The associations of vitamin D status and dietary calcium with the metabolic syndrome: an analysis of the Victorian Health Monitor survey

Objective: To examine the associations between serum 25-hydroxyvitamin D (25(OH) D), dietary Ca intake and presence of the metabolic syndrome (MetS). Design: A stratified cluster sample of a population aged 18-75 years from the Victorian Health Monitor survey. Setting: Non-institutionalized adults living in private dwellings in Victoria, Australia. Subjects: Adults (n 3404) with complete data and without type 1 or type 2 diabetes. Results: Adjusted for sociodemographic factors, physical characteristics and dietary covariates including Ca intake, every 10 nmol/l increase in serum 25(OH) D was significantly associated with decreased odds of MetS (adjusted odds ratio (AOR)=0.85, 95% CI 0.80, 0.89; P < 0.001). Relative to the low 25(OH) D tertile (median 33 nmol/l), there was a progressive decrease in odds of MetS that reached significance with the high 25(OH) D tertile (median 77 nmol/l; AOR=0.35, 95% CI 0.26, 0.48; P < 0.001). Every 500 mg/d increase in Ca intake adjusted for 25(OH) D did not reduce odds of MetS (AOR=0.81, 95% CI 0.66, 1.06; P=0.141) but approached significance if unadjusted for 25(OH) D in the final model (AOR=0.81, 95% CI 0.64, 1.02; P=0.073). No significant effect was obtained for tertiles of Ca intake. However, Ca and vitamin D tertile combinations suggested a beneficial effect of high Ca (median 1233 mg/d) only at low and medium 25(OH) D. The high 25(OH) D tertile was associated with significantly decreased odds of MetS regardless of Ca intake. Conclusions: A high vitamin D status significantly reduced the odds of MetS. A high Ca intake may have a similar favourable outcome but only at lower circulating concentrations of 25(OH)D.