Is Extra-Virgin Olive Oil Healthy? New Data on the Great DebateDr. Joel Kahn
After 44 years on a plant only (vegan) diet, I have lectured, written, and taught countless individuals on the health advantages of a diet from the produce department, farmer’s market, and garden. In my preventive cardiology clinic, I get to listen to and counsel thousands of patients, many on a plant diet, from around the world. Routinely, if it is not the first question asked, it is in the top three: the query ”what about oil,” especially oils thought to be healthy, like olive oil?
So, is extra virgin olive oil healthy or not?
A few years back I wrote a piece supporting the data that a low or no oil plant diet is optimal. Without question, all of the studies focused on reversing disease states as published by Drs. Ornish, Esseltsyn, McDougall, Barnard, and others, have advised avoiding added oils. A new and large study requires discussion and consideration if an oil-free diet is the best recommendation for most on a vegan diet. First, let’s look at two studies supporting the no-oil diet.
In 2000, cardiologist and friend Robert Vogel, MD published a study of 10 healthy subjects studied on several different diets. The end-point was a measurement of artery function called flow-mediated dilation or FMD. It is not good for FMD to drop. The study found FMD dropped significantly with a combination of olive oil and bread. However, when they studied a combination of canola oil and bread, a combination of salmon and cracker, a combination of olive oil with bread and vitamins C and E, and finally, a combination of olive oil, bread, salad, and vinegar, FMD did not demonstrate a significant drop. Olive oil, in this study extra-virgin olive oil or EVOO, appears to affect arteries based on the company it keeps.
Then, in 2007, ten healthy subjects were studied in terms of their response measured by FMD to three soups with either olive oil, soybean oil, or palm oil. All of the soups enriched with oils produced a decline in FMD.
Can you confidently recommend no oil diets to the bulk of people adhering to a plant-based diet on the basis of two studies with a total of 20 patients?
But a new study with 805 patients has just been published and is worthy of attention. The research was done in Cordoba and Madrid, Spain, as part of a larger study called CORDIOPREV. Two healthy diet patterns were evaluated in a randomized manner: a “low-fat” diet versus a Mediterranean diet enhanced with EVOO. Of the 805 subjects who all had prior evidence of heart disease, half were advised to enhance their diet with around four tablespoons of EVOO daily along with vegetables, fruit, legumes, fish, and nuts and seeds. The other half were advised to minimize oil in cooking, not to eat red meat often, to choose low-fat dairy, to avoid oily fish, to avoid nuts and seeds, and to avoid commercial baked goods. All of the subjects underwent unbelievably sophisticated measurements of endothelial (arterial) function at baseline and again at a year follow-up.
At one year, the subjects on the EVOO enriched diet had a higher HDL (healthy) cholesterol, a lower fasting glucose, and a lower inflammatory marker hs-CRP. There was a more favorable FMD measure of artery function in the EVOO group and the also had other markers (endothelial progenitor cells) that indicated better artery function. Elegant analyses of the production of proteins (proteomics) indicated the EVOO-enhanced diet resulted in the suppression of proteins related to inflammation.
The authors concluded that the Mediterranean diet enhanced with EVOO led to better endothelial function, enhanced endothelial repair, and reduced artery damage. They felt the EVOO enhanced diet was the best dietary strategy to recover endothelial function in patients with heart disease.
What are we to do?
On the one hand, this study is the largest and most elegant evaluation of a higher fat diet with EVOO on artery function, and the results are impressive. The fact that they were done in patients with heart disease is important and would suggest the findings would be the same or even better in those without known heart disease. The only drawbacks are the study was funded by a foundation of EVOO producers as the project was undoubtedly quite expensive. The other drawback is that they did not look at heart attacks and other events but the full CORDIOPREV study of 1,002 subjects is evaluation that and there will be future publications.
But, overall, the great fear that EVOO of high quality is dangerous to arteries must be reevaluated in light of this large study. On a personal note, I use EVOO regularly and advise it as okay for the majority of my heart patients.
Joel Kahn, MD, FACC of Detroit, Michigan, is a practicing cardiologist, and a Clinical Professor of Medicine at Wayne State University School of Medicine. He graduated Summa Cum Laude from the University of Michigan Medical School. Known as “America’s Healthy Heart Doc”, Dr. Kahn has triple board certification in Internal Medicine, Cardiovascular Medicine, and Interventional Cardiology. He owns GreenSpace & Go, a health restaurant in suburban Detroit. Dr. Kahn can be found at www.drjoelkahn.com.
- Is Extra-Virgin Olive Oil Healthy? New Data on the Great Debate - September 24, 2020