Study Explores How the Mediterranean Diet May Protect Brain Health Through the Gut

The Mediterranean diet may support brain health through changes in the gut microbiome, but direct human evidence proving this link remains limited, according to a narrative review published in Nutrients.

The Mediterranean diet is rich in fruits, vegetables, whole grains, legumes, nuts and seeds, with moderate amounts of fish, poultry, fermented dairy and olive oil. Studies have linked greater adherence to the diet with slower cognitive decline and a lower risk of dementia, particularly Alzheimer’s disease.

Researchers examined whether changes in the gut microbiome could help explain these benefits. The gut microbiome contains trillions of microorganisms that communicate with the brain through the gut-brain axis using microbial metabolites, immune signals, hormones and nerve pathways.

A Mediterranean-style diet provides fibre and other carbohydrates that gut microbes can ferment into short-chain fatty acids (SCFAs), including butyrate. These compounds may support the intestinal barrier, regulate immune activity and reduce inflammation. Other microbial products, including secondary bile acids and indoles, may also influence intestinal and immune function.

The diet’s unsaturated fats, omega-3 fatty acids and plant compounds may further affect microbial composition, inflammation and oxidative stress. Fermented foods may also influence the microbiome, although their effects can vary between products and bacterial strains.

Researchers proposed that these changes could help maintain the intestinal and blood-brain barriers, reduce systemic inflammation and limit excessive activation of microglia, immune cells involved in brain inflammation. These pathways may also help protect mitochondria and neurons from oxidative stress.

However, most evidence currently comes from separate studies linking the Mediterranean diet, microbiome changes or brain health. Few human studies directly demonstrate that microbiome changes caused by the diet lead to better neurological outcomes.

Researchers concluded that the Mediterranean diet and gut microbiome have a biologically plausible connection to brain health, but long-term intervention studies are needed to establish whether microbiome changes actually mediate protection against Alzheimer’s or Parkinson’s disease.

REFERENCE: Kamalakar, K., Akerele, C., Lafont, E., et al. (2026). Gut Microbiome-Mediated Neuroprotective Effect of the Mediterranean Diet: A Narrative Review of Cognitive Aging, Alzheimer’s Disease, and Parkinson’s Disease. Nutrients. DOI: 10.3390/nu18193146