– First human study links virgin olive oil to improved cognition and greater gut bacteria diversity –
Extra virgin olive oil has long been celebrated as a cornerstone of the heart-healthy Mediterranean diet. Now, new research suggests its benefits may extend directly to the brain, working through the gut microbiome to support cognitive function.
A study led by researchers from the Universitat Rovira i Virgili (URV) in Spain, along with the Pere Virgili Health Research Institute (IISPV) and CIBERobn, has found a meaningful link between extra virgin olive oil consumption, gut bacteria composition, and preserved cognitive health. 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 URV’s Department of Biochemistry and Biotechnology.
What the Study Found
Researchers followed 656 adults aged 55 to 75 who were overweight or obese and had metabolic syndrome—a cluster of risk factors that increase the likelihood of developing cardiovascular disease. Over a two-year period, as part of the PREDIMED-Plus project, scientists tracked participants’ diets, including their intake of virgin and refined olive oil. They also conducted detailed analyses of gut microbiota and monitored changes in cognitive performance over time.
The results showed a clear distinction between oil types. Participants who regularly consumed virgin olive oil experienced improvements in cognitive function and had a more diverse gut microbiota—a hallmark of better intestinal and metabolic health. In contrast, those who consumed refined olive oil tended to show a decline in microbiota diversity over time.
The Key Difference: Processing Matters
The difference between extra virgin and refined olive oil comes down to production methods. Extra virgin olive oil is obtained using mechanical means, which preserves its natural compounds. Refined olive oil undergoes industrial processing to remove impurities—a step that improves shelf life and taste consistency but also strips away beneficial components such as antioxidants, polyphenols, vitamins, and other bioactive substances.
“Not all olive oils have benefits for cognitive function,” Ni explained.
A Specific Gut Bacterium May Play a Role
Researchers also identified a specific group of gut bacteria, known as Adlercreutzia, that may be tied to these brain benefits. The presence of this bacterium could serve as an indicator of the positive relationship between virgin olive oil consumption and preserved cognitive function. This suggests that part of the oil’s brain-supporting effect may come from how it reshapes the gut microbiome.
Implications for Aging Populations
Study co-directors Nancy Babio and Stephanie Nishi highlighted the broader implications as global populations continue to age.
“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,” they said.
Lead investigator Jordi Salas-Salvadó emphasized that the quality of dietary fats matters as much as the quantity.
“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 aging,” he said.
He also noted that identifying a specific microbial profile linked to these benefits “paves the way for new nutrition-based prevention strategies to preserve cognitive functions.”
A Simple Dietary Switch
The study adds to growing evidence that diet plays a key role in both cardiovascular and cognitive health through its influence on the gut microbiota. For older adults, especially those with metabolic risk factors, choosing extra virgin olive oil over refined versions appears to be a simple, accessible strategy with potentially significant brain-protective benefits.
The research was conducted with contributions from the PREDIMED-Plus consortium and international collaborators from Wageningen University in the Netherlands and Harvard University in the United States.