The habit of repeatedly reheating coffee in a microwave can negatively affect digestive health, experts have warned.
Britain's Daily Mail recently reported, citing gastroenterologists, that patients with acid reflux or irritable bowel conditions frequently experience worsening symptoms after consuming reheated coffee.
Freshly brewed coffee is rich in antioxidant compounds, including chlorogenic acid, a substance known to have positive effects on cardiovascular health and in slowing aging. Heating coffee once does not cause significant changes to this compound's composition. However, the situation changes as the number of reheating cycles increases. Through a breakdown process, the acid component is converted into caffeic acid and quinic acid, both of which are more irritating to the stomach lining than the original compound. The uneven heat distribution characteristic of microwaves can accelerate this breakdown reaction, causing bitterness and sourness to stand out and sweetness to disappear with repeated heating.
When it comes to acid reflux, the role of caffeine cannot be overlooked. Caffeine lowers the pressure of the lower esophageal sphincter, creating conditions that make it easier for stomach contents to flow back into the esophagus. When coffee with increased acidity from reheating is added to this, stomach acid secretion is further stimulated, raising the likelihood of heartburn and a burning sensation in the chest. People with sensitive stomach linings are particularly vulnerable to the combined effect of these two factors.
As a preventive measure, experts recommend a simple approach: brew only the amount to be consumed, and if any is left over, transfer it immediately to a sealed insulated container. Caution is also needed because repeatedly heating coffee in containers with fine pores, such as ceramic or ordinary mugs, may cause foreign substances to leach from the container itself. If discomfort has already occurred, diluting stomach acid with water or absorbing acid with plain carbohydrate foods can help relieve symptoms. If there is no improvement, using antacids or consulting a doctor is advisable.
