Oil or no oil; a viewpoint

The whole food plant-based (WFPB) diet community are divided on the topic of added oils in the diet. Just to be clear, we are talking about extracted plant oils and not healthy fats found in whole plant foods. What should also be remembered is that is it always best to concentrate on the quality of the whole diet rather than individual components. A diet centred around whole plant foods, whether it contains added oil or not, is the healthiest choice you can make. Debates around individual components of the diet can detract from this important yet simple message.

The original adopters of a WFPB, including Dr T. Colin Campbell, Dr Dean Ornish and Dr Caldwell Esselstyn, recommend avoiding all added oils in the diet, including olive oil. Dr Esselstyn’s recommendations for me carry a lot of weight as he has dedicated his life to successfully helping patients with heart disease arrest, holt progression and in some cases even reverse the condition. The dietary intervention that he has shown to cause regression of atherosclerotic plaque is one that is very low in fat and avoids all added oil.


However, consensus amongst the general international Cardiology community is that the addition of extra virgin olive oil (EVOO) is beneficial for heart health. This is because EVOO is a source of monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), tocopherols, and polyphenols. Studies show that replacing saturated fat (predominately from animal sources) in the diet with unsaturated fat improves health outcomes and reduces mortality (as shown in the graph below).

Relation between increasing intakes of trans, saturated, unsaturated, monounsaturated, and polyunsaturated fatty acid (compared isocalorically with carbohydrate) in relation to total mortality. Data are based on 126,233 men and women followed for up to 32 years, with assessments every 4 years. The strong inverse association with polyunsaturated fatty acids was primarily due to N-6 polyunsaturated fatty acids; associations with N-3 polyunsaturated fatty acids were weaker. (Dietary fat: From foe to friend? SCIENCE16 NOV 2018 : 764–770)

Polyphenols in general are beneficial for health as they are anti-inflammatory and help counteract oxidative stress. The polyphenols in EVOO are thought to be a major reason why its consumption has been shown in some studies to benefit health. One reason cited to avoid EVOO is that in some, but not all studies, EVOO has been shown to impair flow-mediated vasodilatation (FMD), an indicator of endothelial function. Impaired endothelial function is a major driver of atherosclerosis. However, a 2015 meta-analysis suggested that olive oil had a favourable effect on FMD. Nonetheless, a meta-analysis is only as good as the studies included and the comparator data. Another study compared olive oil with walnuts and demonstrated walnut consumption improved FMD in the context of an already high fat meal, whereas olive oil did not. This suggests that consuming fat from whole plant sources may be better for heart health than olive oil, but it is not clear to me if this study used EVOO. The study that has not yet been performed is a comparison between a non-oil WFPB diet vs WFBP plus EVOO.

Science and nutritional data are never black and white. So here are my take home messages:

1. EVOO is a source of MUFA, PUFA and polyphenols. The consumption of these compounds have been associated with improved health outcomes. The consumption of EVOO for cardiovascular health is supported by the American College of Cardiology and the European Society of Cardiology. The image below is from a paper that is actually co-authored by Dr Caldwell Esselstyn, Dr Neal Barnard and Dr Dean Ornish.

2. EVOO is not an essential component of a healthy WFPB diet as unsaturated fats and polyphenols can be obtained from whole plant sources — olives, nuts/seeds, avocado and berries. So the decision comes down to personal preference.

3. If you are young, fit, physically active, an ideal body weight and are free from health problems then the addition of small amounts of EVOO and other oils such as hemp seed, flax seed and avocado oil to aid nutrient absorption and obtain essential fatty acids is unlikely to result in harm. It just comes down to personal preference. Note: olive oil is not suitable for very high temperature cooking due to a lower smoking point than oils such as canola and avocado oil.

4. Given that most of the Western World is suffering from an epidemic of overweight and obesity, added oil, whether EVOO or other, is a very calorie dense addition to the diet and may make weight loss harder to achieve.

5. EVOO is the least processed or refined type of olive oil and it is this product that has the best data supporting its benefit for heart health. However, EVOO is expensive and most people are likely to be consuming more refined sources of olive oil. For some, EVOO is an expense that is not necessary and money is better spent towards buying whole fruits and vegetables.

5. If you have established atherosclerosis then the only diet shown to halt the progression is a no oil WFPB diet.

6. Certain inflammatory conditions do seem to be aggravated by the addition of processed oils to the diet such as lupus, arthritis, multiple sclerosis and polycystic ovary syndrome. In these situations I would definitely avoid added oil in the diet.

MOST IMPORTANT TAKE HOME MESSAGE: It is best to concentrate on the quality of the whole diet rather than individual components. A diet centred around whole plant foods, whether it contains EVOO or not, is the healthiest choice you can make.

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