About trans fat and cis-fat - what is trans-fat

What is fat

The molecules of fatty acids consist of a long chain of carbon atoms, and at the end of this chain, there is a carboxyl acid group. Bound to the carbon atoms are hydrogen atoms. The carbon atoms are chained together by single or bouble bounds.

Fat is a chemical compund where the molecules consist of the alkohol glycerol and three fatty acids bound together by ester-bridges.

Fatty acids with only single bonds are called saturated fatty acids, and those with one or more double bonds are called unsaturated fatty acids.


What is cis-fat and trans-fat

The two atoms where the double bond is situated have one hydrogen atom each bound to them and each of the atoms also have a part of the carbon chain bound to it. If the hydrogen atoms are at the same side, the carbon chain will be bent as a bow where the double bond is. Such a fatty acid is called cis-acid and fat made from them cis-fat.

Natural fatty acids are of the cis-type. In natural unsaturated fatty acids, the double bounds are orientated such that the part of the carbon chain before and after the double bound are at the same side, making the carbon chain bent.

Fatty acids with these hydrogen atom at different sides, will get streight chains, or rather zig-zag-shaped chains, and these are called trans-fatty acids and fat made from them trans-fat.


What happens with industrially processing of fat

Fat used in industrially processed food has often undergone chemical alternation to give the fat special consistance. One effect of thees processes is to bind new hydrogen atoms into the chains by breaking double bonds and adding one new hydrogen atom to each of the atoms where the double bonds originally were between, thus making the fat more saturated.

Also bouble bonds that remain as such will be altered by these processes. The processing also creates fatty acids where the hydrogen atoms situated at each carbon atom that have a double bond betwen are at different sides. This makes the carbon atom chain streight, they are converted to trans-fatty acids.


The health effects of trans-fat

However, trans fat is unnatural and is not used in the body in a normal way. Also the adding of new hydrogen atoms will make the fat more saturated and possible creating types of fatty acids that is unnatural in other ways.

Many observations suggest that trans fat in industrially processed food causes cancer, heart problems and inflammatory diseases, like rheumatic disease.

There is however one exception. The fatty acid conjugated linoleic acid seems to help reduce weight and to promote skin health if furnished in a moderate amount. Conjugated linoleic acid is partly a trans-fatty-acid with some of the carbon chain streight and partly a sis-faty acid with some of the carbon chain bent.

This fatty acid is made in the digestive system of cows by bacteria, and is transfered to the milk. Therefor milk, butter and cheese contain some amount of this fatty acid.