Centre for Public Health, Queen's University Belfast, Belfast, UK.
Clin Interv Aging. 2019 Jul 18;14:1303-1317. doi: 10.2147/CIA.S186760. eCollection 2019.
Vitamin E has been proposed as a potential clinical intervention for Alzheimer's disease (AD) given the plausibility of its various biological functions in influencing the neurodegenerative processes associated with the condition. The tocopherol and tocotrienol isoforms of vitamin E have multiple properties including potent antioxidant and anti-inflammatory characteristics, in addition to influences on immune function, cellular signalling and lowering cholesterol. Several of these roles offer a theoretical rationale for providing benefit for the treatment of AD-associated pathology. Diminished circulating concentrations of vitamin E have been demonstrated in individuals with AD. Reduced plasma levels have furthermore been associated with an increased risk of AD development while intake, particularly from dietary sources, may limit or reduce the rate of disease progression. This benefit may be linked to synergistic actions between vitamin E isoforms and other micronutrients. Nevertheless, randomised trials have found limited and inconsistent evidence of vitamin E supplementation as an effective clinical intervention. Thus, despite a strong rationale in support of a beneficial role for vitamin E for the treatment of AD, the evidence remains inconclusive. Several factors may partly explain this discrepancy and represent the difficulties of translating complex laboratory evidence and dietary interactions into clinical interventions. Methodological design limitations of existing randomised trials and restrictions to supplementation with a single vitamin E isoform may also limit the influence of effect. Moreover, several factors influence individual responsiveness to vitamin E intake and recent findings suggest variation in the underlying genetic architecture attenuates vitamin E biological availability and activity which likely contributes to the variation in clinical responsiveness and the failure of randomised trials to date. Importantly, the clinical safety of vitamin E remains controversial and warrants further investigation.
维生素 E 因其在影响与该病症相关的神经退行性过程的多种生物学功能方面的合理性，被提议作为治疗阿尔茨海默病（AD）的潜在临床干预手段。维生素 E 的生育酚和三烯生育酚异构体具有多种特性，包括强大的抗氧化和抗炎特性，以及对免疫功能、细胞信号和降低胆固醇的影响。这些作用中的一些为提供 AD 相关病变治疗益处提供了理论依据。已经在 AD 患者中证明了维生素 E 的循环浓度降低。此外，降低的血浆水平与 AD 发展风险增加相关，而摄入（特别是来自饮食来源）可能限制或降低疾病进展的速度。这种益处可能与维生素 E 异构体和其他微量营养素之间的协同作用有关。尽管有强有力的理由支持维生素 E 对治疗 AD 的有益作用，但证据仍然不确定。有几个因素可能部分解释了这种差异，并代表了将复杂的实验室证据和饮食相互作用转化为临床干预的困难。现有随机试验的方法设计限制以及对单一维生素 E 异构体的补充限制也可能限制其效果的影响。此外，有几个因素影响个体对维生素 E 摄入的反应性，最近的研究结果表明，潜在遗传结构的变异会降低维生素 E 的生物利用度和活性，这可能导致临床反应性的变化以及迄今为止随机试验的失败。重要的是，维生素 E 的临床安全性仍然存在争议，需要进一步研究。
