A new human study suggests that extra virgin olive oil may support brain health by influencing the gut microbiome.
Extra virgin olive oil is a fundamental pillar of the Mediterranean diet and is well known for supporting heart and metabolic health. Scientists have long recognized these benefits, but its potential influence on the brain through the digestive system has received far less attention.
New research led by scientists from the Human Nutrition Unit at the Universitat Rovira i Virgili (URV), the Pere Virgili Health Research Institute (IISPV), and CIBERobn suggests that extra virgin olive oil may help protect cognitive function by shaping the gut microbiota.
“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,” explains Jiaqi Ni, first author of the study and a researcher in the URV Department of Biochemistry and Biotechnology.
The research team analyzed data from 656 adults between the ages of 55 and 75 who were overweight or obese and had metabolic syndrome, a group of conditions that increases the risk of cardiovascular disease. The information was gathered over two years as part of the PREDIMED Plus project. Researchers examined participants’ intake of different types of olive oil, including virgin and refined varieties, along with the composition of their gut microbiota. They also monitored changes in cognitive performance during the follow-up period.
Improved cognitive function and more diverse microbiota
The findings showed that participants who regularly consumed virgin olive oil instead of refined olive oil experienced improvements in cognitive performance. These individuals also had greater diversity in their gut microbiota, which is considered an important indicator of digestive and metabolic health.
By comparison, people who consumed refined olive oil tended to show a decline in microbiota diversity over time.
The researchers also identified a bacterial genus in the gut microbiota called Adlercreutzia as a potential marker of the beneficial link between virgin olive oil consumption and preserved cognitive function. According to the scientists, this suggests that part of the brain-related benefit of this oil may come from the way it influences the balance of microbes in the gut.
Why Extra Virgin Olive Oil Stands Out
What makes extra virgin olive oil different from refined olive oil largely comes down to how the oil is produced. Extra virgin olive oil is obtained using only mechanical extraction methods. Refined olive oil, in contrast, undergoes industrial processing designed to remove impurities.
While refining improves certain physical properties of the oil, it also reduces many naturally occurring compounds. These include antioxidants, polyphenols, vitamins, and other bioactive substances that contribute to the oil’s health benefits.
For this reason, Jiaqi Ni emphasizes that “not all olive oils have benefits for cognitive function” and recommends choosing extra virgin olive oil rather than refined varieties.
Quality is as important as quantity
The results contribute to a growing body of research exploring how diet, gut microbes, and long-term health are connected. Jordi Salas-Salvadó, the study’s principal investigator, says the findings highlight the importance of choosing high-quality fats as part of a healthy diet.
“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.”
Salas-Salvadó also notes that identifying a microbial pattern linked to these benefits could open the door to new prevention strategies based on nutrition. According to him, this discovery “paves the way for new nutrition-based prevention strategies to preserve cognitive functions.”
Nancy Babio and Stephanie Nishi, who co-directed the study, emphasize that the findings are particularly relevant as 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 prioritising extra virgin olive oil over other refined versions as an effective, simple and accessible strategy for protecting brain health.”
Reference: “Total and different types of olive oil consumption, gut microbiota, and cognitive function changes in older adults” by Jiaqi Ni, Stephanie K. Nishi, Nancy Babio, Clara Belzer, Jesús Vioque, Dolores Corella, Javier Hernando-Redondo, Josep Vidal, Isabel Moreno-Indias, Laura Compañ-Gabucio, Oscar Coltell, Montse Fitó, Estefanía Toledo, Dong D. Wang, Francisco J. Tinahones and Jordi Salas-Salvadó, 24 January 2026, Microbiome.
DOI: 10.1186/s40168-025-02306-4
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