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BACKGROUND: Over the past decade, emerging evidence has shed light on the role of the gut microbiota in the interface between diet and brain health. Olive oil, particularly virgin olive oil, a key component and major fat source in the Mediterranean diet, has exhibited widespread healthful benefits, including improvements in gut microbiota and cognitive health. Despite insights from preclinical studies into the relationship between virgin olive oil consumption, gut microbiota, and cognitive function, human research in this area remains limited. Therefore, our study aims to investigate the interplay between total olive oil consumption and its subtypes, gut microbiota, and changes in cognitive function in older adults who were cognitively healthy at baseline but at high risk of cognitive decline.METHODS: In this prospective cohort study, we assessed a total of 656 participants aged 55 to 75y (mean age 65.0 ± 4.9y, 47.9% women) with overweight/obesity and metabolic syndrome who provided stool samples and completed a validated semi-quantitative food frequency questionnaire at baseline and a comprehensive battery of neuropsychological tests at baseline and at a 2-y follow-up.RESULTS: Results from the multivariable linear regression models showed that higher consumption of virgin olive oil was associated with improved cognitive function over a 2-y follow-up, and a more diverse gut microbiota overall structure at baseline. Conversely, increased consumption of common olive oil is linked to lower alpha diversity of the microbial communities, and accelerated cognitive decline. Mediation analysis suggests that gut microbiota and particularly the Adlercreutzia, may serve as a mediator taxon in the association between virgin olive oil consumption and positive changes in general cognitive function.CONCLUSIONS: Higher consumption of virgin olive oil was associated with cognitive preservation, possibly mediated by favorable alterations in gut microbiota composition. Our study provides novel insights into the complex interplay between different types of olive oil consumption, gut microbiota, and changes in cognitive function. These findings underscore the potential of microbiota-targeted dietary strategies to promote cognitive health in aging populations, though further high-quality and clinical cohort studies are required. Video Abstract.