Clinical and Metabolic Response to Vitamin D Supplementation in Endometrial Hyperplasia: a Randomized, Double-Blind, Placebo-Controlled Trial

There was inconsistent evidence showing that vitamin D intake may be associated with reduced cancer risk due to optimized metabolic profile and reduced oxidative stress. However, we are not aware of any study evaluating the effects of vitamin D supplementation on clinical response and metabolic status of patients with endometrial hyperplasia (EH). This research was done to evaluate the effects of vitamin D supplementation on clinical response and metabolic status of patients with EH. This randomized, double-blind, placebo-controlled trial was conducted among 60 women diagnosed with EH. EH diagnosis was made based on specific diagnostic procedures of biopsy. Participants were randomly assigned into two groups to intake either 50,000 IU vitamin D3 supplements (n = 30) or placebo (n = 30) every 2 weeks for 12 weeks. After the 12-week intervention, compared with the placebo, vitamin D supplementation increased serum-25(OH) vitamin D levels (+12.0 ± 10.4 vs. +1.9 ± 7.1 ng/mL, P < 0.001). In addition, vitamin D administration was associated with significant decreases in fasting plasma glucose (FPG) (−1.6 ± 7.0 vs. +2.1 ± 6.1 mg/dL, P = 0.03), serum insulin levels (−0.8 ± 1.9 vs. +1.1 ± 3.5 μIU/mL, P = 0.01), homeostasis model of assessment-insulin resistance (HOMA-IR) (−0.2 ± 0.6 vs. +0.3 ± 0.8, P = 0.01), and a significant increase in the quantitative insulin sensitivity check index (QUICKI) (+0.003 ± 0.01 vs. −0.01 ± 0.02, P = 0.02) compared with the placebo. Additionally, a significant decrease in serum high-sensitivity C-reactive protein (hs-CRP) (−1.9 ± 2.8 vs. −0.003 ± 2.0 μg/mL, P = 0.003) and a significant rise in plasma total antioxidant capacity (TAC) values (+62.5 ± 53.5 vs. +7.5 ± 34.1 mmol/L, P < 0.001) were observed following supplementation with vitamin D compared with the placebo. In conclusion, vitamin D3 supplementation for 12 weeks among women with EH had beneficial effects on glucose metabolism, serum hs-CRP, and plasma TAC concentrations. In addition, vitamin D may have played an indirect role in reducing complications of EH due to its effect on improved glycemic control, hs-CRP, and TAC concentrations.