title: Effect of vitamin D supplementation on measures of arterial stiffness: a systematic review and meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Low vitamin D has been associated with poor arterial compliance in observational studies. Arterial stiffness has prognostic value for cardiovascular disease risk. The aim of this systematic review was to clarify the literature surrounding the use of vitamin D to ameliorate arterial stiffness.
  
  
  METHODS
  We conducted a systematic review of the MEDLINE, Scopus and EMBASE databases for randomized controlled clinical trials investigating the effect of vitamin D supplementation on pulse wave velocity (PWV) and/or augmentation index (AI) as indicators of arterial stiffness. We meta-analysed data and calculated standardized mean difference (SMD) and 95% confidence intervals (CI) using inverse-variance models on RevMan v5.3 software. Study quality was assessed using a modified Jadad scale.
  
  
  RESULTS
  A total of 607 unique records were identified, of which 18 satisfied our inclusion and exclusion criteria. Study quality was high, ranging from 9 to 12 (of 13). Study design in terms of vitamin D dosing protocol (range: 1000-5700 IU/day), follow-up times (range: 1-12 months), sample size (range: n = 29-183) and recruitment strategies varied markedly. Thirteen studies had data for meta-analysis. Vitamin D was associated with nonsignificant reductions in PWV [SMD = -0·10; 95% CI: -0·24, 0·04; P = 0·17; n = 806 from ten studies] and AI [-0·15; -0·32, 0·02; 0·08; n = 551 from eight studies].
  
  
  CONCLUSIONS
  There is inconsistent evidence to suggest that vitamin D supplementation improves indicators of arterial stiffness. This may be attributable to the heterogeneity in study design. Therefore, large and well-designed randomized studies are required to determine the casual relationships between vitamin D and arterial stiffness and cardiovascular risk.
authors.affiliation: Bone and Muscle Health Research Group, Department of Medicine, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Vic., Australia.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Rodríguez
authors.affiliation: Melbourne Medical School (Western Campus), Department of Medicine, The University of Melbourne, St Albans, Vic., Australia.
authors.forename: David
authors.initials: D
authors.lastname: Scott
authors.affiliation: Stroke and Ageing Research Group, Department of Medicine, School of Clinical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Vic., Australia.
authors.forename: Velandai
authors.initials: V
authors.lastname: Srikanth
authors.affiliation: Melbourne Medical School (Western Campus), Department of Medicine, The University of Melbourne, St Albans, Vic., Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Ebeling
mesh_terms: D019587:Dietary Supplements; D005500:Follow-Up Studies; D006801:Humans; D063177:Pulse Wave Analysis; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D059289:Vascular Stiffness / Q000187:drug effects*; D014807:Vitamin D / Q000008:administration & dosage / Q000627:therapeutic use*; D014815:Vitamins / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D014815:Vitamins; D014807:Vitamin D