Pirotta S, Kidgell D J, Daly R M
Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
Osteoporos Int. 2015 Jan;26(1):131-40. doi: 10.1007/s00198-014-2855-6. Epub 2014 Aug 20.
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.
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.
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.
维生素D可改善肌肉功能并减少跌倒，但它是否能增强大脑和神经系统内的神经连接尚不清楚。这项为期10周的随机对照试验表明，对于老年人，每天服用2000国际单位维生素D3相对于安慰剂而言，并不会显著改变神经可塑性。
本研究的目的是探讨补充维生素D对老年人神经可塑性、血清脑源性神经营养因子（BDNF）以及肌肉力量和功能的影响。
这是一项为期10周的双盲、安慰剂对照随机试验，26名25-羟维生素D[25OHD]浓度为25-60nmol/L的老年人被随机分为每天服用2000国际单位维生素D3组或匹配的安慰剂组。通过记录对腕伸肌刺激的肌电图（EMG）反应，使用施加于运动皮层的单脉冲和双脉冲经颅磁刺激来分别评估运动诱发电位（MEP）和短间隔皮质内抑制（SICI）的变化，作为皮质脊髓兴奋性和抑制性的指标。还测量了肌肉力量、爬楼梯能力、步态（定时起立行走测试）、动态平衡（四方步测试）、血清25(OH)D和BDNF浓度的变化。
10周后，维生素D组的平均25(OH)D水平从46nmol/L升至81nmol/L，而安慰剂组无变化。与基线相比，维生素D组的肌肉力量显著增加了8-11%，皮质兴奋性（MEP波幅）和SICI降低（所有P<0.05），但这些变化与安慰剂组无显著差异。维生素D对肌肉能力、功能或BDNF没有影响。
与安慰剂相比，每天补充2000国际单位维生素D3持续10周对神经可塑性没有显著影响，但单独使用维生素D治疗与皮质脊髓兴奋性和皮质内抑制降低相关这一发现值得进一步研究，因为这表明它可能会提高皮质脊髓通路内神经传递的效率。
