Phosphatidylcholine (PC) is a naturally occurring, integral component of the cellular membrane, supporting the addition of fluidity and strength to cells. It serves as a source of choline, an important nutrient for methylation, cell-to-cell communication, cognition and liver function. Choline and its metabolites are the major source of methyl groups in the diet. Methylation plays many roles including neurotransmission, vitamin assimilation, DNA synthesis and gene regulation. Choline is required for the synthesis of phospholipids and acetylcholine, a neurotransmitter involved in attention, learning and memory. A 6-month double-blind, placebo-controlled trial suggested that choline-containing lecithin, alpha GPC supports memory in aging individuals. Animal research suggests an adaptogenic effect when exposed to stress. Certain genetic variations in MTHFR and PEMT, enzymes that play critical roles in methylation and choline synthesis, respectively, have been associated with increased dietary choline needs.