Plasma fatty acids and [13C]linoleic acid metabolism in preterm infants fed a formula with medium-chain triglycerides

Abstract

Most preterm infant formulas contain mediumchain triacylglycerols (MCT), but the effects of MCT on polyunsaturated fatty acid status and metabolism are controversial. Thus, we studied the effects of MCT on linoleic acid metabolism using stable isotopes. Enterally fed preterm infants were randomized to receive for 7 days 40% of fat as MCT (n ‫؍‬ 10) or a formula without MCT (n ‫؍‬ 9). At study day 5, infants received orally 2 mg/kg body weight of 13 C-labeled linoleic acid. Fatty acids in plasma lipid classes and 13 C enrichment of phospholipid fatty acids were measured and tracer oxidation was monitored. Compared with the control group, the MCT group showed lower breath 13 CO 2 and higher plasma triacylglycerol contents of octanoic acid, of decanoic acid, and of total long-chain polyunsaturated fatty acids (57.1 ؎ 4.4 mol/l vs. 37.9 ؎ 4.8 mol/l, P Ͻ 0.01). Concentrations of several polyunsaturated fatty acids in plasma phospholipids and non esterified fatty acids were higher in the MCT group. 13 C concentrations in phospholipid n-6 fatty acids indicated no difference in the relative conversion of linoleic to arachidonic acid. We conclude that oral MCT effectively reduce polyunsaturated fatty acid and long chain polyunsaturated fatty acid oxidation in preterm infants without compromising endogenous n-6 long chain polyunsaturated fatty acid synthesis.

Change in Plasma Total, Esterified and Non-esterified Capric Acid Concentrations during a Short-term Oral Administration of Synthetic Tricaprin in Dogs

“…FA10:0 is more likely to be esterified into triglycerides because FA10:0 esterified to phospholipids or cholesterols has not been detected in plasma. 40,42,43 This finding supports the hypothesis that during the oral loading of MCT, the hepatic clearance of MCFA remains incomplete. Therefore, unmetabolized MCFA may be esterified to triglycerides, packed into VLDL and released into the systemic circulation, as MCFA containing VLDL has also been detected following the MCT diet.…”

Medium-chain triglycerides

“…As several studies indicate that moderate doses are better than excessive loads, it will have to be examined which dose and food matrix offers the most benefits, and whether naturally occurring MCFAs at position sn-1,3 of a triglyceride molecule and MCT oils have the same effect. Another interesting aspect is whether MCFAs, due to their preferred oxidation, might ''spare'' polyunsaturated fatty acids from oxidation, as fatty acid tracer exhalation tests and serum fatty acid profiles in preterm infants (Rodriguez et al, 2003) and rats (Nagata et al, 2003) suggest.…”

Metabolic effects of intravenous LCT or MCT/LCT lipid emulsions in preterm infants

“…It has been suggested that during MCT/LCT ingestion, carnitine palmitoyltransferase I is inhibited by the production of malonyl-CoA, and consequently oxidation of long-chain fatty acids is reduced and their incorporation into complex lipids is enhanced (36). Indeed, we recently found reduced LA oxidation in preterm infants fed an enteral formula with 40% of fat provided by MCT compared with a 100% LCT formula (37). Even though the LCT emulsion provided approximately twice the amounts of palmitic acid (C16:0), TABLE n.d., not detected.…”