Could coffee be doing more than simply waking you up?

A fascinating study has been looking at what happens to the gut and brain when regular coffee drinkers stop drinking coffee for two weeks — and then start again.

Researchers found measurable changes in gut microbes and metabolites, and both caffeinated and decaf coffee were associated with lower perceived stress, depression and impulsivity scores during the intervention.

That last bit is especially interesting - it suggests that some of coffee’s effects may not be all about caffeine.


What else is coffee doing inside the body?

Researchers from University College Cork and APC Microbiome Ireland studied 62 healthy participants: 31 regular coffee drinkers and 31 people who did not normally drink coffee.

The regular coffee drinkers were asked to stop drinking coffee for two weeks and researchers tracked changes in things including gut microbes, metabolites, mood, stress and cognitive performance.
After the two-week break, coffee was reintroduced. Some participants received caffeinated coffee and others received decaffeinated coffee without knowing which they were drinking.


What happened when coffee came back?

When coffee was reintroduced, researchers found changes in the gut microbiome and in the metabolites produced by it. Furthermore, during the intervention participants drinking both caffeinated and decaffeinated coffee showed lower perceived stress, depression and impulsivity scores.

One of the most intriguing findings was that caffeinated and decaffeinated coffee did not appear to affect participants in the same way. Improved learning and memory were observed only among participants drinking decaffeinated coffee, while caffeinated coffee was associated with reduced feelings of anxiety, reduced risk of inflammation, and improved vigilance and attention.

Corresponding author of the study, Professor John Cryan, commented: "Our findings reveal the microbiome and neurological responses to coffee, as well as their potential long-term benefits for a healthier microbiome. Coffee may modify what microbes do collectively, and what metabolites they use. As the public continues to think about dietary changes for the right digestive balance, coffee has the potential to also be harnessed as a further intervention as part of a healthy balanced diet."