When we drizzle our dishes with olive oil, we think mainly of the heart, rarely of the brain. A Spanish team, however, shows thatvirgin olive oil could help preserve the cognitive healthby acting on the
intestinal microbiota which connects intestine and neurons.
The study, published in 2026 in the journal Microbiomefollowed for two years 656 Spanish adults aged 55 to 75, overweight or obese and suffering from metabolic syndrome. The researchers compared their habits of using olive oils, the analysis of their stools and a battery of memory, language and attention tests.
Virgin olive oil and brain: the results
The researchers compared people consuming mostly virgin or extra-virgin olive oil to those using refined oils. “This is the first prospective study in humans that specifically analyzes the role of olive oil in the interaction between the intestinal microbiota and cognitive function.“, explains Jiaqi Ni, first author of the article and researcher at the Department of Biochemistry and Biotechnology at Universitat Rovira i Virgili (URV).
They observed that a higher consumption of total olive oil, especially virgin, was accompanied by a better evolution of overall, general, executive cognitive function, but also of attention and language. Each additional 10 g daily, or a teaspoon, was linked to a measurable improvement in scores, while the refined oil went with a more rapid decline.
Extra virgin or refined: what the bottle changes
The gap begins at the mill. Virgin or extra virgin olive oil is obtained only by mechanical processes, which preserve polyphenols, vitamins and other bioactive compounds. Refined oils undergo industrial treatments which largely destroy these protective molecules. Hence Jiaqi Ni’s warning: “Not all olive oils have benefits for cognitive function” and the call to favor extra virgin versions.
For Jordi Salas-Salvadó, principal investigator of the study and professor at the University of Rochester, “This research confirms that the quality of the fats we eat is just as important as the quantity; extra virgin olive oil not only protects the heart, but could also help preserve brain function during aging“. Polyphenols could limit inflammation and oxidative stress, two enemies of memory.
Intestinal microbiota: the link between virgin oil and cognition
The intestinal microbiota brings together billions of microbes that communicate with the brain via the nervous system, hormones and small metabolites. In this study, virgin oil fans had more diverse flora, while refined oil was associated with reduced diversity and lower levels of beneficial bacteria like
Faecalibacterium.
A bacterial genus, Adlercreutziaproved to be central: its lower abundance explained 20% of the link between virgin oil and preservation of general cognitive function. “At a time when cases of cognitive decline and dementia are on the rise, our results serve as a reminder of the importance of improving diet quality and, in particular, favoring extra virgin olive oil over other refined versions as an effective, simple and accessible strategy to protect brain health.“, summarize Nancy Babio and Stephanie Nishi, co-directors of the study.