LONG-CHAIN POLYENE STATUS OF PRETERM INFANTS WITH REGARD TO THE FATTY-ACID COMPOSITION OF THEIR DIET - COMPARISON BETWEEN ABSOLUTE AND RELATIVE FATTY-ACID LEVELS IN PLASMA AND ERYTHROCYTE PHOSPHOLIPIDS

The long-chain polyene (LCP) status of thirty-nine premature infants ( birth weight < 1800 g) was evaluated. Twenty-seven infants were fed on an artificial formula, twelve received their own mother's breast milk . Fatty acid compositions of both plasma and erythrocyte (RBC) phospho lipids (PL) were determined in umbilical venous blood and in weekly po stnatal blood samples until the 28th day of life. Individual fatty aci d levels were expressed as absolute quantities (mg fatty acid/l plasma or RBC suspension) and as relative (mg/100 mg total fatty acids) valu es, The changes with time in the absolute values for 22:6n-3 and 20:4n -6 in plasma were strikingly different from those of the relative valu es for these fatty acids. In plasma PL the inter-group differences in the absolute postnatal values for 22:6n-3 (P < 0.0005) and 20:4n-6 (P < 0.05) and the relative values for 22:6n-3 (P < 0.02) were significan t, with lower fatty acid values in the formula-fed infants. In RBC PL, no significant inter-group differences in the postnatal 22:6n-3 and 2 0:4n-6 values were found. Based on the assumption that it is desirable for formula-fed infants to achieve postnatal plasma LCP values at lea st comparable with those found in infants fed on human milk, the findi ngs of the present study indicate that both n-3 and n-6 LCP should be added to preterm infant formulas. Moreover, the additional importance of absolute fatty acid levels was demonstrated, although analytical pr ocedures need to be standardized to enable effective comparison of res ults from different research groups.