Vitamin B12 deficiency among older adults and its associations with geriatric syndromes

Vitamin B12 deficiency is a common yet frequently underdiagnosed condition in older adults. The growing aging population is experiencing an increasing burden of geriatric syndromes, such as cognitive impairment, frailty, and falls. The aim of this review is to synthesize current evidence on the relationship between B12 deficiency and age-related clinical outcomes to guide early recognition and management.

Recent studies link vitamin B12 deficiency to neurodegenerative and neuromuscular changes via disrupted myelin synthesis, elevated homocysteine and methylmalonic acid, oxidative stress, and neurotransmitter dysregulation. Low B12 levels are consistently associated with cognitive decline, depressive symptoms, balance disturbances, gait disorders, sarcopenia, and frailty. Diagnosis is often challenging due to nonspecific or overlapping clinical features and the limited sensitivity of standard serum B12 assays. Clinical improvements in cognitive and physical function have been observed following supplementation, particularly in early or mild cases.

This narrative review synthesizes current evidence on the epidemiology, pathophysiology, and clinical implications of vitamin B12 deficiency in key geriatric syndromes. Routine screening and early intervention for vitamin B12 deficiency in high-risk older adults may mitigate the progression of geriatric syndromes and preserve functional independence.