Associations of Serum 25-Hydroxyvitamin D3 Levels with Visceral Adipose Tissue in Chinese Men with Normal Glucose Tolerance

OBJECTIVE Decreased serum vitamin D level is a common observation in obese adults. Since no Chinese population-based study has yet evaluated the relationship between serum vitamin D levels and the accurate adiposity variables, this study investigated the association of serum vitamin D (assessed by 25-hydroxyvitamin D3 [25(OH)D3]) levels with precise body fat content and distribution in a cohort of Chinese men. METHODS Serum samples were collected from a total of 567 men with normal glucose tolerance (NGT) for assessment by electrochemiluminescence immunoassay to measure 25(OH)D3 levels. In addition, each participant underwent bioelectrical impedance analysis to quantify total body fat and magnetic resonance imaging to measure visceral fat area (VFA) and subcutaneous fat area (SFA). RESULTS Overweight/obese (BMI ≥25 kg/m(2)) subjects had significantly lower serum 25(OH)D3 levels than non-overweight/non-obese (BMI <25 kg/m(2)) subjects (P  =  0.029). Greater fat mass and VFA were accompanied by a downward trend in serum 25(OH)D3 levels (P for trend <0.01). Among overweight/obese subjects, those with body fat percent ≥25% also had significantly lower serum 25(OH)D3 levels (P <0.05). Moreover, participants with VFA ≥80 cm(2) had significantly lower serum 25(OH)D3 (P <0.05), regardless of BMI value. VFA was independently correlated with serum 25(OH)D3 levels (β  =  -0.023, P <0.001), even after adjustments for confounding factors. In addition, serum 25(OH)D3 levels were found to decrease by 0.26 ng/mL per 10 cm(2) increment of VFA. CONCLUSIONS Serum 25(OH)D3 levels were inversely associated with VFA in Chinese men with NGT.