title: Vitamin D nutritional status of women living on a solitary island in Japan: A population-based study.
abstract: OBJECTIVE
  Serum 25-hydroxyvitamin D [25(OH)D] is a vitamin D metabolite and a good indicator of vitamin D nutritional status. Low 25(OH)D levels accelerate age-related bone loss in women. The aim of this study was to assess 25(OH)D levels using population-based samples from women in a community in Japan.
  
  
  METHODS
  Of all 187 adult women living on a solitary island (Niigata, Japan), 150 (80.2%) were enrolled in a cross-sectional study in early June 1998. After excluding 6 subjects who were undergoing treatment for osteoporosis, 144 female subjects were analyzed. Serum 25(OH)D(2) and 25(OH)D(3) were determined by high-performance liquid chromatography. The sum of 25(OH)D(2) and 25(OH)D(3) was calculated, yielding 25(OH)D, for which a concentration of less than 30 nmol/L was defined as vitamin D insufficiency. Demographic data such as age, height, weight, and body mass index (BMI) were also recorded.
  
  
  RESULTS
  The average age of the subjects was 61.3 years (SD 12.8), ranging from 21 to 87. The average concentrations of 25(OH)D(2) and 25(OH)D(3) were 0.5 nmol/L (SD 3.2) and 64.6 nmol/L (SD 17.6), respectively. The number of subjects with 25(OH)D concentration less than 30 nmol/L was 4 of 149 (2.7%). Serum 25(OH)D concentrations were not significantly correlated with age (r=-0.065, p=0.44l) or BMI (r=0.086, p=0.310).
  
  
  CONCLUSIONS
  The present population-based study confirms adequate levels of 25(OH)D and low prevalence of vitamin D insufficiency in Japanese women. Further research should be directed toward darifying which dietary factors determine vitamin D nutrition.
authors: Department of Hygiene and Preventive Medicine, Niigata University School of Medicine, 1-757 Asahimachi-dori, 951-8510, Niigata City, Japan, kazun@med.niigata-u.ac.jp.
authors: K
authors: K
authors: Nakamura
authors: M
authors: M
authors: Nashimoto
authors: K
authors: K
authors: Endoh
authors: M
authors: M
authors: Yamamoto