The most secretion of gastric acid is when eating. When food enters the stomach, it directly and thoroughly stimulates the receptors of the fundus and body of the stomach, leading to excitation of the vagus nerve and causing a large secretion of gastric juice. The chemical composition of food, such as proteins, especially those rich in phenylalanine and tryptophan, stimulate the stomach to produce gastric acid is the strongest. Sugary foods and fatty foods do not directly stimulate the production of gastric acid, but coffee, tea, milk, ethanol, and foods rich in calcium cause a large secretion of gastric juices and produce a large amount of gastric acid, producing up to 60% of the overall secretion.