Omega-3 Fatty Acids
The last double bond of omega-3 fatty acids is positioned three carbon atoms from the fatty acid omega end. Omega-3 fatty acids are essential fatty acids for humans and have to be taken up by diet. This means that they cannot be synthesized by simple elongation or desaturation steps of palmitic (FA 16:0), stearic (FA 18:0), oleic acid (FA 18:1), or linoleic acid (FA 18:2) by our organism. The starting point for synthesis of all omega-3 fatty acids is linolenic acid (FA 18:3) which is sequentially elongated and desaturated into further omega-3 fatty acids with higher carbon number or higher degree of unsaturation. Linolenic acid is highly abundant in linseed oil. Another good source for omega-3 fatty acids is generally fish, which does not synthesize omega-3 fatty acids by themselves either but rather consumes it by its diet from algae. Omega-3 fatty acids are publicly associated with positive effects on human health, particularly the cardiovascular system. One of the reasons for the healthy nature of omega-3 fatty acids is their anti-inflammatory properties. Within the last decade, protectins and resolvins were discovered to be anti-inflammatory agents derived from docosahexaenoic acid (FA 22:6) and eicosapentaenoic acid (FA 20:5) by enzymatic oxygenation reactions via lipoxygenase. Hence, omega-3 fatty acids are important in diseases associated with chronic inflammation like atherosclerosis. Highly unsaturated omega-3 fatty acids are furthermore found at high quantities in brain, where it is suggested that high concentrations of omega-3 fatty acids facilitate brain development.