title: Effect of high-dose vitamin D supplementation on cardiometabolic risk factors in subjects with metabolic syndrome: a randomized controlled double-blind clinical trial.
abstract: OBJECTIVE
  The evidence in support of the effect of vitamin D deficiency on cardiovascular diseases is inconsistent. The objective of this randomized, controlled, double-blind study was to assess the effect of high-dose vitamin D supplementation on cardiometabolic risk factors in subjects with metabolic syndrome.
  
  
  METHODS
  Eighty subjects were randomized to receive 50,000 IU vitamin D or matching placebo weekly for 16 weeks. Fasting blood sugar, homeostasis model assessment of insulin resistance, insulin sensitivity (Quicki), serum lipid profiles (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglyceride (TG) and total cholesterol), anthropometric factors and blood pressure were assessed before and after intervention. Dietary intake and sun exposure were also determined. The trial was registered at http://www.irct.ir (code: IRCT201409033140N14).
  
  
  RESULTS
  Participants were 40.49 ± 5.04 years and 49 % male. All of the intervention group and 97 % of placebo group were vitamin D deficient or insufficient (25-hydroxyvitamin D <75 nmol/L). After intervention, serum 25(OH)D concentration was increased by 61.93 nmol/L in intervention group, while it was decreased in placebo group (p < 0.001). There was a significant change in TG concentration after 4 months (p < 0.001). Other metabolic or anthropometric factors did not change significantly (p = 0.05).
  
  
  CONCLUSIONS
  Supplementation with high-dose vitamin D for 4 months improved vitamin D status and decreased TG levels in subjects with metabolic syndrome. However, it did not have any beneficial effects on other cardiometabolic risk factors; this might be due to the inadequate vitamin D status attained in this study which was conducted in a severely deficient region.
authors.affiliation: Student Research Committee, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Salekzamani
authors.affiliation: Student Research Committee, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: H
authors.initials: H
authors.lastname: Mehralizadeh
authors.affiliation: Student Research Committee, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Ghezel
authors.affiliation: Physical Medicine and Rehabilitation Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Y
authors.initials: Y
authors.lastname: Salekzamani
authors.affiliation: Road Traffic Injury Research Center, Faculty of Health, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: M A
authors.initials: MA
authors.lastname: Jafarabadi
authors.affiliation: Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: A S
authors.initials: AS
authors.lastname: Bavil
authors.affiliation: Nutrition Research Center, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Golgasht St., Attar Neyshapouri Av., 5166614, Tabriz, Iran. pourghassemb@tbzmed.ac.ir.
authors.forename: B P
authors.initials: BP
authors.lastname: Gargari
mesh_terms: D000328:Adult; D000886:Anthropometry; D015415:Biomarkers / Q000032:analysis; D002318:Cardiovascular Diseases / Q000209:etiology / Q000517:prevention & control*; D019587:Dietary Supplements; D004311:Double-Blind Method; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications* / Q000188:drug therapy; D012307:Risk Factors; D014807:Vitamin D / Q000627:therapeutic use*; D014815:Vitamins / Q000627:therapeutic use*
chemical_list: D015415:Biomarkers; D014815:Vitamins; D014807:Vitamin D
keywords: Anthropometry; Cardiometabolic factors; Lipid profile; Metabolic syndrome; Vitamin D