Virgin olive oil is widely regarded as a central component of the Mediterranean diet and is well known for supporting cardiovascular and metabolic health. It contains a range of beneficial compounds, including antioxidants and polyphenols, which have been linked to reduced inflammation and improved heart function. Despite these recognised benefits, researchers have only recently begun to investigate how olive oil might influence the brain through the digestive system. A new study conducted by researchers from the Human Nutrition Unit at the Universitat Rovira i Virgili, the Pere Virgili Health Research Institute, and CIBERobn suggests that extra virgin olive oil may help protect cognitive function by influencing the gut microbiota.
The research team carried out what they describe as the first long-term human study specifically examining the relationship between olive oil consumption, gut microbiota, and cognitive function. The study analysed data from 656 participants 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. These individuals were part of the PREDIMED-Plus project, a large study focused on diet and health. Over two years, researchers monitored the participants’ diets, particularly their intake of different types of olive oil, while also examining the composition of their gut microbiota and assessing changes in their cognitive performance.
The findings showed clear differences between those who regularly consumed virgin olive oil and those who mainly used refined olive oil. Participants who consumed virgin olive oil demonstrated better cognitive performance over time. They also showed greater diversity in their gut microbiota, which is often considered an indicator of good intestinal and metabolic health. A diverse microbial community in the gut is associated with improved digestion, stronger immune function, and better regulation of inflammation. In contrast, participants who primarily consumed refined olive oil tended to show less diversity in their gut microbiota as the study progressed.
Researchers also identified a particular bacterial genus called Adlercreutzia that appeared to play a role in the relationship between olive oil consumption and cognitive health. Higher levels of this bacterium were linked to both increased intake of virgin olive oil and better preservation of cognitive function. This suggests that certain gut bacteria may help explain how dietary fats influence brain health. The study, therefore, highlights the possibility that the benefits of virgin olive oil extend beyond its direct nutritional properties and may involve complex interactions between diet, gut microorganisms, and brain function.
One important factor that distinguishes extra virgin olive oil from refined olive oil is the way it is produced. Extra virgin olive oil is obtained solely through mechanical pressing of olives, without chemical processing or high heat. This method helps preserve naturally occurring compounds such as antioxidants, polyphenols, and vitamins. Refined olive oil, however, undergoes industrial treatments designed to remove impurities and improve stability. While this process creates a more neutral product, it also removes many of the bioactive substances believed to contribute to olive oil’s health benefits. As a result, not all olive oils provide the same nutritional value.
The researchers emphasise that these findings highlight the importance of both the type and quality of dietary fats. While olive oil is already recognised for its role in heart health, the study suggests it contributes to maintaining cognitive function during ageing. As populations grow older and cases of cognitive decline and dementia become more common, improving diet quality may be a practical strategy for supporting long-term brain health. Choosing extra virgin olive oil instead of refined varieties represents a simple dietary change that may help promote healthier gut microbiota and protect cognitive function over time.
More information: Jiaqi Ni et al, Total and different types of olive oil consumption, gut microbiota, and cognitive function changes in older adults, Microbiome. DOI: 10.1186/s40168-025-02306-4
Journal information: Microbiome Provided by Universitat Rovira i Virgili
