Dependence of human milk essential fatty acids on adipose stores during lactation.

The relationships between essential fatty acid (EFA) composition of colostrum, mature milk, and white adipose tissue (WAT) were examined on days 5 and 30 postpartum in 24 healthy French mothers. Fatty acid composition was assessed by capillary gas chromatography. In WAT, the proportion of individual polyunsaturated fatty acids (PUFAs) did not change during lactation and was greater (18:2n-6) or lower (18:3n-3, long-chain PUFAs) than values found in colostrum or mature milk (P < 0.04). The 18:2n-6 content and the ratio of 18:3n-3 to 18:2n-6 correlated between WAT and colostrum (r = 0.52 and r = 0.57, respectively) or mature milk (r = 0.64 and r = 0.65, respectively). These relationships agree with an expected qualitative effect of WAT fatty acid composition on interindividual variability of milk parent EFA content. The decrease in the long-chain PUFA content observed from colostrum to mature milk and the concomitant occurrence of a precursor-product relationship between the linoleate and its long-chain PUFA are consistent with the mobilization of a preformed long-chain PUFA pool during early lactation.