Another run through the explanation of fatty acid nomenclature:


Fatty acids are discribed first of all by how many carbons and how many double bonds there are:


for 16 carbons and fully saturated


\/\/\/\/\/\/\/\COO-         16:0

                                                         this would be the same in the delta system


for 18 carbons and monounsaturated one needs to call out where the double bond is (remember that

saying 'n' is equal to saying "omega")



/\/\/\/\-/\/\/\/\COO-       n-9 18:1              (since the double bond is between the 9th and 10th carbon

                                                         counting from the methyl [left] end)

                               18:1 delta-9

                                                         (since the double bond is between the 9th and 10th carbon

                                                         counting from the carboxyl [right] end)


for 18 carbons and a polyunsaturated fat it will be (this is linoleate)


\/\/\-/\-/\/\/\/\COO-       n-6 18:2              (since there are 2 double bonds it is 18:2, and since the first

                                                         double bond is at the 6th carbon from the methyl end, and because

                                                         [again this is just the way the enzymes work] there is a single carbon

                                                         between the unsaturated carbons [known as a methylene interruption]

                                                         we automatically know where the second double bond is as soon as

                                                         we know where the first one is.


                               18:2 delta-9,12    (count from carboxyl end, and specify where both double

                                                         bonds are even though we really know where they are if we know where

                                                         the first one is...)


So that's how fatty acids are named, so now you know what an omega-6 fatty acid is (linoleate is one,

and you should be able to figure out what an omega-3 fatty acid is. The use of "n-" is considered more

modern than the use of "omega-" though the latter is still seen in popular usage a lot.


                                                                       Dr. Campbell