Lecithin is a diet supplement that generally comes in two forms. Dry lecithin consists of fatty acids known as phospholipids. These are critical components of cell membranes and the human body needs to get these from the diet. Liquid lecithin, or lecithin oil, has additional glycophospholipids that do not dry out into a powder.
When soy bean oil is extracted from plants, a fraction is partially oily and partially water-soluble. That fraction is known as lecithin. The fatty acids in lecithin have "head groups" that are soluble in water, while the rest of each molecule is not water soluble-it is an oil. These are known as phospholipids.
Phospholipids in Cell Membranes
Phospholipids are major components of cell membranes. They organize in cells with the oily "tails" forming a layer inside the cell membrane. The water-soluble head groups form the outer layers of cell membranes.
The major component of lecithin phospholipids is known as phosphatidylcholine. Other phospholipids in lecithin include phosphatide ethanolamine, phosphatidylserine, phosphatidylinositol and phosphatidic acid. Different lecithin products can be enriched in different phospholipids for various dietary benefits.
Phosphatidylcholine is critical not only for cell membranes, but for neurological processes as well. It can be digested into choline, which is a critical neurotransmitter in the human body.
Liquid lecithin contains glycophospholipids--the same phospholipids as in lecithin granules, but including phospholipids with a glucose molecule attached. These are "oily" and cause the extract to be a liquid. Liquid lecithin is generally about 20 to 30 percent fat, while lecithin granules or powders are generally less than 10 percent fat.