Gut Microbiome Linked to Brain Aging, Study Explores the Connection - Video

What we eat may affect more than digestion. A new review suggests that diet can change gut bacteria and the substances they produce, which may influence inflammation, brain health and cognitive ageing.

Published in Frontiers in Molecular Neuroscience, the review examined evidence linking diet, the gut microbiota and the brain. This is important as dementia cases are expected to rise from more than 55 million globally in 2020 to nearly 139 million by 2050.

As people age, changes in the gut microbiota can affect the gut lining, immune system and communication between the gut and brain. Older adults who are frail or have several health problems often have lower gut bacterial diversity. Some bacteria that produce beneficial substances, such as butyrate, may also decline.

Diet can strongly influence these bacteria. Fibre-rich foods can support beneficial gut bacteria and increase short-chain fatty acids, including butyrate. These substances help maintain the gut lining and regulate inflammation. Foods rich in polyphenols, such as fruits, berries, cocoa and tea, may also encourage healthier changes in the gut microbiota.

On the other hand, diets high in saturated fats have been linked with less diverse gut bacteria, damage to the gut barrier and increased inflammation. Omega-3 fats may have more favourable effects on gut bacteria and inflammatory responses.

Gut bacteria also produce chemicals that can communicate with the brain. These include short-chain fatty acids, tryptophan-related compounds and modified bile acids. Experimental studies suggest these substances may influence brain inflammation, brain immune cells, blood-brain barrier function and connections between nerve cells.

However, researchers caution that much of the evidence comes from animal studies or observational research. Human studies have shown mixed results, and it is not yet clear whether changing the gut microbiota can directly prevent cognitive decline.

The review calls for longer and better-designed human studies to determine how diet and gut health may influence brain ageing and dementia risk.

REFERENCE: Jarfan, M. A., Vimaleswaran, K. S., & Wijeyesekera, A. (2026). Diet–gut microbiota–immune–brain interactions in aging: Mechanistic pathways and clinical implications. Frontiers in Molecular Neuroscience. 19. DOI: 10.3389/fnmol.2026.1847644