Coffee is the most consumed psychoactive drink in the world, but science is just beginning to understand the extent to which it shapes the human organism.
A new study, conducted by researchers at University College Cork (UCC), in Ireland, reveals that stopping drinking coffee, even if only for 14 daystriggers significant changes in gut bacteria, blood pressure, inflammation and cognitive performance.
No, published in April in Nature Communications, a team led by neuroscientist John F. Cryan recruited 62 healthy adults, of whom 31 were daily coffee drinkers and 31 non-drinkers, and tracked them across a range of biological and psychological indicators, including mood, memory, stress hormonesblood composition and gut microbiome diversity.
Coffee consumers completely abstainedfor two weeks, of drinking the drink.
Afterwards, half returned to caffeinated coffee and the other half started drinking decaffeinatedallowing researchers to isolate the role of caffeine from the hundreds of other compounds present in a typical cup.
From the beginning, the gut microbiomes of coffee drinkers and non-coffee drinkers showed notable differences. Certain bacterial species thrived in coffee drinkers, while others flourished in those who avoided it.
After two weeks of abstinence, microbial changes relevant: as bacteria that previously thrived with coffee they disappeared, while a microbial molecule that was suppressed — associated with strengthening the intestinal wall and reducing inflammation — recovered its previous levels.
As blood tests told a similar story. Blood pressure dropped noticeably during the abstinence period. Markers of inflammation, which were found to be lower in habitual coffee drinkers at the start of the study, rose again after just two weeks without the drink.
One of the most revealing conclusions of the study is that caffeine, by itselfcannot explain the Vast biological effects of coffee.
When participants reintroduced decaffeinated coffee, the majority of microbial changes were found to be identical to those in caffeinated coffee — suggesting that plant acids, roasting byproducts, and polyphenols present in the bean itself are biological agents in their own right.
Not cognitive plan, coffee consumers initially presented higher scores on impulsivity and emotional reactivity, having obtained worst results on memory tests than non-consumers.
After two weeks without coffee, these values normalized. Curiously, only participants who returned to decaf coffee registered measurable gains on a memory task verbal.
However, caffeinated coffee demonstrated a clearer ability to reduce markers of inflammation upon reintroduction, while decaffeinated coffee slightly increased them — indicating that caffeine and the remaining compounds in coffee act on the immune system in opposite directions.
Although the sample involved, of just 62 people, prevents a broader generalization from being made, the new study clearly establishes that coffee It’s much more than a simple morning pick-me-up — positioning it as a dietary tool with real meaningcapable of modulating the gut-brain axis and, with it, long-term cognitive and immune health.
