Absolute Quantification of Human Milk Caseins and the Whey/Casein Ratio during the First Year of Lactation

Characteristics of casein phosphopeptides in Chinese human milk and its correlation with infant growth: A cross-sectional study

This research aimed to investigate the characteristics of casein phosphopeptides in Chinese human milk, and their potential relationship to infant growth. Using the liquid chromatography-Orbitrap-mass spectrometry technique, a total of 15 casein phosphopeptides were identified from 200 human milk samples. Also, our results indicate that casein phosphopeptides were phosphorylated with only one phosphate. The relative concentrations of casein phosphopeptides at 6 months postpartum were increased compared with milk at 2 months (FDR < 0.05). Significantly positive correlations were observed between casein phosphopeptides and infant growth, as shown by four casein phosphopeptides were positively correlated with the infants' weight-for-age Z-scores (rs range from 0.20 to 0.29), and three casein phosphopeptides were positively correlated with the infants' length-for-age Z-scores (rs range from 0.19 to 0.27). This study is the first to reveal the phosphorylated level and composition of casein phosphopeptides in Chinese human milk, and their potential relationship with infant growth.

Neonatal Gut and Immune Responses to β-Casein Enriched Formula in Piglets

BACKGROUND

β-casein is the main casein constituent in human milk (HM) and a source of bioactive peptides for the developing gastrointestinal tract and immune system. Infant formulas contain less β-casein than HM, but whether different concentrations of β-casein affect tolerability and gut and immune maturation in newborns is unknown.

OBJECTIVES

Using near-term piglets as a model for newborn infants, we investigated whether increasing the β-casein fraction in bovine-based formula is clinically safe and may improve gut and immune maturation.

METHODS

Three groups of near-term pigs (96% gestation) were fed formula with bovine casein and whey protein (ratio 40:60): 1) standard skim milk casein (BCN-standard, 35% β-casein of total casein, n = 18); 2) β-casein enrichment to HM concentrations (BCN-medium, 65%, n = 19); and 3) high β-casein enrichment (BCN-high, 91%, n = 19). A reference group was fed 100% whey protein concentrate (WPC) as protein (WPC, n = 18). Intestinal and immune parameters were assessed before and after euthanasia on day 5.

RESULTS

Clinical variables (mortality, activity, body growth, and diarrhea) were similar among the groups, and no differences in intestinal or biochemical parameters were observed between BCN-standard and BCN-medium pigs. However, pigs receiving high amounts of β-casein (BCN-high) had lower small intestine weight and tended to have more intestinal complications (highest gut pathology score, permeability, and interleukin-8) than the other groups, particularly those receiving no casein (WPC pigs). Blood lymphocyte, thrombocyte, and reticulocyte counts were increased with higher β-casein, whereas eosinophil counts were reduced. In vitro blood immune cell responses were similar among groups.

CONCLUSIONS

β-casein enrichment of bovine-based formula to HM concentrations is clinically safe, as judged from newborn, near-term pigs, whereas no additional benefits to gut maturation were observed. However, excessive β-casein supplementation, beyond concentrations in HM, may potentially induce gut inflammation together with increased blood cell populations relative to natural β-casein concentrations or pure whey-based formula.

A novel proteomic approach for the identification and relative quantification of disulfide-bridges in the human milk proteome

This study explores the disulfide bridges present in the human milk proteome by a novel approach permitting both positional identification and relative quantification of the disulfide bridges. Human milk from six donors was subjected to trypsin digestion without reduction. The digested human milk proteins were analyzed by nanoLC-timsTOF Pro combined with data analysis using xiSEARCH. A total of 85 unique disulfide bridges were identified in 25 different human milk proteins. The total relative abundance of disulfide bridge-containing peptides constituted approximately 5% of the total amount of tryptic-peptides. Seven inter-molecular disulfide bridges were identified between either α-lactalbumin and lactotransferrin (5) or αS1-casein and κ-casein (2). All cysteines involved in the observed disulfide bridges of α-lactalbumin and lactotransferrin were mapped onto protein models using AlphaFold2 Multimer to estimate the length of the observed disulfide bridges. The lengths of the disulfide bridges of lactotransferrin indicate a potential for multi- or poly-merization of lactotransferrin. The high number of intramolecular lactotransferrin disulfide bridges identified, suggests that these are more heterogeneous than previously presumed. SIGNIFICANCE: Disulfide-bridges in the human milk proteome are an often overseen post-transaltional modification. Thus, mapping the disulfide-bridges, their positions and relative abundance, are valuable new knowledge needed for an improved understanding of human milk protein behaviour. Although glycosylation and phosphorylation have been described, even less information is available on the disulfide bridges and the disulfide-bridge derived protein complexes. This is important for future work in precision fermentation for recombinant production of human milk proteins, as this will highlight which disulfide-bridges are naturally occouring in human milk proteins. Further, this knowledge would be of value for the infant formula industry as it provides more information on how to humanize bovine-milk based infant formula. The novel method developed here can be broadly applied in other biological systems as the disulfid-brigdes are important for the structure and functionality of proteins.

O-linked glycosylations in human milk casein and major whey proteins during lactation

As glycosylations are difficult to analyze, their roles and effects are poorly understood. Glycosylations in human milk (HM) differ across lactation. Glycosylations can be involved in antimicrobial activities and may serve as food for beneficial microorganisms. This study aimed to identify and analyze O-linked glycans in HM by high-throughput mass spectrometry. 184 longitudinal HM samples from 66 donors from day 3 and months 1, 2, and 3 postpartum were subjected to a post-translational modification specific enrichment-based strategy using TiO2 and ZrO2 beads for O-linked glycopeptide enrichment. β-CN was found to be a major O-linked glycoprotein, additionally, αS1-CN, κ-CN, lactotransferrin, and albumin also contained O-linked glycans. As glycosyltransferases and glycosidases are involved in assembling the glycans including O-linked glycosylations, these were further investigated. Some glycosyltransferases and glycosidases were found to be significantly decreasing through lactation, including two O-linked glycan initiator enzymes (GLNT1 and GLNT2). Despite their decrease, the overall level of O-linked glycans remained stable in HM over lactation. Three different motifs for O-linked glycosylation were enriched in HM proteins: Gly-Xxx-Xxx-Gly-Ser/Thr, Arg-Ser/Thr and Lys-Ser/Thr. Further O-linked glycan motifs on β-CN were observed to differ between intact proteins and endogenous peptides in HM.

Whey protein hydrolysates and infant formulas: Effects on physicochemical and biological properties

Whey protein hydrolysates are recognized for their substantial functional and biological properties. Their high digestibility and amino acid composition make them a valuable ingredient to hydrolyzed whey infant formulas, enhancing both product functionality and nutritional values for infant growth. It is important to understand the functional and biological properties of whey protein hydrolysates for their applications in infant formula systems. This review explored preparation methods of whey protein hydrolysates for infant formula-based applications. The effects of whey protein hydrolysate on the physicochemical and biological properties of hydrolyzed whey infant formulas were summarized. The influences of whey protein hydrolysates on the functional and nutritional properties of formulas from manufacturing to infant consumption were discussed. Whey protein hydrolysates are crucial components in the preparation of infant formula, tailored to meet the functional and nutritional demands of the product. The selection of enzyme types and hydrolysis parameters is decisive for obtaining "optimal" whey protein hydrolysates that match the intended characteristics. "Optimal" whey protein hydrolysates offer diverse functionalities, including solubility, emulsification and production stability to hydrolyzed whey infant formulas during manufacturing processes and formulations. They simultaneously promote protein digestibility, infant growth and other potential health benefits, including reduced allergenic potential, as supported by in vitro, in vivo and clinical trials. Overall, the precise selection of enzymes and hydrolysis parameters in the production of whey protein hydrolysates is crucial in achieving the desired characteristics and functional benefits for hydrolyzed whey infant formulas, making them critical in the development of infant nutrition products.

Network analysis of the proteome and peptidome sheds light on human milk as a biological system

Proteins and peptides found in human milk have bioactive potential to benefit the newborn and support healthy development. Research has been carried out on the health benefits of proteins and peptides, but many questions still need to be answered about the nature of these components, how they are formed, and how they end up in the milk. This study explored and elucidated the complexity of the human milk proteome and peptidome. Proteins and peptides were analyzed with non-targeted nanoLC-Orbitrap-MS/MS in a selection of 297 milk samples from the CHILD Cohort Study. Protein and peptide abundances were determined, and a network was inferred using Gaussian graphical modeling (GGM), allowing an investigation of direct associations. This study showed that signatures of (1) specific mechanisms of transport of different groups of proteins, (2) proteolytic degradation by proteases and aminopeptidases, and (3) coagulation and complement activation are present in human milk. These results show the value of an integrated approach in evaluating large-scale omics data sets and provide valuable information for studies that aim to associate protein or peptide profiles from biofluids such as milk with specific physiological characteristics.

Which is the optimal choice for neonates' formula or breast milk?

The incidence of prematurity has been increasing since the twenty-first century. Premature neonates are extremely vulnerable and require a rich supply of nutrients, including carbohydrates, proteins, docosahexaenoic acid (DHA), arachidonic acid (ARA) and others. Typical breast milk serves as the primary source for infants under six months old to provide these nutrients. However, depending on the individual needs of preterm infants, a more diverse and intricate range of nutrients may be necessary. This paper provides a comprehensive review of the current research progress on the physical and chemical properties, biological activity, function, and structure of breast milk, as well as explores the relationship between the main components of milk globular membrane and infant growth. Additionally, compare the nutritional composition of milk from different mammals and newborn milk powder, providing a comprehensive understanding of the differences in milk composition and detailed reference for meeting daily nutritional needs during lactation.

Enteral feeding strategies in patients with acute gastrointestinal injury: From limited to progressive to open feeding

Acute gastrointestinal injury (AGI) is very common in critically ill patients, and its severity is positively correlated with mortality. Critically ill patients with digestive and absorption dysfunction caused by AGI face higher nutritional risks, making nutritional support particularly important. Early enteral nutrition (EN) support is extremely important because it can promote the recovery of intestinal function, protect the intestinal mucosal barrier, reduce microbiota translocation, reduce postoperative complications, shorten hospital stay, and improve clinical prognosis. In recent years, many nutritional guidelines have been proposed for critically ill patients; however, there are few recommendations for the implementation of EN in patients with AGI, and their quality of evidence is low. The use of EN feeding strategies in critically ill patients with AGI remains controversial. The aim of this review was to elaborate on how EN feeding strategies should transition from limited to progressive to open feeding and explain the time window for this transition.

Unravelling the Proteomic Profiles of Bovine Colostrum and Mature Milk Derived from the First and Second Lactations

Bovine colostrum (BC) and mature bovine milk are highly nutritious. In addition to being consumed by adults, these dairy products are also used as protein ingredients for infant formula. However, the differences in the nutritional composition of BC and mature milk, especially regarding proteins present in trace amounts, have not been comprehensively studied. Furthermore, the distinct proteomic profiles of mature milk derived from the first lactation (Milk-L1) and the second lactation (Milk-L2) are not fully understood. To address these gaps, this study aims to uncover the subtle differences in protein compositions of BC, Milk-L1, and Milk-L2 by proteomics. Compared with BC, anti-microbial proteins β-defensins and bovine hemoglobin subunit were up-regulated in Milk-L1, while Milk-L2 exhibited higher levels of enteric β-defensin, sterol regulatory element binding transcription factor 1, sydecan-2, and cysteine-rich secretory protein 2. Additionally, immune proteins such as vacuolar protein sorting-associated protein 4B, polymeric immunoglobulin receptor (PIGR), and Ig-like domain-containing protein were found at higher levels in Milk-L1 compared with Milk-L2. The study provides a comprehensive understanding of the distinct proteomic profiles of BC, Milk-L1, and Milk-L2, which contributes to the development of protein ingredients for infant formula.

Human Milk Nutrient Composition Data is Critically Lacking in the United States and Canada: Results from a Systematic Scoping Review of 2017-2022

Characterization of the nutrients in human milk is important to understand the dietary and developmental requirements of infants. The objective of this review was to summarize the state-of-the-science on the nutrient composition of human milk in the United States and Canada published from 2017 to 2022. Four databases were searched for randomized controlled studies and others given the scoping nature of this review. We limited type to mature milk collected 21 d postpartum and beyond from lactating individuals in the United States and Canada who gave birth at 37-wk gestation or later (full-term). Outcomes of interest included traditional macro- and micronutrients, including human milk oligosaccharides (HMOs), and milk volume. The publication date range was selected as January 1, 2017, to the day the literature search was performed. A total of 32 articles were included in the scoping review from primarily longitudinal cohort or cross-sectional designs. The most prevalent sample collection method was full-breast expression (n = 20) with most studies (n = 26) collecting samples from a single timepoint. Carbohydrates (HMOs [n = 12], glucose [n = 8], and lactose [n = 6]) and protein (n = 5) were the most frequently assessed nutrients in this body of work, with consensus among studies that glucose is present in limited concentrations compared to lactose (24-64 mg/dL compared with 6-7 g/dL) and that HMOs are influenced by temporality and secretor status. Included studies displayed an overall level of heterogeneity and sparsity paralleling previous reports and nutrient data in the USDA FoodData Central system. Much of the data extracted from retained articles generally provided analysis of a specific nutrient or group of nutrients. Moreover, many studies did not use the preferred analytical methods as outlined by the Human Milk Composition Initiative to increase measurement confidence. Up-to-date nutrient composition data of human milk is still greatly needed as it is paramount for the management of infant feeding, assessment of infant and maternal nutritional and health needs, and as a reference for infant formula development.

Fingerprinting of Proteases, Protease Inhibitors and Indigenous Peptides in Human Milk

The presence of proteases and their resulting level of activity on human milk (HM) proteins may aid in the generation of indigenous peptides as part of a pre-digestion process, of which some have potential bioactivity for the infant. The present study investigated the relative abundance of indigenous peptides and their cleavage products in relation to the abundance of observed proteases and protease inhibitors. The proteomes and peptidomes in twelve HM samples, representing six donors at lactation months 1 and 3, were profiled. In the proteome, 39 proteases and 29 protease inhibitors were identified in 2/3 of the samples. Cathepsin D was found to be present in higher abundance in the proteome compared with plasmin, while peptides originating from plasmin cleavage were more abundant than peptides from cathepsin D cleavage. As both proteases are present as a system of pro- and active- forms, their activation indexes were calculated. Plasmin was more active in lactation month 3 than month 1, which correlated with the total relative abundance of the cleavage product ascribed to plasmin. By searching the identified indigenous peptides in the milk bioactive peptide database, 283 peptides were ascribed to 10 groups of bioactivities. Antimicrobial peptides were significantly more abundant in month 1 than month 3; this group comprised 103 peptides, originating from the β-CN C-terminal region.

Protein and growth during the first year of life: a systematic review and meta-analysis

Dietary protein intake in the first year of life might influence later growth. We conducted a systematic review to investigate the growth effects of interventions based on infant formula composition providing different amounts of protein within the first year of life of healthy term infants; in the absence of other comparable information over the investigated period, a meta-analysis further compared weight or length gain at 120 days from high- (>2.0 g/100 kcal) and low-protein (≤2.0 g/100 kcal) content formula groups. Twelve papers (n = 2275) were included and five of them (n = 677) contributed to the meta-analysis. Most studies compared a high-protein formula, a low-protein formula, and breastfeeding. Evidence from the systematic review was inconclusive due to heterogeneity in design and treatments. In the presence of modest heterogeneity but in the absence of publication bias, the weighted mean difference for weight gain at 120 days was -0.02 g/day (95% CI: -1.41, 1.45); with higher heterogeneity, the weighted MD estimate of length gain at 120 days was 0.004 cm/month (95% CI: -0.26, 0.27). Although limited and underpowered, evidence from the meta-analysis does not support the assumption that high- vs. low-protein content formulas during exclusive milk-feeding lead to different growth outcomes in the first months of life. Prospero registration number: CRD42017058535. IMPACT: The optimal amount of dietary protein that should be given to healthy full-term infants early in life is still debated. Despite heterogeneity in study design, treatments, and outcomes, this systematic review showed that there is no clear-cut effect on the growth of different amounts of protein intake from formulas or complementary feeding. Evidence from the meta-analysis based on the five articles enrolling infants <1 month of life does not support the previous assumption that high- vs. low-protein content formulas during exclusive milk-feeding lead to different growth outcomes in the first 4 months of life.

Influence of technical and maternal-infant factors on the measurement and expression of extracellular miRNA in human milk

Breast milk contains thousands of bioactive compounds including extracellular vesicle microRNAs (EV-miRNAs), which may regulate pathways such as infant immune system development and metabolism. We examined the associations between the expression of EV-miRNAs and laboratory variables (i.e., batch effects, sample characteristics), sequencing quality indicators, and maternal-infant characteristics. The study included 109 Latino mother-infant dyads from the Southern California Mother's Milk Study. Mothers were age 28.0 ± 5.6 and 23-46 days postpartum. We used principal components analysis to evaluate whether EV-miRNA expression was associated with factors of interest. Then, we used linear models to estimate relationships between these factors and specific EV-miRNA counts and analyzed functional pathways associated with those EV-miRNAs. Finally, we explored which maternal-infant characteristics predicted sequencing quality indicators. Sequencing quality indicators, predominant breastfeeding, and breastfeedings/day were associated with EV-miRNA principal components. Maternal body mass index and breast milk collection timing predicted proportion of unmapped reads. Expression of 2 EV-miRNAs were associated with days postpartum, 23 EV-miRNAs were associated with breast milk collection time, 23 EV-miRNAs were associated with predominant breastfeeding, and 38 EV-miRNAs were associated with breastfeedings/day. These EV-miRNAs were associated with pathways including Hippo signaling pathway and ECM-receptor interaction, among others. This study identifies several important factors that may contribute to breast milk EV-miRNA expression. Future studies should consider these findings in the design and analysis of breast milk miRNA research.

Perspective: Assuring the Quality of Protein in Infant Formula

Current regulations require that the assessment of protein quality in infant formula be determined using the protein efficiency ratio (PER) rat bioassay where the growth of rats fed a test protein is compared with the growth of rats fed casein. This review cites authoritative body opinions that the PER is not a preferred method for scoring protein quality, particularly as applied to the infant formula. Methodological recommendations specified by FDA and recent guidance propose to control nonprotein dietary variables in the PER. In contrast, the essential amino acid pattern of human milk has been adopted internationally as the standard for protein quality in infant formula. Because casein, the control protein in the PER fails to meet the standard of human milk essential amino acids, the PER based on casein can generate a false assurance of the quality of protein in an infant formula. FDA should revise the method of demonstrating the quality factor for the biological quality of protein to the essential amino acid pattern of human milk, which would be simpler, conform to international standards, and should be considered by FDA under a new statute. Alternate methods of determination of protein quality can be used selectively when there are questions about the digestibility of new protein sources or the effects of manufacturing processes.

Infant formulae - Key components, nutritional value, and new perspectives

Breastfeeding is the most effective strategy for meeting the nutritional demands of infants, whilst infant formulae are manufactured foods that mimic human milk and can be safely used to replace breastfeeding. In this paper, the compositional differences between human milk and other mammalian milk are reviewed, and thus nutritional profiles and compositions of standard bovine milk-based formulae as well as special formulae are discussed. Differences between breast milk and other mammalian milk in composition and content affect their digestion and absorption in infants. Characteristics and mimicking of breast milk have been intensively studied with the objective of narrowing the gap between human milk and infant formulae. The functions of the key nutritional components in infant formulae are examined. This review detailed recent developments in the formulation of different types of special infant formulae and efforts for their humanization, and summarized safety and quality control of infant formulae.

Regenerative Potential of Human Breast Milk: A Natural Reservoir of Nutrients, Bioactive Components and Stem cells

Human milk is a complex fluid that contains carbohydrates, lipids, proteins, and other bioactive molecules (immunoglobulins, lactoferrin, human milk oligosaccharides, lysozyme, leukocytes, cytokines, hormones, and microbiome) which provide nutritional, immunological, and developmental benefits to the infant. In addition to their involvement in the development, these bioactive compounds have a key role in anti-oncogenicity, neuro-cognitive development, cellular communication, and differentiation. As a result of technological advancements, it has been discovered that human breast milk contains cells that display many of the characteristics of stem cells with multilineage differentiation potentials. Do these cells have any specific properties or roles? Research efforts on breast milk cells have been mainly focused on leukocytes based on their immunological perspective in the early postpartum period. This review summarizes the nutritional components in human milk, i.e., the macro and micronutrients required for the growth and development of infants. Further, it discusses the research work reported concerning the purification, propagation, and differentiation of breast milk progenitor cells and highlights the advancements made in this newly emerging field of stem cell biology and regenerative medicine.

Analysis of milk with liquid chromatography–mass spectrometry: a review

As a widely consumed foodstuff, milk and dairy products are increasingly studied over the years. At the present time, milk profiling is used as a benchmark to assess the properties of milk. Modern biomolecular mass spectrometers have become invaluable to fully characterize the milk composition. This review reports the analysis of milk and its components using liquid chromatography coupled with mass spectrometry (LC–MS). LC–MS analysis as a whole will be discussed subdivided into the major constituents of milk, namely, lipids, proteins, sugars and the mineral fraction.

Shaping infant development from the inside out: Bioactive factors in human milk

Human breast milk is the optimal nutrition for all infants and is comprised of many bioactive and immunomodulatory components. The components in human milk, such as probiotics, human milk oligosaccharides (HMOs), extracellular vesicles, peptides, immunoglobulins, growth factors, cytokines, and vitamins, play a critical role in guiding neonatal development beyond somatic growth. In this review, we will describe the bioactive factors in human milk and discuss how these factors shape neonatal immunity, the intestinal microbiome, intestinal development, and more from the inside out.

Identification of common and distinct origins of human serum and breastmilk IgA1 by mass spectrometry-based clonal profiling

The most abundant immunoglobulin present in the human body is IgA. It has the highest concentrations at the mucosal lining and in biofluids such as milk and is the second most abundant class of antibodies in serum. We assessed the structural diversity and clonal repertoire of IgA1-containing molecular assemblies longitudinally in human serum and milk from three donors using a mass spectrometry-based approach. IgA-containing molecules purified from serum or milk were assessed by the release and subsequent analysis of their Fab fragments. Our data revealed that serum IgA1 consists of two distinct structural populations, namely monomeric IgA1 (∼80%) and dimeric joining (J-) chain coupled IgA1 (∼20%). Also, we confirmed that IgA1 in milk is present solely as secretory (S)IgA, consisting of two (∼50%), three (∼33%) or four (∼17%) IgA1 molecules assembled with a J-chain and secretory component (SC). Interestingly, the serum and milk IgA1-Fab repertoires were distinct between monomeric, and J-chain coupled dimeric IgA1. The serum dimeric J-chain coupled IgA1 repertoire contained several abundant clones also observed in the milk IgA1 repertoire. The latter repertoire had little to no overlap with the serum monomeric IgA1 repertoire. This suggests that human IgA1s have (at least) two distinct origins; one of these produces dimeric J-chain coupled IgA1 molecules, shared in human serum and milk, and another produces monomeric IgA1 ending up exclusively in serum.

The Appearance and Establishment of Breastfeeding Amongst Animals: From Echidna and Platypus to Mammals and Human

The paper provides review of the scientific literature dedicated to the evolutionary aspects of breastfeeding in the animal kingdom. Differences in breast milk composition amongst different mammals along with changes in breast milk composition during evolution provided. Special attention is paid to oligosaccharides — unique components of the breast milk of Homo sapiens.

Effects of a Novel Infant Formula on Weight Gain, Body Composition, Safety and Tolerability to Infants: The INNOVA 2020 Study

Exclusive breastfeeding is recommended for the first six months of life to promote adequate infant growth and development, and to reduce infant morbidity and mortality. However, whenever some mothers are not able to breastfeed their infants, infant formulas mimicking human milk are needed, and the safety and efficacy of each formula should be tested. Here, we report the results of a multicenter, randomized, blinded, controlled clinical trial that aimed to evaluate a novel starting formula on weight gain and body composition of infants up to 6 and 12 months, as well as safety and tolerability. For the intervention period, infants were divided into three groups: group 1 received formula 1 (Nutribén® Innova 1 (Alter Farmacia S.A., Madrid, Spain) or INN (n = 70)), with a lower amount of protein, a lower casein to whey protein ratio by increasing the content of α-lactalbumin, and a double amount of docosahexaenoic acid/arachidonic acid than the standard formula; it also contained a thermally inactivated postbiotic (Bifidobacterium animalis subsp. lactis, BPL1TM HT). Group 2 received the standard formula or formula 2 (Nutriben® Natal (Alter Farmacia S.A., Madrid, Spain) or STD (n = 70)) and the third group was exclusively breastfed for exploratory analysis and used as a reference (BFD group (n = 70)). During the study, visits were made at 21 days and 2, 4, 6, and 12 months of age. Weight gain was higher in both formula groups than in the BFD group at 6 and 12 months, whereas no differences were found between STD and INN groups either at 6 or at 12 months. Likewise, body mass index was higher in infants fed the two formulas compared with the BFD group. Regarding body composition, length, head circumference and tricipital/subscapular skinfolds were alike between groups. The INN formula was considered safe as weight gain and body composition were within the normal limits, according to WHO standards. The BFD group exhibited more liquid consistency in the stools compared to both formula groups. All groups showed similar digestive tolerance and infant behavior. However, a higher frequency of gastrointestinal symptoms was reported by the STD formula group (n = 291), followed by the INN formula (n = 282), and the BFD groups (n = 227). There were fewer respiratory, thoracic, and mediastinal disorders among BFD children. Additionally, infants receiving the INN formula experienced significantly fewer general disorders and disturbances than those receiving the STD formula. Indeed, atopic dermatitis, bronchitis, and bronchiolitis were significantly more prevalent among infants who were fed the STD formula compared to those fed the INN formula or breastfed. To evaluate whether there were significant differences between formula treatments, beyond growth parameters, it would seem necessary to examine more precise health biomarkers and to carry out long-term longitudinal studies.

Perspective: Human Milk Composition and Related Data for National Health and Nutrition Monitoring and Related Research

National health and nutrition monitoring is an important federal effort in the United States and Canada, and the basis for many of their nutrition and health policies. Understanding of child exposures through human milk (HM) remains out of reach due to lack of current and representative data on HM's composition and intake volume. This article provides an overview of the current national health and nutrition monitoring activities for HM-fed children, HM composition (HMC) and volume data used for exposure assessment, categories of potential measures in HM, and associated variability factors. In this Perspective, we advocate for a framework for collection and reporting of HMC data for national health and nutrition monitoring and programmatic needs, including a shared vision for a publicly available Human Milk Composition Data Repository (HMCD-R) to include essential metadata associated with HMC. HMCD-R can provide a central, integrated platform for researchers and public health officials for compiling, evaluating, and sharing HMC data. The compiled compositional and metadata in HMCD-R would provide pertinent measures of central tendency and variability and allow use of modeling techniques to approximate compositional profiles for subgroups, providing more accurate exposure assessments for purposes of monitoring and surveillance. HMC and related metadata could facilitate understanding the complexity and variability of HM composition, provide crucial data for assessment of infant and maternal nutritional needs, and inform public health policies, food and nutrition programs, and clinical practice guidelines.

Analysis of Minor Proteins Present in Breast Milk by Using WGA Lectin

Breast milk is a complex and dynamic biological fluid and considered an essential source of nutrition in early life. In its composition, the proteins have a relevant biological activity and are related to the multiple benefits demonstrated when compared with artificial milks derived from cow’s milk. Understanding human milk composition provides an important tool for health care providers toward the management of infant feeding and the establishment of breastfeeding. In this work, a new technique was developed to increase the knowledge of human milk, because many of the components remain unknown. To isolate minor proteins present in breast milk by using WGA lectin, breast milk was centrifuged to remove cells and separate the fat phase from the serum phase. The serum obtained was separated into two groups: control (n = 3; whole serum sample from mature milk) and WGA lectin (n = 3; sample processed with WGA lectin to isolate glycosylated proteins). The samples were analyzed by high-performance liquid chromatography coupled to mass spectrometry (HPLC/MS). A total of 84 different proteins were identified from all of the samples. In the WGA lectin group, 55 different proteins were isolated, 77% of which had biological functions related to the immune response. Of these proteins, there were eight WGA lectin group exclusives, and two had not previously been described in breast milk (polyubiquitin-B and POTE ankyrin domain family member F). Isolation by WGA lectin is a useful technique to detect minor proteins in breast milk and to identify proteins that could not be observed in whole serum.

Proteomic Analysis of Human Milk Reveals Nutritional and Immune Benefits in the Colostrum from Mothers with COVID-19

Despite the well-known benefits of breastfeeding and the World Health Organization’s breastfeeding recommendations for COVID-19 infected mothers, whether these mothers should be encouraged to breastfeed is under debate due to concern about the risk of virus transmission and lack of evidence of breastmilk’s protective effects against the virus. Here, we provide a molecular basis for the breastfeeding recommendation through mass spectrometry (MS)-based proteomics and glycosylation analysis of immune-related proteins in both colostrum and mature breastmilk collected from COVID-19 patients and healthy donors. The total protein amounts in the COVID-19 colostrum group were significantly higher than in the control group. While casein proteins in COVID-19 colostrum exhibited significantly lower abundances, immune-related proteins, especially whey proteins with antiviral properties against SARS-CoV-2, were upregulated. These proteins were detected with unique site-specific glycan structures and improved glycosylation diversity that are beneficial for recognizing epitopes and blocking viral entry. Such adaptive differences in milk from COVID-19 mothers tended to fade in mature milk from the same mothers one month postpartum. These results suggest that feeding infants colostrum from COVID-19 mothers confers both nutritional and immune benefits, and provide molecular-level insights that aid breastmilk feeding decisions in cases of active infection.

Natural Association of Lysozyme and Casein Micelles in Human Milk

Using reversed phase high-performance liquid chromatography with ultraviolet (UV) detection and electrospray ionization (ESI)-quadrupole time-of-flight mass spectrometry (RP-HPLC-UV-ESI-Q-TOF), the lysozyme content in the milk of 10 volunteering mothers was quantified, ranging from 29 to 96 μg/mL. Following ultracentifugation, it was found that the lysozyme in human milk, unlike other whey proteins, is mainly bound to casein micelles (ca. 75%). The enzymatic activity of human lysozyme, measured as lytic activity against cell walls of Micrococcus lysodeikticus, was similar for the micelle-bound and free protein, indicating that the micellar structure should not affect the antibacterial activity of lysozyme. The results indicate that lysozyme is an integral component of casein micelles in human milk.

Comparison of conventional heat-treated and membrane filtered infant formula using an in vitro semi-dynamic digestion method

Introducing membrane filtration steps into infant milk formula (IMF) manufacture can partly preserve native whey proteins in the final products. In this study, IMF produced by membrane filtration (MEM-IMF) and...

Studies and Application of Sialylated Milk Components on Regulating Neonatal Gut Microbiota and Health

Breast milk is rich in sialic acids (SA), which are commonly combined with milk oligosaccharides and glycoconjugates. As a functional nutrient component, SA-containing milk components have received increasing attention in recent years. Sialylated human milk oligosaccharides (HMOs) have been demonstrated to promote the growth and metabolism of beneficial gut microbiota in infants, bringing positive outcomes to intestinal health and immune function. They also exhibit antiviral and bacteriostatic activities in the intestinal mucosa of new-borns, thereby inhibiting the adhesion of pathogens to host cells. These properties play a pivotal role in regulating the intestinal microbial ecosystem and preventing the occurrence of neonatal inflammatory diseases. In addition, some recent studies also support the promoting effects of sialylated HMOs on neonatal bone and brain development. In addition to HMOs, sialylated glycoproteins and glycolipids are abundant in milk, and are also critical to neonatal health. This article reviews the current research progress in the regulation of sialylated milk oligosaccharides and glycoconjugates on neonatal gut microbiota and health.

Physicochemical properties of human breast milk during the second year of lactation

The present study examined the microstructure as well as the physicochemical properties of human milk during the second year of lactation in an attempt to explore its applicability for the formulation of food products. It was observed that human milk fat globules (MFG) droplet size increased within 3 days of milk extraction due to coalescence, as evidenced by confocal microscopy. Furthermore, a gradual decrease of the average MFG size was noted from the sixteenth (16th) to twenty-fifth (25th) month of lactation. It was also found that the size of casein micellar structures increased upon acidification to pH 4.3 (isoelectric point of human caseins). In addition, human milk proteins enhanced the stability of oil-in-water emulsions against coalescence compared to cow, sheep, and goat milk proteins employed as macromolecular emulsifying ingredients. The cold-acid-gels of human milk proteins showed a less elastic behavior than the other milk samples, possibly due to the different structure, composition and size of human casein micelles. Furthermore, the DSC thermograms showed that human whey proteins are denatured in the same temperature range as do the cow whey proteins, but exhibit different thermal transition profiles. Overall, the findings of this research confirm that both the structure and the physicochemical properties of human milk are affected by the stage of lactation. Moreover, the particular composition and structure of human milk proteins seem to be responsible for the special functional characteristics of human milk that may lead towards the formulation of innovative products.

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The physicochemical properties of human milk in the 2 nd year were examined.

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Enhanced stabilization of oil-in-water emulsions with human milk proteins (HMP).

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Less elastic behavior of cold-acid HMP gels compared to other milk species proteins.

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HMP exhibited different thermal transition profiles than cow milk proteins.

Comparative Proteomics of Human Milk From Eight Cities in China During Six Months of Lactation in the Chinese Human Milk Project Study

Human milk (HM) is the golden standard of infant nutrition that can protect immature body function and enhance nutrition metabolism to ensure infant growth. Region specificity and lactation period could change the protein composition in HM. In this research, proteomics analysis was used to compare proteomes across eight cities, namely Harbin, Lanzhou, Guangzhou, Chengdu, Jinhua, Weihai, Zhengzhou, and Beijing, which represented the northeast, northwest, southeast, southwest, east, and north and central regions of China,. Proteins varied significantly among the cities. These different proteins were mainly involved in the process of platelet degranulation, innate immune response, and triglyceride metabolic process, which might be due to different living environments. These differences also lead to variation in protection and fat metabolism from mothers to infants in different cities. Four proteins were expressed differently during 6 months of lactation, namely Dipeptidyl peptidase 1, Lysozyme C, Carbonic anhydrase 6, and Chordin-like protein 2. The changes in these proteins might be because of the change of growth needs of the infants. The findings from our results might help to improve the understanding of HM as well as to design infant formula.

Monitoring Human Milk β-Casein Phosphorylation and O-Glycosylation Over Lactation Reveals Distinct Differences between the Proteome and Endogenous Peptidome

Human milk is a vital biofluid containing a myriad of molecular components to ensure an infant’s best start at a healthy life. One key component of human milk is β-casein, a protein which is not only a structural constituent of casein micelles but also a source of bioactive, often antimicrobial, peptides contributing to milk’s endogenous peptidome. Importantly, post-translational modifications (PTMs) like phosphorylation and glycosylation typically affect the function of proteins and peptides; however, here our understanding of β-casein is critically limited. To uncover the scope of proteoforms and endogenous peptidoforms we utilized mass spectrometry (LC-MS/MS) to achieve in-depth longitudinal profiling of β-casein from human milk, studying two donors across 16 weeks of lactation. We not only observed changes in β-casein’s known protein and endogenous peptide phosphorylation, but also in previously unexplored O-glycosylation. This newly discovered PTM of β-casein may be important as it resides on known β-casein-derived antimicrobial peptide sequences.

Casein and Whey Protein in the Breast Milk Ratio: Could It Promote Protein Metabolism Enhancement in Physically Active Adults?

Due to the utilization of milk proteins such as whey protein (WP) and casein as sports nutrition ergogenic aids, the present study investigated the effects of the association of WP and casein in a ratio of 80:20, a similar ratio of human breast milk, on blood branched-chain amino acid (BCAA) profiles, markers of protein metabolism and delayed onset muscle soreness (DOMS), after a single bout of resistance exercise. A double-blind, crossover and acute study was carried out with ten men (age 29 ± 8 years; BMI: 25.4 ± 2.9 kg/m²; 77 ± 12 kg; 1.74 ± 0.09 m); each one consumed the following supplements randomly, one per session: WP, CAS (casein), WP/CAS (80% WP/20% CAS), CAS/WP (80% CAS/20% WP) and PLA (placebo). They were also subjected to the following evaluations: the one repetition maximum (1RM) test; resistance training session; blood extraction during each session to determine the BCAA profile; two food records; 3-day evaluation of DOMS (24 h, 48 h and 72 h) and nitrogen balance in each treatment. The intervention resulted in similar nitrogen urinary, creatinine and urea plasma levels and showed a positive nitrogen balance in all the trials. Regarding the BCAAs, the peak occurred at 60 min post-ingestion and remained higher until 120 min for WP, WP/CAS and CAS/WP. The DOMS was significantly lower for WP, WP/CAS and CAS/WP compared to the CAS and PLA treatments. There were no advantages in the association of WP and CAS in the BCAAs profile when compared to WP itself, but it induced a lower DOMS compared to CAS and PLA (Clinical Trial registration number: clinicaltrials.gov, NCT04648384).

Human milk proteome: what's new?

PURPOSE OF REVIEW

The proteome is one of the most complicated and multifunctional components in human milk. Recently, numerous novel characteristics of the human milk proteome have been discovered, which are described and critically examined in this review.

RECENT FINDINGS

Recent human milk proteomics studies have focused on how external factors like geography and environment, or maternal and infant's factors affect the milk proteins, endogenous peptides, their posttransitional modifications (PTMs) and infant utilization. Most of these studies have shown that major protein and endogenous peptide profiles are similar for healthy women and infants. The human milk proteome has been expanded by providing novel insights into PTMs like glycosylation and phosphorylation, and how the proteins and peptides are digested and utilized by the infant. All human milk proteomics studies are subject to conditions in which the samples were collected, handled and stored.

SUMMARY

Significant technological advancements in mass spectrometry have considerably enabled a deeper and more comprehensive identification and characterization of the expanded human milk proteome. However, data concerning human milk from mothers with infections or illnesses and mothers nursing more vulnerable infants are still limited and the roles of the components of the human milk proteome have not yet been sufficiently elucidated.

Protein Profile and Simulated Digestive Behavior of Breast Milk from Overweight and Normal Weight Mothers

Human milk proteins have shown to vary in concentration and distribution through lactation. However, while some regulatory components, such as hormones, have shown associations with regard to the mothers' body mass index, there is limited information on the possible influence of this condition on the whole protein distribution. The objective of this study was to evaluate the protein profile of human milk from normal weight and overweight or obese mothers to identify differences in protein expression in colostrum, transitional and mature milk. The mass spectrometry analysis showed the ability to class with a high degree of confidence the lactation state and the milk profile according to the mother's condition. Individual milk samples were subjected to a digestion in vitro model that takes into account the specificities of the gastrointestinal conditions of full-term newborn infants. The digestion products were compared with available data from the digestive contents in newborns. The behavior of the most abundant proteins and the overall peptide generation and survival, showed good correspondence with in vivo data.

Human milk composition promotes optimal infant growth, development and health

Human milk is a living dynamic fluid that promotes optimal nutrition and development of the infant and impacts health across the lifespan. This review reports on the diverse range of nutrients, immune protection factors, hormones, microbes and metabolites in human milk and their impacts on infant nutrition and health. While many of these components are stable across lactation and similar between women, some vary over time, and in response to maternal and infant health status, maternal diet and geographic location. Human milk may be considered as personalized nutrition, with many components working synergistically to stimulate and support the infant's immature immune system, while enhancing appropriate development, growth and body composition.

Iron-Enriched Nutritional Supplements for the 2030 Pharmacy Shelves

Iron deficiency (ID) affects people of all ages in many countries. Due to intestinal blood loss and reduced iron absorption, ID is a threat to IBD patients, women, and children the most. Current therapies can efficiently recover normal serum transferrin saturation and hemoglobin concentration but may cause several side effects, including intestinal inflammation. ID patients may benefit from innovative nutritional supplements that may satisfy iron needs without side effects. There is a growing interest in new iron-rich superfoods, like algae and mushrooms, which combine antioxidant and anti-inflammatory properties with iron richness.

Human body-fluid proteome: quantitative profiling and computational prediction

Empowered by the advancement of high-throughput bio technologies, recent research on body-fluid proteomes has led to the discoveries of numerous novel disease biomarkers and therapeutic drugs. In the meantime, a tremendous progress in disclosing the body-fluid proteomes was made, resulting in a collection of over 15 000 different proteins detected in major human body fluids. However, common challenges remain with current proteomics technologies about how to effectively handle the large variety of protein modifications in those fluids. To this end, computational effort utilizing statistical and machine-learning approaches has shown early successes in identifying biomarker proteins in specific human diseases. In this article, we first summarized the experimental progresses using a combination of conventional and high-throughput technologies, along with the major discoveries, and focused on current research status of 16 types of body-fluid proteins. Next, the emerging computational work on protein prediction based on support vector machine, ranking algorithm, and protein-protein interaction network were also surveyed, followed by algorithm and application discussion. At last, we discuss additional critical concerns about these topics and close the review by providing future perspectives especially toward the realization of clinical disease biomarker discovery.

Protein levels and protease activity in milk from mothers of pre-term infants: A prospective longitudinal study of human milk macronutrient composition

BACKGROUND AND AIMS

The composition and enzymology of human milk changes throughout the lactation period, and differ for mothers who give birth prematurely compared to those who deliver at full-term. Understanding the composition of milk from mothers of very low birth weight premature infants is of great significance, and the objective of this study was to evaluate the composition, protein profile and plasmin activity of milk from mothers who delivered infants at different gestational ages.

METHODS

Samples of human milk were donated by women (n = 74) in the Cork, Ireland, area who gave birth to full-term (>37 weeks gestation, FT), pre-term (32-37 weeks, PT) and very pre-term (≤32 weeks, VPT) infants. FT milk was collected at 1, 3, 6 and 10 weeks post-partum (PP), while PT and VPT milk was collected weekly until the FT due date of the infant and subsequently followed the FT protocol.

RESULTS

Gestational age did not significantly affect lactose or fat content or total energy content of milk. However, protein content, and levels of some individual proteins, were significantly affected by both gestational age at birth and duration of lactation, with significantly higher protein levels in PT or VPT milk samples at 0-7 days and 1-2 months, respectively. Plasmin activity was significantly higher in VPT milk, indicating differences in proteolytic processing in milk.

CONCLUSION

Compositional differences between the milk of mothers of term and pre-term infants were greatest in terms of the protein profile, which showed both qualitative and quantitative differences, as well as difference in proteolytic activity.

Longitudinal changes in the bioactive proteins in human milk of the Chinese population: A systematic review

This systematic review aimed at investigating longitudinal changes in human milk bioactive protein concentrations in Chinese population. Both English and Chinese databases were searched. The data were pooled into six defined lactation stages. Weighted means of protein concentrations in each stage and the statistical significance of means of different lactation stages were calculated. The data of 11 bioactive proteins were retrieved. Concentrations of sIgA, IgM, and IgG decreased sharply during the first 14 days of lactation. The levels of α-lactalbumin, lactoferrin, and β-casein also decreased throughout lactation. Conversely, lysozyme levels increased over lactation. The changing patterns of the serum albumin, osteopontin, and bile salt-stimulated lipase (BSSL) were not conclusive. This study represents the most comprehensive summary of bioactive proteins in Chinese human milk. In the future, mass spectrometry-based analysis of human milk proteomics may be used to investigate the longitudinal changes of many more bioactive proteins.

Human milk microbiota development during lactation and its relation to maternal geographic location and gestational hypertensive status

Bacteria in human milk could directly seed the infant intestinal microbiota, while information about how milk microbiota develops during lactation and how geographic location, gestational hypertensive status, and maternal age influence this process is limited. Here, we collected human milk samples from mothers of term infants at the first day, 2 weeks, and 6 weeks postpartum from 117 longitudinally followed-up mothers (age: 28.7 ± 3.6 y) recruited from three cities in China. We found that milk microbial diversity and richness were the highest in colostrum but gradually decreased over lactation. Microbial composition changed across lactation and exhibited more discrete compositional patterns in 2-week and 6-week milk samples compared with colostrum samples. At phylum level, the abundance of Proteobacteria increased during lactation, while Firmicutes showed the opposite trend. At genus level, Staphylococcus, Streptococcus, Acinetobacter, Pseudomonas, and Lactobacillus were predominant in colostrum samples and showed distinct variations across lactation. Maternal geographic location was significantly associated with the milk microbiota development and the abundance of predominant genus. In addition, milk from mothers with gestational prehypertension had a different and less diverse microbial community at genus level in early lactation times, and contained less Lactobacillus in the 2-week milk samples than those from normotensive mothers. Findings of our study outlined the human milk microbial diversity and community development over lactation, and underscored the importance of maternal geographic locations and gestational hypertensive status on milk microbiota, which might have important implications in the establishment of the infant intestinal microbiota via breastfeeding.

Formula Diet Alters the Ileal Metagenome and Transcriptome at Weaning and during the Postweaning Period in a Porcine Model

Exclusive breastfeeding impacts the intestinal microbiome and is associated with a better immune function than is seen with milk formula (MF) feeding in infants and yet with mechanisms poorly defined. The porcine model was used to evaluate the impact of MF on ileum microbial communities and gene expression relative to human milk (HM)-fed piglets. Fifty-two Dutch Landrace male piglets were fed an isocaloric diet of either HM (n = 26) or MF (n = 26) from day 2 through day 21 of age and weaned to a solid diet until day 51. Eleven piglets from each group were euthanized at day 21, while the remaining piglets (HM, n = 15; MF, n = 15) were euthanized at day 51 to collect ileal epithelium (EP) scrapings and ileal (IL) tissues. The epithelial mucosa was subjected to shotgun metagenome sequencing, and EP and IL tissues were used for transcriptome analysis. On day 21, transcriptome data revealed that the levels of pathways involved in inflammation and apoptosis were significantly higher in MF piglets than in HM piglets, whereas the levels of tight junctions and pathogen detection systems were lower in MF piglets than in HM piglets. The MF impacts on the small intestine were maintained over the postweaning period (day 51) as indicated by higher levels of Dialister invisus bacteria and higher levels of expression of genes associated with inflammation and apoptosis pathways relative to HM group. The current study demonstrated that MF might impact local intestinal inflammation, apoptosis, and tight junctions and might suppress pathogen recognition in the small intestine compared with HM.IMPORTANCE Exclusive human milk (HM) breastfeeding for the first 6 months of age in infants is recommended to improve health outcomes during early life and beyond. When women are unable to provide sufficient HM, milk formula (MF) is often recommended as a complementary or alternative source of nutrition. Previous studies in piglets demonstrated that MF alters the gut microbiome and induces inflammatory cytokine production. The links between MF feeding, gut microbiome, and inflammation status are unclear due to challenges associated with the collection of intestinal samples from human infants. The current report provides the first insight into MF-microbiome-inflammation connections in the small intestine compared with HM feeding using a porcine model. The present results showed that, compared with HM, MF might impact immune function through the induction of ileal inflammation, apoptosis, and tight junction disruptions and likely compromised immune defense against pathogen detection in the small intestine relative to piglets that were fed HM.

Components of human breast milk: from macronutrient to microbiome and microRNA

Human breast milk (HBM) is essential for the infant's growth and development right after birth and is an irreplaceable source of nutrition for early human survival. Various infant formulas have many similarities to HBM in many components, but there is no perfect substitute for HBM. Recently, various breast milk components and their roles have been studied according to the development of various analysis techniques. As is already well known, HBM contains about 87%-88% water, and 124- g/L solid components as macronutrients, including about 7% (60-70 g/L) carbohydrates, 1% (8-10 g/L) protein, and 3.8% (35-40 g/L) fat. The composition may vary depending on the environmental factors, including maternal diet. Colostrum is low in fat but high in protein and relatively rich in immuneprotective components. Although HBM contains enough vitamins to ensure normal growth of the infant, vitamins D and K may be insufficient, and the infant may require their supplementation. Growth factors in HBM also serve as various bioactive proteins and peptides on the intestinal tract, vasculature, nervous system, and endocrine system. In the past, HBM of a healthy mother was thought to be sterile. However, several subsequent studies have confirmed the presence of rich and diverse microbial communities in HBM. Some studies suggested that the genera Staphylococcus and Streptococcus may be universally predominant in HBM, but the origin of microbiota still remains controversial. Lastly, milk is the one of most abundant body fluid of microRNAs, which are known to play a role in various functions, such as immunoprotection and developmental programming, through delivering from HBM and absorption by intestinal epithelial cells. In conclusion, HBM is the most important source of nutrition for infants and includes microbiomes and miRNAs for growth, development, and immunity.

Quantitative Longitudinal Inventory of the N-Glycoproteome of Human Milk from a Single Donor Reveals the Highly Variable Repertoire and Dynamic Site-Specific Changes

Protein N-glycosylation on human milk proteins assists in protecting an infant's health and functions among others as competitive inhibitors of pathogen binding and immunomodulators. Due to the individual uniqueness of each mother's milk and the overall complexity and temporal changes of protein N-glycosylation, analysis of the human milk N-glycoproteome requires longitudinal personalized approaches, providing protein- and N-site-specific quantitative information. Here, we describe an automated platform using hydrophilic-interaction chromatography (HILIC)-based cartridges enabling the proteome-wide monitoring of intact N-glycopeptides using just a digest of 150 μg of breast milk protein. We were able to map around 1700 glycopeptides from 110 glycoproteins covering 191 glycosites, of which 43 sites have not been previously reported with experimental evidence. We next quantified 287 of these glycopeptides originating from 50 glycoproteins using a targeted proteomics approach. Although each glycoprotein, N-glycosylation site, and attached glycan revealed distinct dynamic changes, we did observe a few general trends. For instance, fucosylation, especially terminal fucosylation, increased across the lactation period. Building on the improved glycoproteomics approach outlined above, future studies are warranted to reveal the potential impact of the observed glycosylation microheterogeneity on the healthy development of infants.