Stomach acid can digest and corrode most substances, and over or under secretion of stomach acid will have adverse effects on the human body. The main component of human stomach acid is hydrochloric acid, with strong acidity, ph between 1.8-3.5, can digest and corrode most of the substances, including food, metal, viruses, etc., and it will also damage its own organs, such as gastric acid reflux esophagus, will damage the esophagus, so that the esophagus is eroded by the emergence of ulceration, will also be accompanied by a feeling of burning behind the sternum; too much acid reflux will also lead to inflammation of the pancreatic door and then ulcerated, resulting in closure of the incomplete! And so on. Excessive secretion of gastric acid will affect the stomach and duodenum, leading to gastric ulcer or duodenal ulcer; if the secretion is insufficient, it will cause indigestion, bloating, diarrhea and other gastrointestinal symptoms.