Lecithin is used in many foods as an emulsifying agent (emulsifiers help keep the fat from separating). The richest natural sources of lecithin are from foods which are also high in fat, such as eggs and beef liver, but other foods such as peanuts, beef steak and some fruits and vegetables are lesser sources. Commercial lecithin is obtained as a by-product in the production of soybean flour and oil. The name is derived from the Greek word for egg yolk (lekithos), which is a rich source of lecithin. Commercial lecithin is purified and non-allergenic for people with soy bean or chicken allergies.

Lecithin chemically is phosphatidylcholine, a phospholipid that is part of the cell structure in both animals as plants. Phospholipids are needed by every cell in the body and are key building blocks of cell membranes; without it, the cell membranes would harden. Lecithin also protects cells from oxidation and largely comprises the protective sheaths surrounding the brain in humans. Chemical structure of lecithin

Structure of a lecithin

Lecithin is also sold in the form of soft gelatine capsules or granular powder and is consumed for a variety of health reasons, since some people believe its benefits include lowering cholesterol and improving memory and liver function.
Lecithin has been examined for its ability to lower cholesterol in humans. However, in a 1989 review of 24 studies published in the American Journal of Clinical Nutrition, the conclusion was that there is little evidence that lecithin directly lowers cholesterol (Knuiman et al., 1989).

Lecithin has also been studied in regards to effects on memory function. It is not certain whether lecithin improves memory, however, as studies in humans have yielded inconsistent results. Other potential benefits of lecithin may include a role in liver and reproductive health, as well as improved physical performance in certain activities. Additional research is needed to confirm these health benefits of lecithin supplementation.