Bile is a digestive fluid that helps the body digest large molecules such as proteins and fats. It is secreted by liver cells, and during feeding, bile secreted through liver cells enters the intestinal cavity to help digestion and absorption of food. If the bile is not fully utilized, that is, when a person does not eat, the bile secreted by liver cells will enter the gallbladder, where it is concentrated and stored, and then discharged into the intestinal cavity by the contraction of the gallbladder when a person eats to help digestion and absorption. Therefore, bile is a digestive fluid that helps to break down macromolecules and is part of the digestion and absorption of human food.