The primary digestive agent in the human stomach, hydrochloric acid, makes the stomach capable of dissolving metal. The body produces hydrochloric acid in the beginning stages of digestion.
Hydrochloric acid forms in the stomach when hydrogen and chloride combine. Hydrochloric acid's low pH of about two means that it can dissolve metal, so the stomach needs protection from the harsh acid. The stomach is coated with mucus, enabling food to be broken down by the acid without damaging the stomach lining. When the body works properly, it produces just the right amount of this gastric acid that it needs for digestion.