ABSTRACT
The B vitamins are a class of water-soluble vitamins, many of which are involved in several signicant metabolic processes within the brain and whose deciency have been shown to exert negative cognitive effects. The B vitamins, which consist of thiamin (B1), riboavin (B2), niacin (B3), pantothenic acid (B5), B6, biotin (B7), folate (B9), and cobalamin (B12), are an interrelated group of essential nutrients that are not synthesized in the body, and thus, they need to be obtained from food and require ongoing replenishment. Although choline is not by strict denition a vitamin, it is also an essential nutrient. Choline and several B vitamins (i.e. folate, vitamin B2, vitamin B6, and vitamin B12) are cofactors in the one-carbon metabolism pathway (Figure 5.1). In this ATP-driven reaction, methionine is converted into S-adenosylmethionine (SAM), the universal cellular methyl donor. DNA methyltransferases (DNMTs) covalently attach methyl groups from SAM to the carbon-5 position of cytosine bases, generating 5-methylcytosine thus methylating DNA (Anderson et al. 2012).
