Monounsaturated Fatty Acid-Rich Foods and Gut Microbiota Composition: A Systematic Review of In Vivo Studies and...

Monounsaturated fatty acids (MUFAs) have been recognized for their beneficial effects on cardiometabolic health. However, their influence on gut microbiota composition remains less defined.

To evaluate the effects of MUFA-rich foods on gut microbiota composition, diversity, and related metabolic outcomes in both clinical and experimental studies.

A comprehensive search was conducted in PubMed, Scopus, and Web of Science databases.

The review process involved a comprehensive search for studies evaluating the impact of MUFA-rich foods (extra-virgin olive oil, avocado, nuts) on the gut microbiota in animal models or human participants. Risk of bias was assessed using the Systematic Review Center for Laboratory Animal Experimentation Risk of Bias and Risk of Bias-2 tools. A qualitative synthesis of microbiota-related and secondary metabolic outcomes was conducted.

Thirty-seven studies were included in this review. Interventions enriched in MUFAs, particularly those using nuts and olive oil, demonstrated selective modulation of gut microbiota composition and diversity. Nut-based interventions were more consistently associated with increases in short-chain fatty acid (SCFA)-producing genera, including Faecalibacterium and Roseburia, as well as the Ruminococcaceae family, along with improvements in lipid profile, body weight, and fat mass. Olive oil-based interventions yielded more variable microbial shifts, including increases in Lactobacillus and Akkermansia, as well as decreases in some beneficial taxa, depending on the experimental conditions. Proposed mechanistic pathways included SCFA-mediated signaling, bile acid metabolism, and host immune modulation.

MUFA-rich foods, particularly nuts and olive oil, exert modulatory effects on the gut microbiota with potential benefits for metabolic health. These findings support the inclusion of MUFAs in dietary strategies aimed at improving microbiota composition and cardiometabolic outcomes. Studies are needed to disentangle the effects of MUFAs from coexisting bioactive compounds and confirm causal relationships.

PROSPERO registration no. CRD420251148388.