Effects of Vitamin D on Migraine: A Meta-Analysis.

Objective: The aim of this study was to evaluate the difference in mean serum 25-hydroxy vitamin D level between migraineurs and nonmigraineurs, the association between hypovitaminosis D and migraine, and the effects of oral vitamin D supplementation on migraine-related symptoms as compared to placebo.

Methods: Relevant databases were searched for observational studies and randomized-controlled trials (RCTs) which evaluated the difference in mean serum 25-hydroxy vitamin D level between migraineurs and nonmigraineurs; the association between hypovitaminosis D and migraine; and the effects of vitamin D supplementation on migraine-frequency, duration, and severity. Pooled mean difference and odds ratio were calculated (random-effects model, RevMan version 5.3).

Results: Ten observational studies and two RCTs were included. The serum 25-hydroxy vitamin D level in the migraineurs was significantly lower than that in the nonmigraineurs [mean difference - 4.44 ng/mL (95% CI: -6.11, -2.77)] (low-GRADE evidence). Hypovitaminosis D was found to be significantly associated with migraine [OR: 1.95 (95% CI: 1.07, 3.58)] (low-GRADE evidence). As compared to placebo, oral vitamin D supplementation significantly reduced the monthly migraine-frequency [mean difference: -2.20 (95% CI: -3.04, -1.36)].

,: although it did not reduce the migraine-duration [mean difference: -16.00 hours per month (95% CI: -42.77, 10.76)] and migraine-severity score [standardized mean difference: -0.23 (95% CI: -0.79, 0.32)] (moderate-GRADE evidence).

Conclusion: Serum 25-hydroxy vitamin D level was significantly lower in the migraineurs than that in the nonmigraineurs, and hypovitaminosis D was significantly associated with migraine. Oral vitamin D supplementation significantly reduced migraine-frequency, but not its duration and severity.