title: Serum vitamin D status of Korean postmenopausal women during the winter months.
abstract: OBJECTIVE
  To determine the vitamin D status of Korean postmenopausal women during the winter months according to the intake of vitamin D supplements.
  
  
  METHODS
  Cross sectional study of serum 25(OH)D levels according to the intake of vitamin D supplements in postmenopausal women.
  
  
  METHODS
  Between November 2006 and February 2007, 254 postmenopausal women who visited our menopausal clinic for hormone therapy or osteoporosis medication were recruited. Serum 25(OH)D levels were measured with a radioimmunoassay kit and the results were compared among groups that were classified according to the intake amount of vitamin D supplements.
  
  
  RESULTS
  The mean serum 25(OH)D level was 83.3 +/- 32.8 nmol/L and it increased as the intake amount of vitamin D supplements increased. The mean serum 25(OH)D level was not significantly different between groups 1 (no vitamin D supplements) and 2 (daily 100-300 IU supplements). However, the mean serum 25(OH)D level was significantly higher in group 3 (daily 400 IU supplements) than in group 1. While the mean value of group 4 (daily 600 IU) was not significantly different from that of group 3, it was significantly lower than that of group 5 (daily 800-900 IU).
  
  
  CONCLUSIONS
  Vitamin D supplementation is highly effective in improving vitamin D status and the vitamin D status in this study population was improved considerably when compared to previous studies. Therefore, it is concluded that the prevalence of vitamin D insufficiency should be re-evaluated in postmenopausal women in most countries including Korea.
authors.affiliation: Department of Obstetrics and Gynecology, Chung-Ang University, School of Medicine, Yongsan Gu, Seoul, Korea.
authors.forename: Eun Sil
authors.initials: ES
authors.lastname: Lee
authors.forename: Jihyun
authors.initials: J
authors.lastname: Ahn
authors.forename: Hyoung Moo
authors.initials: HM
authors.lastname: Park