Longitudinal multicentric study of plasma and red blood cell fatty acids and lipids in preterm newborns fed human milk.

The present multicentric study (three centers) deals with the values of plasma and red blood cell fatty acids obtained in a group of 18 preterm newborns after 2 days (D2), 15 days (D15) and 5 weeks (37th week postconception: 37th wk) of human milk feeding. Analytical methods were randomized between the three centers and quality control was evaluated by repeated analysis of reference samples. 20:4 n-6 varied from 10.71 +/- 1.58% to 9.51 +/- 1.65 and 10.10 +/- 1.42% in plasma phospholipids and from 16.59 +/- 3.30% to 14.68 +/- 3.14 and 18.24 +/- 4.09% in red blood cell phosphatidylethanolamine (RBC-PE) at D2, D15 and 37th wk, respectively, contrasting with the important rise of the precursor (18:2 n-6) in all the fractions studied. In RBC-PE, 22:6 n-3 significantly declined from 3.52 +/- 1. 03% at D2 to 2.56 +/- 0.83% at D15 (p < 0.02) and recovered its initial level at 37th wk (4.08 +/- 1.94%). The recovery of long chain polyunsaturated fatty acid homeostasis at that time was also confirmed by the decline of 16:1 n-7 in cholesterol esters (10.69 +/- 3.92 to 4.32 +/- 2.38%).