What Makes Extra Virgin Olive Oil So Healthy?

Extra virgin olive oil and pasta
Nadine Greeff/Stocksy United

With headlines like “fat is back” appearing so regularly in the news, it is perhaps wise to remember that healthy fats, such as the monounsaturated fats in extra virgin olive oil have never really “been away.” Olive oil has been at the heart of the traditional Mediterranean diet for thousands of years and evidence is revealing even more fascinating ways in which it may contribute, as a central part of a healthy lifestyle, to preventing chronic diseases including heart disease, some cancers, and even dementia.

Verywell’s Senior Medical Advisor, David L. Katz, MD, spoke to his True Health Initiative colleague and council member Dr. Simon Poole about his new book “The Olive Oil Diet," written with Judy Ridgway. The book explains not only the most recent scientific discoveries on the food which Homer called “liquid gold,” but also how to choose and use the best extra virgin olive oils and incorporate them into recipes for every day.

David L. Katz, MD: Many people might not think of oil as part of a diet, so how do you explain the title of your book?

Simon Poole, MD: I use the word “diet” in its original sense, derived from the Latin “diaeta” which means “way of life.” Olive oil is a fundamental to the cultures of the Mediterranean region, part of ancient traditions, including religious ceremonies as well the ubiquitous fat in the diet for cooking, lubricating and flavoring. We should think more about our diet as a way to keep healthy rather than simply as a way to lose weight.

Although high in calories, olive oil contains good fats which not only promote a feeling of being full, but also reduce the speed of absorption of carbohydrates and help the hormone insulin respond to the potentially fattening sugars released from a meal.

DK: The subtitle talks of the “secrets of the original superfood”—what do you think makes olive oil a “superfood”?

SP: I have heard it said, rather irreverently, that the definition of a superfood is a food with a publicist! And that may well be the case for exotic berries from the Himalayas or green algae, for example. That said, if we accept that the word is here to stay, and that it describes foods with particular nutritional advantages, then extra virgin olive oil is perhaps the most extensively studied single ingredient which has clear benefits for health.

DK: What is the role of olive oil in the Mediterranean diet as a whole?

SP: The most recent US Dietary Guidelines have recommended we focus on the types of fat we eat, rather than on limiting the total fats in our diet, and the book takes a look at the whole Mediterranean diet from the perspective of the part this ubiquitous ingredient plays in the diet, especially when combined with colorful vegetables, fruits, whole grains, beans, nuts, fish, herbs, and spices.

DK: What is the evidence that olive oil, per se, is important in the health benefits of the traditional Mediterranean diet?

SP: Whilst the evidence of the health benefits of the Mediterranean diet are now well established, it is more challenging to take a detailed look at individual foods that are part of the scoring methods researchers use.

However, there have been notable published papers in particular from a study called the EPIC (European Prospective Investigation into Cancer and Nutrition) study, which is a collaboration of research in different European countries. A cohort of the population in Greece demonstrated a significant benefit attributed to the type of fat in the diet and analysis of the work in Spain reported that the participants who consumed the most olive oil appeared to have a relative decrease in death rates of 26 percent.

It is of course very important to look at diets as a whole, and consider the benefits of, for example, combining olive oil with vegetables and other important healthy foods.

DK: What are thoughts on other "healthy" cooking oils? How does olive oil compare? Do any other oils figure in the Mediterranean diet mix?

SP: Certainly the traditional Mediterranean diet includes olive oil as the main source of fat. Although we know that other oils such as canola oil contain monounsaturated fats and other oil manufacturers are increasing the proportion of healthy unsaturated fats in their products, there is increasing interest in the role of the many antioxidants found uniquely in extra virgin olive oil.

Since the evidence for the benefits of the Mediterranean diet has overwhelmingly been gathered in populations who use extra virgin olive oil, it seems wise to follow the pattern of eating practices of this traditional diet.

DK: Are there any healthy ways in which olive oil combines with other foods?

SP: There is evidence to suggest that olive oil combines with nitrate compounds in salads and this can lower blood pressure and protect the good omega-3 oils in fish when fried or baked.

It provides a protective antioxidant glaze when meat is marinated and cooked in olive oil, reducing harmful chemicals released at high temperatures, and also an easily absorbed mixture of healthy fat soluble antioxidants and vitamins is created when vegetables are cooked together with extra virgin olive oil.

DK: How important for health are the antioxidant compounds in olive oil?

SP: Antioxidants in foods and their effect on our health is a really interesting area of research. The European Food Safety Authority has acknowledged, for example, the importance of antioxidants in extra virgin olive oil in reducing a process called “oxidative stress” of LDL cholesterol, one of the key factors thought to occur in the development of heart disease. The antioxidants in olive oil may, in effect, neutralize some of the harmful chemistry which can occur in our body and cause disease. 

DK: What are the different types of olive oil and is it safe to use for cooking?

SP: Unless specified as extra virgin, which is created directly from the juice of the olive in a temperature regulated process, olive oil may be made by an industrial process of refining low quality oil in order to make it fit for consumption.

The refining process destroys many of the antioxidants in extra virgin olive oil which contribute to its very special health properties. Frying, roasting, and baking is generally done at temperatures well below the “smoke point” of a good extra virgin olive oil (200 degrees Celcius) so there is no need to be concerned about the risk of producing harmful chemicals during most types of cooking.

This was confirmed by the large EPIC study which showed that there was no increased risk of heart disease with the regular use of olive oil in cooking. Levels of some of the health giving antioxidants in the oil gradually reduce during prolonged heating, but many remain intact.

DK: Are all extra virgin oils equally healthy?

SP: Quantities of antioxidants in extra virgin olive oil can vary considerably, depending on the olive tree variety, how olives are grown, and how the oil is produced and stored.  Over-intensive farming with too much irrigation and fertilization may increase the amount of oil produced, but it reduces the “stress” on trees, so they need to produce less protective antioxidants. It is possible to taste the difference. A healthy oil, rich is antioxidants, will be peppery and strong in flavor. 

DK: Are there any top tips for how to incorporate healthy extra virgin olive oil into our diets?

SP: Extra virgin olive oil can be used for all types of roasting, frying, and baking as well as having a bottle on the table to be used for drizzling, dipping, and flavoring, just as they do in the Mediterranean. The Mediterranean Foundation recommends olive oil with every meal, and certainly it can be used on toast with honey for breakfast and with baked fruit and nuts as a dessert, and not just confined to dressings or as a cooking oil.

Sources:

Guallar-castillón P, et al. Consumption of fried foods and risk of coronary heart disease: Spanish cohort of the European Prospective Investigation into Cancer and Nutrition study. BMJ. 2012;344:e363.

Ramírez-anaya Jdel P, et al. Phenols and the antioxidant capacity of Mediterranean vegetables prepared with extra virgin olive oil using different domestic cooking techniques. Food Chem. 2015;188:430-8.

Schwingshackl L, et al. Monounsaturated fatty acids, olive oil and health status: a systematic review and meta-analysis of cohort studies. Lipids Health Dis. 2014;13:154.

Sleiman D, et al. Effect of mediterranean diet in diabetes control and cardiovascular risk modification: a systematic review. Front Public Health. 2015;3:69.

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