LECITHIN AND CHOLINE IN HUMAN HEALTH AND DISEASE

Choline is involved in methyl group metabolism and lipid transport and is a component of a number of important biological compounds includin g the membrane phospholipids lecithin, sphingomyelin, and plasmalogen; the neurotransmitter acetylcholine; and platelet activating factor Al though a required nutrient for several animal species, choline is not currently designated as essential for humans. However, recent clinical studies show it to be essential for normal liver function. Additional ly, a large body of evidence from the fields of molecular and cell bio logy shows that certain phospholipids play a critical role in generati ng second messengers for cell membrane signal transduction. This proce ss involves a cascade of reactions that translate an external cell sti mulus such as a hormone or growth factor into a change in cell transpo rt, metabolism, growth, function, or gene expression. Disruptions in p hospholipid metabolism can interfere with this process and may underli e certain disease states such as cancer and Alzheimer's disease. These recent findings may be appropriate in the consideration of choline as an essential nutrient for humans.