Chitosan has two mechanisms for lowering cholesterol. One is to prevent the absorption of fat, and the other is to excrete cholesterol in human blood. Firstly, chitosan inhibits the activity of lipase which contributes to fat absorption. Lipase breaks down fat and makes it absorbed by human body. The other is to excrete cholic acid. Once cholic acid is excreted, cholesterol in the blood is used to make cholic acid. These two mechanisms make chitosan a powerful cholesterol scavenger. Chitosan is a natural material with strong anion adsorption, which is suitable for lowering cholesterol without any side effects.

It has long been found that simple chitosan can absorb several times its own weight of oil. Related animal experiments have found that chitosan can effectively prevent the digestive system from absorbing cholesterol and triglycerides and prevent cholesterol and fatty acids from accumulating in the body. For example, rats fed with high-fat mixed feed and chitosan for two weeks at the same time, the fat content in feces of the experimental group was significantly higher than that of the control group. Generally speaking, the mechanism that chitosan can adsorb oil is that its amino group makes it a polycationic body, which can adsorb chitosan with negatively charged fatty acid ions, and can also combine with bile acids to affect lipid emulsification and reduce its absorption. Chitosan can also promote the conversion of cholesterol into bile acids. Because chitosan is easy to combine with bile acids and excrete them all, cholesterol must be converted into bile acids in the liver in order to maintain the normal content of bile acids. In this way, the cholesterol content in the blood will inevitably decrease, and the weight loss function value will also increase significantly. Floccules adsorbed by chitosan (including chitosan, bile acids, adsorbed fat and cholesterol) will not enter the blood, can not be digested, and are normally excreted. These characteristics determine that chitosan itself is very suitable for human body to lose weight, but chitosan, as a polycationic compound, generally cannot adsorb neutral oil, and its adsorption capacity for neutral oil such as cholesterol and triglyceride, which can decompose fatty substances in the stomach, is not strong. Moreover, because chitosan is insoluble in fat, the interaction between chitosan and fat and fatty acid is greatly limited; Furthermore, chitosan is insoluble in intestinal environment, which reduces the adsorption efficiency of fatty acids. Therefore, people began to use chitosan together with other substances that can reduce weight or inhibit its side effects, so as to improve its oil adsorption capacity. In addition, chitosan can be modified, and its derivatives can be used to improve oil adsorption efficiency.