Pediatric Nutrition Handbook

The protein content of breast milk provides a foundation for estimating protein requirements of infants. Because it serves as a guideline for regulatory agencies issuing regulations for infant formula composition, it is critical that information on the protein content of breast milk is reliable. We have therefore carried out a meta-analysis of the protein and amino acid contents of breast milk and how they evolve during lactation. As several bioactive proteins are not completely digested in the infant and therefore represent "non-utilizable" protein, we evaluated the quantity, mechanism of action and digestive fate of several major breast milk proteins. A better knowledge of the development of the protein contents of breast milk and to what extent protein utilization changes with age of the infant will help improve understanding of protein needs in infancy. It is also essential when designing the composition of infant formulas, particularly when the formula uses a "staging" approach in which the composition of the formula is modified in stages to reflect changes in breast milk and changing requirements as the infant ages.

Longitudinal evolution of true protein, amino acids and bioactive proteins in breast milk: a developmental perspective ☆

Human milk is uniquely optimized for the needs of the developing infant. Its composition is complex and dynamic, driven primarily by maternal genetics, and to a lesser extent by diet and environment. One important component that is gaining attention is the milk fat globule (MFG). The MFG is composed of a triglyceride-rich core surrounded by a tri-layer membrane, also known as the milk fat globule membrane (MFGM) that originates from mammary gland epithelia. The MFGM is enriched with glycerophospholipids, sphingolipids, cholesterol, and proteins, some of which are glycosylated, and are known to exert numerous biological roles. Mounting evidence suggests that the structure of the MFG and bioactive components of the MFGM may benefit the infant by aiding in the structural and functional maturation of the gut through the provision of essential nutrients and/or regulating various cellular events during infant growth and immune education. Further, antimicrobial peptides and surface carbohydrate moieties surrounding the MFG might have a pivotal role in shaping gut microbial populations, which in turn may promote protection against immune and inflammatory diseases early in life. This review seeks to: (1) understand the components of the MFG, as well as maternal factors including genetic and lifestyle factors that influence its characteristics; (2) examine the potential role of this milk component on the intestinal immune system; and (3) delineate the mechanistic roles of the MFG in infant intestinal maturation and establishment of the microbiota in the alimentary canal.

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Compositional Dynamics of the Milk Fat Globule and Its Role in Infant Development.

The provision of essential and non-essential amino acids for breast-fed infants is the major function of milk proteins. In addition, breast-fed infants might benefit from bioactivities of milk proteins, which are exhibited in the intestine during the digestive phase and by absorption of intact proteins or derived peptides. For lactoferrin, osteopontin and milk fat globule membrane proteins/lipids, which have not until recently been included in substantial amounts in infant formulas, in vitro experiments and animal models provide a convincing base of evidence for bioactivities, which contribute to the protection of the infant from pathogens, improve nutrient absorption, support the development of the immune system and provide components for optimal neurodevelopment. Technologies have become available to obtain these compounds from cow´s milk and the bovine compounds also exhibit bioactivities in humans. Randomized clinical trials with experimental infant formulas incorporating lactoferrin, osteopontin, or milk fat globule membranes have already provided some evidence for clinical benefits. This review aims to compare findings from laboratory and animal experiments with outcomes of clinical studies. There is good justification from basic science and there are promising results from clinical studies for beneficial effects of lactoferrin, osteopontin and the milk fat globule membrane complex of proteins and lipids. Further studies should ideally be adequately powered to investigate effects on clinically relevant endpoints in healthy term infants.

Benefits of Lactoferrin, Osteopontin and Milk Fat Globule Membranes for Infants

Donor Human Milk Update: Evidence, Mechanisms, and Priorities for Research and Practice.

Lactoferrin is the second most abundant whey protein in human milk and is known for its functional benefits, particularly antimicrobial activities. We report a comprehensive evaluation of the published literature on quantitative changes in lactoferrin in term and preterm human milk through the course of lactation. We also considered methods used to quantify lactoferrin. We critically evaluated 94 articles on human milk with 52 meeting study inclusion criteria (2724 women). A descriptive analysis of the data was performed. Lactoferrin concentration was highest during early lactation and rapidly declined to remain relatively unchanged from 1 month to 2 years of lactation. The unweighted mean of mean (±SEM) concentrations of lactoferrin in early milk (<28 days lactation) was 4.91 ± 0.31 g/L (range of means 0.34–17.94 g/L; median 4.03). For mature milk, the mean of means was 2.10 ± 0.87 g/L (range of means 0.44–4.4 g/L; median 1.91). The majority of data were derived from Europe with fewer studies from Africa...

Weihong Zhuang

Papers

Longitudinal Changes in Lactoferrin Concentrations in Human Milk: A Global Systematic Review,