We as Europeans have a bad deal: our legislation, unlike that passed in the United States in recent years, does nothing to protect us from trans fatty acids (most commonly referred to as trans fats). With the exception of Denmark since 2004, the trans fat content does not have to be listed on food labels of products sold in Europe. In addition, unlike for many countries, the trans fat content of food served in restaurants (traditional and fast-food), and by street vendors, is not controlled by the health services.
Canada however introduced such legislation in 2003 and the United States followed in 2006: what are we in Europe waiting for? Trans fats are essentially altered versions of natural polyunsaturated fatty acids (omega 3 and omega 6) or monounsaturated fatty acids (omega 9) whose spatial configuration is always of the “cis” type, rather than the “trans” type.
Derived from Latin, this means that in the natural version, the missing hydrogen atoms (the principle of desaturation) are found on the same side of the chain of carbon atoms (‘cis’), whereas in the altered version, they are positioned on both sides of the carbon chain (‘trans’). However, the question is: how and why does this transformation take place?
It comes from the industrial treatment of products containing unsaturated vegetable oils, and here we are talking about virtually all types of oils, with the exception of coconut oil, palm oil and palm kernel oil. Specifically it is a consequence of their oxidation at high temperatures, hence the labeling of some oils as being “cold-pressed”, although even here we are suffering from a lack of sufficient legislation. For example, there is no European regulation as to what temperature cannot be exceeded for the label to read “cold-pressed” hence there exists the most abominable abuses by some manufacturers.
On this topic, one should never buy refined oil, and should be more attentive to potentially misleading labels. For example, a so-called "pure" olive oil is a blend of virgin olive oil and refined oil rich in trans fats. Even when you have acquired your extra virgin olive oil, it is imperative that it doesn’t become a refined olive oil in your oven or in your frying pan: respect the maximum cooking temperature of 180C!
In terms of practicalities, this means that every time you cook with olive oil it should remain almost silent (from a distance of one to two meters) and in any case, it should never splash… If you are using an oven, do not exceed 160C to allow for a safety margin. It may take a little more time, but all will be perfectly cooked and will remain healthy.
If you wish to use higher cooking temperatures, although this is not really recommended, you are left with the option of macadamia oil (upper limit is 250C) or saturated fats, either vegetable (coconut oil, palm or palm kernel) or animal (butter, ghee, duck fat, ox fat, lard). These saturated fats should not be abused (in fact, some people lack them because they have totally excluded them from their diet) but it is important to realize that it is much more toxic to generate trans fats in your own kitchen!
We are talking about your health and even your survival. I will discuss this further, but you can already get an idea of the danger of consuming these trans fatty acids by visiting my website www.gmouton.com. See the article “Danger of Trans Fatty Acids” and the conference “Danger of Trans Fatty Acids” (in the section entitled “Unsaturated Fatty Acids”).