Compared with many other options, olive oil is healthy, but we need to be sure we are not being fooled when we buy it. University of California Davis in July 2010 suggested that more than 2 out of 3 extra virgin olive oils from Europe are diluted with vegetable oils.
The most common advice we hear is to buy “extra virgin - cold pressed”. But what does this really mean? Extra virgin means that it is taken from the first extraction. Cold pressed means that is is not heated during extraction. It originally described the process of pressing the olives to extract the oil, but most Olive oil is extracted using centrifuges these days. It is generally only boutique olive oil companies that still use a press.
After the first extraction, various other processes are used to extract the last remaining oil from the olives including heat and this can damage the oil and speed up its degradation to a rancid oil which is very bad for your health. So if the label does not mention “cold pressed and extra virgin” maybe put it back on the shelf.
As soon as olive oil is extracted it begins to oxidize, becoming rancid. This is the same process whereby iron oxidizes causing rust. The conditions that accelerate this process are exposure to air, heat and light. Of course the older the oil, the more time it has to go rancid.
One impact of poor quality oils is oxidation of your body tissues. Excess oxygen in the body is toxic and “rusts” your body from within. A byproduct of the processes that make ATP, the body’s energy molecule, is unstable oxygen molecules which react in your body, rusting you, causing inflammation. Antioxidants mop-up these excess oxygen molecules preventing them from damaging you by faster aging. When you eat oxidized oils you transport excess oxygen molecules into your body.
If the highest quality extra virgin oils are often diluted with vegetable oils, then cheaper oils labelled refined, blended, pure or anything else will almost certainly include vegetable oils. So what’s wrong with that? Vegetable oils are industrial oils made with lots of heat, pressure, often with added chemicals (hexane) to help extraction plus dyes, deodorizers and antioxidants to make them palatable. These processes accelerate oxidation, reduce the shelf life dramatically and will promote whole body inflammation.
Vegetable oils are heavy in Omega 6 oils which changes the fine Omega 3 to Omega 6 balance in your body, promoting inflammation. The excess Omega 6 oils replace oils in your nerves and mitochondria membranes, damaging them and reducing their ability to produce energy.
Although there are organisations and standards set to assist with guaranteeing that your olive oil is undiluted, my reading suggests that in many European countries there is often poor compliance with these standards. Perhaps the lure of additional profits overrides the concern for your health, or perhaps the true cost of high quality olive oil makes it hard for suppliers to compete when they don't dilute with cheaper vegetable oils. Aparently Australia has a very robust quality and inspection framework.
The first step is to select an oil that is high quality. To get the best quality, buy local, in very dark bottles, keep in a cool dark place with the top tight and buy smaller bottles so that it does not sit in your house for long. It will cost more but your body will thank you.
Seek professional medical advice before making dietary changes, particularly if taking medications. I can answer questions. Find my book at Amazon here
Good health, George Elder, Diet Researcher, Dip. Nutrition.