The potential anticarcinogenic conjugated linoleic acid, cis-9,trans-11 C18:2, in milk of different species:: Cow, goat, ewe, sow, mare, woman

The distribution of the potential anticarcinogenic fatty acid cis-9,trans-11-octadecadienoic acid (rumenic acid) and other trans and cis fatty acids in milk fat of different ruminants and non-ruminants including human milk was determined by gas-liquid chromatography. The CLA isomer cis-9,trans-11 was the predominant found. Its variation in milk fat of the bulk and individual samples was substantial (0.07 - 1.35 % of FAME). Because feed composition and rumen microflora influence isomerisation of linoleic acid in the rumen, factors such as farm management and season were taken into consideration. CLA in milk of all ruminants was season-dependent and there exists a close positive correlation to trans vaccenic acid. Ewe milk is rich in CLA(1.1 %). Among non-ruminants mare milk was nearly CLA-free (0.09 %). Human milk contained significantly more CLA (0.42 %, P < 0.01) in comparison wih the analyzed milk of the other monogastrides. There are differences between milk- and non-milk drinkers. The arrangement of the species according to the increasing CLA concentration in milk is: mare, sow, woman, great, cow, ewe. The higher CLA content of ruminant milk compared with non-ruminant species is inversely correlated to the content of PUFA and partly to MUFA (C) 1999 Elsevier Science Inc.