Effects on Fatty Acid Metabolism of a New Powdered Human Milk Fortifier Containing Medium-Chain Triacylglycerols and Docosahexaenoic Acid in Preterm Infants

Abstract

Preterm infants require fortification of human milk (HM) with essential fatty acids (FA) to ensure adequate post-natal development. As part of a larger randomized controlled study, we investigated FA metabolism in a subset of 47 clinically stable preterm infants (birth weight ≤1500 g or gestational age ≤32 weeks). Infants were randomized to receive HM supplemented with either a new HM fortifier (nHMF; n = 26) containing 12.5 g medium-chain FA (MCFA), 958 mg linoleic acid (LA), 417 mg α-linolenic acid (ALA), and 157 mg docosahexaenoic acid (DHA) per 100 g of powder (in compliance with the latest guidelines) or a fat-free HMF (cHMF; n = 21). Plasma phospholipid (PL) and triacylglycerol (TAG), and red blood cell phosphatidylcholine (RBC-PC) and phosphatidylethanolamine (RBC-PE) FA profiles were assessed before and after 21 days of feeding. In the nHMF group, significantly increased levels of n-9 monounsaturated fatty acids were observed, formed most likely by elongation and desaturation of dietary saturated fatty acids present in HM. ALA fortification increased ALA assimilation into plasma TAG. Similarly, DHA fortification enriched the DHA content in RBC-PE, which, in this compartment, was not associated with lower arachidonic acid levels as observed in plasma TAG and phospholipids. RBC-PE, a reliable indicator of FA metabolism and accretion, was the most sensitive compartment in this study.

Keywords: arachidonic acid; docosahexaenoic acid; fatty acid metabolism; medium-chain fatty acids; preterm infants.

Figure 1

Schematic representation of the influence of dietary fatty acids provided by the nHMF. Differences (shown by the ↑ and ↓ symbols) between relative concentrations of FA provided by the nHMF or the cHMF in the compartments assessed are statistically significant (p <0.05). Metabolic pathways responsible for the biosynthesis of FA from the n-3, n-6, n-7, and n-9 series are displayed together with the enzymes involved (Δ9D, Δ9-desaturase; Δ6D, Δ6-desaturase, EL5, elongase 5; Δ5D, Δ5-desaturase; EL2, elongase 2; βOX, β-oxidation).