Omega-3 and omega-6 fatty acids

These fatty acids are unique due to the position of double bonds in the chain. Animals cannot produce these fatty acids and they must be supplied in the diet. Hence they are described as ‘essential’ fatty acids and animals not receiving sufficient of these will show deficiency symptoms.

Many vegetable oils contain a high proportion of omega-6 fatty acids but there are only a few sources of omega-3 in nature, the most common being green grass, linseed and fish oil/marine sources. The major omega-3 and omega-6 fatty acids are as follows :

  1. Omega-3 : cis-9, cis-12, cis-15 α-linolenic acid (C18:3)
  2. Omega-6 : cis-9, cis-12 linoleic acid (C18:2)


Omega-3 and omega-6 fatty acids are very active in the body, particularly as components of cell membranes to help maintain cell function. However omega-3 and omega-6 fatty acids generally have differing effects in animals. Omega-6 fatty acids stimulate aspects of the immune system, whereas omega-3 fatty acids are referred to as ‘anti-inflammatory’, damping down the immune response while promoting infection-fighting components of immunity.

These fatty acids can also have a strong influence on fertility through differential effects on production of PGF by the uterus. Omega-6 fatty acids effectively promote production of PGF, resulting in regression of the corpus luteum and stopping of progesterone production, while omega-3 fatty acids help reduce this effect.