title: The effects of vitamin D on skeletal muscle strength, muscle mass, and muscle power: a systematic review and meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  There is growing evidence that vitamin D plays a role on several tissues including skeletal muscle.
  
  
  OBJECTIVE
  The aim was to summarize with a meta-analysis, the effects of vitamin D supplementation on muscle function.
  
  
  METHODS
  A systematic research of randomized controlled trials, performed between 1966 and January 2014 has been conducted on Medline, Cochrane Database of Systematics Reviews, Cochrane Central Register of Controlled and completed by a manual review of the literature and congressional abstracts.
  
  
  METHODS
  All forms and doses of vitamin D supplementation, with or without calcium supplementation, compared with placebo or control were included. Out of the 225 potentially relevant articles, 30 randomized controlled trials involving 5615 individuals (mean age: 61.1 years) met the inclusion criteria.
  
  
  METHODS
  Data were extracted by two independent reviewers.
  
  
  RESULTS
  Results revealed a small but significant positive effect of vitamin D supplementation on global muscle strength with a standardized mean difference (SMD) of 0.17 (P = .02). No significant effect was found on muscle mass (SMD 0.058; P = .52) or muscle power (SMD 0.057; P = .657). Results on muscle strength were significantly more important with people who presented a 25-hydroxyvitamin D level <30 nmol/L. Supplementation seems also more effective on people aged 65 years or older compared to younger subjects (SMD 0.25; 95% CI 0.01 to 0.48 vs SMD 0.03; 95% CI -0.08 to 0.14).
  
  
  CONCLUSIONS
  Vitamin D supplementation has a small positive impact on muscle strength, but additional studies are needed to define optimal treatment modalities, including dose, mode of administration, and duration.
authors.affiliation: Department of Public Health (C.B., F.B., V.R., J.S., J-Y.R., O.B.), Epidemiology and Health Economics, University of Liège, Liège, Belgium; Support Unit in Epidemiology and Biostatistics (C.B., F.B., J.S., J-Y.R., O.B.), University of Liège, Belgium; Geriatric Department (S.G., J.P.), CHU Liège, Liège, Belgium; Department of Clinical Chemistry (E.C.), University of Liège, CHU Sart-Tilman, Liège, Belgium; Bone and Cartilage Metabolism Department (J-Y.R.), CHU Liège, Liège, Belgium; and Department of Motricity Sciences (O.B.), University of Liège, Liège, Belgium.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Beaudart
authors.forename: Fanny
authors.initials: F
authors.lastname: Buckinx
authors.forename: Véronique
authors.initials: V
authors.lastname: Rabenda
authors.forename: Sophie
authors.initials: S
authors.lastname: Gillain
authors.forename: Etienne
authors.initials: E
authors.lastname: Cavalier
authors.forename: Justine
authors.initials: J
authors.lastname: Slomian
authors.forename: Jean
authors.initials: J
authors.lastname: Petermans
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Reginster
authors.forename: Olivier
authors.initials: O
authors.lastname: Bruyère
mesh_terms: D019587:Dietary Supplements; D006801:Humans; D008875:Middle Aged; D053580:Muscle Strength / Q000187:drug effects* / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D016032:Randomized Controlled Trials as Topic; D014807:Vitamin D / Q000008:administration & dosage*
chemical_list: D014807:Vitamin D