TRANS MONOUNSATURATED AND POLYUNSATURATED FATTY-ACIDS IN HUMAN-MILK

Objective: The aim of the present study was to identify the trans isom ers of C18 fatty acids in some human milk samples. Subjects: Ten human milk samples from French women were collected in a local milk bank in order to assess their trans mono and polyunsaturated fatty acids (PUF A) content. Intervention: The fatty acid profile was examined using me thyl and isopropyl ester derivatives. The combination of gas-liquid ch romatography, high-performance liquid chromatography and silver nitrat e thin-layer chromatography was needed to describe the detailed fatty acid compositions, including the trans isomers of unsaturated C18 fatt y acids. Results: All the samples contained trans isomers of C18:1 aci d (mean level 1.9 +/- 0.2% of total fatty acids), with trans vaccenic acid being the major isomer. The samples also contained various isomer s of linoleic and alpha-linolenic acid, but at lower levels. Trans iso mers of PUFA are the same as those present in deodorised or deep-fried oils. One sample presented an abnormally high degree of isomerisation of alpha-linolenic acid (almost 50%). This was related to the dietary habit or consuming foods that were deep-fried in rapeseed oil. This m ilk sample also contained some cyclic fatty acid monomers. Conclusion: The human milk samples collected in this study contained some trans f atty acids, including isomers of essential fatty acids. This should be taken into account in the dietary intake of the newborn.