METABOLIC CONSEQUENCES OF INCREASING ENERGY-INTAKE BY ADDING LIPID TOPARENTERAL-NUTRITION IN FULL-TERM INFANTS

The effect on energy metabolism and fuel utilization of increasing ene rgy intake by adding intravenous lipid to a glucose and amino acid reg imen was examined. Twenty fullterm, appropriate-for-gestational-age, i ntravenously fed neonates were entered into one of two groups: total e nergy intake was 261 kJ.kg(-1).d(-1) (62 kcal kg(-1).d(-1)) in group 1 and 355 kJ.kg(-1).d(-1) (85 kcal.kg(-1).d(-1)) in group 2. Both group s received 2.8 g protein.kg(-1).d(-1) and 14 g glucose.kg(-1).d(-1). G roup 2 received an additional 2 g lipid.kg(-1).d(-1). Metabolic rate, respiratory gas exchange, and nonprotein substrate oxidation were simi lar in both groups. The addition of energy as lipid enhanced nitrogen retention (230 vs 306 mg.kg(-1).d(-1); P < 0.02) and utilization (52.8 % vs 66.5%; P < 0.03). Our data suggest that nitrogen utilization is i mproved in parenterally fed neonates by adding fat and increasing ener gy intake without change in metabolic rate, carbon dioxide production, oxygen consumption, and nonprotein substrate utilization. Energy expe nditure does not necessarily increase with increasing energy intake in dependently of diet composition.