A fat molecule consists of three fatty acids and glycerol backbone. Fatty acids can be grouped according to the length of the carbon chain, the number of atoms, the number of double bonds and their position in the carbon chain. According with the number of double bonds in the carbon chain, FA are classified as saturated if no double bonds are in the carbon chain, the monounsaturated have only one double bond and polyunsaturated have two or more double bonds in the carbon chain.
An important classification of the unsaturated fatty acids is the cis-trans isomerism, the spatial arrangement of C – C bonds adjacent to double bonds. “Cis” means that the hydrogen atoms attached to the double bonded carbon atoms are on the same side of the fatty acid chain.
“Trans” means that the hydrogen atoms attached to the double bonded carbon are now on the opposite side of the fatty acid chain. The trans configuration is formed during the hydrogenation of unsaturated fatty acids. During the process, the twisted cis isomers are transformed into stable and straight-chain trans isomers, which are easier to combine with each other.
Visual taken from https://chemistrytalk.org/cis-trans-isomers/
Trans fat can be found in many food items nowadays, but the quantity and range of products that contain it have plummeted over the last 30 years.
Trans-fat can lead to severe health consequences and even lead to death. As soon as this was clear in the scientific community, actions to reduce its consumption took place. This urgency was justified as the trans-fat extinction could result in half a million lives being saved yearly, which would have otherwise been lost due to heart diseases.
Despite the massive wave of actions to eradicate their existence, many food items still contain a noticeable amount of trans fat.