Vitamin D deficiency and the risk of anemia: a meta-analysis of observational studies

Aims: Anemia and vitamin D deficiency (VDD) are both very important health issues, recent accumulating evidence shows that VDD is prevalent in individuals with anemia. This meta-analysis aimed to detect a relationship between VDD and anemia. Methods: We identified eligible studies by searching the Pub Med, Embase and Cochrane Library before October 2014. Quality assessments were performed with the Newcastle-Ottawa Scale. Heterogeneity was evaluated by Cochran's Q test and source of heterogeneity was detected by subgroup analysis and sensitivity analysis. Results: A total of seven studies involving 5183 participants were included in the meta-analysis. VDD was associated with an increased incidence of anemia (OR = 2.25, 95% CI = 1.47-3.44), with significant evidence of heterogeneity among these studies (p for heterogeneity <0.001, I-2 = 84.0%). The subgroup and sensitivity analysis confirmed the stability of the results and no publication bias was detected. Conclusion: Our outcomes showed that VDD increased the risk of developing anemia. More researches are warranted to clarify an understanding of the association between VDD and risk of anemia.