Authors: Kayaniyil S, Vieth R, Harris SB, et. al
Emerging evidence suggests that 25-hydroxy vitamin D [25(OH)D] and PTH may play a role in the etiology of the metabolic syndrome (MetS). However, evidence to date is limited and inconsistent, and few studies have examined associations with nontraditional MetS components. Objective: The objective of the study was to examine the association of vitamin D and PTH with MetS and its traditional and nontraditional components in a large multiethnic sample. Design, Setting, and Participants: In this cross-sectional study, we examined 654 participants from London and Toronto, Ontario, Canada, aged 30 yr and older with risk factors for type 2 diabetes. Main Outcome Measures: Presence of MetS and its traditional and nontraditional components was measured. Results: Approximately 43% of the study participants were classified as having MetS. Higher 25(OH)D was significantly associated with a reduced presence of MetS after adjustment for age, sex, season, ethnicity, supplement use, physical activity, and PTH (odds ratio 0.76, 95% confidence interval 0.62-0.93). PTH was not associated with the presence of MetS after multivariate adjustment. Multivariate linear regression analyses indicated significant adjusted inverse associations of 25(OH)D with waist circumference, triglyceride level, fasting insulin, and alanine transaminase (P < 0.041). Elevated PTH was positively associated with waist circumference and high-density lipoprotein cholesterol (P < 0.04). Other associations between PTH and MetS components were attenuated after adjustment for adiposity. Conclusions: Serum 25(OH)D, but not PTH, was significantly associated with MetS as well as a number of MetS components after multivariate adjustment. These results suggest that low 25(OH)D may play a role in the etiology of the MetS.