How Coffee Affects The Microbiome

A literature review published in Nutrients explored how drinking coffee affects the gut microbiome—the community of trillions of bacteria living in the digestive system. These bacteria play a major role in digestion, immune health, and even mood.

The review looked at dozens of studies on both humans and animals to understand how coffee changes the types and amounts of gut bacteria. Most research showed that drinking a moderate amount of coffee (less than four cups per day) can increase helpful bacteria like Bifidobacterium and reduce harmful ones like Enterobacteria. It also appears to boost the diversity of gut microbes, which is generally linked to better health. A more diverse gut microbiome means more types of bacteria are present, which helps the body function more effectively.

Coffee has many components outside of caffeine. Other natural compounds in coffee, such as chlorogenic acid and polyphenols, also affect gut bacteria. Some of these compounds act like prebiotics, which are substances that feed good bacteria. However, in some lab and animal studies, both regular and decaf coffee reduced the total number of bacteria, showing that coffee might also have bacteria-killing effects in certain conditions.

The review also explains that coffee might help with digestion and bowel movements through its effects on gut bacteria. Still, drinking too much coffee (more than five cups a day) could cause problems like acid reflux or worsen certain gut diseases like Crohn’s disease. The study acknowledges that existing literature on coffee’s effect on the gut is often conflicting.