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 located 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 only one 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 organism can in fact synthesize them starting from other unsaturated fatty acids. In the total lack of essential fatty acids, oleic - which normally is not further converted - converts to eicosatrienoic acid (20: 3 ω-9). The ratio of this fatty acid to arachidonic within the plasma membranes can therefore be considered a biochemical index of essential fatty acid deficiency.
Oleic Acid: the most important omega-9
Oleic acid represents the best known and most appreciated fatty acid of the omega-nine series, followed by popularity, but certainly not by nutritional value, by erucic acid (22: 1, n−9).
Oleic acid is an omega-9 contained mainly in olive oil (60-80%), where it represents the main component of the various triglycerides. Rapeseed, sesame and tea seed oils also contain interesting quantities, as well as various sunflower hybrids introduced on the market to provide oils with a higher oleic acid content. This omega 9 fat is in fact stable at high temperatures and as such is particularly suitable for frying; on the other hand, oleic is known in the health sector for its ability to prevent cardiovascular diseases (unlike animal fats and omega 6 fat consumed in high quantities).
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 single double bond is located between the ninth and tenth carbon atom starting from "methyl end.
At high dosages, erucic is cardiotoxic and increases lipid deposits in the heart of experimental animals. This omega 9 abounds in rapeseed oil, which in recent decades has however undergone a series of selections to obtain particularly low-fat varieties saturated and erucic acid.
