Coffee altered gut microbes and metabolites linked to mood and cognition.

Some microbiome changes occurred with both caffeinated and decaf coffee.

Caffeine aided alertness, while decaf showed possible memory benefits.

Coffee is often treated as a simple delivery system for caffeine. We drink it to feel more awake, improve concentration, and overcome the mental drag of an early morning or afternoon slump.

But coffee contains hundreds of biologically active compounds, including polyphenols, alkaloids, and fiber-like substances that interact with the digestive system. A new study suggests that coffee may also influence mental functioning by changing the gut microbiome and the chemical signals passing between the digestive tract and the brain.

While the findings do not establish that coffee can be used to treat depression, anxiety, or cognitive impairment, they do suggest that the psychological effects of coffee are more complicated than the temporary stimulation produced by caffeine.

The Microbiota-Gut-Brain Axis

The digestive tract and brain communicate continuously through what scientists call the microbiota-gut-brain axis.

This bidirectional network includes the vagus nerve, immune system, hormones, microbial metabolites, and neurotransmitter-related chemicals. Gut bacteria help process components of our diet and produce substances that may influence inflammation, stress responses, mood, and cognition.

That does not mean that individual bacteria determine how we feel or think. The microbiome is a complex ecosystem shaped by diet, medication, sleep, stress, genetics, and many other influences. But accumulating evidence suggests that food and beverages can alter microbial activity in ways that may eventually affect the brain.

Coffee is a particularly interesting candidate because it........

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