Drinking coffee every day may provide benefits beyond a morning energy boost, with new research suggesting that both regular and decaffeinated coffee could influence emotional well-being, memory and the bacteria living in the digestive system.

Researchers at University College Cork in Ireland examined how coffee consumption affects the relationship between the gut and the brain, finding that participants who resumed drinking coffee reported improvements in several measures of mood, including reduced stress, depression and impulsivity.

The study also identified differences between caffeinated and decaffeinated coffee, suggesting that some potential benefits may come from compounds other than caffeine.

“Coffee is more than just caffeine. It’s a complex dietary factor that interacts with our gut microbes, our metabolism and even our emotional wellbeing,” said John Cryan, the study’s corresponding author.

Cryan explained that the two varieties of coffee may affect the body “in distinct but complementary ways.”

The research involved 62 healthy adults, divided equally between habitual coffee drinkers and individuals who generally avoided the beverage. Those accustomed to drinking coffee, typically consuming three to five cups daily, were instructed to abstain for two weeks before beginning a three-week period of drinking either caffeinated or decaffeinated coffee.

Throughout the experiment, researchers assessed participants’ emotional states and performance on cognitive examinations. They also collected urine and stool samples to investigate metabolic activity and changes in intestinal bacteria.

Following the return of coffee to their routines, participants in both coffee groups reported lower levels of stress, depressive symptoms and impulsive behavior compared with their earlier assessments.

Those consuming caffeinated coffee experienced an additional decline in reported anxiety and performed better on a test measuring attention. Participants assigned decaffeinated coffee, meanwhile, demonstrated improvement in episodic memory, the ability to remember events and previously encountered information.

Researchers also observed changes in the composition of gut bacteria following coffee consumption. However, the findings did not establish that the microbial changes were responsible for the improvements recorded in mood or mental performance.

“Public interest in gut health has risen hugely,” Cryan said. “The relationship between digestive and mental health is also increasingly being better understood, but the mechanisms behind coffee’s effects on this gut-brain axis have remained unclear.”

The findings add to growing scientific interest in the gut-brain connection, which examines how microorganisms in the digestive tract may interact with the nervous system and influence psychological and cognitive functioning.

Nevertheless, outside specialists warned that the relatively small number of participants makes it difficult to draw firm conclusions about coffee’s long-term health effects.

Rebecca Steele, a New York-based clinical psychologist who was not involved in the research, said improvements observed during laboratory testing do not necessarily mean individuals will experience comparable benefits in everyday activities.

“How I perform with a paper-and-pen test might not be the same way that I perform when I’m out in the real world,” she said.

Steele also noted that researchers must account for other factors that could influence the results, including changes in sleep patterns, exercise habits and participants becoming more familiar with cognitive tests after completing them repeatedly.

Although caffeine has long been associated with temporary improvements in alertness and concentration, evidence concerning its lasting effects on memory and broader cognitive health remains uncertain.

The psychologist also cautioned against interpreting lower depression scores as proof that coffee can prevent or treat psychiatric conditions.

“Changes in self-reported stress and depression scores should not be confused with evidence that coffee treats clinical depression,” she said.

The researchers said larger and longer studies will be necessary to determine whether the observed changes persist over time and to establish which ingredients in coffee may be responsible for its possible effects on mood, memory and intestinal health.