A large prospective cohort study finds that older adults who eat more virgin olive oil — a key component of the Mediterranean diet — have slower cognitive decline and a more diverse gut microbiota over two years of follow-up; in contrast, higher intake of common refined olive oil was tied to lower microbial diversity and faster decline.
Extra-virgin olive oil, a major component of the Mediterranean diet, protects against cognitive decline. Image credit: Steve Buissinne.
Virgin olive oil is a cornerstone of the Mediterranean diet and is rich in phenolic compounds with anti-inflammatory and antioxidant properties.
Previous laboratory and animal studies have suggested neuroprotective effects, but human evidence linking olive oil, gut microbiota and cognition has been limited.
The new findings draw on participants from the PREvención con DIeta MEDiterránea-Plus (PREDIMED-Plus) study, a large ongoing trial designed to examine how diet and lifestyle changes affect cardiovascular and metabolic health.
“This is the first prospective study in humans to specifically analyze the role of olive oil in the interaction between gut microbiota and cognitive function,” said Dr. Jiaqi Ni, a researcher at the Universitat Rovira I Virgili.
The researchers followed more than 650 adults aged 55 to 75 who were overweight or obese and at high risk of cognitive decline but cognitively healthy at the start of the research.
Over a two-year period, they tracked participants’ olive oil intake, gut microbiota profiles and performance on a comprehensive battery of cognitive tests.
Higher consumption of virgin olive oil was associated with improvements or preservation in global cognition, executive function and language skills.
In contrast, higher intake of common olive oil, which is largely refined, was linked to reduced microbial diversity in the gut and faster cognitive decline.
“At a time when cases of cognitive decline and dementia are on the rise, our findings drive home the importance of improving diet quality, and in particular prioritizing extra virgin olive oil over other refined versions as an effective, simple and accessible strategy for protecting brain health,” said Universitat Rovira I Virgili researchers Nancy Babio and Stephanie Nishi.
To explore why virgin olive oil might benefit cognition, the scientists analyzed stool samples collected at baseline.
People who consumed more virgin olive oil had a more diverse gut microbiota and distinct microbial community structures compared with those who consumed less.
Further analyses suggested that specific gut bacteria may help explain the cognitive benefits.
Changes in the abundance of certain microbial species, such as Adlercreutzia, appeared to statistically mediate the link between virgin olive oil intake and improved general cognitive performance, supporting the idea that diet may influence brain health through the gut-brain axis.
“This research reinforces the idea that the quality of the fat we consume is as important as the quantity,” said Dr. Jordi Salas-Salvadó, also from the Universitat Rovira I Virgili.
“Extra virgin olive oil not only protects the heart, but can also help preserve the brain during aging.”
“The fact that a microbial profile plays a role in these benefits paves the way for new nutrition-based prevention strategies to preserve cognitive functions.”
The study was published in the journal Microbiome.
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J. Ni et al. 2026. Total and different types of olive oil consumption, gut microbiota, and cognitive function changes in older adults. Microbiome 14, 68; doi: 10.1186/s40168-025-02306-4
