The pain on the left side of the stomach in the elderly may be caused by physiological factors such as diet, or it may be caused by pathological factors such as digestive system diseases and cardiovascular system diseases. 1. Physiological factors: when the elderly eat too much cold and spicy food such as chili peppers or fried food that is difficult to digest, it will stimulate the gastrointestinal tract and lead to pain on the left side of the stomach. Certain bad eating habits, such as eating too fast, overeating, etc., can also cause pain on the left side of the stomach. 2. Diseases of digestive system: such as peptic ulcer, dyspepsia, chronic gastritis, pancreatitis, gastrointestinal cancer, pancreatic cancer and other diseases, which can also lead to the symptoms of pain on the left side of the stomach. At this time, patients may also have bloating, acid reflux, belching, nausea, vomiting and other symptoms. 3. Diseases of cardiovascular system: Since the heart is located in the upper left side of the stomach, when the patient has coronary heart disease, myocardial infarction, angina pectoris and other diseases, it may also lead to pain in the left side of the stomach. When the elderly long-term or recurrent pain in the left side of the stomach, it is recommended to consult a doctor in a timely manner to identify the cause of the disease and carry out targeted treatment to avoid delaying the condition.