The role of bile is to facilitate the digestion and absorption of fats. Bile is secreted by liver cells and consists mainly of bile salts, bile pigments, cholesterol, lecithin, potassium, sodium and calcium. Bile is secreted and stored in the gallbladder. After eating, bile is drained from the gallbladder to the duodenum to aid in the digestion and breakdown of fats and the absorption of fat-soluble vitamins. The bile salts, lecithin and cholesterol in bile act as emulsifiers, lowering the surface tension of fats and aiding in digestion and absorption. Bile can promote the absorption of fat and fat-soluble vitamins. Fat decomposition products in the intestinal lumen, such as fatty acids and triglycerides, penetrate into the microfocus particles made of aggregated bile salts to form water-soluble mixed microgelatin particles, which promote the microgelatin particles to pass through the surface of intestinal mucosa to be absorbed. Bile can also neutralize gastric acid and promote the secretion of bile itself. Bile is weakly alkaline, which is conducive to the neutralization of gastric acid discharged into the intestinal lumen and plays the role of neutralization of gastric acid, and promotes the secretion of bile itself, mainly through the enterohepatic cycle of bile salts returned to the liver bile salts, which stimulates the liver to make bile secretion.