Coffee is one of the world's most popular beverages, offering numerous health benefits, including increased alertness, improved athletic performance, and enhanced brain function. While many individuals can safely consume coffee on an empty stomach, others may experience digestive issues and other symptoms.

As an acidic beverage, coffee can stimulate the stomach to produce more acid when consumed on an empty stomach. This excess stomach acid can irritate the stomach lining and cause heartburn. Caffeine also relaxes the lower esophageal sphincter, a muscle ring between the esophagus (food pipe) and the stomach, which can worsen reflux. Individuals with a history of heartburn, gastroesophageal reflux disease (GERD), or irritable bowel syndrome (IBS) should exercise caution when drinking coffee on an empty stomach and consider having a light snack beforehand.

Caffeine, a natural stimulant, can induce feelings of anxiety or restlessness. Drinking coffee on an empty stomach may lead to faster caffeine absorption. Caffeine can also cause headaches and increase blood pressure.

Some individuals may experience digestive problems when consuming coffee on an empty stomach. Symptoms include bloating, cramps, nausea, heartburn, or diarrhea. Some may also feel a stronger urge for bowel movements. People with irritable bowel syndrome (IBS) might notice gastrointestinal discomfort or diarrhea after drinking coffee.

Furthermore, drinking coffee on an empty stomach can trigger hormonal changes in the body. The caffeine in coffee stimulates the release of cortisol, often called the stress hormone. Cortisol regulates metabolism and blood pressure. Elevated cortisol levels can increase the risk of anxiety, irritability, and sleep problems.

This information is provided by Nutritionist Pham Hong Ngoc from the Vietnam Institute of Applied Medicine.