Olive oil: a true ‘essential oil’

Olive oil is a core staple in a Mediterranean-style diet. And it is for good reasons that it takes a central place as a ‘go to’ salad and cooking oil in kitchens around the world. In this age where too many foods are dubiously anointed with the title of ‘superfood’, extra virgin olive oil may just be one food deserving of this name in the oil category. In this podcast, I’ll look at the unique properties of olive oil and delve into what the scientific evidence says about its health benefits.

Links referred to in the podcast

• Olive oil consumption and risk of cardiovascular disease and all-cause mortality https://www.frontiersin.org/articles/10.3389/fnut.2022.1041203/full
• The PREDIMED Study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030221
• Coconut oil consumption and cardiovascular disease risk https://academic.oup.com/nutritionreviews/article/74/4/267/1807413

Episode transcript
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Transcript

Olive oil is a core staple in a Mediterranean-style diet. And it is for good reasons that it takes a central place as a ‘go to’ salad and cooking oil in kitchens around the world. In this age where too many foods are dubiously anointed with the title of ‘superfood’, extra virgin olive oil may just be one food deserving of this name in the oil category. In this podcast, I’ll look at the unique properties of olive oil and delve into what the scientific evidence says about its health benefits.

Say the word olive oil, and it is natural that your mind goes to the Mediterranean. Olive oil has been a staple cooking oil in many cultures around the world for thousands of years. Olive oil is mostly made up of monounsaturated fats and is about the highest dietary source of these. In fact, the primary monounsaturated fat in it is called oleic acid – named, you guessed it, after olive oil itself. But it is not just the type of fatty acids present in olive oil, but a range of antioxidants and other bioactive compounds that could lend it its deserved ‘healthy oil’ reputation.

So just for noting here, for most of this podcast, I’ll be referring to extra virgin olive oil when I’m talking about olive oil. Extra virgin olive oil is the highest quality and least refined form of olive oil. It also has the strongest taste and aroma. Extra virgin olive oil is made from the cold pressing of olives with no chemicals or heat used and is bottled soon after to preserve the quality of the oil. It is also the most expensive of the olive oils, but that price premium is well worth it for the quality, taste and health benefits.

The other types of olive oils go under different names such as virgin olive oil, refined olive oil and pure or extra light olive oil. As the grading changes, so too does the taste decline and the amount of beneficial compounds decrease. Now, these types of oils do have a role to play in cooking and other uses, but it really should be extra virgin olive oil that is the main olive oil in your pantry.

So, let’s get on to why extra virgin olive oil deserves so much of the health spotlight. And here, I want to first profile some of the key nutrients found in olive oil.

As I’ve already said, olive oil is very high in monounsaturated fat which makes up around three-quarters of the total triglyceride content. That is a lot of healthy fat.

But if you’ve ever tasted extra virgin olive on its own, you’ll be familiar with its grassy aroma and peppery bite that you can feel in the back of your throat. They are all signs of plenty of bioactive compounds in the oil.

Extra virgin olive oil is known for having a high content of antioxidant compounds with protective properties against free radicals. The compounds include various phenols such as oleocanthal, hydroxytyrosol and tyrosol as well as phytosterols, vitamin E and squalene that are all linked to the antioxidant and anti-inflammatory properties of olive oil. It’s well beyond the scope of a single podcast to go into all these compounds separately, so instead just know that as a food source added to the diet, it is the interplay between all these compounds in olive oil that is also the reason it is linked with so many health claims. And what are those health claims?

When you think of olive oil, it is the Mediterranean diet and heart health that likely immediately come to mind. And for good reason, the presence of extra virgin olive oil is considered one of the factors in explaining the benefits of this dietary pattern. And a recent meta-analysis looked at just how much influence the olive oil component of the Mediterranean diet could have. Thirteen studies were included in the review which looked at associations between olive oil consumption and cardiovascular disease risk or all-cause mortality risk with studies running from 4 up to 28 years.  And the summary here is that for every 5-gram increase in consumption of olive oil per day, up to 20 grams per day, it was associated with a 4 percent lower risk for cardiovascular disease and all-cause mortality. And I’ll link to the study in the show notes. https://www.frontiersin.org/articles/10.3389/fnut.2022.1041203/full

And compared to people who had the lowest amount of olive oil in their diet, people having the most had a 15 percent lower risk of cardiovascular disease and a 17 percent lower chance of dying over the time the study ran. The studies though were observational so it is possible there could be other things that explained the benefit such as people having more olive oil also having a healthier lifestyle. However, most of the included studies did adjust for this by taking into account BMI, energy intake and a person’s overall dietary pattern.

But we do at least have one key dietary intervention study in this field. Called the PREDIMED Study, it looked at how a Mediterranean diet supplemented with nuts or extra virgin olive oil, or a control low-fat diet could affect the risk of cardiovascular disease. And it was studied in people aged 55 to 80 years at high risk of cardiovascular disease. Each person was randomised to one of the three different diets for several years.

And the clear finding was that for every 10 grams per day increase in extra virgin olive oil consumption, cardiovascular disease risk fell by 10 percent and the risk of earlier mortality fell by 7 percent which nicely agrees with the observational research. The greatest benefits though were seen when olive oil was part of a Mediterranean-style diet rather than a low-fat diet. And I’ll link to this study in the show notes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030221

And related to heart disease, several large studies have shown that people who consume olive oil have a much lower risk of stroke. Stroke shares many of the same risk factors with heart disease such as high cholesterol and high blood pressure.

There are several plausible reasons to explain why olive oil could be having benefits on the heart and circulatory system. From direct human intervention food trials, you can see an effect of olive oil on blood lipids, blood pressure, insulin sensitivity, and glycaemic control. And our old friend the gut microbiota seems to benefit as well where olive oil has been shown to positively modulate the gut microbiota composition and microbially produced products.

You’ll also find other health links related to olive oil that reference a benefit in reducing the risk of Alzheimer’s disease, type 2 diabetes, bone fractures and some forms of cancer. But I caution here that most of the research is observational that could not always adequately isolate the effect of olive oil and is likely heavily influenced by people usually following a Mediterranean-style diet. So even though there are plausible mechanisms to explain a benefit of extra virgin olive oil in helping with these conditions, they don’t stand alone for what other beneficial aspects of a healthy diet can provide. Instead, think about it this way: olive oil adds to the overall health of the diet rather than is a single superfood agent that will give you top health on its own.

And when it comes to heart health, I really do need to make mention of that superfood imposter coconut oil. Coconut oil is attracting much attention for its many claimed health benefits. Many of the health claims though represent marketing being well advanced of the science. Coconut oil is a pin-up food to showcase the power of the Internet to propagate any food to ‘superfood’ status. Coconut oil is very high in saturated fat, at around 90 percent. It is claimed that the type of saturated fat found in it is healthier than other types of saturated fat so it doesn’t represent a risk to cardiovascular health.

Now in truth populations that use coconut oil as part of their traditional lifestyles do appear to have lower rates of heart disease. So this gives some credence to the heart-health claims. But of course, such observational studies can be heavily biased by all sorts of other lifestyle factors. In such diets, coconut oil is eaten together with the fibre from the coconut along with plenty of omega-3 fats from fish. These traditional diets also are low in highly refined carbohydrates and sugar. Compare that to the popular coconut oil dessert-based dishes that abound in its promotion through social media.

There have been some clinical trials that appear to show that coconut oil may have less of an adverse effect on blood cholesterol than other types of saturated fat. But that doesn’t mean then that it is healthier than other types of oils.

Looking at the observational and clinical trial evidence together, what sort of conclusions can be drawn? Combining 21 published studies in a review, researchers found that coconut oil did raise the less favourable LDL-cholesterol to a greater extent than other types of plant oils. Butter however was found to raise LDL-cholesterol even more. And I’ll link to this study in the show notes. https://academic.oup.com/nutritionreviews/article/74/4/267/1807413

What this means is that coconut oil is not some miracle health elixir. On balance, it should not be viewed as much different from other sources of dietary saturated fat. It has its place in cooking like any oil or fat, but it is better to consider using a variety of oils in cooking for the job at hand and the taste outcome a person wants.

And don’t believe what you may hear that olive oil is bad for you because it has low stability and is heat sensitive. Yes, olive oil will oxidise and go rancid eventually, but ‘so what’? All oils will do that eventually given enough time. That’s why it comes in a dark bottle, is recommended to be stored in a cool dark place, and used within about 6 months after opening for its optimal taste and benefits.

Coconut oil will oxidise and go rancid exactly like olive oil, just that may take longer to do it. It’s like arguing that UHT milk is ‘better’ because it has a longer shelf life compared to fresh milk.

And as for heat stability, the smoke point of extra virgin olive oil is on par with unrefined coconut oil. The smoke point of an oil is the temperature at which it begins to smoke and break down, creating harmful compounds and unpleasant flavours and odours. This temperature varies depending on the type and quality of the oil, as well as its level of refinement and how it was processed. Oils with high smoke points, such as refined olive oil, canola oil, and safflower oil, are more suitable for high-heat cooking methods like frying and roasting, as they can withstand high temperatures without burning or smoking. Oils with lower smoke points, such as unrefined flaxseed oil or extra virgin olive oil, are better suited for low-heat cooking methods like sautéing or as a finishing oil, as they are more prone to smoke and break down when exposed to high heat. But because of the abundance of antioxidants in extra virgin olive oil, it offers a large degree of protection of the oil from breakdown during heating.

So, let’s wrap all this up. Extra virgin olive oil is considered a healthy oil due to its high content of monounsaturated fatty acids, polyphenols and other beneficial bioactive compounds. Studies have shown that extra virgin olive oil can improve markers of heart health, such as blood pressure and cholesterol levels, and may also have anti-inflammatory and anti-cancer properties. And on top of that, extra virgin olive oil is a versatile ingredient that can be used in a variety of dishes and cooking methods, making it an easy and delicious way to incorporate healthy fats into your diet. In your kitchen, it pays to have a variety of oils and fats depending on your cooking and flavour goals, but no pantry should be lacking a bottle of extra virgin olive oil.

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.

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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.