Effect of oral consumption of vitamin D on uterine fibroids: A randomized clinical trial

and purpose: Uterine fibroids are common tumors of the female reproductive system. Symptomatic uterine fibroids require surgical or medical therapy depending on the severity of the symptoms. This study was conducted to investigate the effect of vitamin D on uterine fibroids. A randomized clinical trial was conducted from June to November 2018. Eligible women were randomly assigned to receive vitamin D or a placebo for 12 weeks. The change in the volume of fibroids was considered to be the main variable in the efficacy evaluation. No statistically significant decrease in the volume of fibroids was observed in the experimental group [mean difference (MD): −0.71, 95% confidence interval (CI): −0.1 to 1.53, P = 0.085], and a significant increase was observed in the size of fibroids in the control group (MD: 2.53, 95% CI: 1.9 to 4.05, p = 0.001). Vitamin D consumption might inhibit growth of uterine fibroids; however, the long-term effects remain unclear. •Fibroid volume was reduced slightly by vitamin D but not statistically significant with a significantly increase in size in control group.•Vitamin D supplementation might inhibit the growth of uterine fibroids.•Consumption of vitamin D can be beneficial as an interventional treatment for delaying surgery.•Weekly consumption of 50,000 IU vitamin D is not associated with serious adverse events in patients with uterine fibroids.