Serum 25-Hydroxyvitamin D is an Independent Predictor of High-Density Lipoprotein Cholesterol and Metabolic Syndrome in Men and Women

Abstract

Objective: This cross-sectional study assessed the relationships between serum 25(OH)D and selected markers for cardiovascular disease risk, including the metabolic syndrome and its components, in men and women. Methods: Fasting blood samples, anthropometric measurements, and blood pressure were assessed in 257 men and women. Dietary intake and physical activity were assessed with the Harvard Food Frequency Questionnaire, the Stanford 7-day Physical Activity Recall Questionnaire, and questionnaires designed to assess dietary supplement use and sun exposure. Data were collected over a 7-week period in August and September 2008. Results: Total vitamin D intake and intake from dietary supplements were strongly associated with serum 25(OH)D tertile (both P , 0.001). Mean 6 SEM values for serum 25(OH)D were 29.7 6 0.4, 39.8 6 0.3, and 52.1 6 0.8 ng/ml in the first through third tertiles, respectively. Mean 6 SEM serum high-density lipoprotein cholesterol (HDL-C) concentration increased in a graded fashion (P , .001) from the lowest (48.4 6 1.8 mg/dl) to the highest (62.3 6 2.1 mg/dl) 25(OH)D tertile. This relationship remained significant (P , .001) after adjustment for established determinants of the HDL-C concentration (age, sex, waist circumference, body mass index, physical activity, alcohol consumption, cigarette smoking), with each 10 ng/ml increase in 25(OH)D associated with a 4.2 mg/dl increase in HDL-C concentration. Serum triglycerides (P 5 .008), waist circumference (P , .001), and body mass index (P , .001) showed graded, inverse relationships with 25(OH)D tertile, and the prevalence of metabolic syndrome decreased significantly from the lowest to the highest tertile of 25(OH)D (31%, 14%, and 10%, respectively, P for trend 5 0.001). The relationship with serum triglycerides was no longer significant in multivariate models, but waist circumference (P, .001) and metabolic syndrome (P, .01) remained significantly associated with serum 25(OH)D concentration after adjustment for demographic and lifestyle factors (age, sex, physical activity, alcohol consumption, cigarette smoking). Conclusion: A lower serum 25(OH)D level is associated with the metabolic syndrome and less favorable values for some metabolic syndrome risk factors, particularly the HDL-C concentration. Research is warranted to assess whether increasing vitamin D intake will improve the metabolic cardiovascular risk factor profile.