The Effect of Vitamin D Supplementation on Breast Density Changes: A Clinical Trial Study

The aim of this study was to determine the effect of supplementation with 50,000IU/monthly vitamin D for 1yr on breast density in Iranian women. Methods: This double-blind, placebo-controlled, single center clinical trial was conducted among 400 women aged 40yr and older. Participants were allocated to 2 groups. Group 1 received vitamin D (Cholecalciferol) 50,000IU in tablet form, monthly, for 1yr. Group 2 received vitamin E 400IU in tablet form, monthly, for the same period of time. Participants had follow-up clinic visits every 6mo and received an annual mammogram. Results: Final data were evaluated based on 216 and 194 women in the vitamin D and control groups. The mean decrease in mammographic density was -5.01%(95% CI, -9.9% to -0.01%) and -2.34 %(95% CI, -6.84% to -2.15%) in the vitamin D and control groups, respectively. There was no significant association between vitamin D consumption and breast density after 1yr (OR = 0.7, 95% CI, 0.46 to 1.06; P = 0.1).Similar results were observed when multivariate model of logistic regression analysis was performed. Conclusions: This study showed that monthly consumption of 50,000IU of vitamin D supplementation for 1yr did not affect breast density.