Role of Soy Lecithin in Lipid Metabolism
Soy lecithin has been used in the food and cosmetic industries because it can emulsify lipid-soluble materials. Soy lecithin has been implicated in absorption, transport, and metabolism of lipids in the intestine, circulation, and liver, thereby contributing to health promotion. Soy lecithin is used instead of phosphatidylcholine (PC), although commercially available soy lecithin contains triacylglycerols (TGs) and phospholipids other than PC. Commercially available crude soy lecithin contains various proportions of neutral and polar lipids. Neutral lipids are mainly TGs, whereas polar lipids consist of phospholipids and glycolipids. The hypocholesterolemic effect of soy lecithin may be due to the high content of linoleic acid, because linoleic acid lowers serum cholesterol, compared to the saturated fatty acids, in humans and experimental animals. To clarify the underlying mechanisms of the alteration of serum lipids and apolipoproteins, secretion of lipids and apolipoproteins from isolated perfused livers of rats fed soy lecithin and soy oil were compared.