Fatty acid composition of French infant formulas with emphasis on the content and detailed profile of trans fatty acids

The aim of the present study was to identify and quantitate trans isomers of C18 fatty acids in some French infant formulas. Twenty powdered infant formulas were purchased in pharmacies and supermarkets in order to assess their trans mono- and poly-unsaturated fatty acids content. The fatty acid profiles were examined using methyl and isopropyl ester derivatives. The combination of gas-liquid chromatography, high-performance liquid chromatography, and silver nitrate thin-layer chromatography was needed to describe the detailed fatty acid compositions of the samples, including trans isomers of unsaturated C18 fatty acids. All the samples contained trans isomers of C18:1 acid (mean level 1.97 +/- 0.28% of total fatty acids), with vaccenic acid being generally the major isomer (15 out of 20 samples), thus indicating the origin from bovine milk. All the formulas also contained various isomers of linoleic and alpha-linolenic acids, but at lower levels. Trans PUFA isomers are the same as those present in deodorized oils. In conclusion, all the infant formulas analyzed in this study contained some trans fatty acids, including isomers of essential fatty acids. This should be taken into account in the dietary intake of the newborn.