14 Choline 14 . 1 Choline in health and disease

Choline is a water-soluble nutrient that is often grouped with the vitamin B complex. However, its functions suggest it is more than just another vitamin. Choline is crucial for the normal function of all cells (Zeisel and Blusztajn, 1994). It is needed for the structural integrity and signaling functions of cell membranes; it directly affects cholinergic neurotransmission; it is the major source of methyl groups in the diet; and it is required for lipid transport from liver and for normal muscle function (Zeisel and Blusztajn, 1994; Zeisel, 2006b). In early life, choline is crucial for fetal brain development; in later life, prolonged ingestion of a choline-defi cient diet leads to fatty liver, and liver and muscle damage in humans (Zeisel, 2006b). Choline defi ciency also reduces an individual’s ability to handle a methionine (Met) load, resulting in elevated homocysteine (Hcy), a risk factor for cardiovascular diseases (CVDs) (da Costa et al., 2005). Conversely, choline supplementation in animal models might mitigate or ameliorate the symptoms of fetal alcohol syndrome (Thomas et al., 2009), traumatic brain injury (Guseva et al., 2008), brain abnormalities in mouse models of Rett syndrome (Nag et al., 2008; Ward et al., 2009) and schizophrenia (Stevens et al., 2008). In this chapter, we focus on the new observations that enhance our understanding of the roles of choline in human health and disease.