A recent study co-authored by Yale School of Public Health Assistant Professor of Biostatistics Tassos C. Kyriakides finds that the daily consumption of extra-virgin olive oil could improve cognitive function in individuals with mild cognitive impairment. Mild cognitive impairment and early Alzheimer’s disease are characterized by a breakdown of the blood–brain barrier. In the study, the researchers found that consumption of extra-virgin olive oil significantly improved both clinical dementia rating and behavioral scores, in addition to reducing blood-brain barrier permeability and enhancing functional connectivity.
Kyriakides and Vasilis Vasiliou, the Susan Dwight Bliss Professor of Epidemiology (Environmental Health Sciences) and chair of the Yale School of Public Health’s Department of Environmental Health Sciences, have been investigating the health benefits of olive oil in the context of a healthy diet for years and, as part of their efforts, are working to establish a Yale Institute for Olive Science and Health that would explore the science of the olive tree and seek ways to integrate olives and olive products into daily nutrition.
Kyriakides recently discussed the new study’s findings, which were published in the journal Nutrients on Dec. 1. Professor Amal Kaddoumi of the Harrison College of Pharmacy at Auburn University is the lead author.
What are the most important findings of this study?
Tassos C. Kyriakides (TCK): We found that extra virgin olive oil enhanced brain connectivity and reduced blood-brain barrier permeability, both markers of mild cognitive impairment and early Alzheimer’s disease. In addition, even though both extra-virgin olive oil and refined olive oil (with phenolic components removed) improved clinical dementia rating and behavioral scores, only extra-virgin olive oil had an effect on blood-brain barrier permeability, suggesting that it was its biophenols that contributed to such an effect.
What methods were used in conducting this study?
TCK: Seventy-four individuals with mild cognitive impairment were screened and those eligible for the study were randomly assigned to receive either extra-virgin olive oil or refined olive oil. There were 13 participants in each group. Study participants underwent neuropsychological evaluations, imaging, and blood sample collection at baseline and at the end of their olive oil consumption, which was 30mL daily for 6 months.
How exactly did the daily consumption of refined and extra-virgin olive oil improve cognitive processes in people with Alzheimer’s disease or mild dementia?
TCK: Extra-virgin olive oil consumption resulted in improvements in blood-brain barrier function and enhanced brain function and memory in individuals with mild cognitive impairment.
How do these findings support the health benefits of olive oil?
TK: Recent studies on the effect of extra-virgin olive oil intake on memory function in subjects with mild cognitive impairment in Greece, showed that after one year of consumption of high- or medium-phenolic extra-virgin olive oil, cognitive function improved, and Alzheimer’s disease blood biomarkers showed improvement. Some beneficial effects were also seen with refined olive oil, suggesting that in addition to phenolic compounds, monounsaturated fats such as oleic acid, the major fat in olive oil, might also contribute to the health effects of olive oil.
Are there any limitations to this study, and are you considering pursuing this concept with further research?
TCK: This pilot, proof-of-concept study has a small sample size and did not include a ‘control’ arm of patients with mild cognitive impairment who did not receive olive oil. Further, a longer duration of olive oil consumption would be necessary to better assess the long-term effect of olive oil on the brain and cognitive function. Hence, findings from this study support further research and point to the design and conduct of larger clinical trials to assess and compare olive oil’s protective effects against Alzheimer’s disease and its potential role in preventing mild cognitive impairment and its conversion to Alzheimer’s disease and related dementias. Our collaborators in this study are already looking into designing future studies to definitively answer the role of extra-virgin olive oil in brain and cognitive health.