Lecithin (LEH-suh-thun) is a waxy material found in the protective sheath that surrounds nerve fibers and plays a vital role in keeping the nervous system healthy. It contains a substance known as 'choline' (KOE-leen), which can be found in egg yolks, liver, beef, and soybeans. Under normal circumstances, choline and lecithin supplements aren't necessary, because the body naturally manufactures choline. Ingesting large amounts of choline or lecithin may have toxic effects. The American Academy of Pediatrics recommends that infant formula supply at least seven milligrams of choline per 100 calories, which is thesame amount present in human breast milk.