Abstract P284: Race and Gender Differences in the Association between Vitamin D and Adiponectin and its Relationship with Body Mass Index: The Meta-Health Study

Abstract

Background: Low vitamin D and adiponectin levels are both associated with obesity and cardiovascular disease. Previous studies have indicated that vitamin D levels are directly associated with adiponectin, and that this association varies across body mass index (BMI) categories; stronger with increasing BMI. Few studies examined this association in African Americans (AA), known to have lower levels of vitamin D and adiponectin, and in whites. Methods: We assessed whether serum vitamin D is associated with serum adiponectin in a biracial population-based sample. Cross-sectional analyses were performed on 426 non-diabetic participants (218 whites and 208 AA) from the Meta-Health study, a random sample from the metropolitan Atlanta. Age-adjusted correlations and multivariable linear regression were used to analyze this association. We investigated the effect modification of the BMI categories of lean, overweight and obese as defined by standard cut-points (25 and 30 kg/m 2 ). The dietary intake of vitamin D, available in a subsample of participants (n = 167; n = 68 AA), was used for correlations with serum vitamin D. Results: The mean (SD) age of our study sample was 50.5 (9) years. The mean (SD) levels of vitamin D were 27.4 (9.8) ng/mL in white women, 25.5 (9.3) ng/mL in white men, 16.9 (7.3) ng/mL in AA women and 18.8 (7.3) ng/mL in AA men. The mean (SD) levels of adiponectin were 17.0 (17.1) μg/mL in white women, 9.9 (11.3) μg/mL in white men, 6.6 (4.8) μg/mL in AA women and 9.4 (11.6) μg/mL in AA men. The age-adjusted correlations between vitamin D and adiponectin were r = 0.38 (p < 0.0001) in white women but not significant among white men and AA. Among whites, vitamin D was significantly associated with BMI (r = - 0.28) in both genders, and with HDL-cholesterol (r = 0.29) in women. Among AA, vitamin D was significantly associated in women with HDL-cholesterol (r = 0.20) and HOMA-IR (r = - 0.23). There was an effect modification by BMI among the different races by gender subgroups (p = 0.05). Among lean white women (n = 63), there was a significant direct association between vitamin D and adiponectin (β = 0.02, p = 0.04) after adjustment for age, systolic blood pressure, HDL-cholesterol, triglycerides, income and season of blood drawing. On the contrary, in lean AA women (n = 23) there was a significant inverse association (β = - 0.06, p = 0.01) after the same adjustment. Dietary vitamin D was significantly associated with serum vitamin D in both white women (r = 0.30) and white men (r = 0.52), but among AA only in women (r = 0.43). Conclusion: The association of vitamin D and adiponectin is dependent on race, gender and BMI category. Among lean white women there is a significant direct association, whereas in lean AA women the association is inverse. No association was present among obese individuals. Our study informs the trials that aim to evaluate the effect of vitamin D therapy on circulating adiponectin in relationship with obesity.