Caldwell Esselstyn claims here that studies show that all oils, including olive oil, contribute to heart disease. From other sources I get that the tension between what he is saying and the positive scientific opinion on olive oil, is due to Esselstyn comparing using olive oil to using no oil at all, while almost all other studies compare different diets where some fixed fraction of the energy comes from fat. So, if olive oil is seen to have benefits that's then relative to using something worse, this then doesn't prove that olive oil is healthy in an absolute sense.

Olive oil may thus be harmful and the studies Esselstyn cites suggests that it indeed is. But I'm not all that convinced; the arguments are indirect, I like to see studies that go more directly to the heart of the matter like a clinical trial comparing the Mediterranean diet to an extreme low fat diet. There are hints from older studies that an extreme low fat diet might work better, see e.g. here:

Shaper started with the observation as a clinician in the 1950s that coronary heart disease in the African population in Uganda was almost non-existent, and this appeared to be confirmed by necropsy studies. On the other hand, coronary heart disease appeared to be a major problem in the Asian community in Ugandawith a high proportion of deaths attributed to coronary heart disease.

Though Shaper and Jones did not appear to collect detailed dietary data from individuals in the study apart from identifying vegetarians and non-vegetarians in the Asian group, they presented descriptions of dietary patterns then prevalent in African and Asian communities around Kampala. They cited reports from other studies indicating relatively low meat and fat intakes (∼16–20 g a day) in the African communities, with possibly up to 40 g fat a day in more well-to-do families. With estimated intake of 2000 calories per day, this would be ∼10–20% of total caloric intake.

But it seems that there are no clinical trials comparing conventional diets that use oils as we are all used to doing to an extreme diet that uses no oil at all.

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  1. Intake of repeatedly heated olive oil was noted to produce harmful effects on endothelial function in normal young healthy volunteers.

Long-term intake of diet comprising reheated vegetable oil leads to endothelial dysfunction. Repeatedly heated dietary vegetable oil promotes oxidative stress, resulting in NO inactivation and reduced bioavailability. Moreover, antioxidant effect of fresh vegetable oil against free radicals may be reduced gradually as the oil is repeatedly heated. Production of free radicals and reduction of antioxidant and vitamin levels eventually lead to oxidative stress. Oxidative stress and endothelial dysfunction play pivotal roles in the pathogenesis of cardiovascular diseases, which may be controlled by diet modification. Ingestion of repeatedly heated vegetable oil should be restricted due to the detrimental consequences on health. Source: Effects of Repeated Heating of Cooking Oils on Antioxidant Content and Endothelial Function

  1. The positive effects depends on the type of olive oil used and its components.

Minor components constitute only 1-2% of virgin olive oil (VOO) and are composed of hydrocarbons, polyphenols, tocopherols, sterols, triterpenoids and other components usually found in traces. Source: The role of virgin olive oil components in the modulation of endothelial function

  1. Functional virgin olive oil (FVOO) enriched with phenolic compounds provided benefits on endothelial function in hypertensive patients.

After FVOO ingestion, oxidised LDL decreased (P=0.010) in an inverse relationship with IRH AUC values (P=0.01). FVOO provided more benefits on endothelial function than a standard natural virgin olive oil in pre- and hypertensive patients. Source: Effects of functional olive oil enriched with its own phenolic compounds on endothelial function in hypertensive patients. A randomised controlled trial

  1. Polyphenol-rich olive oil is noted to improve endothelial function in young women with high-normal BP or stage 1 essential hypertension

When compared to baseline values, only the polyphenol-rich olive oil diet led to a significant (P < 0.01) decrease of 7.91 mm Hg in systolic and 6.65 mm Hg of diastolic BP. A similar finding was found for serum asymmetric dimethylarginine (ADMA) (-0.09 ± 0.01 µmol/l, P < 0.01), oxidized low-density lipoprotein (ox-LDL) (-28.2 ± 28.5 µg/l, P < 0.01), and plasma C-reactive protein (CRP) (-1.9 ± 1.3 mg/l, P < 0.001). The polyphenol-rich olive oil diet also elicited an increase in plasma nitrites/nitrates (+4.7 ± 6.6 µmol/l, P < 0.001) and hyperemic area after ischemia (+345 ± 386 perfusion units (PU)/sec, P < 0.001). Source: Olive oil polyphenols decrease blood pressure and improve endothelial function in young women with mild hypertension

The beneficial effects of olive oil is attributed to its polyphenol content.

In this context, it is relevant to consider the beneficial effects on FMD that have been reported in subjects given virgin olive oil which are now being attributed to its polyphenol content rather than its HM content. Source: SFAs do not impair endothelial function and arterial stiffness

TL;DR: Olive oil is a healthy fat but it is not as healthy as canola oil, fish oil and flaxseed oil.

It’s clear that olive oil is a healthier fat than many others, but not as healthful as canola oil or fish oil. A study by Dr. Robert Vogel in the Journal of the American College of Cardiology found that olive oil significantly reduces blood flow to different parts of your body, whereas canola oil and salmon do not. This measure of blood flow, called flow-mediated vasodilation (FMD), is a standard, well-accepted test by the American Heart Association and others. In this study, blood flow (FMD) was reduced by 31% after an olive-oil meal but was not reduced by a meal with a similar amount of fat from canola oil or salmon, probably due to the higher content of the protective omega-3 fatty acids in canola oil and salmon. Source: The Great Olive Oil Misconception

Recent research by a study partly supported by Olivi Agri Team Srl-Grosetto, Italy shows that long term supplementation of olive oil improves endothelial function in individuals with low to intermediate CV risk.

A concomitant reduction in white blood cells, particularly monocytes and neutrophils, as well as sICAM points to a potential mechanism for improved endothelial function through a reduction in vascular inflammation. Interestingly, patients with low endothelial function at baseline appear to garner the most benefit from OO. Thus, supplementation with OO seems a reasonably easy and relatively cheap dietary measure to improve endothelial function and perhaps favorably alter the progression of atherosclerotic disease, particularly in patients with already markedly impaired endothelial function. Source: Beneficial effects of polyphenol-rich Olive Oil in patients with early atherosclerosis

Replacing saturated fats with high quality carbs such as whole grains along with the intake of unsaturated fats was found to be most effective at lowering risk of heart disease.

A study published today in the Journal of the American College of Cardiology shows that replacing saturated fats with unsaturated fats and high-quality carbohydrates has the most impact on reducing the risk of heart disease. When saturated fats were replaced with highly processed foods, there was no benefit. In an accompanying editorial, Robert A. Vogel, M.D., Cardiology Section at the Department of Veterans Affairs Medical Center in Denver, said, "Healthfulness clearly lies in the quality or type of both fat and carbohydrate." Source: Unsaturated Fats, High-Quality Carbs Lower Risk of Heart Disease

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    "High Quality Carbohydrates" xD xD ... there are many studies showing that there is a direct causal relation between 'wholegrain' carbohydrates and inflammatory diseases such as IBD, IBS, etc. Please don't replace saturated fats with carbs - bad idea.
    – Cloud
    Sep 19, 2018 at 15:10

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