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Review · Nutrients · 2020Conflicts declared

Coffee, its compounds and the gut-brain axis

Iriondo-DeHond A, Uranga JA, Del Castillo MD, Abalo R · Free full text

What it found

Coffee and its components have been studied for effects on the gut lining, gut movement and the gut-brain connection, but much remains unknown.

Evidence comes from lab tests, animals and some studies in people.

What they found

Studies in people

Cancer risk and coffee

In 2016, after looking at more than 1000 studies, 23 scientists from 10 countries concluded that the scientific literature does not show a link between coffee drinking and cancer. Coffee was moved out of the possibly carcinogenic group.

Gut movement in people

In people, coffee was found to stimulate colonic motor activity. In one study with 12 healthy volunteers, caffeinated coffee increased colonic motor activity by 60% compared with water and 23% compared with decaffeinated coffee.

Postoperative ileus trials

Four randomised controlled trials with 341 patients found that coffee after surgery reduced the time to first bowel movement, first flatus and first defecation. It did not significantly increase complications or shorten hospital stay.

Animal and lab studies

Gut lining effects

Lab tests on gut cells show coffee and its compounds can have antioxidant, anti-inflammatory and antiproliferative effects on the gut lining. Some compounds also affect tight junction proteins that control gut permeability.

Animal cancer studies

In rodents, coffee decreased spontaneous tumours in some cases and protected against carcinogen effects in the colon. Caffeine and other compounds reduced preneoplastic lesions in rats.

Studies in people and animals

Gut bacteria changes

Coffee drinking, even 3 cups a day, changed gut bacteria in animals and people. Amounts of E. coli, Enterococcus, Clostridium and Bacteroides went down, while Lactobacillus and Bifidobacterium went up.

What the authors conclude

“Further studies are needed to understand the mechanisms of action of certain health-promoting properties of coffee on the gastrointestinal tract and to transfer this knowledge to the industry to develop functional foods to improve the gastrointestinal and brain-gut axis health.”
Iriondo-DeHond A, Uranga JA, Del Castillo MD, Abalo R, 2020

Also in their conclusions

  • They say that further studies are needed to understand the mechanisms of action of certain health-promoting properties of coffee on the gastrointestinal tract.
  • They suggest transferring this knowledge to the industry to develop functional foods to improve gastrointestinal and brain-gut axis health.

How it was done

The authors note that coffee has been studied a lot for its effects on the heart and brain, but much less is known about its effects on the gut and the connection between the gut and the brain.

The authors pulled together and described existing studies on coffee, its by-products and its components, looking at the gut lining, gut muscle and nerves, and the gut-brain axis. They included lab tests, animal studies and studies in people.

What it can’t tell you

  • Many findings come from lab tests or animals, so they cannot show what happens in people.
  • Studies that follow people over time can show a link but cannot prove that coffee causes an effect.
  • The exact compounds in coffee responsible for the effects are often not known.

The paper

Title
Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain-Gut Axis
Type
ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
Evidence
Studies in people · animals · lab
Summarised from
Full text
Cite
Iriondo-DeHond A, Uranga JA, Del Castillo MD, Abalo R (2020). Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain-Gut Axis. Nutrients. doi:10.3390/nu13010088Free full textPubMed 33383958DOI

Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error