Phosphatidylcholine (PC), derived from eggs, soybeans, mustard, sunflowers and other foods, is a natural chemical. It occurs naturally in all cells of the body. Together with phosphatidylethanolamine (PE), it is the most abundant phospholipid in all mammalian cell membranes. Phosphatidylcholine is also the source of choline in the body.PC is a phospholipid attached to choline particles. Phospholipids contain fatty acids, glycerol, and phosphorus. The phosphorus portion of the phospholipid substance (lecithin) consists of PC. Therefore, the terms phosphatidylcholine and lecithin are often used interchangeably, but they are different. Foods containing lecithin are the best dietary sources of PC.