Transport of long-chain polyunsaturated fatty acids in preterm infant plasma is dominated by phosphatidylcholine

BACKGROUND: Docosahexaenoic (C22:6) and arachidonic (C20:4) acids are long-chain polyunsaturated fatty acids (LC-PUFA) essential to neonatal development, being present in the glycerophospholipids of all organs, particularly the brain. In plasma, LC-PUFAs are mainly present in lipoprotein lipids, which are neutral lipids (triglycerides and cholesterol esters) and glycerophospholipids, like choline containing phosphatidylcholine (PC). PURPOSE: To guide future supplementation strategies of C22:6 and C20:4 in combination with choline, we determined the distribution of C20:4 and C22:6 between PC and neutral lipid. METHODS: Preterm infant plasma (N = 59, postmenstrual age [PMA] 33.9 wk (32.4–36.0)) and cord plasma (N = 34, PMA 34.0 wk (30.86–38.4)) were investigated. PC and neutral lipids were extracted and analyzed using tandem mass spectrometry and gas chromatography, respectively. Data are reported as medians and 25th/75th percentiles. RESULTS: In cord blood, C20:4-PC and C22:6-PC comprised 36.1% (34.2–38.6) and 10.2% (8.8–12.8) of total PC, respectively. In preterm infant plasma, values were only 20.8% (19.2–23.1) and 5.7% (5.2–6.0), respectively (p < 0.001 each). Nevertheless, in preterm infant plasma, 80.6% (77.6–83.0) of C20:4 and 86.0% (83.0–88.9) of C22:6 were found in PC. These values exceeded the proportions of C20:4 and C22:6 in PC of cord plasma [71.3% (67.8–72.9) and 79.2% (75.2–85.4), respectively] (p < 0.0001 each). CONCLUSION: Irrespective of the low proportions of C20:4-PC and C22:6-PC in preterm infant plasma lipids, PC is the major transporter for C20:4 and C22:6. Our data support the hypotheses that choline deficiency may impair end-organ availability of these LC-PUFA in preterm infants. Therefore, supplementation of C20:4 and C22:6 might better be accompanied by choline supplementation.