What causes heartburn in the stomach?

Heartburn is a common uncomfortable symptom, mainly characterized by a burning sensation behind the breastbone. This symptom is usually caused by stomach acid flowing back into the esophagus, a condition known as gastroesophageal reflux disease (GERD). 1. Excessive stomach acid production or delayed gastric emptying may lead to acid reflux. High-fat foods, spicy foods, coffee, and alcohol can stimulate acid secretion and worsen heartburn symptoms. 2. Dysfunction of the gastroesophageal sphincter may also allow stomach acid to enter the esophagus. Normally, this sphincter, located at the junction between the esophagus and stomach, prevents acid reflux. If its function is impaired, acid may flow backward and cause discomfort. 3. Irregular eating habits and overeating can increase pressure within the stomach, promoting acid reflux. Therefore, maintaining a reasonable and regular diet can help alleviate symptoms. If symptoms occur frequently or significantly affect quality of life, prompt medical attention is recommended.