Lecithin is utilized in a wide variety of food and industrial applications. Biochemically, it is a lipid material belonging to the class known as phospholipids and is a component of all living cells. Lecithin was first discovered in 1850 by the French scientist, Maurice Gobley, who named it "lekithos", the Greek term for egg yolk. Until the advent of soybean processing, the egg remained the major source of commercial lecithin. Because of its high lecithin content, egg yolk is still used today to produce quality food emulsions such as mayonnaise.

Physiologically, lecithin is an integral part of all organs and glands. The brain itself contains 25% phospholipids on a dry weight basis. Vital organs such as the liver and reproductive tract, and muscles contain high concentration of phospholipids. Phospholipids are also among the primary building blocks of all cellular membranes. Membrane functions include cellular transport of nutrients and wastes, internal cellular pressure regulation, and ion exchange.

Info taken from lecithin.com