A new study in the Journal of the American College of Cardiology suggests that the phenolic compounds in olive oil may be behind the cardiovascular health benefits associated with the Mediterranean Diet. The phenolic compounds in olive oil are known to have antioxidant, anti-inflammatory and anti-clotting properties.
Participants in the study - who all had high cholesterol levels but were otherwise healthy - were fed breakfasts that included olive oil that was either high or low in phenolic content. The researchers then measured the functioning of the endothelium (inner lining) of small blood vessels of the fingers and the concentrations of certain components in blood samples. Previous studies have linked high-fat meals to poor endothelial function lasting for several hours after eating.
The researchers found that the functioning of the endothelium improved after the phenol-rich breakfast. Additionally, the concentration of nitric oxide in the blood of the participants also showed improvement. The results indicate that a very small change in diet, like using olive oil with a high phenolic content, may have a significant impact in the progression of atherosclerosis. "This is the first study that shows a direct benefit of an olive oil with high content in phenolic compounds on endothelial function. We think, looking at our results, that the reduction in oxidative stress and the increase in the nitric oxide bioavailability are behind the observed improvements," said researcher Francisco Pérez Jiménez, from the Reina Sofia University Hospital in Spain.
He speculated that the benefits of the Mediterranean diet to the cardiovascular system might be due to a number of components. "It could be that the beneficial effect of the Mediterranean diet on cardiovascular disease and arteriosclerosis depends on the synergistic effects of the different nutrients that constitute complete foods and, as an example, virgin olive oil is more than fat because it is a real juice with other healthy micronutrients," he added.
The researchers believe that olive oil may be superior to seed oils (sunflowers, soybeans and canola) because it is pressed directly from olives, as opposed to seed oils which go through quite complex processing.
Commenting on the study, Robert F. Wilson, from the University of Minnesota, noted that the health benefits of a Mediterranean diet were described over 50 years ago. "This study demonstrates one possible mechanism by which olive oil rich in phenolic substances improves the functioning of the circulation. The authors found that after test subjects took olive oil spiked with phenolic compounds, their blood vessels could dilate better, which could improve blood flow," he said. But Wilson said consumers should not expect all olive oils to have high phenolic content. "So these results might not be true for all olive oil on the shelf at the grocery store," he concluded.
Source: American College of Cardiology