The importance of infants’ lipid intake in human milk research

Abstract

Human milk lipids are among the many nutrients delivered to the infant, providing >50% of the infant’s calorie intake. These lipids are highly complex and variable, and bioactive, contributing to infant growth, development, and health. The lipid concentration of milk samples is often measured in human cohorts; however, few studies measure infant intake of milk. Intake is important because it considers the variability of both lipid concentration and infants’ consumed volume of milk. Measurement of infants’ lipid intake in exclusively breastfeeding infants requires 3 main considerations: human milk sampling protocol (ie, the collection of representative samples); measurement of the infant milk intake, because volume varies widely between infants; and appropriate analytical laboratory methods. The purpose of this review was to provide an overview of existing methodology and demonstrate the importance of measuring infants’ lipid intake to understand the impact that human milk lipids have on infant outcomes.

The Fatty Acid Species and Quantity Consumed by the Breastfed Infant Are Important for Growth and Development

“…This is supported by a study that supplemented lactating women with carbon-13-labelled DHA and demonstrated that only approximately 20% of dietary DHA contributes to the HM DHA composition [5]. The proportion of HM DHA, and other FAs, however, does not represent the quantity consumed by the infant as they consume vastly different milk volumes (473-946 mL/day in this study); thus, we calculated infant FA intake, which enabled elucidation of relationships with infant growth [25].…”

“…It also emphasises that relationships with infant intake can differ greatly compared to concentrations when considering infant outcomes. Where infant outcomes are concerned, a key factor in understanding the role of these FAs will be to measure infant intake in future studies, by studying exclusively breastfeeding cohorts and recording other food sources that may have a confounding effect [25].…”

Healthy Breastfeeding Infants Consume Different Quantities of Milk Fat Globule Membrane Lipids

“…Using an LC-MS method, we achieved the quantitation of 166 MFGM lipid species. High degrees of variation both between women and between months were demonstrated, but it is important to remember that the total lipid content of human milk is dependent on breast fullness, which means that the concentration of randomly collected samples may not be biologically relevant, and thus, sampling is particularly important when linking the results to infant outcomes [ 11 ]. To ensure that concentrations between our samples were comparable, a strict sampling protocol was followed with timed morning and evening prefeed samples collected at months one and three of lactation.…”

“…In addition to HM compositional variances, breastfeeding infants consume vastly different milk volumes, ranging from <500 to >1300 mL/day [ 10 ]. As a result, the daily intake of MFGM lipid species is expected to be an important factor in understanding the role of lipids in infant growth and development [ 11 ]. MFGM lipids are proposed to have both nutritive and non-nutritive functions for the infant, including roles in immune and neural development, and in supporting the infant gut microbiota [ 12 ].…”

25 Years of Research in Human Lactation: From Discovery to Translation

“…This is consistent with our previous study that showed reductions in the proportion of capric (C10:0) and lauric acids and increases in palmitoleic and stearic acid [ 260 ] in unwell mothers and infants. Indeed it also highlights both the importance of measuring component intake [ 261 ] and with respect to total lipid employing extensive sampling [ 253 ].…”