title: Effect of vitamin D supplementation on polycystic ovary syndrome: A systematic review and meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  To evaluate the effect of vitamin D supplementation on patients with PCOS.
  
  
  METHODS
  We performed a literature search in database and identified all of the RCTs published before December 2015 that compared the effect of vitamin D supplementation with placebo or metformin in PCOS patients.
  
  
  RESULTS
  Nine out of 463 identified studies were included, involving 502 women presenting with PCOS. Vitamin D supplementation had significant effect on the improvement of follicular development with a higher number of dominant follicles (OR, 2.34; 95% CI, 1.39 to 3.92). Differences in regular menstrual cycles were also observed when metformin plus vitamin D was compared with metformin alone (OR, 1.85; 95% CI, 1.01 to 3.39).
  
  
  CONCLUSIONS
  Evidence from available RCTs suggests vitamin D supplementation may be beneficial for follicular development and menstrual cycle regulation in patients with PCOS. Additional high-quality RCTs are required to confirm the effectiveness of vitamin D on PCOS.
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Ke
authors.initials: K
authors.lastname: Ni
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Yiting
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Jin
authors.initials: J
authors.lastname: Shang
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China; Wuhan Tongji Reproductive Medicine Hospital, Wuhan, People's Republic of China. Electronic address: clxiong951@sina.com.
authors.forename: Chengliang
authors.initials: C
authors.lastname: Xiong
mesh_terms: D005260:Female; D006801:Humans; D011085:Polycystic Ovary Syndrome / Q000188:drug therapy*; D016032:Randomized Controlled Trials as Topic; D014807:Vitamin D / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D014807:Vitamin D
keywords: Meta-analysis; PCOS; RCTs; Vitamin D