Mediterranean Diet Post 6: Olive Oil Promotes Atherosclerosis, Impairs Endothelial Function

Some of this is a repost from 2014. I added a couple studies at the bottom.
Olive OilThe following studies provide evidence for the atherosclerosis-promoting effect of olive oil, in monkeys, mice, and humans:

1. Hepatic Origin of Cholesteryl Oleate in Coronary Artery Atherosclerosis In African Green Monkeys, Enrichment By Dietary Monounsaturated Fat, Journal of Clinical Investigation, 1997

“[We observed in monkeys] that the amount of coronary artery atherosclerosis was similar in the monounsaturated and saturated fat groups, in spite of the significantly improved LDL cholesterol concentration and LDL/HDL cholesterol ratio in the former.”

2. Dietary Monounsaturated Fatty Acids Promote Aortic Atherosclerosis In LDL Receptor–Null, Human ApoB100–Overexpressing Transgenic Mice, Arteriosclerosis, Thrombosis, and Vascular Biology, 1998

Mice were fed one of 6 diets with different fatty acid content: saturated, monounsaturated (cis and trans), polyunsaturated (n-3 and n-6), and a control diet.

“The reduction in aortic atherosclerosis was not found when either cis or trans monounsaturated fatty acids were fed. Rather, just as much atherosclerosis was seen when cis monounsaturated fat diets were fed as when saturated fat was fed, and significantly more atherosclerosis was seen when the trans monounsaturated fatty acids were fed.”

This is an important outcome when one considers that monounsaturated fats, often in the form of olive oil, are widely promoted as being healthful and effective for protection against heart disease.

3. Effect Of Fat And Carbohydrate Consumption On Endothelial Function, Lancet, December, 1999

“Consumption of a meal high in monounsaturated fat was associated with acute impairment of endothelial function when compared with a [low-fat] carbohydrate-rich meal.”

4. The Postprandial Effect Of Components Of The Mediterranean Diet On Endothelial Function, Journal of the American College of Cardiology, November 2000

“Contrary to part of our hypothesis, our study found that omega-9 (oleic acid)-rich olive oil impairs endothelial function postprandially.

The mechanism appears to be oxidative stress because the decrease in FMD was reduced (71%) by the concomitant administration of vitamins C and E. Balsamic vinegar (red wine product) and salad reduced the postprandial impairment in endothelial function to a similar extent (65%).

In a clinical study, olive oil was shown to activate coagulation factor VII to the same extent as does butter (44). Thus, olive oil does not have a clearly beneficial effect on vascular function.”

The major unsaturated fatty acids in olive oil are oleic acid (18:1n-9) and linoleic acid (18:2n-6) (42). A high-oleic and linoleic acid meal has recently been shown to impair FMD in comparison with a low-fat meal (28). (That’s the study above by Ong et al.)

In terms of their effects on postprandial endothelial function, the beneficial components of the Mediterranean and Lyon Diet Heart Study diets appear to be the antioxidant-rich foods—vegetables, fruits … not olive oil. Dietary fruits, vegetables, and their products appear to provide some protection against the direct impairment in endothelial function produced by high-fat foods, including olive oil.”

To these I will add:

5. The Influence Of Diet On The Appearance Of New Lesions In Human Coronary Arteries, JAMA, March 1990

The likelihood of new lesions developing increased significantly with each quartile of increasing consumption of total fat, monounsaturated fat [olive oil], and polyunsaturated fat.

Fatty acids significantly increasing the likelihood of the appearance of new lesions were lauric [coconut oil and palm kernel oil], oleic [olive oil], and linoleic [olive oil]

Reports of the reduction in arterial lesions at autopsy following semi-starvation conditions during World Wars I and II have suggested the necessity of austere diets to ameliorate atherosclerosis. However, more reasonable alterations of diet [substitution of low-fat foods for high-fat foods] appear adequate to produce detectable improvement of coronary lesions in angiographic studies.

6. Olive, Soybean And Palm Oils Intake Have A Similar Acute Detrimental Effect Over The Endothelial Function In Healthy Young Subjects, Nutrition, Metabolism, and Cardiovascular Diseases, January 2007

Conclusions: No difference was found in the acute adverse effect of the ingestion of different vegetable oils on the endothelial function. All the vegetable oils, fresh and deep-fried, produced an increase in the triglyceride plasma levels in healthy subjects.

I’m going to go ahead and say that this is why 179 people who were eating the Mediterranean diet in the PREDIMED study who had “no cardiovascular disease at enrollment” experienced a “major cardiovascular event” in the ~ 4.8 years of the study … because they were consuming a lot of fat, especially olive oil.

Clearly, olive oil is not the heart-healthy food it’s made out to be. It is a feat of marketing that a food which has been shown to impair artery function exists in people’s minds as an elixir.

3 thoughts on “Mediterranean Diet Post 6: Olive Oil Promotes Atherosclerosis, Impairs Endothelial Function

  1. forumholitorium

    For decades, the only fat/oil I have regularly used at home is olive oil – and just one tablespoon per cooked meal to sauté vegetables – but thanks to your posts and links (I got lost on the UC Davis site yesterday) I have decided to go about breaking this habit.

    I assume study 4 above is probably the explanation for the so-called French paradox. What exactly do the authors of study 5 mean by an austere diet? Would the Mount Athos diet qualify as austere? And isn’t there a component in olive oil that is supposed to protect against breast cancer? (I think I may have read that in Dr. Greger’s How Not to Die.)

    Recently I read that “the body” (=usually an average male body) needs 30 grams of fat per day in order to absorb vitamins A, E, and D properly. For my weight, my RDA of protein is 33 grams. Do I really need nearly as much fat as protein? How can I calculate fat requirements related to body weight, sex, and age (40+)?


    1. Bix Post author

      I do think that the diet Mount Athos monks eat is austere, at least as described. You never know what someone is eating unless you ask them, even then they may not tell you the truth. The monks eat two meals a day, mostly plant food, restrict oils and alcohol, and periodically fast. It is, like many diets I’ve see that improve health, low-fat and high-carb.


  2. Pingback: Mediterranean Diet Posts | Fanatic Cook

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