Coffee can trigger heartburn, a common symptom of acid reflux where stomach acid moves back up into the esophagus. This burning sensation occurs because of chemical compounds naturally present in the coffee bean and the brewed beverage. While coffee is a daily ritual for many, its stimulating properties can interfere with the normal function of the digestive system for those who are sensitive.
How Coffee Triggers Heartburn
The primary mechanism relates to the Lower Esophageal Sphincter (LES), the muscle separating the stomach from the food pipe. Caffeine, the central nervous system stimulant, causes this muscle to relax. When the LES loosens, the barrier keeping stomach contents contained is compromised, allowing acidic fluids to splash back into the esophagus.
Beyond the physical relaxation of the LES, coffee consumption also stimulates the stomach to produce more hydrochloric acid. Coffee contains compounds, including chlorogenic acids and catechols, that signal the stomach to increase acid secretion. This surge in gastric acid compounds the problem, as there is now both a relaxed sphincter and an increased volume of acidic liquid ready to reflux.
The combined action of a relaxed LES and acid overproduction creates a digestive environment primed for discomfort, leading to the characteristic burning sensation of heartburn. For individuals prone to reflux, this dual action makes coffee a frequent trigger. One study suggested that LES dysfunction is a greater factor in coffee-induced heartburn than acid overproduction for susceptible people.
Coffee Characteristics That Increase Risk
The potential for coffee to cause heartburn is not uniform across all types of beans or roasts, as specific characteristics influence their chemical makeup. Generally, light-roast coffees carry a greater risk for sensitive individuals. Light roasts retain higher concentrations of chlorogenic acids, which are believed to be strong stimulants of stomach acid production.
The concentration of caffeine is also a factor, as lighter roasts typically contain more caffeine per bean than darker roasts. Since caffeine is a primary agent for relaxing the LES, a higher concentration translates to a greater chance of reflux. Additionally, brewed coffee has an average pH range of 4.5 to 6.0, and this natural acidity can irritate the digestive tract lining.
Dark-roast coffees, while still acidic, are exposed to higher temperatures and longer roasting times, which breaks down some of the chlorogenic acids. Furthermore, the roasting process creates a compound called N-methylpyridinium (NMP), which some research suggests may paradoxically reduce stomach acid secretion. However, the presence of various natural acids, regardless of the roast, means all coffee carries some potential for irritation.
Strategies for Reducing Coffee-Related Heartburn
Adjusting your coffee choice and consumption habits can allow you to enjoy the beverage without resulting heartburn. One effective strategy is switching to cold brew coffee. Cold brewing involves steeping grounds in cold water for an extended period, which extracts fewer acidic compounds and can result in a brew with up to 70% less acidity than its hot-brewed counterpart.
The specific preparation of your coffee can also help buffer its effect on your stomach. Adding milk or cream introduces an alkaline base that helps neutralize some of the coffee’s natural acidity. You can also look for low-acid coffee brands, which are often processed or blended specifically to minimize the presence of irritating acids.
Changing when and how you drink coffee is equally important for symptom management. Consuming coffee alongside a meal, rather than on an empty stomach, allows food to act as a buffer against the gastric acid. Reducing your total volume of coffee intake and sipping your cup slowly throughout the morning can also lessen the sudden impact on your digestive system.