This study examined the effects of long term vitamin D administration on the regression and metabolic status of patients with cervical intraepithelial neoplasia grade 1 (CIN1) (1). This randomized, double-blind, placebo-controlled trial was performed among 58 women diagnosed with CIN1. CIN1 diagnosis was performed based on specific diagnostic procedures of biopsy, pathological diagnosis, and colposcopy. Patients were randomly allocated into two groups to take 50,000 IU vitamin D3 supplements (n = 29) or placebo (n = 29) every 2 weeks for 6 months. The results showed that Vitamin D intake led to significant decreases in serum insulin levels, and an increase in total antioxidant capacity. The authors conclude that vitamin D3 administration for 6 months among women with CIN1 resulted in its regression and had beneficial effects on markers of insulin metabolism and other health markers.