title: Vitamin D3 supplementation has no effect on conventional cardiovascular risk factors: a parallel-group, double-blind, placebo-controlled RCT.
abstract: BACKGROUND
  Observational studies show an association between low vitamin D status assessed by circulating 25-hydroxyvitamin D and cardiovascular events and mortality. Data from randomized controlled trials are limited.
  
  
  OBJECTIVE
  The aim of this study was to test whether daily doses of vitamin D(3) at 400 or 1000 IU/d for 1 yr affected conventional markers of cardiovascular disease (CVD) risk.
  
  
  METHODS
  We conducted a parallel-group, double-blind, placebo-controlled randomized controlled trial. Randomization was computer generated. Participants and study investigators were blinded to intervention groupings throughout the trial.
  
  
  METHODS
  The study was conducted at the Clinical Research Facility, University of Aberdeen, United Kingdom.
  
  
  METHODS
  A total of 305 healthy postmenopausal women aged 60-70 yr were recruited for the study.
  
  
  METHODS
  Each woman received a daily capsule of 400 or 1000 IU vitamin D(3) or placebo randomly allocated.
  
  
  METHODS
  Primary outcomes were serum lipid profile [total, high-density lipoprotein, and low-density lipoprotein cholesterol; triglycerides; and apolipoproteins A-1 and B100], insulin resistance (homeostatic model assessment), inflammatory biomarkers (high-sensitivity C-reactive protein, IL-6, soluble intracellular adhesion molecule-1), and blood pressure.
  
  
  RESULTS
  A total of 265 (87%) participants completed all study visits. Small differences between groups for serum apolipoprotein B100 change [repeated measures ANOVA, P=0.04; mean (sd), -1.0 (10.0) mg/dl (400 IU); -1.0 (10.0) mg/dl (1000 IU); and +0.02 (10.0) mg/dl (placebo)] were not considered clinically significant. Other systemic markers for CVD risk remained unchanged. There was significant seasonal variation in systolic and diastolic blood pressure independent of vitamin D dose (P<0.001, linear mixed model). Mean (sd) reduction in systolic blood pressure from winter to summer was -6.6 (10.8) mm Hg.
  
  
  CONCLUSIONS
  Improving vitamin D status through dietary supplementation is unlikely to reduce CVD risk factors. Confounding of seasonality should be recognized and addressed in future studies of vitamin D.
authors.affiliation: School of Medicine and Dentistry, Health Sciences Building, University of Aberdeen, and Grampian Osteoporosis Service, Woolmanhill Hospital, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
authors.forename: Adrian D
authors.initials: AD
authors.lastname: Wood
authors.forename: Karen R
authors.initials: KR
authors.lastname: Secombes
authors.forename: Frank
authors.initials: F
authors.lastname: Thies
authors.forename: Lorna
authors.initials: L
authors.lastname: Aucott
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Black
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mavroeidi
authors.forename: William G
authors.initials: WG
authors.lastname: Simpson
authors.forename: William D
authors.initials: WD
authors.lastname: Fraser
authors.forename: David M
authors.initials: DM
authors.lastname: Reid
authors.forename: Helen M
authors.initials: HM
authors.lastname: Macdonald
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000401:mortality*; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008875:Middle Aged; D010919:Placebos; D017698:Postmenopause; D012307:Risk Factors; D040242:Risk Reduction Behavior; D014815:Vitamins / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D015415:Biomarkers; D010919:Placebos; D014815:Vitamins; D002762:Cholecalciferol