Extra virgin olive oil is often highlighted as a key component of the Mediterranean diet. A new study suggests its benefits may extend beyond heart health and into the gut and brain.
Researchers analyzing data from 656 adults ages 55 to 75 found that those who consumed virgin olive oil, rather than refined olive oil, showed greater gut microbiota diversity and more favorable changes in cognitive function over a two-year period. The findings were published in the journal Microbiome.
“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 Jiaqi Ni, first author of the study and a researcher at Universitat Rovira i Virgili in Spain.
The participants were part of the larger PREDIMED-Plus study and were overweight or obese with metabolic syndrome, a cluster of risk factors linked to cardiovascular disease. Researchers examined reported intake of different types of olive oil, analyzed gut microbiota composition and assessed cognitive performance over time.
Those who consumed virgin olive oil had greater microbial diversity, a marker often associated with gut health. In contrast, refined olive oil intake was associated with lower microbial diversity over time. The researchers also identified a bacterial genus, Adlercreutzia, that may be involved in the observed associations between virgin olive oil intake and preserved cognitive function.
The study does not prove that extra virgin olive oil prevents cognitive decline or dementia. It identifies associations within a specific population already participating in a Mediterranean-style dietary intervention. Still, the findings suggest that the type of fat consumed may matter.
The primary difference between virgin and refined olive oil lies in processing. Virgin olive oil is obtained through mechanical methods, while refined olive oil undergoes industrial treatments that reduce impurities but also lower levels of naturally occurring antioxidants and polyphenols.
“Not all olive oils have benefits for cognitive function,” Ni said, noting the distinction between virgin and refined oils.
Jordi Salas-Salvadó, the study’s principal investigator, emphasized the broader dietary context.
“This research reinforces the idea that the quality of the fat we consume is as important as the quantity; extra virgin olive oil not only protects the heart, but can also help preserve the brain during ageing,” he said.
While the study strengthens the case for prioritizing minimally processed fats within a Mediterranean-style pattern, it does not isolate olive oil as a standalone intervention. Participants were part of a structured dietary program, and other aspects of diet and lifestyle may also contribute to cognitive outcomes.
Still, the research adds to growing evidence that diet quality influences both gut microbiota and brain health. It also underscores the complexity of appetite, metabolism and cognitive aging, which appear to be shaped by interactions between dietary components and the gut-brain axis.
This research was supported by multiple Spanish public biomedical research institutions, including CIBER Fisiopatología de la Obesidad y Nutrición and Instituto de Salud Carlos III, co-funded in part by the European Regional Development Fund. Additional funding came from European Union Horizon 2020 programs, the U.S. National Institutes of Health and other academic and governmental research grants. Individual authors received fellowship support from Spanish and Canadian funding agencies.