Parkinson’s disease (PD) has been linked to a vast array of vitamins among which vitamin B12 (Vit B12) is the most relevant and often investigated specially in the context of intrajejunal levodopa infusion therapy. Vit B12 deficiency, itself, has been reported to cause acute parkinsonism. Nevertheless, concrete mechanisms through which B12 deficiency interacts with PD in terms of pathophysiology, clinical manifestation and progression remains unclear. Recent studies have suggested that Vit B12 deficiency along with the induced hyperhomocysteinemia are correlated with specific PD phenotypes characterized with early postural instability and falls and more rapid motor progression, cognitive impairment, visual hallucinations and autonomic dysfunction. Specific clinical features such as polyneuropathy have also been linked to Vit B12 deficiency specifically in context of intrajejunal levodopa therapy. In this review, we explore the link between Vit B12 and PD in terms of physiopathology regarding dysfunctional neural pathways, neuropathological processes as well as reviewing the major clinical traits of Vit B12 deficiency in PD and Levodopa-mediated neuropathy. Finally, we provide an overview of the therapeutic effect of Vit B12 supplementation in PD and posit a practical guideline for Vit B12 testing and supplementation.

帕金森病 (PD) 与多种维生素有关，其中维生素 B12 (Vit B12) 最为相关，并且经常在空肠内左旋多巴输注治疗的背景下进行专门研究。据报道，维生素 B12 缺乏本身会导致急性帕金森病。然而，B12 缺乏与 PD 在病理生理学、临床表现和进展方面相互作用的具体机制仍不清楚。最近的研究表明，维生素 B12 缺乏以及诱发的高同型半胱氨酸血症与特定的 PD 表型相关，其特征是早期姿势不稳定和跌倒以及更快的运动进展、认知障碍、幻视和自主神经功能障碍。特定的临床特征（例如多发性神经病）也与维生素 B12 缺乏有关，特别是在空肠内左旋多巴治疗的情况下。在这篇综述中，我们从功能失调的神经通路、神经病理过程的病理生理学角度探讨了维生素 B12 与帕金森病之间的联系，并回顾了帕金森病和左旋多巴介导的神经病中维生素 B12 缺乏的主要临床特征。最后，我们概述了补充维生素 B12 对帕金森病的治疗效果，并提出了维生素 B12 测试和补充的实用指南。