Amanda (Santa Barbara, CA) on 03/01/2004:

"Omega-3 (you may sometimes see it written as n-3 or w-3) is the name given to a family of polyunsaturated fatty acids. The parent omega-3 - alpha-linolenic acid (ALA) - is described as 'essential' as, like vitamins, it must be obtained from diet. It is polyunsaturated and has 18 carbon atoms and 3 double bonds (18:3).

However, from the point of view of human nutrition, the long-chain omega-3 fatty acids eicosapentaenoic acid (20:5)and docosahexaenoic acid (22:6) - EPA and DHA - are considered much more valuable as these are the forms the body requires. In theory, humans are able to synthesise EPA and DHA from dietary ALA, but in practice this process is inefficient. Scientists have therefore concluded that EPA and DHA should be obtained from diet. Oil-rich fish and supplements such as fish oil and cod liver oil, are the richest and most readily available sources. Other sources such as krill and fortified everyday foods like bread and fruit juices are in production in a minor way in various parts of the world.