B12 is an essential vitamin for human body which reduces the chances of neurological diseases, birth defects, and chronic disorders. It is a vital micro-nutrient for maintaining the brain health. This review sorts out some causes of vitamin B12 (B12) deficiency and develops its link with neurological disorders. The portals include PubMed, Google Scholar, Directory of Open Access Journals (DOAJ), Pak MediNet, and Science Direct were search for literature retrieval. Study of literature revealed that deficiency of this vitamin occurs primarily due to insufficient dietary intake which results in a group of neurological symptoms in adults as well as infants. These neurological disorders include apathy, anorexia, irritability, growth retardation, and developmental regression. It may also involve in delayed myelination or demyelination of neurons. It was concluded that B12 is vital micro-nutrient for healthy brain in children, younger, and elders. Various conditions are responsible for deficiency of B12. A timely and proper supplementation is necessary if it is dietary deficiency.

中文翻译：

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维生素 B12 缺乏及其与神经系统疾病的关系：批判性评论

B12 是人体必需的维生素，可减少神经系统疾病、先天缺陷和慢性疾病的机会。它是维持大脑健康的重要微量营养素。本综述梳理了维生素 B12 (B12) 缺乏症的一些原因，并探讨了其与神经系统疾病的联系。门户网站包括 PubMed、Google Scholar、开放获取期刊目录 (DOAJ)、Pak MediNet 和 Science Direct，用于检索文献。文献研究表明，这种维生素缺乏主要是由于饮食摄入不足导致成人和婴儿出现一组神经系统症状。这些神经系统疾病包括冷漠、厌食、易怒、生长迟缓和发育倒退。它还可能涉及神经元的延迟髓鞘形成或脱髓鞘。得出的结论是，B12 是儿童、年轻人和老年人大脑健康的重要微量营养素。各种条件导致 B12 缺乏。如果是饮食缺乏，及时适当的补充是必要的。