Trans fat is a solid fatty mass obtained from vegetable oils by hydrogenation. At high temperatures, liquid vegetable oils are saturated with hydrogen bubbles, resulting in the formation of unsaturated fatty acids with a distorted molecular structure.
Products with trans fats surround us everywhere:
Palm oil and trans fats are completely unrelated things.
In general, all fats are triglycerides of fatty acids. Fatty acids are limiting and unsaturated, in unsaturated there are double bonds, and in limiting they are not. Fats with unsaturated acids are usually liquid at room temperature (for example, ordinary vegetable oils, sunflower, olive), and fats with saturated acids are usually solid (butter, and just refined palm oil).
Fragments with double bonds of natural origin have a cis-structure, that is, enzymes make them so in plants, and enzymes in the body of animals are able to break them down. But when solid margarine is made from liquid vegetable oils by hydrogenation, the formation of trans fragments is possible as a side reaction:
(Picture from the Trans Fat article on Wikipedia)
These trans fragments cannot be cleaved by the body's enzymes and therefore tend to accumulation, well, it's harmful. A small amount of trans fats is also present in butter, made by bacteria in the stomachs of cows. Still, the main source of trans fat is margarine.
The so-called "trans fats" are the same fats and are also composed of glycerin and carboxylic acids. But it's not that simple. In the 11th grade, you were told that there are molecules that have the same atomic composition, but different spatial arrangement of atoms. Now, this is called isomerism, and molecules are called isomers. This refers to cis-trans isomerism. So, the organism for millions of years has become accustomed to the properties of cis-isomers, this is when the substituents are on one side (from the German word "Zusammen" - "together"). And for trans isomers, when the substituents are on opposite sides, the properties are different. The body is used to certain properties, but in reality they are different. I think you guessed what I mean.
But the so-called "palm oil" is a little different. Its harm is somewhat different - it enters into reactions at body temperature very reluctantly, and at temperatures from 39 degrees - only on the way. But for the body, such a temperature is cuckoo, dosvidos. Do you get it?