Emerging Roles of Vitamin B₁₂ in Aging and Inflammation

Vitamin B₁₂ (cobalamin) is an essential nutrient for humans and animals. Metabolically active forms of B₁₂-methylcobalamin and 5-deoxyadenosylcobalamin are cofactors for the enzymes methionine synthase and mitochondrial methylmalonyl-CoA mutase. Malfunction of these enzymes due to a scarcity of vitamin B₁₂ leads to disturbance of one-carbon metabolism and impaired mitochondrial function. A significant fraction of the population (up to 20%) is deficient in vitamin B₁₂, with a higher rate of deficiency among elderly people. B₁₂ deficiency is associated with numerous hallmarks of aging at the cellular and organismal levels. Cellular senescence is characterized by high levels of DNA damage by metabolic abnormalities, increased mitochondrial dysfunction, and disturbance of epigenetic regulation. B₁₂ deficiency could be responsible for or play a crucial part in these disorders. In this review, we focus on a comprehensive analysis of molecular mechanisms through which vitamin B₁₂ influences aging. We review new data about how deficiency in vitamin B₁₂ may accelerate cellular aging. Despite indications that vitamin B₁₂ has an important role in health and healthy aging, knowledge of the influence of vitamin B₁₂ on aging is still limited and requires further research.