Hyperhomocysteinemia is an independent predictor of the risk for cognitive decline and may be a result of low levels of vitamins B₁₂, B₆, and folate. Previous findings suggest that adequate intake of these vitamins may reduce homocysteine levels. This review aimed to assess the effects of treatment with vitamins B_6, B₁₂, and/or folic acid in the homocysteine levels in patients with mild cognitive impairment (MCI). A systematic literature review was conducted in EMBASE, MEDLINE®, PsycINFO, and Cochrane Central Register of Controlled Trials. The research question was formulated using the Population, Intervention, Comparison, and Outcome (PICO) framework: in patients with MCI (P); what is the efficacy of vitamins B₆, B₁₂, and/or folic acid intake (I); compared with baseline values, and/or compared with controls (C); in reducing homocysteine levels from baseline (O). A total of eight primary studies with a total of 1,140 participants were included in the review. Four were randomized controlled trials, one was a quasi-controlled trial, and three were observational studies. All studies included folic acid in their intervention, seven vitamin B₁₂, and four vitamin B₆. Mean (SD) length of the intervention period was 18.8 (19.3) months, ranging from 1 to 60 months. All studies showed a statistically significant decrease in homocysteine levels in groups treated with vitamins B_6, B₁₂, and/or folic acid compared to controls, with a mean decline of homocysteine concentration of 31.9% in the intervention arms whereas it increased by 0.7% in the control arm. This review identified evidence of a reduction of plasma homocysteine levels in MCI patients taking vitamins B_6, B₁₂, and/or folic acid supplements, with statistically significant declines being observed after 1 month of supplementation. Findings support that supplementation with these vitamins might be an option to reduce homocysteine levels in people with MCI and elevated plasma homocysteine.

中文翻译：

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补充维生素 B6、B12 和/或叶酸对降低轻度认知障碍患者同型半胱氨酸水平的影响：系统评价

高同型半胱氨酸血症是认知能力下降风险的独立预测因素，可能是维生素 B ₁₂、B ₆和叶酸水平低的结果。先前的研究结果表明，摄入足够的这些维生素可能会降低同型半胱氨酸水平。本综述旨在评估维生素 B _6、 B ₁₂和/或叶酸治疗对轻度认知障碍 (MCI) 患者同型半胱氨酸水平的影响。在 EMBASE、MEDLINE®、PsycINFO 和 Cochrane Central Register of Controlled Trials 中进行了系统的文献回顾。研究问题是使用人口、干预、比较和结果 (PICO) 框架制定的：在 MCI 患者中 (P)；_{维生素B 6}的功效是什么、B ₁₂和/或叶酸摄入量 (I)；与基线值比较，和/或与对照比较 (C)；从基线（O）降低同型半胱氨酸水平。该评价共纳入了 8 项主要研究，共有 1,140 名参与者。四项为随机对照试验，一项为准对照试验，三项为观察性研究。所有研究都在干预中加入了叶酸、七种维生素 B ₁₂和四种维生素 B ₆。干预期的平均 ( SD ) 长度为 18.8 (19.3) 个月，范围为 1 至 60 个月。_{所有研究均显示维生素 B 6、} B ₁₂治疗组的同型半胱氨酸水平显着降低和/或叶酸与对照组相比，干预组同型半胱氨酸浓度平均下降 31.9%，而对照组增加 0.7%。_{本综述确定了服用维生素 B 6、} B ₁₂和/或叶酸补充剂的 MCI 患者血浆同型半胱氨酸水平降低的证据，补充 1 个月后观察到统计学上显着的下降。研究结果支持补充这些维生素可能是降低 MCI 和血浆同型半胱氨酸升高患者同型半胱氨酸水平的一种选择。