title: Higher visceral fat area increases the risk of vitamin D insufficiency and deficiency in Chinese adults.
abstract: BACKGROUND
  Visceral fat area (VFA), a novel sex-specific index for visceral fat obesity (VFO) might play a major role in the development of vitamin D deficiency. However, the association between VFA and vitamin D insufficiency and deficiency in Chinese population is less clear. The aim of this study was to explore the population-level association between VFA and vitamin D insufficiency and deficiency among Chinese men and women.
  
  
  METHODS
  This cross-sectional study involved 1105 adults aged 20-70 years living in Tianjin who were randomly selected and medically examined. All subjects underwent the bioelectrical impedance analysis (BIA) method to estimate the VFA. Serum 25-hydroxyvitamin D3 (25(OH) D3) level was assayed by the high-performance liquid chromatography (HPLC) method and defined insufficiency and deficiency following recommended cutoffs. The association between VFA and vitamin D insufficiency and deficiency was estimated using binary regression analysis.
  
  
  RESULTS
  The total prevalence of vitamin D insufficiency (25(OH) D3: 20-29 μg/L) and deficiency (25(OH) D3 < 20 μg/L) were 26.60 % and 24.89 %, respectively. Significant negative association was observed for VFA with serum 25(OH) D3 levels in men and pre-menopausal women (P < 0.05), not in post-menopausal women (P > 0.05). Moreover, increased VFA was observed to be associated with higher vitamin D insufficiency or deficiency risk with a positive dose-response trend (P for trend < 0.001). As compared to individuals with the lowest VFA, those who had the highest VFA were at 4.9-fold risk of vitamin D insufficiency and deficiency [95 % confidence interval (95 % CI): 1.792-13.365] in men and 1.8-fold risk of vitamin D insufficiency and deficiency (95 % CI: 1.051-3.210) in pre-menopausal women, but not in post-menopausal women [odds ratio (OR) (95 % CI): 2.326(0.903-5.991)].
  
  
  CONCLUSIONS
  These results suggest that higher VFA increases the risk of vitamin D insufficiency and deficiency in men and pre-menopausal women, but not in post-menopausal women. VFA is a better and convenience surrogate marker for visceral adipose measurement and could be used in identifying the risk of vitamin D insufficiency and deficiency in routine health examination.
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Meilin
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070 China ; Department of Rehabilitation and Sports Medicine, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chang
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Health Education and Guidance Center of Heping District, Tianjin, 300040 China.
authors.forename: Weiqiao
authors.initials: W
authors.lastname: Liu
authors.affiliation: Health Education and Guidance Center of Heping District, Tianjin, 300040 China.
authors.forename: Yuwen
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Huang
keywords: 25-hydroxyvitamin D3; Visceral fat area; Visceral fat obesity; Vitamin D deficiency