Is cooking with olive oil harmful to your health? I used to think so but updated research has shed new light on the topic. Keep reading to see what changed my mind.
Olive oil — the food that brings us all together.
Whether you’re keto, paleo, vegan, vegetarian, eat a low-fat/high carb diet, or low carb/high-fat diet, it seems everyone agrees that olive oil has impressive health-promoting properties and should be consumed regularly, especially in cold applications like salad dressings.
Winner, winner, amazing olive oil for dinner! 😉
But should we be cooking with olive oil?
For many years I thought the answer to that question was “probably not,” or at least, “keep it to low heat cooking methods.”
I believed, as did many others at the time, that heat damaged the vitamin E and polyphenols in olive oil and that if you heated the oil beyond its smoke point, it would begin to break down and create health-harming compounds.
Actual scientific studies were lacking, so I tested the actual temperature of olive oil with various cooking methods in my kitchen and was comfortable with roasting or baking with olive oil, but I steered clear of sautéing, searing, and frying.
In the intervening ten years, science has caught up with us real-foodies.
Now we have legitimate scientific studies showing the effects of cooking on various oils – including Extra Virgin Olive Oil ().
So, what’s changed? Let’s dig in and find out.
What is Olive Oil?
Olives are the fruit of the olive tree, which, when pressed, will yield a healthy, antioxidant-rich oil. Olive trees grow in climates with long, hot summers and cool (but not bitterly cold) winters.
Olive oil is one of the staples of the Mediterranean diet and is thought to protect against heart disease and many other serious health conditions. Its benefits are lauded by nearly everyone – from traditional health care professionals to those in natural health spheres.
The fatty acid composition of olive oil varies, but it can contain up to 83% monounsaturated fat, with polyunsaturated fat and saturated fats comprising the remainder of the fatty acid profile.
Throughout history and up to today, olive oil has been used in the kitchen, for skincare, as a natural remedy, and even as fuel.
How to Read an Olive Oil Label
Decoding the labels on the grocery store shelves can be a little confusing, and descriptions of how the oil is picked and pressed and processed and stored can make your head swim.
Here’s a quick primer on olive oil vocabulary.
- Extra Virgin: first press, should be unrefined. All the nutrients are intact, the flavor is “delicate,” and it is as natural as you’re going to get.
- Virgin: also from the first press, but more acidic, fewer health benefits, and stronger taste. The oil was extracted without the aid of chemical treatment.
- Refined: the opposite of virgin, above. Chemicals are often added to extract the oil and to neutralize strong tastes and fatty acids (except for in organic oils – no chemicals allowed there!). Refined oils will last longer and withstand heat, but their health benefits may be reduced. Light or extra light tasting olive oils will fall into this category.
- Pure: a marketing term. Simply means a mix of refined oil and virgin oils. Don’t bother with this one!
- Cold-Pressed: The oil must be physically removed from its source without heat. All extra virgin olive oil, for example, is cold-pressed by default because the heat would cause the oil to miss the mark for the “extra-virgin” status.
- Expeller-Pressed: a way of saying “without chemicals” in the oil world. The oil may be processed using heat, which may or may not affect the quality and nutrients of the oil.
- Solvent-Extracted: The oil is extracted first by a physical or mechanical process. The oil source is washed with a chemical like Hexane or Heptane to further extract any remaining oil. The chemical is removed from the oil with further processing and refining.
From this point forward, I will be discussing extra virgin olive oil, as it’s the one with the most health benefits and closest to its natural state.
For the sake of ease, I will use extra virgin olive oil (EVOO) and olive oil interchangeably.
The Smoke Point of Olive Oil – Does it Matter?
The smoke point of any particular oil is the point at which the oil gets hot enough to release a bluish smoke. The blue smoke indicates a chemical breakdown.
It was the smoke point that was always considered ‘the smoking gun’ so to speak, as to when oils would become unsafe.
Different oils have different smoke points – even different kinds of olive oil have different smoke points.
So the recommendation was always to choose a higher smoke point oil (like avocado oil or coconut oil or perhaps even refined olive oil) for higher heat applications like frying or sautéing.
Consider heat for a moment: It cooks food, kills bacteria, melts plastics, can burn skin, etc. Heat is a strong source of energy.
It isn’t a huge leap of logic to realize that processing foods with heat will most certainly affect them more than without heat.
But how does it affect them? And does the change make the food less beneficial or even harmful to us?
It is a fact that oils will begin to degrade as they are heated.
The level of deterioration can be measured by the presence of polar compounds in the oil.
Polar compounds are known to be detrimental to human health and have been consistently associated with various forms of cancer and neurodegenerative diseases like Alzheimer’s and Parkinson’s disease.1
As with most things, the dose makes the poison.
A study performed by researchers in Australia measured polar compounds found in 10 common cooking oils after heating the oil to 464 F for 20 minutes and after being heated to 356 F for 6 hours.2
This is what they found:
- Under the conditions used in the study, the smoke point does not predict oil performance when heated.
- Oxidative stability and UV coefficients are better predictors when combined with total levels of polyunsaturated fatty acids (PUFAs).
- EVOO performed best of all ten cooking oils – yielding low levels of polar compounds and oxidative byproducts, especially when compared to high PUFA seed oils, like Canola.
- Extra virgin olive oil’s fatty acid profile (consisting largely of monounsaturated fats) and high levels of antioxidants allow the oil to remain stable when heated (unlike high PUFA oils, which degraded more rapidly). That’s even more evidence to avoid high PUFA canola and soybean oil.
- Close behind EVOO were coconut oil, avocado oil, and high oleic peanut oil.
So what does this mean in plain English?
It implies that EVOO is an excellent choice for cooking!
There have even been studies that show that EVOO boosts antioxidant levels in vegetables when used for sautéing or frying.3
Can You Fry with Olive Oil?
As part of their study, the researchers in Australia tested oil performance after being heated to 356 F (180 C) for 6 hours to simulate a deep-frying type of experience. Based on their results, I think it’s clear that EVOO can be used for frying and may actually be the best choice.
That being said, high-quality EVOO is expensive, and deep-frying requires a lot of oil – most of which will need to be discarded.
Because oils are damaged by heat, they become more susceptible to oxidation each time they are reused. For this reason, I would not recommend ever reusing frying oil.
I rarely, if ever, deep fry my food, preferring a quick shallow fry or sauté, but if you’re set on deep-frying, you might give high oleic peanut oil a try.
It’s less expensive than olive oil and still looks to be a great choice based on the study.
Is it Safe to Sauté with Olive Oil?
The second part of the Australian study heated oil to 464 F (240 C) for 20 minutes.
This is very similar to what I would do in my cast iron pan if I were going to sauté in olive oil (or even shallow fry).
Hands down, it looks like EVOO is the best choice for this too! Surprise!
However, I wouldn’t hesitate to use avocado oil, coconut oil, tallow, or even lard, ghee, or bacon drippings depending on the flavor I want to impart and what I had on hand.
Even though the Australian study didn’t test solid animal fats, I feel sure that their low PUFA/high saturated fat content would still make them a safe choice for cooking.
Can you Bake with Olive Oil?
We know that it’s safe to bring oil to deep frying temperatures (350ish) for 6 hours and up to 464 for 20 minutes, but what about baking?
Is it safe to use olive oil in a recipe that you’re going to put in the oven at 400 degrees for 35 minutes?
Absolutely, without a doubt, yes!
The temperature of the oven doesn’t equal the temperature of the ingredients in the oven. Think of roasting a turkey. You might have the oven on 375 for hours, but you’re waiting for the turkey to reach 165 degrees to be finished.
This same line of thinking can be applied to roasting veggies in olive oil.
In this case, the oil is on the exterior of the vegetable, but the veggies will be done long before the olive oil exceeds the smoke point (or the temperatures in the study).
I tested this out myself back when I was only worried about the smoke point of the oil.
I put shallow bowls of olive oil in the oven at various heat levels and used a thermometer to test the temperature of the oil. It’s the only reason I felt safe roasting veggies in olive oil before this updated research.
Which Olive Oil is Best for Cooking?
Extra Virgin olive oil is the way to go, although it may cost a bit more than the alternatives.
You’re getting what you pay for in nutrition, health benefits, and antioxidant protection against oil deterioration.
Unfortunately, in this day and age, we have to worry about crazy things like olive oil fraud. This is where olive oil companies intentionally cut the olive oil or replace it altogether with less expensive (read – high PUFA) oils and still try to pass the product off as EVOO.
The best way to avoid this is to know your farmer – but the fact of the matter is that many of us don’t live anywhere near locations where olive trees can be grown successfully.
The next best thing is to buy from a company you trust. One who is transparent about their growing, harvesting, and bottling practices.
I have purchased my olive oil from Wildly Organic
One company that has recently caught my eye is Kosterina (use the code KOSTERINA for 15% off orders over $50 at that site!). Kosterina provides premium, organic extra virgin olive oil straight from Greece and ships directly to your doorstep.
Kosterina organic extra virgin olive oil is cold-pressed in small batches in Crete from a single blend of early harvest olives grown in Koroni, Greece. Their EVOO is exceptionally high in polyphenols – the antioxidants that have been proven to have anti-inflammatory effects, and has a light, fruity flavor.
Another company with high standards and a great product is Sardel. Sardel Kitchen offers an organic Extra Virgin Olive Oil produced in Italy and uses local Coratina olives, grown on centuries-old trees that Puglia is known for.
Sardel’s olive oil has a unique balance of spice, fruitiness, and bitterness, which will enhance and accent the flavors of whatever it is you’re cooking.
If you are buying your olive oil from the grocery store, you can use a few tricks to try to get the best product possible.
- Reference back to the section in this article on ‘how to read an olive oil label’
- Look for a source listed for the olives (note that ‘bottled in’ and ‘grown in’ are two very different things)
- Look for olive oil that has a harvest date listed on the bottle (the more recent, the better!)
- As a general rule of thumb, avoid clear glass or plastic bottles.
Important Notes on How to Store Olive Oil
Light damages oil just as heat does, so be sure to buy opaque or dark glass containers.
If you can only find clear glass containers of EVOO, at least grab it from the back of the shelf and shop at a store that is busy enough to be restocking often (from opaque cardboard boxes, right?).
Don’t put your oil in a fancy glass bottle on the counter, and be sure to store it away from heat sources.
If you buy in bulk, store most of your oil in a cool, dark place (out of the kitchen if possible), and use it all up within a year.
Extra Virgin Olive Oil – A Superfood for a Reason!
I love that we have this new science on the safety of cooking with olive oil. For years I didn’t feel safe using olive oil with high heat, but now we know more.
And when you know better, you can do better.
I still tend to be hesitant and cautious, but it’s nice to learn about one more thing we don’t have to worry about.
Extra virgin olive oil really is impressive!
I think it’s clear that to keep the balance of all its nutrients and antioxidants in our diet, it should be consumed in its raw form when possible.
But it’s so nice to know that nature has provided protective benefits to also make it an excellent choice for cooking.
Now I can feel safe grabbing a bottle for a quick pour rather than a knife to scoop out a solid fat – one more score for saving time in the kitchen!
- Fried food risks: Toxic aldehydes detected in reheated oil. (2012, February 22). Retrieved October 29, 2020, from https://www.sciencedaily.com/releases/2012/02/120222093508.htm
- De Alzaa, F., Guillaume, C., & Ravetti, L. (2018). Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating. ACTA Scientific Nutritional Health, 2(6). Retrieved from https://actascientific.com/ASNH/pdf/ASNH-02-0083.pdf
- Ramírez-Anaya, J. D., Castañeda-Saucedo, M. C., Olalla-Herrera, M., Villalón-Mir, M., Serrana, H. L., & Samaniego-Sánchez, C. (2019). Changes in the Antioxidant Properties of Extra Virgin Olive Oil after Cooking Typical Mediterranean Vegetables. Antioxidants, 8(8), 246. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6719931/