Vitamin B12 deficiency, cerebral myelination, and language development: biological evidence from an integrative review

OBJECTIVE: This study aimed to analyze scientific evidence on the relationship between vitamin B12 deficiency, cerebral myelination, and its potential implications for language development and speech fluency. METHODS: An integrative literature review was conducted using the PubMed, Scopus, and Cochrane databases between August 2025 and July 2026. The search strategy included terms related to vitamin B12, myelination, brain development, language, and speech. Original studies published in English investigating the effects of vitamin B12 deficiency on the central nervous system, neurodevelopment, or structural brain changes were included. RESULTS: Thirteen studies met the eligibility criteria and were synthesized through thematic narrative analysis. The findings indicated a relationship between vitamin B12 deficiency and delayed neuropsychomotor development, impaired myelination, reduced white matter integrity, and structural brain abnormalities identified by neuroimaging. Furthermore, studies investigating the neural circuits underlying language showed that these same structures are essential for language organization and speech fluency, providing biological plausibility for a potential relationship between vitamin B12 deficiency and impairments in these processes. CONCLUSION: Vitamin B12 deficiency may adversely affect neurodevelopment and cerebral myelination, representing a potential mechanism underlying alterations in the maturation of neural circuits involved in language. These findings support the biological plausibility that vitamin B12 deficiency may contribute to impaired language development through disrupted cerebral myelination, although direct clinical evidence remains lacking.