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, this does not mean that everyone needs to adopt a no oil, WFPB diet.
Consensus amongst the international Cardiology community and medical community in general 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, from sources such as W=EVOO, improves health outcomes and reduces mortality (as also shown in the graph below). There are also documented benefits from consuming other plant-based sources of fat, including vegetable or seed oils such as canola oil, that tend to be higher in omega-6 fatty acids. In addition, these plant sources of oil may have benefits for lowering inflammation, improving cardiometabolic health and EVOO may specifically be beneficial for brain health and cancer prevention.
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 has a favourable effect on FMD and reduces inflammation. Similarly, the Mediterranean diet pattern, high in EVOO has been shown to lower inflammation and improve vascular health. 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 could suggest that consuming fat from whole plant sources may be better for heart health than olive oil, but it is not clear if this study used EVOO. In general, studies of EVOO and vegetable oils are in population consuming an omnivorous diet or a typical Western diet. As already stated, these oils are definitely better for health when they replace saturated fat in the diet.
We finally have a study of a WFPB diet with or without extra virgin olive, which investigated the impact of adding EVOO on cardiovascular risk factors. The randomised, crossover study found that a WFPB diet (plant-exclusive/vegan) with EVOO (4 tablespoons per day) and without EVOO (<1 teaspoon a day) improved a number of cardiometabolic risk factors, but minimising/avoiding EVOO led to further improvements in total and LDL-cholesterol levels and body weight. Of note, the study was small with only 40 participants, and short in duration with participants following the two different diets for 4 weeks each. In addition, the study cannot tell us about any impacts on long-term health outcomes such as heart attacks and stroke.
Science and nutritional data are never black and white. So here are some 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. Vegetable oils, rich in omega-6 fatty acids, have not been shown to harm health and are certainly better for health than consuming saturated fats, predominantly found in animal source foods.
3. EVOO and other vegetable oils are 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. If you are trying to optimise your LDL-cholesterol level then avoiding added oils may be beneficial.
4. 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 vegetable oils to aid nutrient absorption and obtain essential fatty acids is unlikely to result in harm. It just comes down to personal preference.
5. 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.
6. 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.
7. If you have established atherosclerosis then you may want to try a no oil WFPB diet as used by Drs Ornish and Esselstyn with excellent outcomes..
8. Certain inflammatory conditions do anecdotally seem to be aggravated by the addition of processed oils to the diet such as lupus, arthritis, multiple sclerosis and polycystic ovary syndrome. If this is you, then it’s fine to avoid added oil in the diet and prioritise whole plant sources of fat such as nuts and seeds.
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/vegetable oils or not, is the healthiest choice you can make.
