title: Effects of vitamin D supplementation on neuroplasticity in older adults: a double-blinded, placebo-controlled randomised trial.
abstract: Vitamin D can improve muscle function and reduce falls, but whether it can strengthen neural connections within the brain and nervous system is not known. This 10-week randomised controlled trial indicates that treatment with 2,000 IU/day vitamin D3 does not significantly alter neuroplasticity relative to placebo in older adults.
  
  
  BACKGROUND
  The purpose of this study was to examine the effects of vitamin D supplementation on neuroplasticity, serum brain-derived neurotrophic factor (BDNF) and muscle strength and function in older adults.
  
  
  METHODS
  This was a 10-week double-blinded, placebo-controlled randomised trial in which 26 older adults with 25-hydroxyvitamin D [25OHD] concentrations 25-60 nmol/L were randomised to 2,000 IU/day vitamin D3 or matched placebo. Single- and paired-pulse transcranial magnetic stimulation applied over the motor cortex was used to assess changes in motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI), as measures of corticospinal excitability and inhibition respectively, by recording electromyography (EMG) responses to stimulation from the wrist extensors. Changes in muscle strength, stair climbing power, gait (timed-up-and-go), dynamic balance (four square step test), serum 25(OH)D and BDNF concentrations were also measured.
  
  
  RESULTS
  After 10 weeks, mean 25(OH)D levels increased from 46 to 81 nmol/L in the vitamin D group with no change in the placebo group. The vitamin D group experienced a significant 8-11% increase in muscle strength and a reduction in cortical excitability (MEP amplitude) and SICI relative to baseline (all P < 0.05), but these changes were not significantly different from placebo. There was no effect of vitamin D on muscle power, function or BDNF.
  
  
  CONCLUSIONS
  Daily supplementation with 2,000 IU vitamin D3 for 10 weeks had no significant effect on neuroplasticity compared to placebo, but the finding that vitamin D treatment alone was associated with a decrease in corticospinal excitability and intracortical inhibition warrants further investigation as this suggests that it may improve the efficacy of neural transmission within the corticospinal pathway.
authors.affiliation: Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Pirotta
authors.forename: D J
authors.initials: DJ
authors.lastname: Kidgell
authors.forename: R M
authors.initials: RM
authors.lastname: Daly
mesh_terms: D000368:Aged; D000886:Anthropometry / Q000379:methods; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood; D002762:Cholecalciferol / Q000494:pharmacology*; D004032:Diet; D019587:Dietary Supplements; D004311:Double-Blind Method; D058620:Elder Nutritional Physiological Phenomena / Q000502:physiology; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D053580:Muscle Strength / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects* / Q000502:physiology; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D016903:Drug Monitoring
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D014807:Vitamin D; D002762:Cholecalciferol; C579455:BDNF protein, human; C104450:25-hydroxyvitamin D