Faculty of Epidemiology and Population Health, Department of Population Health, London School of Hygiene and Tropical Medicine, London, UK.
Clinical Trial Services Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
Eur J Clin Nutr. 2017 Oct;71(10):1166-1172. doi: 10.1038/ejcn.2017.7. Epub 2017 Feb 22.
BACKGROUND/OBJECTIVES: The available evidence from randomised controlled trials suggests that vitamin B12 supplementation does not improve neurologic function in older people with marginal but not deficient Vitamin B12 status. This secondary analysis used data from the Older People and Enhanced Neurological function (OPEN) randomised controlled trial to assess whether baseline vitamin B12 status or change in vitamin B12 status over 12 months altered the effectiveness of dietary vitamin B12 supplementation on neurologic function in asymptomatic older people with depleted vitamin B12 status at study entry.
SUBJECTS/METHODS: Vitamin B12 status was measured as serum concentrations of vitamin B12, holotranscobalamin, homocysteine and via a composite indicator (cB12). Neurological function outcomes included eleven electrophysiological measures of sensory and motor components of peripheral and central nerve function. Linear regression analyses were restricted to participants randomised into the intervention arm of the OPEN trial (n=91).
Analyses revealed an inconsistent pattern of moderate associations between some measures of baseline vitamin B12 status and some neurological responses to supplementation. The directions of effect varied and heterogeneity in effect across outcomes could not be explained according to type of neurological outcome. There was no evidence of differences in the neurological response to vitamin B12 supplementation according to change from baseline over 12 months in any indicator of B12 status.
This secondary analysis of high-quality data from the OPEN trial provides no evidence that baseline (or change from baseline) vitamin B12 status modifies the effect of vitamin B12 supplementation on peripheral or central nerve conduction among older people with marginal vitamin B12 status. There is currently insufficient evidence of efficacy for neurological function to support population-wide recommendations for vitamin B12 supplementation in healthy asymptomatic older people with marginal vitamin B12 status.
背景/目的：随机对照试验的现有证据表明，维生素 B12 补充剂并不能改善边缘但不缺乏维生素 B12 状态的老年人的神经功能。这项二次分析使用了来自老年人和增强神经功能（OPEN）随机对照试验的数据，评估了基线维生素 B12 状态或 12 个月内维生素 B12 状态的变化是否改变了补充膳食维生素 B12 对研究开始时维生素 B12 状态耗尽的无症状老年人神经功能的有效性。
受试者/方法：维生素 B12 状态通过血清维生素 B12、全钴胺素、同型半胱氨酸和复合指标（cB12）浓度来衡量。神经功能结果包括十一项感觉和运动成分的周围和中枢神经功能的电生理测量。线性回归分析仅限于 OPEN 试验干预组随机分配的参与者（n=91）。
分析显示，一些基线维生素 B12 状态指标与一些补充剂对神经功能的反应之间存在不一致的中度关联模式。效应的方向不同，并且无法根据神经学结果的类型来解释效应在结果之间的异质性。根据 12 个月内任何 B12 状态指标的基线变化，没有证据表明维生素 B12 补充对维生素 B12 状态的神经反应存在差异。
这项对 OPEN 试验高质量数据的二次分析没有提供证据表明基线（或从基线变化）维生素 B12 状态会改变边缘维生素 B12 状态的老年人补充维生素 B12 对周围或中枢神经传导的影响。目前，尚无足够的证据表明神经功能的疗效能够支持在边缘性维生素 B12 状态的健康无症状老年人中广泛推荐补充维生素 B12。
