MUFA-Rich Foods and Gut Microbiota in a Systematic Review

Key Takeaways

• The evidence base included randomized clinical trials and in vivo studies in human participants and animal models and focused on extra-virgin olive oil, avocado, and nuts.
• Nut-based interventions were more often linked with higher Faecalibacterium, Roseburia, and Ruminococcaceae, alongside improved lipid profile and improvements in body weight and fat mass.
• Olive oil–based interventions showed a less uniform microbiota pattern, and the authors noted that causal interpretation remains unsettled.

A Nutrition Reviews systematic review found that MUFA-rich foods were linked with selective gut microbiota changes across in vivo studies and randomized clinical trials. Across 37 included studies, the clearest recurring pattern appeared with nut-based interventions, while olive oil showed a less uniform microbiota signal. Overall, the findings remained suggestive rather than definitive across the clinical and experimental settings examined.

This systematic review evaluated MUFA-rich foods and their effects on gut microbiota composition, diversity, and related metabolic outcomes. The evidence base spanned human participants and animal models and focused on extra-virgin olive oil, avocado, and nuts. Searches covered PubMed, Scopus, and Web of Science, and risk of bias was assessed with SYRCLE RoB and RoB-2. Findings were synthesized qualitatively, and the review was registered in PROSPERO as CRD420251148388.

Nut-based interventions were more consistently associated with increases in short-chain fatty acid–producing genera, particularly Faecalibacterium and Roseburia, with Ruminococcaceae also appearing repeatedly. These microbiota findings appeared alongside improved lipid profile and improvements in body weight and fat mass. Among the foods examined, this was the most consistent microbiota and metabolic pattern identified in the review.

Olive oil–based interventions produced a more variable set of microbial shifts across studies. Reported changes included increases in Lactobacillus and Akkermansia, but some studies also described decreases in beneficial taxa. Findings varied with the experimental conditions summarized in the review. Avocado was part of the review scope, but the abstract gave far less detail on its microbiota findings than on nuts or olive oil. Overall, microbiota responses differed across food sources and study contexts.

The authors proposed several pathways that could connect these dietary exposures with microbial and metabolic findings, including short-chain fatty acid–mediated signaling, bile acid metabolism, and host immune modulation. In their overall synthesis across heterogeneous study designs, foods, and experimental models, they concluded that the pattern supported inclusion of MUFA-rich foods in dietary strategies aimed at microbiota and cardiometabolic outcomes, while noting that MUFA-specific effects still need separation from coexisting bioactive compounds. They also noted that the heterogeneous evidence did not yet confirm causal relationships.