Effects of vitamin D supplementation on neuroplasticity in older adults: a double-blinded, placebo-controlled randomised trial

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.

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.

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.

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.