trans Octadecenoic acid and trans octadecadienoic acid are inversely related to long-chain polyunsaturates in human milk: results of a large birth cohort study.

Background: Several observational studies indicate that trans isomeric fatty acids may interfere with the metabolism of essential fatty acids in the human organism.

Objective: The objective was to investigate the relation between trans fatty acids and long-chain polyunsaturates in mature human milk.

Design: Human milk samples (n=769) were obtained at the 6th week of lactation from mothers participating in a birth cohort study in Germany. The fatty acid composition of the milk samples was measured by high-resolution capillary gas-liquid chromatography.

Results: trans Octadecenoic and trans octadecadienoic acids were inversely correlated with linoleic acid (r=-0.32 and -0.33, P<0.0001 for both), alpha-linolenic acid (r=-0.35 and -0.27, P<0.0001), arachidonic acid (r=-0.60 and -0.47, P<0.0001), and docosahexaenoic acid (r=-0.51 and -0.33, P<0.0001). In contrast, no inverse correlations were observed between trans hexadecenoic acid and polyunsaturated fatty acids.

Conclusions: The data obtained in the present study suggest that the availability of 18-carbon trans isomeric fatty acids may be inversely related to the availability of long-chain polyunsaturated fatty acids in mature human milk.