Triglicerides and fatty acids

Phospholipids and cell membranes

Sterols: cholesterol and testosterone


Extra topics:

Fuel made from fat: Biodiesel

Eating fat without gaining weight:Olestra

Trans fats





Trans Fats

The term trans fat comes from the geometrical isomerism nomenclature.

A natural occurring (unsaturated) fatty acid, like oleic acid (shown below), has only 1 double bond. The structure is kinked because rotation is not possible at the double bond position (all the other carbon-carbon bonds are single and can be rotated). The hydrogens on the double bond are on the same side, what means that it is a CIS isomer:

Oleic acid (CIS isomer - naturally occurring)

The TRANS isomer is also possible (below). In this case the hydrogens at the double bond are on opposite sides (that is why the name TRANS).


Oleic acid (TRANS isomer - it can only be made artificially )


All the naturally occurring unsaturated fatty acids have a kinked structure, as seen on the fatty acids page.

Cis unsaturated fatty acids are healthy. They are present in olive oil, omega 3 and others.

Trans Fatty acids, however, are very unhealthy. They cause a lowering of the good cholesterol as well as increasing of the bad cholesterol.

Trans fats are a by product of the hydrogenation of fats, which is an industrial process that transforms liquid fats into solid fats (like margarine).

Fortunately it is possible nowadays to avoid trans fats by paying attention to food labeling.

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