Vitamin B12 and cognitive impairment

Vitamin B12 is an essential vitamin required for neurological health. The main causes of deficiency (hypoacidity of the stomach, pernicious anemia, and lack of dietary intake) are more prevalent with increasing age. This chapter discusses the epidemiological evidence that suggests an association between low vitamin B12 levels and cognitive decline. To date, short term clinical trials have only shown B12 supplementation to be effective in improving cognition in those with preexisting deficiency (<150. ρmol/L). Improving dietary B12 intake by better food selection, fortified foods, or supplements, may have a role in maintaining cognitive function in those who are at risk of developing B12 deficiency. To be effective, such intervention may need to be commenced before the onset of neuronal damage in middle age, particularly in those with a B12 level of less than 250. ρmol/L. Trials to study when and for how long to provide B12 supplementation are needed.