From Lab to Life: Coffee Helps Our Gut

A great many people around the world drink coffee – me included.  “There are an estimated one billion coffee drinkers worldwide, or one person in every 12.   The world drinks 2.25 billion cups of coffee every day (I drink two or three of those);  Global coffee consumption runs at about a billion kgs. (2.2 billion pounds) of coffee beans  per year.”

Scientists have long researched the question, is coffee good or us, or bad for us?  Science Daily reports:

“New research suggests that both regular and decaffeinated coffee can alter the gut microbiome and may influence mood, stress, memory, and attention through the gut brain connection.   Scientists at APC Microbiome Ireland, a research center at University College Cork, investigated in detail how coffee may influence communication between the digestive system and the brain. **

“Researchers examined 31 regular coffee drinkers and 31 people who did not normally drink coffee. Participants completed psychological assessments and kept records of caffeine intake and diet. Researchers also collected stool and urine samples to track changes in gut microbes, metabolism, mood, and perceived stress.   For the study, ‘Coffee drinkers’ were set as those who regularly consume 3-5 cups of coffee a day, defined by the European Food Safety Authority (EFSA) as a safe and moderate amount for most people.

What Happened When Coffee Was Removed:   “The regular coffee drinkers first stopped consuming coffee for two weeks. During that period, participants repeatedly completed psychological assessments and provided stool and urine samples.

“When coffee drinkers stopped drinking coffee, researchers observed substantial shifts in their gut metabolite profiles compared with people who did not normally consume coffee. Metabolites are small molecules produced or altered during metabolism, including compounds created by gut microbes as they process food and other substances.

“Coffee was then reintroduced without participants knowing whether they were receiving caffeinated or decaffeinated coffee. Half received decaf, while the other half received caffeinated coffee.  After coffee returned to their diets, both groups reported lower perceived stress, depression and impulsivity scores. The findings suggest that some of coffee’s effects on mood may not depend entirely on caffeine.”

It sounds trite, but coffee is probably like a great many things we consume – good for us in moderation, bad in excess.

Serena Boscaini, Thomaz F. S. Bastiaanssen, Gerard M. Moloney, Federica Bergamo, Laila Zeraik, Caroline O’Leary, Aimone Ferri, Maha Irfan, Maaike van der Rhee, Thaïs I. F. Lindemann, Elizabeth Schneider, Arthi Chinna Meyyappan, Kirsten Berding Harold, Caitríona M. Long-Smith, Carina Carbia, Kenneth J. O’Riordan, José Fernando Rinaldi de Alvarenga, Nicole Tosi, Daniele Del Rio, Alice Rosi, Letizia Bresciani, Pedro Mena, Gerard Clarke, John F. Cryan. Habitual coffee intake shapes the gut microbiome and modifies host physiology and cognition. Nature Communications, 2026; 17 (1) DOI: 10.1038/s41467-026-71264-8