Transcript: Olive Oil and Artery Function
The relative paralysis of our arteries for hours after eating fast food and cheesecake may also occur after olive oil. Olive oil was found to have the same impairment to endothelial function as the rest of these high-fat meals. Sausage and Egg McMuffin was the worst, but olive oil wasn’t far behind.
Studies that have suggested endothelial benefits after olive oil consumption have measured something different—ischemia-induced, as opposed to flow-mediated, dilation—and there’s just not good evidence that that’s actually an index of endothelial function, which is what predicts heart disease. Hundreds of studies have shown that the test can give a false negative result.
But, it’s not just olive oil. Other oils have also been shown to have deleterious results on endothelial function; a significant and constant decrease in endothelial function three hours after each meal, independent of the type of oil, and whether the oil was fresh, or deep fried. Olive oil may be better than omega-6-rich oils, or saturated fats, but most of the studies showing adverse effects were done on regular, refined olive oil, not extra virgin.
Extra virgin olive oil retains a fraction of the anti-inflammatory phytonutrients found in the olive fruit, and so doesn’t appear to induce the spike in inflammatory markers caused by regular olive oil. But what does that mean for our arteries?
Extra virgin olive oil may have more of a neutral effect, compared to butter, which exerted a noxious effect that lasted for up to six hours—basically right up to our next meal. In the largest prospective study ever to assess the relationship between olive oil consumption and cardiac events, like heart attacks, there was a suggestion that virgin olive oil may be better than regular olive oil, but neither were found to significantly reduce heart attack rates after controlling for healthy dietary behaviors, like vegetable intake, which tends to go hand-in-hand with olive oil intake.
There have been studies, though, showing even extra virgin olive oil, contrary to expectations, may significantly impair endothelial function as well. So why do some studies suggest people’s endothelial function improves on a Mediterranean diet, a diet rich in olive oil? Perhaps because it’s also rich in whole grains, fruits, vegetables, beans, and walnuts, as well. Dietary fruits and vegetables appear to provide some protection against the direct impairment of endothelial function produced by high-fat foods, including olive oil. So, improvements in health may be in spite of, rather than because of, the oil. In terms of their effects on postprandial endothelial function (after a meal), the beneficial components of the Mediterranean diet may primarily be the antioxidant-rich foods—the vegetables, fruits, and their derivatives, such as balsamic vinegar. Just adding some vegetables to a fatty meal may partially restore arterial functioning and blood flow.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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