Pepsin

Pepsin requires an extremely narrow and highly acidic pH window of 1.5 to 1.6 to digest protein. Pepsin is an inactive precursor (pepsinogen) that converts to an active protein-digesting enzyme when stomach pH is sufficiently low. Large fluid intake during meals reduces pepsinogen availability. The body produces mucus to protect the vocal cords from pepsin-related damage. Pepsin can travel upward into the esophagus and throat with stomach acid. Pepsin activation requires any acid with a sufficiently low pH, not hydrochloric acid specifically. Pepsin is supposed to be active only in the stomach, where stomach acid activates it to break down food. Undigested protein in the intestinal tract undergoes putrefaction, creating toxic byproducts, gas, and inflammation. Antacids, alkaline water, or baking soda that raise stomach pH inactivate pepsin. When active pepsin is present in refluxed contents, it digests the esophageal lining itself because the esophageal lining is protein. Removing the protective mucus layer can lead to vocal cord damage and voice symptoms.