LINOLEIC ACID METABOLISM IN PARENTERALLY FED INFANTS

Abstract

The major essential fatty acid in intralipid is linoleic acid (LIN; 18:2w6). The hepatic metabolism of LIN supplied with intravenous lipid emulsions is reflected by the composition of very low density lipoproteins (VLDL). We studied the essential fatty acid content of VLDL triglycerides (TG), cholesterol esters (CE) and phospholipids (PL) in 17 fullterm, appropriate for gestational age infants (birthweigth 3126 ± 70s, gest. age 39.4 ± 0.3 weeks; M±SE) during i.v. alimentation with glucose/amino acid solutions only (GL/A; age 6.5±0.5 days) and after addition of Intralipid (GL/A/IL; age 13.2±0.7days). Results: Total lipid content of VLDL was not altered by transition from GL/A to GL/A/IL (39.4±6.2 vs. 35.6±5.7 mg/dl). The administration of Intralipid led to a pronounced increase of LIN in all lipid classes (cf. Table). Arachidonic acid (AA; 20: 4w6), the major functional metabolite of LIN, was not changed in TG, but decreased markedly in CE and PL. Conclusions: 1. Linoleic acid administered witn Intraiipid is avidly incorporated into all lipid classes of VLDL. 2. The high linoleic acid load of the lipid emulsion results in a reduced content of LIN-metabolites, such as arachidonic acid, in VLDL-CE and -PL. 3. Both a competition of linoleic acid with its metabolites for incorporation into CE and PL as well as an inhibition of hepatic chain elongation and desaturation by the high LIN intake may be responsible for the reduction of AA.