Prospective association of 25(OH)D with metabolic syndrome

Context: Vitamin D may play a role in the aetiology of the metabolic syndrome (MetS), yet the majority of previous studies have been cross-sectional, and the limited number of prospective studies has yielded inconsistent results.

Objective: To examine the prospective association of vitamin D [25-hydroxyvitamin D, 25(OH)D] with MetS in a multi-ethnic cohort of adults in Ontario, Canada.

Design: Nondiabetic individuals with pre-existing MetS risk factors were recruited for participation in the PROspective Metabolism and ISlet cell Evaluation (PROMISE) cohort study, a longitudinal study of the determinants of insulin resistance and MetS.

Methods: Of the 654 participants enrolled at baseline, 489 attended a 3-year follow-up visit. There were 301 participants eligible for the analysis of 25(OH)D with incident MetS (age 49·2 ± 9·3 years old, 75·4% female), after excluding 188 (38·5%) prevalent MetS cases at baseline. Longitudinal change in MetS components was assessed in the entire follow-up cohort.

Results: There were 76 (15·5%) participants who developed MetS over the 3-years of follow-up. Multivariate logistic regression analyses indicated a decreased risk of MetS at follow-up per standard deviation increase in baseline 25(OH)D after adjustment for sociodemographics, season, baseline and change in supplement use and physical activity and insulin resistance (OR = 0·63, 95% CI 0·44-0·90). Multivariate linear regression analyses revealed a significant inverse association of baseline 25(OH)D with fasting glucose at follow-up (β = -0·0005, P = 0·025).

Conclusions: There was a significant inverse association of baseline 25(OH)D with incident MetS, which may be partly driven by its association with glucose homoeostasis.