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"...highly processed..." I think this is an important distinction for evaluating oils. For example, you mention avocado oil and coconut oil. Are these processe

"...highly processed..." I think this is an important distinction for evaluating oils. For example, you mention avocado oil and coconut oil. Are these processed with heat (and possibly solvents)? Or are they cold-pressed with no other chemicals used to aid extraction? In the UK, it is very common to find cold-pressed rapeseed oil (canola oil) in supermarkets. The canola oil sold in US supermarkets is highly processed. Is the cold-pressed version still bad? The problem is that when seed oils are demonised, no distinction is made of the method of extraction. There are hundreds of researchers (and YouTubers) repeating the mantra 'seed oil = bad' without further distinction between heat-pressed and cold-press oil extraction. If extraction methods don't matter, then researchers need to provide evidence to confirm this.

adrian_b 5y ago
You are right that the extraction method matters a lot for any oil. Any method that uses high temperatures may cause various chemical reactions that degrade some of the oil components. Some of the methods that use solvents for extraction may leave very small quantities of the solvents in the oils (e.g. hexane, i.e. a light fraction of gasoline), which are undesirable. Nevertheless, cold-pressing is not necessarily the best method, even if it is preferable to most other old methods. While the extraction using carbon dioxide at high pressure (supercritical CO2) is also classified as a solvent extraction method, it does not leave anything in the oil and it is able to extract any oil more completely and with less degradation than any other method. However this modern method is encountered only in relatively recent oil production facilities, and unlike cold pressing it is not known by most people so it is not used in marketing. Thus, except for cold pressing, the buyer cannot know whether the oil has been produced by a worse method like hexane extraction or by a better method, like CO2 extraction.

adrian_b 5y ago

You are right that the extraction method matters a lot for any oil. Any method that uses high temperatures may cause various chemical reactions that degrade some of the oil components. Some of the methods that use solvents for extraction may leave very small quantities of the solvents in the oils (e.g. hexane, i.e. a light fraction of gasoline), which are undesirable. Nevertheless, cold-pressing is not necessarily the best method, even if it is preferable to most other old methods. While the extraction using carbon dioxide at high pressure (supercritical CO2) is also classified as a solvent extraction method, it does not leave anything in the oil and it is able to extract any oil more completely and with less degradation than any other method. However this modern method is encountered only in relatively recent oil production facilities, and unlike cold pressing it is not known by most people so it is not used in marketing. Thus, except for cold pressing, the buyer cannot know whether the oil has been produced by a worse method like hexane extraction or by a better method, like CO2 extraction.