Omega 6 fatty acids are double carbonated fatty acids counted sixthly from the omega carbon atom. The omega is the last letter of the Greek alphabet. The omega carbon atom is thus the last carbon atom, starting from the beginning of the fatty acid, the carboxyl group.
The group of omega 6 fatty acids include the following fatty acids. In parenthesis, the number of carbon atoms in the fatty acid chain is stated as well as the total number of double bonds (degree of unsaturation):
• Linoleic acid (18: 2), often the English abbreviation LA is used
• Gamma-linolenic acid (18: 3), often the English abbreviation GLA is used
• Dihomo-gammalinoleic acid (20: 3), often the English abbreviation DGLA is used
• Arachidonic acid (20: 4), often the English abbreviation AA is used
The omega 6 type fatty acids can all be formed from linoleic acid. Via the delta-6-desaturase enzyme linoleic acid can be converted to gamma linolenic acid (GLA). GLA can also be absorbed from nutrition from borage oil and sunflower oil. It also occurs in relatively high amounts in breast milk. GLA is then converted to dihomo-gammalinoleic acid (DGLA), which is a direct source of first type eicosanoids (type 1 eicosanoids). DGLA can also be converted to arachidonic acid, source of second type eicosanoids (type 2 eicosanoids). Type 1 eicosanoids play an anti-inflammatory role, stimulate the immune system and protect heart and blood vessels. Type 2 eicosanoids, on the other hand, work pro-inflammatory and contribute to allergic reactions.