Scientists Discover Something Interesting About Coffee

New research is out about coffee.

And it's good news.
Thank goodness.

A 2026 study from University College Cork examined coffee and its relationship with the gut and the brain.

Researchers found that drinking coffee was associated with changes in gut bacteria, microbial metabolites, mood, stress, and cognitive function.

By analyzing stool and urine samples of participants, researchers could examine what happened to the participants' gut microbiome and metabolism when coffee was removed - and what happened when it was introduced again.

After coffee was reintroduced, participants showed lower perceived stress, depressive symptoms, and impulsivity, and these findings were seen with both caffeinated and decaffeinated coffee. But one of the most intriguing findings was that caffeinated and decaffeinated coffee appeared to affect participants differently.

Caffeinated coffee was associated with less anxiety and psychological distress, along with improved attention and vigilance. Decaf was associated with improvements in certain measures of learning and memory.

Researchers also observed changes in markers related to inflammation and immune function. Regular coffee consumption was associated with lower levels of C-reactive protein (CRP), an inflammatory marker, and higher levels of IL-10, an anti-inflammatory cytokine.

What was particularly interesting was how responsive the gut was. When the regular coffee drinkers stopped drinking coffee, their metabolite profiles changed significantly. When researchers added coffee back, they observed changes in specific microbial strains. These changes occurred with both caffeinated and decaffeinated coffee. 

Bacteria that increased with coffee consumption included Eggerthella species and Cryptobacterium curtum.  'Eggertella sp' is thought to contribute to acid secretion in the stomach and intestines, while 'Cryptobacterium curtum' may participate in bile acid production.

Researchers also observed higher levels of Firmicutes bacteria which previous research has associated with positive emotions in females. Interestingly, however, that research in women found that higher levels of these bacteria were associated with lower levels of positive emotions. Which certainly adds a layer of confusion that warrants further investigation. 

The biggest takeaway is that coffee may be much more than caffeine. The compounds in coffee appear to interact with our gut microbes, and those microbes may influence processes throughout the body, including in our brain.

Fascinating!

Who knew your gut microbes were coffee drinkers, too?