Looking for your morning coffee?
A new study suggests that regular coffee consumption reshapes the human gut microbiome and may selectively influence memory, impulsivity, and inflammation levels in the body.
The 2026 study, published in Nature Communications, tracked physiological, microbial, and cognitive changes in habitual coffee drinkers during periods of consumption, a two-week abstinence phase, and reintroduction, highlighting coffee’s effects on both the gut and the brain.
Researchers found that while habitual coffee intake does not significantly alter overall gut microbial diversity, it drives targeted, strain-specific changes.
The study identified an increased presence of certain bacterial species among coffee drinkers, including Cryptobacterium curtum and strains of Eggerthella.
Researchers observed that after two weeks of complete coffee abstinence, populations of these bacteria declined. However, upon reintroduction of coffee—whether caffeinated or decaffeinated—these bacterial strains were rapidly restored.
This suggests that non-caffeine compounds such as polyphenols and dietary fibers may act as prebiotics that support specific gut microbes.
Fecal metabolomic analyses further showed that regular coffee drinkers had lower baseline levels of key neuroactive metabolites linked to cognitive function and gut barrier integrity.
The study also identified distinct behavioral patterns between coffee consumers and non-consumers, as well as differences between caffeinated and decaffeinated coffee intake.
Habitual coffee drinkers showed higher levels of impulsivity and emotional reactivity compared to non-drinkers.
After two weeks of coffee abstinence, participants who resumed coffee consumption experienced reduced trait anxiety, lower psychological distress, improved information processing speed, and fewer withdrawal symptoms.
“Attention and vigilance increased while impulsivity and emotional reactivity decreased upon withdrawal. Behaviourally, returning to caffeinated or decaffeinated coffee decreased perceived stress and self-reported symptoms of depression,” researchers said.
For decaffeinated coffee drinkers, the study found distinct neurocognitive benefits, including improved memory and learning performance, as well as better sleep quality.
“Coffee intake is consistently associated with a reduced risk of Parkinson’s disease in a dose-dependent manner, across multiple human cohorts,” the researchers added.
COFFEE’S EFFECT ON BLOOD PRESSURE
The study also found that regular coffee consumption was associated with favorable inflammatory markers. When participants abstained from coffee for two weeks, inflammatory markers increased but returned to lower levels upon reintroduction.
Additionally, the two-week coffee abstinence period led to a statistically significant reduction in both systolic and diastolic blood pressure among regular drinkers.
“During the intervention phase, CD participants showed a significant decrease in systolic and diastolic blood pressure after 2 weeks of coffee abstinence (Supplementary Data 5). BMI remained unchanged in both caffeinated and decaffeinated groups after the washout and coffee intervention, while those consuming caffeinated coffee had a decrease in systolic blood pressure compared with the decaffeinated group,” the researchers said.
Interestingly, baseline stress-related measures remained largely unchanged. Habitual coffee intake, withdrawal, and reintroduction showed no significant effects on salivary cortisol levels or cortisol reactivity under acute stress tests.
Overall, the researchers concluded that the findings highlight previously underrecognized effects of coffee on the gut-brain axis, with potential implications for microbial activity, cognitive function, and inflammation.
