Characteristics of lipids

Lipids are constituted about 98% of triglycerids which are combinations of three fatty acids and glycerol.
Remaining 2% are phospholipids (lecithins), sterols (cholesterol, ergosterol) and liposoluble vitamins (A,D,E,K).
There are seven main fatty acids in our body.

Fatty acids are categorized by the Greek letter omega (ω), and a number designating the position of the carbon-carbon double bond.

Poly-unsaturated fatty acids

Named essential fatty acids, they are indispensable because our body is not capable to produce them.
They are contained in the vegetable oils and the fat fishes (salmon, tuna, sardines, etc.).
The linoleic acid (ω-6) is contained in oil of sunflower, nut, corn, soya.
The alpha linolenic acid (ω-3) is contained in oil of nut, colza, soya.
These acids are sub-used in the food.

Mono-unsaturated fatty acids

They are the most common and not essential because our body can produce them from other unsaturated fatty acids.
The oleic acid (ω-9) is contained in the majority of oils, it is stable in temperature. It is the most spread fatty acid in our body which can produce it from the glucose.

Saturated fatty acids

They are the less good because they increase the rate of the bad cholesterol (LDL).
They are contained in meats, eggs, dairies.
The palmitic acid (very spread in our body), lauric, myristic, stearic are the most common.
These acids are unfortunately over-used in the food.

Composition of oils (in fatty acids)

The need of our body is the following: linoleic 15%, alpha linolenic 3%, oleic 60%, saturated 22%.

Composition of oils

For comparison, the composition in fatty acids of the butter is: linoleic 3%, alpha linolenic 1%, oleic 30%, saturated 66%.

Trans fatty acids

These are unsaturated acids coming from industrial techniques. They are harmful for our body because they are not natural. They are contained in the margarines, oils, industrial foods where it is mentioned "partially hydrogenated fat".