Details on PUFA

There are 2 distinct types of PUFA, which are described as belonging either to the n-3 or n-6 families. This separation refers to whether the first (chemical) double bond is found between the 6th and 7th carbon atom from the methyl end (as in the n-6 family) or between the 3d and 4th carbon atom (as in the n-3 family). These families cannot be intraconverted.

The parent fatty acids -

• alpha linolenic acid of the n-3 family
• linoleic acid of the n-6 family

are compounds that cannot be made by the human body. They have to be provided in our diet by plant sources and are termed “essential” fatty acids.

The n-6 family is descended from linoleic acid and the human body can readily make n-6 PUFA with longer chain lengths and more double bonds, such as arachidonic acid.

Alpha linolenic acid is the parent of the n-3 PUFA family and both humand and plant cells tend to have difficulty in converting it into is longer chained, more unsaturated derivatives, EPA and DHA.

Since algae are the only form of life that are efficient at making these long chain PUFA, and all fish feed on algae, it is the fish oils that are a rich source of EPA and DHA.

based on the documentation of "Nutritional Aspects of Fish" prepared by the Irish Sea Fisheries Board (AN BORD IASCAIGH MHARA)