Although lecithin itself is a lipid (fat), it is partially soluble in water and thus acts as an emulsifying agent, enabling fats to be dispersed in water. This supports both absorption of fats and fat-soluble nutrients and in removal of fats from the body. But its value doesnt end there. Cell membranes, which regulate the flow of nutrients into and out of cells, are largely composed of lecithin. The bodys highest concentration of lecithin is in the vital organs. It makes up about 30% of the dry weight of the brain and nearly two-thirds of the fat in the liver.