nutrition

Omega-9 fatty acids

Definition and chemical structure

See also: essential fatty acids

The fatty acids belonging to the omega nine series are accumulated by a particular biochemical characteristic:

within their molecules, the first double bond is found between the ninth and tenth carbon atom starting from the terminal methyl group (omega is the last letter of the Greek alphabet).

In the figure below we see represented the oleic acid, a fatty acid with 18 carbon atoms containing a single double bond (therefore defined as monounsaturated). Starting to count from the methyl end (CH3) on the left, we see that, as anticipated, this bond involves the ninth and tenth carbon atom (oleic acid = 18: 1, ω-9).

Unlike omega-3 and omega-6 fatty acids, those belonging to the omega-9 series are not considered essential; the human body can in fact synthesize them starting from other unsaturated fatty acids. In the total lack of essential fatty acids, the oleic - which is normally not further converted - converts to eicosatrienoic acid (20: 3 ω-9). The ratio of this fatty acid to the arachidonic acid within the plasma membranes can therefore be considered a biochemical index of lack of essential fatty acids.

Oleic acid: the most important omega-9

Oleic acid is the best known and most appreciated fatty acid of the omega-nine series, followed by popularity, but certainly not for nutritional value, by erucic acid (22: 1, n −9).

Oleic acid is an omega-9 content mainly in olive oil (60-80%), where it represents the main component of the various triglycerides. Rape, sesame and tea seed oils also contain interesting quantities, as well as various sunflower hybrids introduced to the market to supply oils with a higher content of oleic acid. This omega 9 fat is in fact stable at high temperatures and as such is particularly suitable for frying; on the other hand, the oleic is known in the health sector for its ability to prevent cardiovascular diseases (unlike animal fats and omega 6 ones consumed in high quantities).

The erucic acid is represented by the formula 22: 1 ω-9. We are therefore talking about a monounsaturated fatty acid with 22 carbon atoms, in which the only double bond is between the ninth and tenth carbon atom starting from the methyl end.

At high doses, the erucic acid is cardiotoxic and increases the lipid deposits in the heart of experimental animals. This omega 9 is abundant in rapeseed oil, which in recent decades has however undergone a series of selections to obtain varieties particularly poor in saturated fats and erucic acid.

List of ω-9 fatty acids

Common nameName of fatty acidChemical nomenclature
oleic acid18: 1 (omega − 9)9-octadecenoic acid
eicosenoic acid20: 1 (omega − 9)11-eicoosenoic acid
erucic acid22: 1 (omega − 9)13-docosenoic acid
nervonic acid24: 1 (omega − 9)15-tetracosenoic acid
eicosatrienoic acid20: 3 (omega − 9)5, 8, 11-eicosatrienoic acid