According to a two‑year prospective analysis of more than 650 older adults at high risk of cognitive decline published in the journal Microbiome, greater intake of virgin olive oil (VOO) is associated with improvements across multiple cognitive domains, while higher consumption of common olive oil (COO) was linked to accelerated cognitive decline. Mediation analyses suggest that changes in gut microbiota composition may partially explain these divergent effects.
“The present study marks a significant advancement in the understanding of the interplay between the consumption of total and different olive oil types, gut microbiota diversity and composition, and changes in cognitive function in older adults at high risk of cognitive decline,” wrote the researchers in Spain, funded by the country’s biomedical research system.
They noted that the findings support the existence of a potential “olive oil–gut–brain axis”, highlighting gut microbiota as a biological pathway linking diet quality with cognitive aging and underscoring the importance of olive oil quality and processing.
Olive oil, the Mediterranean diet and brain health
Olive oil is a central fat source in the Mediterranean diet, a dietary pattern consistently associated with reduced risk of cognitive decline and neurodegenerative disease. Most studies to date have assessed olive oil as a single category, without distinguishing between virgin and refined forms.
Virgin olive oil is obtained solely through mechanical extraction and retains high levels of phenolic compounds such as hydroxytyrosol and oleuropein, which have demonstrated antioxidant, anti‑inflammatory and neuroprotective properties. These bioactives can cross the blood–brain barrier and may act directly on pathways involved in neurodegeneration. In contrast, common olive oil is largely refined and contains substantially lower concentrations of these compounds, despite a similar fatty acid profile.
Emerging human and preclinical research also suggests that virgin olive oil may influence brain health indirectly via the gut–brain axis. Polyphenols can modulate gut microbiota composition, promote microbial diversity and stimulate the production of metabolites involved in immune regulation, blood–brain barrier integrity and synaptic function.
“Given the critical role of gut microbiota in regulating cognitive function and modifying neurodegenerative disease risk through the ‘gut-brain’ axis, investigating the mechanism underlaying olive oil’s effect on gut microbiota as a target of nutritional strategies for improving brain health and function is of particular interest,” the researchers wrote.
Study details: Cognitive change and microbiota mediation
The new study analyzed data from 656 participants between the ages of 55 and 75 years enrolled in the PREDIMED‑Plus trial. All participants were overweight or obese with metabolic syndrome but were cognitively healthy at baseline. Dietary intake was assessed using a validated food frequency questionnaire, while cognitive function was measured at baseline and after two years using a comprehensive neuropsychological test battery.
After multivariable adjustment, higher baseline intake of total olive oil and virgin olive oil was associated with improvements in global cognitive function, general cognition, executive function, attention and language over the follow‑up period. Each additional 10 g/day of virgin olive oil intake was linked to positive changes across several cognitive domains. In contrast, higher consumption of common olive oil was associated with declines in global, general, executive and language‑related cognitive performance.
Gut microbiota analyses based on 16S rRNA sequencing showed that higher virgin olive oil intake was associated with greater alpha diversity, while common olive oil intake was linked to reduced microbial diversity. Distinct microbial signatures were associated with each olive oil type.
“Mediation analysis suggests that gut microbiota and particularly Adlercreutzia, may serve as a mediator taxon in the association between VOO consumption and changes in general cognitive function," the researchers noted, adding that Akkermansia, inversely associated with VOO consumption, showed a negative association with changes in attention.
Overall microbial community composition also mediated associations between virgin olive oil intake and changes in executive function and language.
While the researchers cautioned that the observational design precludes causal inference, they suggested that the findings support the potential “olive oil–gut–brain axis” and highlight the need to distinguish olive oil types in future research and microbiota‑targeted nutrition strategies for healthy cognitive aging.
Source: Microbiome. doi: 10.1186/s40168-025-02306-4. “Total and different types of olive oil consumption, gut microbiota, and cognitive function changes in older adults”. Authors: Jiaqi Ni et al.
