Lecithin, also known as Phosphatidylcholine

Lecithin is usually used as synonym for phosphatidylcholine, a phospholipid which is the major component of a phosphatide fraction which may be isolated from either egg yolk (in Greek lekithos - λεκιθος), or soy beans. It is commercially available in high purity as a food supplement and for medical uses.

In biology

Nervous and circulatory lecithin is produced by the liver if the diet is adequate. It is needed by every cell in the body and is a key building block of cell membranes; without it, they would harden. Lecithin protects cells from oxidation and largely comprises the protective sheaths surrounding the brain. It is composed mostly of B vitamins, phosphoric acid, choline, linoleic acid and inositol. Hence, it supports the circulatory system.

As a food additive

Lecithin is regarded as a well tolerated and non-toxic surfactant. It is approved by the United States Food and Drug Administration for human consumption with the status "Generally Recognized As Safe". Lecithin is an integral part of cell membranes, and can be totally metabolised, so it is virtually non-toxic to humans. Other emulsifiers can only be excreted via the kidneys.

Lecithin is used commercially for anything requiring a natural emulsifier and/or lubricant, from pharmaceuticals to protective coverings. For example, lecithin is the emulsifier that keeps chocolate and cocoa butter in a candy bar from separating.

Various studies (Brook et al 1986, Spilburg et al 2003) indicate that soy-derived lecithin may positively affect cholesterol and triglyceride levels in the blood.

Egg-derived lecithin may be a concern for certain diets; it is considered pareve (neutral, e.g. may be mixed with both meat and dairy) under kashrut, but is restricted under sharia.

See also

• biochemistry
• choline
• lipid
• lipid bilayer

References

• Brook JG, Linn S, Aviram M. Dietary soya lecithin decreases plasma triglyceride levels and inhibits collagen-and ADP-induced platelet aggregation. Biochem Med Metab Biol 1986;35:31-9. PMID 3778675.
• Spilburg CA, Goldberg AC, McGill JB, Stenson WF, Racette SB, Bateman J, McPherson TB, Ostlund RE Jr. Fat-free foods supplemented with soy stanol-lecithin powder reduce cholesterol absorption and LDL cholesterol. J Am Diet Assoc 2003;103:577-81. PMID 12728215.

External links

• Introduction to Lecithin (http://www2.chemie.uni-erlangen.de/services/dissonline/data/dissertation/Christoph_Wabel/html/Chapter1.html) (University of Erlangen)