Lecithin was discovered in 1850 by Maurice Gobley, who isolated it in egg yolks and identified it as the substance that allowed oil and water to mix. The name is derived from the Greek word lekithos, which means "yolk of egg." Lecithin is a naturally occurring fatty substance found in several foods including soybeans, whole grains and egg yolks. It is often used as an emulsification agent in processed foods. It can be taken in various forms as a nutritional supplement, often derived from soybeans. The body breaks lecithin down into its component parts: choline, phosphate, glycerol and fatty acids. The body's highest concentration of lecithin is found in the vital organs, where it makes up about 30% of the dry weight of the brain and nearly two-thirds of the fat in the liver.
Lecithin acts as an emulsifier and helps the body in the absorption of fats. A 1999 study indicates that soy lecithin improves the metabolism of cholesterol in the digestive system. Therefore, lecithin has been touted as a treatment for high cholesterol. It has also been said to be a treatment for neurologic and liver disorders. Promoters claim that supplemental lecithin can be used to help lower cholesterol and deter memory loss. Some proponents of lecithin warn that the low fat and low cholesterol diets that many Americans follow may lower the amount of lecithin that we consume, creating a deficit and necessitating supplemental lecithin. As Americans eat fewer eggs, meats, and dairy products, the amount of choline that they consume may be less than required. Choline is the key element in lecithin that researchers believe may have a beneficial effect on cholesterol and memory.
Lecithin has been identified as a possible resource for lowering blood cholesterol because of its reputation as a source of polyunsaturated fats. In addition, choline helps the liver metabolize fat and form lipoproteins. However, there is still scanty evidence to support the use of lecithin in lowering cholesterol. Researchers in some studies have found a drop in cholesterol levels, while others have found no drop in cholesterol levels at all. A group of researchers from the Netherlands summarized findings in the American Journal of Clinical Nutrition that found that many studies of the effects of lecithin had faulty methods, and the few good studies proved that lecithin was not effective in lowering cholesterol. More recently, a group of American researchers solved part of the mystery concerning the fact that eggs, which are packed with cholesterol, don't impact people's cholesterol much if eaten in moderation. The reason seems to be the lecithin found in eggs that reduces cholesterol's absorption in the bloodstream.
Lecithin is also considered to be of possible benefit to brain function, and supporters claim that it may help prevent Alzheimer's disease. Promoters indicate that the choline in lecithin may have the ability to penetrate the blood-brain barrier and impact the production of acetylcholine, a neurotransmitter that facilitates brain function. They claim that long-term use of lecithin as a dietary supplement could help minimize memory loss. However, studies on the use of lecithin for the treatment of Alzheimer's disease have found that it has no marked benefit.
Amy Cooper, Teresa G. Odle, The Gale Group Inc., Gale, Detroit,