Increased Prevalence of Vitamin D Deficiency in Patients with Alopecia Areata: A Systematic Review and Meta-Analysis

In a systematic review and meta-analysis of 14 studies involving 1,255 subjects with alopecia areata (AA) and 784 non-AA controls, it was found that individuals with AA had significantly lower mean serum 25-hydroxyvitamin D levels, with a difference of -8.52 ng/dL, and were more likely to have vitamin D deficiency, with an odds ratio of 3.89. The mean prevalence of vitamin D deficiency in AA subjects was 73.8%. Despite these findings, the study did not establish a clear correlation between serum vitamin D levels and the extent of hair loss in AA subjects. The results suggest that vitamin D deficiency is common in AA patients and that assessment and potential supplementation of vitamin D could be beneficial for these individuals. However, the study noted high heterogeneity among the included studies.