Virgin olive oil is considered one of the fundamental pillars of the Mediterranean diet and is widely recognised for its cardiovascular and metabolic health benefits. However, its direct influence on the human brain through the digestive system had not been explored in depth. A new study led by researchers from the Human Nutrition Unit at the Universitat Rovira i Virgili (URV), the Pere Virgili Health Research Institute (IISPV) and CIBERobn reveals that extra virgin olive oil may play a decisive role in protecting cognitive function through its effects on the gut microbiota.
‘This is the first prospective study in humans to specifically analyse the role of olive oil in the interaction between gut microbiota and cognitive function,’ explains Jiaqi Ni, first author of the article and researcher at the URV's Department of Biochemistry and Biotechnology. To carry out the study, the research team worked with data from 656 people aged between 55 and 75 who were overweight or obese and had metabolic syndrome—a set of risk factors that increase the likelihood of developing cardiovascular disease. This information was collected over a two-year period as part of the PREDIMED-Plus project and also included data on the participants’ consumption of different types of olive oil (virgin and refined) and the composition of their gut microbiota, as well as a follow-up that sought to identify any changes to their cognitive function.
Improved cognitive function and more diverse microbiota
The results reveal that people who consumed virgin olive oil rather than refined olive oil showed improved cognitive function and greater diversity in their gut microbiota, which is an important marker of intestinal and metabolic health. In contrast, consumption of refined olive oil was associated with less diverse microbiota over time. In addition, the researchers identified a genus of bacteria in the microbiota, known as Adlercreutzia, as a possible indicator of the beneficial association between virgin olive oil consumption and the preservation of cognitive function. The researchers’ findings suggests that some of the benefits for brain function of consuming this type of oil may be due to its impact on the composition of the gut microbiota.
So what is it about extra virgin olive oil that makes it healthier than refined olive oil? The main difference lies in their production processes: the former is obtained exclusively through mechanical procedures, whereas refined olive oil undergoes industrial treatments to remove impurities. The problem is that these treatments also degrade the oil’s natural antioxidants, polyphenols, vitamins and other bioactive compounds that are beneficial to health. Hence Jiaqi Ni’s warning that ‘not all olive oils have benefits for cognitive function’ and that we should aim to consume extra virgin olive oils rather than refined ones.
Quality is as important as quantity
Findings such as these advance our understanding of the mechanisms linking cardiovascular and cognitive health to gut microbiota. Jordi Salas-Salvadó, principal investigator of the study, highlights the importance of olive oil quality as a central component of the Mediterranean 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.’ The URV professor also points out that the fact that they have identified a microbial profile that plays a role in these benefits ‘paves the way for new nutrition-based prevention strategies to preserve cognitive functions.’
At the same time, researchers Nancy Babio and Stephanie Nishi, co-directors of the study, point out the relevance of the results in the current context of an ageing population: ‘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.’
This study was made possible thanks to the leadership of the Human Nutrition Unit of the Department of Biochemistry and Biotechnology at the URV and the participation of institutions such as the Pere Virgili Health Research Institute (IISPV-CERCA) and the CIBER area on the Physiopathology of Obesity and Nutrition (CIBEROBN) of the Carlos III Health Institute. The project also benefited from the collaboration of researchers from the PREDIMED-Plus consortium and international universities such as Wageningen (Netherlands) and Harvard (United States).
Microbiome
Total and different types of olive oil consumption, gut microbiota, and cognitive function changes in older adults
25-Jan-2026