Trans fatty acids from milk of Brazilian mothers of premature infants.

Aim: The presence of trans fatty acids (TFA) in human milk may be a concern because of their possible adverse nutritional effects on the infant development. TFA may interfere with the metabolism of long-chain polyunsaturated fatty acids (LC-PUFA). Marked variation in TFA of milk appears in different populations. No data have yet been reported in Brazil, particularly as regards the milk of mothers of premature infants. Because of the importance of LC-PUFA in infant growth and development, we investigated the fatty acids composition of the milk of Brazilian mothers of premature infants.

Methods: We analysed, through gas-liquid chromatography, the content of fatty acids of 37 milk samples obtained from mothers delivering prematurely. Samples were collected from colostrum and mature milk of exclusive breastfeeding.

Results: All samples contained trans isomers of C18:1 acid with trans isomers of PUFA in lower proportion. The percentage of TFA (mean +/- SD) in the colostrum was 2.34 +/- 0.75, and 2.19 +/- 0.47 in the mature milk. For the LC-PUFA these values were 0.97 +/- 0.34 in the colostrum and 0.66 +/- 0.25 in the mature milk. The contents of total essential fatty acids and PUFA n-6 were inversely correlated with TFA in colostrum and mature milk. We found a positive correlation between levels of arachidonic acid in mature milk and change in the children's height.

Conclusions: The study showed that the intake of TFA occupies an intermediate position between the values of North America and European countries, reflecting the ongoing transition to industrialised foods in Brazil.