Reference: Flynn MM, Tierney A, Itsiopoulos C. Is extra virgin olive oil the critical ingredient driving the health benefits of a Mediterranean diet? Nutrients. 2023;15:2915.
A recent scientific review, published in the journal Nutrients, provides strong evidence that the phenols in EVOO—which are not present in lower grades of olive oil—play a primary role in the heart-health benefits associated with olive oil and the Mediterranean diet.
Phenols are bioactive compounds in plant-based foods. EVOO is rich in phenols, whereas refined olive oils are stripped of these health-promoting compounds by chemical production processes.
Study Objectives
Dr. Mary Flynn, PhD, registered dietician, and associate professor of medicine at Brown University, identified 34 randomized, controlled trials published between 2000 and 2022 that evaluated the effects of EVOO on risk factors for heart disease: blood pressure, levels of LDL (“bad”) and HDL (“good”) cholesterol, blood sugar, and body weight.
A main aim of the review was to isolate the effects of the phenols in EVOO from the potential effects of monounsaturated fatty acids (MUFAs), which are present in all grades of olive oil and other vegetable oils. Flynn hypothesized that the MUFA content is not responsible for the many health benefits of EVOO.
Another objective was to identify a minimum daily amount of EVOO required to experience its health benefits and the timing for improvements in heart-health risk factors to be observed.
Findings
Across the 34 studies, EVOO improved multiple risk factors for heart disease as compared to other grades of olive oil, other plant oils, and low-fat diets:
- Lowered blood pressure
- Lowered LDL and increased HDL
- Improved insulin sensitivity
- Proved effective in weight-loss diets and improved long-term weight management
Daily dose of EVOO
According to Flynn and colleagues, “Daily use of EVOO starting at approximately two tablespoons a day will improve a plethora of risk factors in as few as three weeks.”
Phenomenal phenols
It is the phenols in EVOO that confer its heart-health benefits, the authors concluded. In order to obtain optimal levels of phenols, they recommend consuming the freshest olive oil: “The phenol content of extra virgin olive oil is highest in olive oil made close to the harvesting of the olive and will decrease with age and storage. Thus, for maximum health benefits, the EVOO should be produced and consumed as close to harvesting the fruit as possible.”
The authors noted some limitations of this review: most studies did not include the specific phenolic content of the EVOO used, and many were conducted in the EU, where EVOO has been a part of the diet for centuries. More investigation, especially studies that identify the specific levels of phenols, is needed to confirm and build on these findings.