Beneficial Effect of Mediterranean (MD) Components on the Structure and Functions of Gut Microbiome and Metabolome in Subjects With Low Adherence to MD

The composition and functions of the microbiome impact human metabolism and health status. Dietary habits play a fundamental role in shaping the structure of the gut microbiome, modulating the interactions between the gut microbiome and the human host. Western dietary patterns, including a high consumption of red and processed meat, refined grains and sugars, and dairy products, have been associated with a high incidence of chronic diseases. It is widely recognised that there is a higher consumption of plant-based foods in Mediterranean countries than in other Western countries. The Mediterranean diet involves a high intake of fruits, vegetables, legumes, nuts, minimally processed cereals, moderate consumption of fish and a low consumption of saturated fats, meat and dairy products with regular intake of extra virgin olive oil. The Mediterranean diet (MD) reduces the incidence of cardiovascular, metabolic and neurodegenerative diseases. Interesting results emerged from the evaluation of the microbiome-metabolome interaction, which shows that individuals with the highest adherence to the Mediterranean diet had much higher levels of short-chain fatty acids (SCFAs) and increased levels of the beneficial fiber-degrading bacteria compared to subjects with low adherence to the Mediterranean diet. The study of the effect on the microbiota of specific foods with anti-inflammatory/antioxidant properties is interesting and of potential clinical impact.

Extent and evaluation of current knowledge directly linked to the scientific question(s) to be answered by the clinical study: The Mediterranean diet exerts beneficial effects on health status. Evidence has shown that the two mechanisms by which consuming a Mediterranean diet patterns may contribute to improved metabolic health are modulation of the gastrointestinal microbiota and reduction of metabolic endotoxemia.

Outcomes (efficacy, safety) of completed and number of ongoing clinical studies utilising the same intervention in the same indication: The available evidence focuses on a broader concept of food and nutrient consumption, which do not consider that the beneficial effect of the Mediterranean Diet might due to the synergic and interactive combinations of nutrients, rather than to isolated nutrients.

Level of evidence related to the mechanism of action of the intervention in the planned clinical study population: Although several studies have shown the effects of Mediterranean dietary pattern on health status by modulating intestinal microbiota, a comprehensive evaluation of the synergetic and combined effects of selected dietary pattern on metabolic patterns as well as on the intestinal microbiota and its metabolites is still not totally clarified and recognized.

Objective(s) of the clinical study: