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25 Hydroxyvitamin D Levels Are Negatively And Independently Associated With Fat Mass In A Cohort Of Healthy Overweight And Obese Subjects.

Research paper by Giovanni G De Pergola, Tommaso T Martino, Roberta R Zupo, Domenico D Caccavo, Claudio C Pecorella, Silvia S Paradiso, Franco F Silvestris, Vincenzo V Triggiani

Indexed on: 23 Jan '19Published on: 23 Jan '19Published in: Endocrine, metabolic & immune disorders drug targets



Abstract

Obesity is associated with lower serum vitamin D (25(OH)D) levels through several mechanisms. The aim of the study was to examine the possibility of a negative association between fat mass and 25(OH)D levels in a cohort of otherwise healthy overweight and obese subjects, independently of age, sex, blood pressure levels and anthropometric and metabolic parameters. 147 overweight and obese subjects (106 women and 41 men), aged between 18 and 69 years, were enrolled into the study. All of them did not show any clinically evident metabolic or chronic diseases (i.e. hypertension, diabetes mellitus, renal failure, etc.) and did not use any kind of drug. Serum fasting levels of 25(OH)D, insulin, glucose, uric acid and lipids (triglycerides, total, HDL and LDL cholesterol) were measured. Insulin resistance was assessed by using the homeostasis model assessment (HOMA-IR). Body composition parameters (fat mass [FM], fat free mass [FFM], body cell mass [BCM], total body water [TBW]) were measured by electrical bioimpedance analysis (BIA). Lastly, demographic, anthropometric and clinical parameters (age, body mass index [BMI], waist circumference [WC], systolic (SBP) and diastolic (DBP) blood pressure) were also assessed. 25(OH)D levels were significantly and negatively correlated with BMI (P <0.001), WC (P <0.01), DBP (P <0.05), insulin (P <0.001), HOMA-IR (P <0.01), triglycerides (P <0.01), and fat mass (P <0.001). A multivariate regression analysis was performed by considering 25(OH)D levels as the dependent variable and sex, waist circumference, fat mass, DBP, triglycerides, and insulin (or HOMA-IR) as the independent ones, and 25(OH)D levels maintained a significant and independent relationship only with fat mass (negative) (P <0.01). This study clearly shows that vitamin D circulating levels are progressively lower with the increase of fat mass, independently of sex, body fat distribution, blood pressure and insulin and metabolic parameters. These data strongly show that adipose tissue accumulation per se is absolutely the main responsible factor for lower vitamin D levels in obese subjects, possibly through sequestration of fat soluble vitamin D in fat mass. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.