EN
Various components of food and feed such as fat or carbohydrates can affect the cholesterol level in human or animal blood. Proteins can also change it and according to the most experiments the animal proteins show the hyper- while the plant proteins the hypocholesterolemic activity. The way proteins exert their effect on cholesterol metabolism is still unknown. There is a possibility that the amino acid composition of proteins, especially their sulphur amino acid content is the primary cause of such changes. According to another view the undigested fraction of protein absorbs bile acids and makes impossible reabsorption of cholesterol from the intestinal tract. The liver is probably the first site of changes of cholesterol metabolism but, according to some authors, the proteins can affect cholesterol level by changing thyroid activity.