When medical researchers use the term lecithin, they are referring to a purified substance called phosphatidylcholine (PC). Supplements labeled as lecithin usually contain 10-20% PC. Relatively pure PC supplements are generally labeled as phosphatidylcholine. PC best duplicates supplements used in medical research.
Choline by itself (without the phosphatidyl group) is also available in foods and supplements. In high amounts, however, pure choline can make people smell like fish, so it's rarely used, except in the small amounts found in multivitamin supplements.
What does it do? PC acts as a supplier of choline, which is needed for cell membrane integrity and to facilitate the movement of fats in and out of cells. It is also a component of the neurotransmitter acetylcholine and is needed for normal brain functioning, particularly in infants. Although the human body can synthesize choline, additional amounts from the diet are considered essential under certain circumstances. For this reason, PC has been used in a number of preliminary studies for a wide variety of neurological and psychiatric disorders, though not every study suggests that supplemental choline is capable of reaching the brain. Choline participates in many functions involving cellular components called phospholipids.
Where is it found? Choline, the major constituent of PC, is found in soybeans, liver, oatmeal, cabbage, and cauliflower. Soybeans, egg yolks, meat, and some vegetables contain PC. Lecithin (containing 10-20% PC) is added to many processed foods in small amounts for the purpose of maintaining texture consistency.
Lecithin contains 25% phosphatidyl choline, which comprises a major portion of all cell membranes. NOW Lecithin Granules are derived entirely from soybeans. Lecithin is also used to emulsify fats in baking and cooking.