Most habitual coffee drinkers will be familiar with the stimulant effects of the drink, but apparently, coffee is much more than that and as far as these other health effects go, it’s all good news.
Regular coffee consumption, according to a recent study published in Nature Communications noted, influences the gut-brain axis (GBA), a bidirectional communication network that connects the digestive system with brain activity. The results reveal a highly complex interaction that goes beyond caffeine.
“Public interest in gut health has increased tremendously,” said John Cryan, a coauthor of the study and the principal investigator at ACP Microbiome Ireland, the research centre at the University of Cork, which undertook this study. “The relationship between digestive and mental health is also increasingly well understood, but the mechanisms that explain the effects of coffee on this gut-brain axis remain unclear,” he noted.
Scientists at APC Microbiome Ireland compared 31 healthy adults who regularly consume coffee with 31 non-coffee drinkers. The European Food Safety Authority defines a “regular” coffee drinker as one who knocks back between three and five cups a day, a safe and moderate intake for most people.
The researchers also analysed the result of giving up coffee for a fortnight before resuming intake – either with caffeinated or decaffeinated coffee. This period of abstinence made it possible to distinguish the effects of caffeine from the other compounds present in coffee.
“Coffee is more than caffeine,” noted Cryan in a press release, “it is a complex dietary factor that interacts with our gut microbiota, our metabolism and even our emotional wellbeing. Our findings suggest that coffee, whether caffeinated or decaffeinated, can influence health in distinct but complementary ways.”
The Surprising Effects of Coffee
One of the most relevant findings was that coffee consumption modifies the composition of the intestinal microbiota. In regular drinkers, changes were detected in the abundance of certain bacteria, such as Eggerthella species and Cryptobacterium curtum, suggesting that coffee favours specific microorganisms. The former are believed to contribute to gastric and intestinal acid secretion, while the latter are involved in bile acid synthesis. Both bacteria, according to the scientists at APC Microbiome Ireland, contribute to the elimination of harmful intestinal bacteria, preventing infections.
On the behavioural level, the study found that regular coffee drinkers showed higher levels of impulsivity and emotional reactivity compared to non-consumers. However, when coffee intake was suspended for two weeks, these traits decreased (along with some symptoms associated with regular consumption, such as fatigue or headache in the initial days of abstinence).
The reintroduction of coffee produced different effects depending on the type. Both caffeinated and decaffeinated varieties reduced perceived stress and certain indicators of depression. Specifically, caffeinated coffee was associated with improvement in anxiety and some aspects of attention, while decaffeinated coffee demonstrated benefits in memory, sleep quality and physical activity. This indicates that many effects of coffee do not depend exclusively on caffeine, but on other bioactive compounds, such as polyphenols.