Caffeinated and decaf coffee affect mood and memory differently, study finds
New research from University College Cork suggests both caffeinated and decaffeinated coffee change the gut microbiome and influence mood, with some distinct effects on cognition.
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Researchers from University College Cork in Ireland have found that drinking coffee—whether regular or decaffeinated—can alter the gut microbiome and influence mood, stress, memory and attention in different ways.
For the study, 31 people who typically drank three to five cups of coffee per day and 31 non-coffee drinkers were recruited. Coffee drinkers first gave up coffee for two weeks, during which they underwent psychological assessments and various analyses. Coffee was then reintroduced without participants knowing which type they received: half got decaffeinated coffee and half got caffeinated coffee.
When regular coffee drinkers stopped drinking coffee, researchers observed substantial changes in the profiles of metabolites in the gut compared with people who do not usually consume coffee. Metabolites are small molecules produced or modified during metabolism.
Professor John Cryan, who led the research, said coffee is "more than caffeine" and described it as a complex dietary factor that interacts with gut microbes. "Coffee can change what microbes do collectively," he explained.
After coffee returned to their diets, both groups reported lower scores for stress, depression and impulsivity. The research suggests that both regular and decaffeinated coffee can modify the gut microbiome and influence mood, stress, memory and attention through the gut-brain connection.
However, improvements in learning and memory were observed only in participants who drank decaffeinated coffee. This suggests that substances other than caffeine may contribute to some of coffee's effects on cognition. Caffeinated coffee, on the other hand, was associated with reduced anxiety as well as better vigilance and attention.
Cryan concluded that "coffee, with or without caffeine, can influence health in different but complementary ways."
The study included 62 people, a small number, and measured associations and short-term changes. It was funded by the Institute for Scientific Information on Coffee, an organisation linked to the coffee industry. The results do not mean that more coffee is always better: people sensitive to caffeine, pregnant women and those with heart conditions should consult a doctor.
