B vitamin therapy lowers plasma total homocysteine concentrations, and might be a beneficial intervention for stroke prevention; however, cyanocobalamin (a form of vitamin B12) can accelerate decline in renal function and increase the risk of cardiovascular events in patients with impaired renal function. Although early trials did not show benefit in reduction of stroke, these results might have been due to harm in participants with impaired renal function. In patients with diabetic nephropathy, cyanocobalamin is harmful, whereas B vitamins appear to reduce cardiovascular events in study participants with normal renal function. Our meta-analysis of individual patient data from two large trials of B vitamin therapy (VISP and VITATOPS) indicates that patients with impaired renal function who are exposed to high-dose cyanocobalamin do not benefit from therapy with B vitamins for the prevention of stroke (risk ratio 1·04, 95% CI 0·84-1·27), however, patients with normal renal function who are not exposed to high-dose cyanocobalamin benefit significantly from this treatment (0.78, 0·67-0·90; interaction p=0·03). The potential benefits of B vitamin therapy with folic acid and methylcobalamin or hydroxycobalamin, instead of cyanocobalamin, to lower homocysteine concentrations in people at high risk of stroke warrant further investigation.

中文翻译：

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预防中风中的B族维生素：需要重新考虑的时间。

维生素B疗法可降低血浆总同型半胱氨酸浓度，可能是预防中风的有益干预措施；然而，氰钴胺（维生素B12的一种形式）可以加速肾功能下降，并增加肾功能受损患者发生心血管事件的风险。尽管早期试验并未显示出减少卒中的益处，但这些结果可能归因于肾功能受损的参与者的伤害。在患有糖尿病肾病的患者中，氰钴胺对人体有害，而维生素B似乎可以降低肾功能正常的受试者的心血管事件。我们对来自两项大型B维生素治疗试验（VISP和VITATOPS）的患者数据的荟萃分析表明，暴露于高剂量氰钴胺素的肾功能受损的患者无法从B维生素治疗中受益（风险比为1·04，95％CI 0·84-1·27），但是，未暴露于高剂量氰钴胺素的肾功能正常的患者可从该治疗中显着受益（0.78，0·67-0·90;相互作用p = 0·03）。用叶酸和甲基钴胺素或羟基钴胺素代替氰钴胺素进行B维生素疗法降低中风高危人群中同型半胱氨酸浓度的潜在益处值得进一步研究。没有暴露于高剂量氰钴胺素的肾功能正常的患者可从该治疗中显着受益（0.78，0·67-0·90；相互作用p = 0·03）。用叶酸和甲基钴胺素或羟基钴胺素代替氰钴胺素进行B维生素疗法降低中风高危人群中同型半胱氨酸浓度的潜在益处值得进一步研究。没有暴露于高剂量氰钴胺素的肾功能正常的患者可从该治疗中显着受益（0.78，0·67-0·90；相互作用p = 0·03）。用叶酸和甲基钴胺素或羟钴胺素代替氰钴胺素进行B维生素疗法降低中风高危人群中同型半胱氨酸浓度的潜在益处值得进一步研究。