that serum 25(OH)D concentration increases by 0.7 nmol/L for every 100 IU of vitamin D intake after adjustment for age, baseline serum 25(OH)D and latitude which is far less than the reported amount in adults. CONCLUSIONS: Altogether, these findings indicate that in a mass vitamin D fortification program, circulating 25(OH)D concentration response in children may be lower in children than in adults and vitamin D supplementation may still be needed in this subpopulation.