I get a lot of questions, and frankly, have had a lot of questions myself about oils and specifically olive oil. It is quite confusing when you look at the all the olive oils on the shelf as to what is good, what is not and what are the differences in the types of oils. Also, there is a lot conflicting information about whether or not you should cook with it. In this prattle I dive into some of these topics and much more.
First, let's define some terms.
This means that high heat or chemicals were used to extract the oil from the seed. Most soy, corn, canola and "light" olive oils are refined (particularly when used in processed foods). The oil that is most prevalent in processed food in the US is soy oil and it is nearly always refined. One of the reasons refined oils are used instead of unrefined is because they have a longer shelf life - they are much more stable and won't become rancid after sitting on the shelf for a long time. The problem with refined oils however is that for one, any nutrients that they might have had has been cooked out of them during processing. The oils are also cheaper to make, they can use lower quality product to start with, and they can use GMO seeds. Now there is some controversy over whether GMO products are inherently "bad" however, there is no doubt that one of the main reasons why GMO seeds are used is so they are resistant to Roundup (glyphosate), which is a toxic pesticide that has ramifications in the body that we are only now tapping the surface of understanding. It is a proven carcinogen at high doses - especially amongst farmers, fruit pickers and the like that interact with it, that much is sure. That's why I always look for organic or at least a label stating that it is non-GMO when it comes to the oils that I consume (and all products actually).
Now, there might be a couple reasons to purchase a refined oil. For one, as I said, it has a longer shelf life. Also, refined oils have, for the most part, have much higher smoke point than unrefined oils. They don't break down so easily when exposed to heat and therefore, if you are going to say, deep fry something, it's best to use a refined oil (and it's best not to use the oil to fry more than once because the longer it is exposed to high heats or the more times it is used and cooled and used again, the chains of carbon atoms break down creating free fatty acids which are toxic for the body).
This is one reason why it was such a bad thing for the health of people who eat french fries at McDonalds when they switched (because of misguided public pressure) to go from a much more stable beef tallow to a much more unstable vegetable oil. There is this mistaken notion that vegetable oil must be good because, duh, it comes from vegetables. But in fact, it's a much more unstable oil meaning it breaks down more easily which creates toxic byproducts. It also is much higher in omega 6 fatty acids and is one of the reasons why the US population's balance of omega 6 and omega 3 fatty acids is so skewed. The average person in the US ingests close to a 16:1 (some have determined that it's closer to 25:1) ratio of omega 6 to omega 3 fatty acids. Traditional cultures who eat in the way that we used to eat a ratio of around 2:1 or 4:1. Eskimo populations who eat a lot of whale blubber, for instance, the ratio is closer to 1:4. Many think that one of the main drivers of chronic disease in our culture is due to the dominance of omega 6 fatty acids in our diet which in large part derives from seed oils and is highly inflammatory leading to heart disease, diabetes, cancer, neurological disorders and much more.
I know this is a tangent but I just want to get the point across that avoiding refined soy, corn and canola oils (or all seed oils for that matter) would be a step in the right direction to provide protection from one of the many chronic diseases that is ripping apart so many lives. As much as you can, avoid foods made in a factory that come in bags and boxes as they so often contain unrefined seed oils which can set off a chain reaction in your body leading to disease. Eat food, not too much, mostly plants.
Unrefined oils are usually made from pressing or centrifuging the fruit. Unrefined olive oils are made using presses and unrefined avocado oils are made, for the most part, using a centrifuge. These oils are more delicate than refined oils but are high in polyphenols, phytonutrients, and vitamins because the nutrients haven't been cooked or "chemicaled" out of them in the extraction process. Most of the time, when it comes to unrefined oils, you will see that they are "cold pressed" or "cold processed". This is because the pressing process can get hot and therefore, they do the processing in a cold environment so the oil doesn't heat up and degrade.
For the most part, you should use your unrefined oil within 4-6 months of purchase if not sooner. Oils, unlike wine, do not get better with age. They become rancid. Keep your oil in a cool, dark place but best not to refrigerate it.
Extra virgin olive oil
Extra virgin olive oil (EVOO) is by definition unrefined and cold pressed. The best quality olive oils start with a high quality olive. Then, the shorter the time between the picking of the olive and the bottling of the oil, the better. A good oil will have low acidity, under .8% for sure and the best stuff is around .3%. This is one way you can tell if the oil is high quality and it will sometimes tell you on the bottle. Also, a good oil will taste maybe somewhat bitter and / or spicy. It it is just kind of oily or greasy, it's probably not so great.
I tend to prefer olive oil that is from California. For one, it has to travel less distance than oils from Europe. Also, there are organizations such as the California Olive Oil Council that certifies producers to guarantee what they say is actually what they are doing when it comes to their methods of growing, processing and bottling.
The downside of good quality EVOO is the price. It can get a bit pricy for sure. Just do the best you can and enjoy.
Cooking with Olive Oil
This is one area of controversy. Some people say never expose unrefined olive oils to heat. It is proven that heat will damage, if not completely ruin the amazing nutritional benefits of olive oil. There is debate, however, around whether heating olive oil will harm you by causing it to break down and therefore exposing you to toxic byproducts. This is the part of the discussion where people start talking about smoke points. The assumption is that when an oil starts smoking, that that is when it starts becoming unstable and unsafe. And for the most part, that is a reasonable rule of thumb that I like to go by, though it's not necessarily the case in all instances (and some studies seem to indicate that EVOO doesn't break down into carcinogenic compounds even at or past the smoke point). But to make it easy, I would say, you can sauté with olive oil if you wish, just know that you will lose most if not all the good stuff that makes EVOO great to eat. It also might be better to cook with oils such as avocado oil which has a very high smoke point, up to 480 degrees, or saturated fats like coconut oil, ghee, beef tallow or lard. The saturated fats are the most stable fats and do well under high heat conditions.
Health Benefits of Olive Oil - One Study
One large population study that looked at the health benefits of olive oil was the Predimed study which took place in Spain and began in 2003 and lasted almost five years. Over 7000 people (all who had high risk for cardiovascular disease) were divided into 3 groups. One group ate a low fat Mediterranean diet, one group ate a Mediterranean diet and 30g of nuts per day (about 10 almonds, 5 hazelnuts and 5 walnuts) and one group ate a Mediterranean diet plus four tablespoons of olive oil a day. They ended up having to stop the study early (after about 4 and 1/2 years) because the low fat Mediterranean group had such worse outcomes than the high fat groups. They found that the olive oil and nut groups had a 30% lower incidence of major cardiovascular incidents such as heart attacks or strokes. They also had a 40% less risk of getting diabetes. It turns out that olive oil and other healthy fats like those found in nuts are extremely protective against heart disease and other cardiovascular pathologies. Of course this is just one study and according to some it has some flaws, but it certainly becomes part of a larger body of evidence that points toward olive oil being a good dietary intervention, especially for people with cardiovascular disease.
I hope you enjoyed this little dive into oils and olive oil in particular. If you have any questions or comments feel free to write me and I'd be happy to talk to you about it.