Influence of dietary components on the gut microbiota of middle-aged adults: the gut-Mediterranean connection.

BACKGROUND

A plant-focused, healthy dietary pattern, such as the Mediterranean diet enriched with dietary fiber, polyphenols, and polyunsaturated fats, is well known to positively influence the gut microbiota. Conversely, a processed diet high in saturated fats and sugars negatively impacts gut diversity, potentially leading to weight gain, insulin resistance, and chronic, low-grade inflammation. Despite this understanding, the mechanisms by which the Mediterranean diet impacts the gut microbiota and its associated health benefits remain unclear.

METHODS

This retrospective, observational study explored the relationships between Mediterranean dietary components-vegetables, fruits and nuts, legumes, whole grains, fish, meat, dairy, alcohol, saturated and unsaturated fats-and the gut microbiota in middle-aged adults enrolled in Alberta's Tomorrow Project, Canada. Diet was recorded using the Canadian Dietary History Questionnaire (CDHQ-II) and participants were classified into four quartiles based on a modified Mediterranean Diet Score. Blood and fecal samples were collected for metabolomics and 16S rRNA sequencing, respectively.

RESULTS

Findings revealed that higher adherence to the Mediterranean diet was associated with increased alpha diversity and a greater abundance of beneficial fiber-degrading bacteria, including Prevotella, Parabacteroides, Clostridium XIVb, Coprobacter, and Turicibacter. Furthermore, participants who consumed more Mediterranean diet components exhibited higher concentrations of serum microbial metabolites including p-hydroxy hippuric acid and indole-acetaldehyde.

CONCLUSIONS

Results demonstrate a pivotal role of the gut microbiota, via its metabolites in harnessing the health benefits of the Mediterranean diet, highlighting its potential to promote metabolic health and prevent chronic disease.