Gastrin: The Key Hormone Regulating Stomach Acidity

The hormone that regulates the pH of the stomach is gastrin. Gastrin is produced by the G cells in the stomach and the duodenum. It stimulates the parietal cells in the stomach to secrete hydrochloric acid (HCl), which lowers the pH of the stomach. HCl is necessary for the digestion of proteins and for the absorption of iron and calcium. Gastrin also stimulates the growth of the gastric mucosa and the secretion of pepsin, a digestive enzyme.