In recent years, there has been growing interest in the study of gut microbiota and its relationship with multiple diseases, ranging from digestive problems to cognitive disorders. The composition of this microbiota is determined by external and internal factors—such as psychosocial or environmental aspects—and is closely linked to diet, since the foods we consume provide nutrients and establish the conditions of the intestinal environment. The gut–brain axis describes how the intestinal microbial flora and the compounds it produces generate and transmit signals that act on our nervous system and regulate multiple processes in the body. This systematic review aims to explore the impact of the Mediterranean Diet on the composition of the gut microbiota and to analyze its effects on various cognitive conditions, such as memory. Based on a review of 20 articles, we examined how the Mediterranean Diet—characterized by high consumption of olive oil, fruits, vegetables, legumes, and fish—modulates the microbiota in the human gut. The results showed that adherence to the Mediterranean Diet is associated with an increase in beneficial bacteria such as Faecalibacterium prausnitzii and Bifidobacterium , and with greater production of short-chain fatty acids (SCFAs), especially butyrate. The Mediterranean Diet appears to exert a neuroprotective role in disorders such as mild cognitive impairment, schizophrenia, Parkinson’s disease, and metabolic diseases. This protective function, derived from changes in the gut microbiota, leads to improvements in cognitive function. Overall, the findings underscore the direct relationship between nutrition and mental health and reinforce the value of the Mediterranean Diet as a preventive strategy and a modulator of cognition through the gut–brain axis, promoting brain health across the lifespan. Systematic review registration https://www.crd.york.ac.uk/prospero/ , identifier CRD420251273990.
Ibeas-Pérez et al. (2026) studied this question.