The gut-brain axis, a bidirectional signaling pathway between the gastrointestinal tract and the nervous system, plays a critical role in human health, including aspects of cognition. Key elements of this pathway are the tens of trillions of microbes that comprise the intestinal microbiota. A recent study found that taking a prebiotic supplement altered the gut microbiota, improving cognitive performance in older adults.

The randomized controlled study involved 36 older adult twin pairs. One twin within each pair consumed a prebiotic supplement containing inulin and fructo-oligosaccharides for 12 weeks, while the other twin took a placebo. Participants provided information about their daily dietary intake and underwent cognitive tests before and after the supplement intervention. Researchers analyzed the participants' gut microbial populations.

They found that the prebiotic supplement increased the number of Bifidobacterium – a type of bacteria commonly associated with gut health – in the participants' guts. Those who took the prebiotic performed better on cognitive tests than those who took the placebo. In particular, they performed better on a paired associate learning test, a memory assessment commonly used for the early detection of Alzheimer’s disease.

These findings suggest that prebiotics influence cognitive health via gut-brain axis interactions. Prebiotics are food components that support the maintenance of a healthy microbiota and create an environment conducive to its survival. Inulin and fructo-oligosaccharides are among the most abundant prebiotics in the human diet, present in apples, bananas, legumes, and dietary supplement forms. Their fermentation by gut microbiota produces short-chain fatty acids, including acetate, propionate, and butyrate.

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