Human Milk Oligosaccharides in Colostrum and Mature Milk of Chinese Mothers: Lewis Positive Secretor Subgroups

Comprehensive profiling and development of a collision cross section database for milk oligosaccharides via orthogonal UPLC-cyclic ion mobility-mass spectrometry system

Human milk oligosaccharides (HMOs) have attracted immense interest in the infant formula industry for their health benefits. Herein, we utilized liquid chromatography-cyclic ion mobility-mass spectrometry (LC-cIM-MS) to develop a robust and multidimensional HMO profiling workflow. This workflow relies on a self-built glycan library, allowing high-throughput searching of oligosaccharides. cIM-MS demonstrated high resolving power in discriminating glycan isomers and increasing peak capacity. This also facilitated the accurate elucidation of most oligosaccharides at sequence levels. A remarkably diverse milk oligosaccharide profile (n = 98) was observed and enabled the discovery of distinctive chromatographic retention patterns. To provide supplementary selectivity for future routine assignment in the absence of standards, we further developed a comprehensive database of experiment-derived traveling wave collision cross section in nitrogen (TWCCSN2) for 98 HMOs, including isomer-resolved TWCCSN2 values. Finally, the profile revealed 64 oligosaccharides unique to human milk compared with infant formula, indicating the potential ingredients for formula improvement.

Association Between Human Milk Oligosaccharides and Early Adiposity Rebound in Children: A Case-Control Study of the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study

BACKGROUND

Adiposity rebound (AR) is the point when the BMI begins to rise again during early childhood. Early AR (before age 5) is associated with higher risk of lifelong obesity and metabolic disorders and may be influenced by breastfeeding. Although human milk oligosaccharides (HMOs) in breast milk are crucial for child growth, their association with AR status has not been studied.

OBJECTIVES

This study aimed to explore the association between breast milk HMOs and AR status in children.

METHODS

In this case-control study, we included 184 mother-child pairs from the Tohoku Medical Megabank Project Birth and Three-Generation (TMM BirThree) Cohort Study (93 AR cases, 91 controls). Breast milk was collected 1 mo postpartum, and the concentration of 15 HMO molecules and α-diversity index (Inverse Simpson index) were quantified. Wilcoxon rank-sum test and partial least squares-discriminant analysis identified candidate HMOs, and multivariable logistic regression analysis evaluated associations between candidate HMOs and AR status. Analyses were stratified by maternal secretor status (secretor or nonsecretor).

RESULTS

In secretor mothers, multivariable logistic regression showed that the inverse Simpson index [odds ratio (OR): 0.54; 95% CI: 0.36, 0.82), the sum of sialic acid-bound HMOs (OR: 0.61; 95% CI: 0.41, 0.91), and 3'-sialyllactose (OR: 0.67; 95% CI: 0.46, 0.98) were inversely associated with early AR in the fully adjusted model. A trend of interaction between sialyl-lacto-N-tetraose-a (LSTa) and maternal secretor status regarding AR was observed in the fully adjusted model (P-interaction = 0.051).

CONCLUSIONS

α-Diversity, sialic acid-bound HMOs, and 3'-sialyllactose may involved in inhibiting AR in children of secretor mothers, and a trend of interactive effect between LSTa and maternal secretor status regarding AR is indicated. These findings offer novel perspectives on the associations between breastfeeding and a childhood adiposity as well as potential metabolic disorders later in life. This trial is registered at https://www.umin.ac.jp/ as UMIN000047160.

In Vivo Evidence on the Emerging Potential of Non-Digestible Oligosaccharides as Therapeutic Agents in Bacterial and Viral Infections

The issue of antibiotic-resistant bacterial infections, coupled with the rise in viral pandemics and the slow development of new antibacterial and antiviral treatments, underscores the critical need for novel strategies to mitigate the spread of drug-resistant pathogens, enhance the efficacy of existing therapies, and accelerate the discovery and deployment of innovative antimicrobial and antiviral solutions. One promising approach to address these challenges is the dietary supplementation of non-digestible oligosaccharides (NDOs). NDOs, including human milk oligosaccharides (HMOs), play a vital role in shaping and sustaining a healthy gut microbiota. Beyond stimulating the growth and activity of beneficial gut bacteria, NDOs can also interact directly with pathogenic bacteria and viruses. Their antiviral and antibacterial properties arise from their unique interactions with pathogens and their ability to modulate the host's immune system. NDOs can function as decoy receptors, inhibit pathogen growth, bind to bacterial toxins, stimulate the host immune response, exhibit anti-biofilm properties, and enhance barrier protection. However, a notable gap exists in the comprehensive assessment of in vivo and clinical data on this topic. This review aims to provide an in-depth overview of the in vivo evidence related to the antiviral and antibacterial effects of various NDOs and HMOs, with a focus on discussing their possible mechanisms of action.

Sensitive and high-throughput isomer-specific analysis of human milk oligosaccharides using UPLC-MS/MS and its application to secretor status assignment

Human milk oligosaccharides (HMOs) are now the principal component of the latest infant formula generation. However, it is challenging to separate and quantify highly heterogeneous isomers when analyzing HMOs. Here, we developed a high-throughput isomer-resolved quantification method for 21 native HMOs based on ultrahigh-performance liquid chromatography-mass spectrometry-multiple reaction monitoring (UPLC-MS-MRM) technology. High-resolution cyclic ion mobility-mass spectrometry technology was applied to distinguish HMO isomers and identify specific ion pairs for quantification to solve the measurement challenge of HMOs without available standards. Simultaneously, nine HMO standards were used to create universal calibration curves to quantify those without standards. This MRM approach features wide isomer coverage (seven series of isomers), short analysis time (12 min), high sensitivity (ng/L level detection limit), and a broad 5-order-of-magnitude quantitation range. After that, the technique was used on 58 Chinese human milk samples, which showed that the three genotype milk groups had different HMO profiles at the isomer level. Four crucial fucosylated HMOs were identified as markers to rapidly assign secretor status. Moreover, correlations analysis unveiled a co-regulatory relationship among Fuc-(α1-3/4), Fuc-(α1-2), and sialylated glycanforms. Our research offers a comprehensive solution for isomeric glycome profiling, and provides a crucial reference for designing precise nutrition formula for infants.

MELK study: an observational study on human milk composition and infant health determinants during the first year of life in a Dutch cohort

INTRODUCTION

Human milk plays a crucial role in infants' nutrition and immunity, with its composition being influenced by different factors. The role of maternal diet on human milk fatty acid composition, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is well studied. Higher fish intake is associated with higher DHA levels in human milk, while fewer associations have been reported for EPA. Yet, maternal diet's impact on human milk composition for other nutrients is understudied, and variations in sampling protocols and study quality hinder definitive conclusions on its overall impact. Ethnicity may also impact milk composition, with different dietary habits intertwined with different genetic backgrounds, but also here research lacks standardised protocols. Our study aims to investigate maternal diet, ethnicity, and their association with human milk composition, along with their potential short-term associations with infant health and development, through detailed dietary assessment and by recruiting participants from diverse backgrounds. Understanding these associations could inform the development of tailored nutritional guidelines for mothers and infants, ultimately promoting optimal health and well-being for both. The study design, with its strict sampling procedure, can guide and inspire future studies.

METHODS AND ANALYSIS

We will conduct an observational study involving 120 healthy mothers from three ethnic backgrounds (Chinese, Caucasian and Turkish), exclusively breastfeeding their 2-month-old infants. We will collect human milk samples at two time points and assess maternal dietary intake over 4 days. Additionally, we will collect data on various maternal and child characteristics, including maternal stress, socioeconomic status and health, and infant feeding, sleeping, crying, gastrointestinal health and developmental status.

ETHICS AND DISSEMINATION

The study has been approved by the Medical Ethical Committee Oost-Nederland (NL79447.091.21), and all participants provided written informed consent before entering the study. Findings will be widely disseminated at international conferences and meetings including the annual Nutrition & Growth conference, ESPGHAN, and through publication in scientific peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN registry (ISRCTN35735283).

Analysis of human milk oligosaccharides from women with gestational diabetes mellitus

Human milk oligosaccharides (HMOs) are bioactive components which play an important role in infant health. HMO composition is vulnerable to changes of maternal conditions including lactation stages and maternal phenotypes. Pregnant diseases such as gestational diabetes mellitus (GDM) are commonly found in women during pragnancy, and may cause disorder in maternal physiological metabolism which is harmful to infants. Unfortunately, anlysis of oligosaccharides from women with GDM is limited. To address this issue, we analyzed HMO compositions and profiles in breast milk from women with GDM using an established 96-well plate permethylation platform and MALDI-TOF-MS. We enrolled 127 women with GDM, and investigated HMO abundances in colostrum, transition milk, and mature milk respectively. We found that GDM affected HMO compositions in breast milk, and the level of fucosylation became higher over the course of lactation for all the women with GDM. Interestingly, the relative abundances of fucosylated HMOs in different lactation stages were affected differentially by GDM, with the most pronounced effect in colostrum. In particular, the relative abundances of H3N1F1 and H3N1F2 sharply decreased over time, showing very low levels in late lactation. These differences in our findings need further investigation to develop optimal feeding for mothers with GDM.

Human milk microbiota and oligosaccharides in colostrum and mature milk: comparison and correlation

Background

The interaction between the human breast milk microbiota and human milk oligosaccharides (HMOs) plays a crucial role in the healthy growth and development of infants. We aimed to clarify the link between the breast milk microbiota and HMOs at two stages of lactation.

Methods

The microbiota and HMOs of 20 colostrum samples (C group, 1-5 days postpartum) and 20 mature milk samples (S group, 42 days postpartum) collected from postpartum mothers were analyzed using 16S rRNA gene high-throughput sequencing and high-performance liquid chromatography-tandem mass spectrometry.

Result

The total average HMO content was significantly higher in the C group than in the S group (6.76 ± 1.40 g/L vs. 10.27 ± 2.00 g/L, p < 0.05). Among the HMOs, the average values of 2'-fucosyllactose (2'-FL, 1.64 ± 1.54 g/L vs. 3.03 ± 1.79 g/L), 3'-sialyllactose (3'-SL, 0.10 ± 0.02 g/L vs. 0.21 ± 0.06), 6'-SL (0.22 ± 0.09 g/L vs. 0.33 ± 0.11 g/L), and lacto-N-triaose 2 (LNT2, 0.03 ± 0.01 g/L vs. 0.16 ± 0.08 g/L) were significantly lower in the S group than in the C group (p < 0.05), while that of 3'-FL was significantly higher in the S group than in the C group (1.35 ± 1.00 g/L vs. 0.41 ± 0.43 g/L, p < 0.05). The diversity and structure of the microbiota in the S and C groups were also significantly different (p < 0.05). Comparative analysis of the microbial communities revealed that Proteobacteria and Firmicutes were the most abundant phyla, in both groups, with the keystone species (Serratia, Streptococcus and Staphylococcus) of breast milk closely interacting with HMOs, including 3'-SL, 6'-SL, and LNT2. In PICRUSt2 functional prediction analysis, the S group exhibited significant reduction in the expression of genes involved in several infectious disease pathways.

Discussion

Our findings support the recognition of human milk as a synbiotic comprising beneficial bacteria and prebiotic HMOs.

Research progress on factors affecting the human milk metabolome

Human milk is the gold standard for infant nutrition and contains macronutrients, micronutrients, and various bioactive substances. The human milk composition and metabolite profiles are complex and dynamic, complicating its specific analysis. Metabolomics, a recently emerging technology, has been used to identify human milk metabolites classes. Applying metabolomics to study the factors affecting human milk metabolites can provide significant insights into the relationship between infant nutrition, health, and development and better meet the nutritional needs of infants during growth. Here, we systematically review the current status of human milk metabolomic research, and related methods, offering an in-depth analysis of the influencing factors and results of human milk metabolomics from a metabolic perspective to provide novel ideas to further advance human milk metabolomics.

Systematic Characterization of the Oligosaccharide Profile of Human Milk in Rural Areas of Central China: Quantitative Tracking of Human Milk Oligosaccharide Composition during 12 Months of Lactation

This study investigates changes in human milk oligosaccharide (HMO) composition over a 12 month breastfeeding period in rural central China. The HMO profiles of 97 mothers were analyzed by graphitized carbon liquid chromatography-electrospray ionization-mass spectrometry. This method was simple to prepare samples and can simultaneously and absolutely quantify at least 20 neutral and acidic HMOs. All mothers were classified into four milk groups based on the presence or absence of specific α-1,2 and α-1,4-fucosylated HMOs. The main oligosaccharides in milk groups I and II were 2'-FL, LDFT, LNFP-I, and LNDFH-I, while LNT, 3-FL, LNFP-II, LNFP-V, LNDFH-II, and DFLNH-b were predominant in milk groups III and IV. Additionally, the lactation period was the primary factor affecting the concentration of individual HMOs. The concentrations of most HMOs decreased with lactation and stabilized after 180 days. However, the concentrations of 3-FL, LDFT, and LNDFH II increased gradually over the lactation period, and the concentration of 3'-SL decreased during early lactation (5-180 days) but increased during later lactation (180-365 days). Furthermore, Spearman correlation analysis revealed that maternal factors and infant factors may also affect the concentration of various HMOs. These findings provide fundamental insights for the development of a comprehensive human milk database.

Consumption of different combinations of human milk oligosaccharides in the first 6 mo of infancy is positively associated with early cognition at 2 y of age in a longitudinal cohort of Latino children

BACKGROUND

Lactation has been widely associated with optimal neurocognitive development, but the underlying mechanism remains unknown. Human milk oligosaccharides (HMOs) are complex sugars that support brain development, but previous studies examining their associations with cognition have yielded inconsistent findings.

OBJECTIVES

This study aimed to provide a broader understanding of how HMOs jointly influence cognition.

METHODS

We used data from an ongoing longitudinal cohort of Latino mother-infant dyads. Human milk samples from 1 mo (n = 157) and 6 mo (n = 107) postpartum were assessed for the 19 most abundant HMOs. Cognitive performance was assessed at 2 y using the Bayley Scale of Infant and Toddler Development. A partial least squares model identified HMO combinations predictive of cognitive scores.

RESULTS

At 1 mo, the combination of higher concentrations of lacto-N-neotetraose (LNnT), lacto-N-tetraose (LNT), lacto-N-fucopentaose (LNFP)-III, 6'-sialyllactose, and 2'-fucosyllactose (FL) with lower concentrations of sialyllacto-N-tetraose (LST) b, LNFP-II, fucodisialyllacto-N-hexaose, and 3-FL significantly predicted higher cognitive scores (β: 0.61; 95% confidence interval [CI]: 0.30, 0.92), explaining an additional 8% of the variance over a model with only nuisance covariates (11%). Additional analyses revealed that the combination of higher LNFP-III and lower LSTb alone explained 5% more of the variation in cognitive scores (β: 0.66; 95% CI: 0.24, 1.09). At 6 mo (n = 107), higher LNnT, LNT, and LNFP-III and lower 3FL and LSTb concentrations explained an extra 6% of the variance in cognitive scores (β: 0.43; 95% CI: 0.12, 0.75).

CONCLUSIONS

This study highlights specific HMO combinations in early life influencing cognitive performance at 2 y.

Modifiable and Non-Modifiable Factors That Affect Human Milk Oligosaccharides Composition

Human milk, the gold standard in infant nutrition, is a unique fluid that provides essential nutrients such as lactose, lipids, proteins, and free oligosaccharides. While its primary role is nutritional, it also protects against pathogens. This protection mainly comes from immunoglobulins, with human milk oligosaccharides (HMOs) providing additional support by inhibiting pathogen binding to host cell ligands. The prebiotic and immune-modulatory activity of HMOs strongly depends on their structure. Over 200 individual structures have been identified so far, with the composition varying significantly among women. The structure and composition of HMOs are influenced by factors such as the Lewis blood group, secretor status, and the duration of nursing. HMO profiles are heavily influenced by maternal phenotypes, which are defined based on the expression of two specific fucosyltransferases. However, recent data have shown that HMO content can be modified by various factors, both changeable and unchangeable, including diet, maternal age, gestational age, mode of delivery, breastfeeding frequency, and race. The first part of this overview presents the historical background of these sugars and the efforts by scientists to extract them using the latest chromatography methods. The second part is divided into subchapters that examine modifiable and non-modifiable factors, reviewing the most recent articles on HMO composition variations due to specific reasons and summarizing potential future challenges in conducting these types of studies.

Human Milk Oligosaccharides and Respiratory Syncytial Virus Infection in Infants

In infants worldwide, respiratory syncytial virus (RSV) is the leading cause of lower respiratory infections, including bronchiolitis, which is a major source of infant mortality. Bronchiolitis is the most common lower respiratory infection and the major cause of hospitalization in the first 6 mo of life. Infant responses to RSV infection are highly diverse, with symptoms varying from asymptomatic or mild to so severe as to require mechanical ventilation. Breastfed infants present a lower incidence and less severe forms of RSV lower respiratory infections. Among the multitude of human milk bioactive compounds, human milk oligosaccharides (hMOSs) are strong candidates for having a protective effect against RSV. hMOS reduces the viral load and the inflammatory signaling in cultured RSV-infected respiratory human cells. In addition to this direct effect, indirect mechanisms, notably gut microbiota composition and metabolism, have been proposed to mediate the protective effect of hMOS. Intake of infant formula containing synthetic hMOS has been shown to increase Bifidobacterium abundance and that of its metabolites, especially acetate, in infant feces and to reduce lower respiratory tract infections during the first year of life. Breastfeeding and the use of hMOS are promising approaches to protect against and treat RSV disease. Here, we review current evidence on the role of hMOS with regard to RSV infection and disease, attending to knowledge gaps and future research directions.

Patterns of Human Milk Oligosaccharides in Mature Milk Are Associated with Certain Gut Microbiota in Infants

Human milk oligosaccharides (HMOs) are complexes that play a crucial role in shaping the early-life gut microbiota. This study intends to explore whether HMO patterns are associated with the gut microbiota of infants. We included 96 Chinese breastfeeding mother-infant dyads. Breast milk and infant faecal samples were collected and tested. With milk 2'-fucosyllactose, difucosyllactose, and lacto-N-fucopentaose-I as biomarkers, we divided the mothers into secretor and non-secretor groups. HMO patterns were extracted using principal component analysis. The majority (70.7%) of mothers were categorised as secretor and five different HMO patterns were identified. After adjustment, the infants of secretor mothers exhibited a lower relative abundance of Bifidobacterium bifidum (β = -0.245, 95%CI: -0.465~-0.025). An HMO pattern characterised by high levels of 3-fucosyllactose, lacto-N-fucopentaose-III, and lacto-N-neodifucohexaose-II was positively associated with the relative abundance of Bifidobacterium breve (p = 0.014), while the pattern characterised by lacto-N-neotetraose, 6'-sialyllactose, and sialyllacto-N-tetraose-b was negatively associated with Bifidobacterium breve (p = 0.027). The pattern characterised by high levels of monofucosyl-lacto-N-hexaose-III and monofucosyl-lacto-N-neohexaose was positively associated with Bifidobacterium dentium (p = 0.025) and Bifidobacterium bifidum (p < 0.001), respectively. This study suggests that HMO patterns from mature breast milk were associated with certain gut microbiota of breastfed infants.

Human Milk-The Biofluid That Nourishes Infants from the First Day of Life

Human milk is a biofluid with a unique composition among mammalian milks. Besides this milk's major components, its bioactive compounds, like hormones, immune factors, and oligosaccharides, are unique and important for infant growth and development. The best form of nutrition for term and preterm infants is the mother's own milk. However, in the absence of the mother's own milk, donor milk should be made available. Milk banks support neonatal intensive care units by providing preterm infants with human milk that generally has reasonable nutritive value for this sensitive population. However, neither mother's own milk nor donor milk has sufficient energy content for the growth of preterm babies, so adequate human milk supplementation is crucial for their progress. Due to the different characteristics of human breast milk, as well as ubiquitous environmental pollutants, such as microplastics, new methods are required for monitoring the quality and characteristics of human milk, which will lay a solid foundation for the further development and progress of human milk research.

Exploring the visualization of human milk odor profiles: Intuitive characterization and construction of the link between odor compounds and sensory attributes

Studies on odor are not negligible in the human milk (HM) science field because it plays an irreplaceable role in the feeding process of infants. This study aimed to investigate the odor skeleton components (OSCs) in HM and verify and construct an intuitive link between them and the HM odor attributes. A total of 72 odor-active compounds were identified from 32 HMs using the comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry. Twenty of these compounds were identified as OSCs (average FD ≥ 1 and average OAV ≥ 1), and their actual odor contribution was clarified. Furthermore, the connection of the 20 OSCs with their corresponding eight odor attributes was visualized by constructing a molecular sensory odor wheel. Of them, 2,3-butanedione, (E)-2-decenal, nonanal, (E)-2-nonenal, octanal, 1-octen-3-one, hexanal, methional, and butanoic acid were the most important contributors to dairy-sweet, fishy, dairy-fat, metallic/iron, flour, grassy/green, cooked, and sweaty/rancid odor of HM.

Consistency and Variability of the Human Milk Oligosaccharide Profile in Repeat Pregnancies

Human milk oligosaccharides (HMOs) are a set of complex carbohydrates and the third largest solid component of human milk, after lactose and lipids. To date, over 150 HMOs have been identified and the diversity of structures produced by lactating women is influenced by maternal genetics as well as other maternal, infant, and environmental factors. While the concentrations of individual HMOs have been shown to vary between individuals and throughout the course of lactation, the variability of HMO concentration profiles following different pregnancies occurring in the same woman is presently unknown. As such, the objective of this study was to compare HMO concentrations in human milk samples provided by the same women (n = 34) following repeat pregnancies. We leveraged existing human milk samples and metadata from the UC San Diego Human Milk Research Biorepository (HMB) and measured the concentrations of the 19 most abundant HMOs using high-performance liquid chromatography with fluorescence detection (HPLC-FL). By assessing dissimilarities in HMO concentration profiles, as well as concentration trends in individual structures between pregnancies of each participant, we discovered that HMO profiles largely follow a highly personalized and predictable trajectory following different pregnancies irrespective of non-genetic influences. In conclusion, this is the first study to assess the interactions between parity and time following delivery on variations in HMO compositions.

Human milk oligosaccharides in milk of mothers with term and preterm delivery at different lactation stage

Human milk oligosaccharides (HMOs) are structurally diverse unconjugated glycans, and play crucial roles in protecting infants from infections. Preterm birth is one of the leading causes of neonatal mortality, and preterm infants are particularly vulnerable and are in need of improved outcomes from breast-feeding due to the presence of bioactive HMOs. However, studies on specific difference in HMOs as a function of gestation time have been very limited. We established an approach to extract and analyze HMOs based on 96-well plate extraction and mass spectrometry, and determined maternal phenotypes through distinctive fragments in product-ion spectra. We enrolled 85 women delivering at different gestation times (25-41 weeks), and observed different HMOs correlating with gestation time based on 233 samples from the 85 donors. With the increase of postpartum age, we observed a regular changing trajectory of HMOs in composition and relative abundance, and found significant differences in HMOs secreted at different postpartum times. Preterm delivery induced more variations between participants with different phenotypes compared with term delivery, and more HMOs varied with postpartum age in the population of secretors. The sialylation level in mature milk decreased for women delivering preterm while such decrease was not observed for women delivering on term.

Lactational and geographical variation in the concentration of six oligosaccharides in Chinese breast milk: a multicenter study over 13 months postpartum

Introduction

Understanding the variations of oligosaccharide in breast milk contribute to better study how human milk oligosaccharides (HMOs) play a role in health-promoting benefits in infants.

Methods

Six abundant HMOs, 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3-FL), Lacto-N-tetraose (LNT), Lacto-N-neotetraose (LNnT), 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), in breast milk collected at 0-5 days, 10-15 days, 40-45 days, 200-240 days, and 300-400 days postpartum from six locations across China were analyzed using high-performance anion-exchange chromatography-pulsed amperometric detector.

Results

The concentration of individual HMO fluctuated dynamically during lactational stages. The median ranges of 2'-FL, 3-FL, LNT, LNnT, 3'-SL, and 6'-SL across the five lactational stages were 935-2865 mg/L, 206-1325 mg/L, 300-1473 mg/L, 32-317 mg/L, 106-228 mg/L, and 20-616 mg/L, respectively. The prominent variation was observed in the content of 6'-SL, which demonstrates a pattern of initial increase followed by a subsequent decrease. Among the five lactational stages, the transitional milk has the highest concentration, which was 31 times greater than the concentration in mature milk at 300-400 days postpartum, where the content is the lowest. Geographical location also influenced the content of HMOs. LNT and LNnT were the highest in mature milk of mothers from Lanzhou among the six sites at 40-240 days postpartum. Breast milks were categorized into two groups base on the abundance of 2'-FL (high and low). There was no significant difference in the proportions of high and low 2'-FL phenotypes among the six sites, and the percentages of high and low 2'-FL phenotypes were 79% and 21%, respectively, across all sites in China.

Discussion

This study provided a comprehensive dataset on 6 HMOs concentrations in Chinese breast milk during the extended postpartum period across a wide geographic range and stratified by high and low 2'-FL phenotypes.

Human Milk Oligosaccharide Profiles and the Secretor and Lewis Gene Status of Indonesian Lactating Mothers

Purpose

Human milk oligosaccharides (HMOs) may be genetically determined based on the secretor and Lewis status of the mother. This study aims to determine the HMO profile and the secretor and Lewis gene status of Indonesian lactating mothers.

Methods

Baseline data of 120 mother-infant pairs between 0-4 months post-partum obtained from a prospective longitudinal study was used. The concentrations of 2'-fucosyllactose (2'FL), lacto-N-fucopentaose I (LNFP I), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT), 3'-sialyllactose (3'SL), and 6'-sialyllactose (6'SL) were measured. Genetic analysis was performed for mothers using targeted next-generation sequencing and Sanger sequencing. Wild-type AA with the rs1047781 (A385T) polymorphism was categorized as secretor positive, while heterozygous mutant AT was classified as a weak secretor. The presence of rs28362459 (T59G) heterozygous mutant AC and rs3745635 (G508A) heterozygous mutant CT genes indicated a Lewis negative status, and the absence of these genes indicated a positive status. Subsequently, breast milk was classified into various groups, namely Group 1: Secretor+Lewis+ (Se+Le+), Group 2: Secretor-Lewis+ (Se-Le+), Group 3: Secretor+Lewis- (Se+Le-), and Group 4: Secretor-Lewis- (Se-Le-). Data were analyzed using the Mann-Whitney and Kruskal-Wallis rank tests, and a p-value of 0.05 indicated statistical significance.

Results

A total of 58.3% and 41.7% of the samples had positive and weak secretor statuses, respectively. The proportion of those in Group 1 was 85%, while 15% were Group 3. The results showed that only 2'FL significantly differed according to the secretor status (p-value=0.018).

Conclusion

All Indonesian lactating mothers in this study were secretor positive, and most of them had a Lewis-positive status.

Human Milk Oligosaccharide Profile across Lactation Stages in Israeli Women-A Prospective Observational Study

Human milk oligosaccharides (HMOs) stimulate the growth of gut commensals, prevent the adhesion of enteropathogens and modulate host immunity. The major factors influencing variations in the HMO profile are polymorphisms in the secretor (Se) or Lewis (Le) gene, which affect the activity of the enzymes fucoslytransferase 2 and 3 (FUT2 and FUT3) that lead to the formation of four major fucosylated and non-fucosylated oligosaccharides (OS). This pilot study aimed to determine the HMO profile of Israeli breastfeeding mothers of 16 term and 4 preterm infants, from a single tertiary center in the Tel Aviv area. Fifty-two human milk samples were collected from 20 mothers at three-time points: colostrum, transitional milk and mature milk. The concentrations of nine HMOs were assessed using liquid chromatography coupled with mass spectra chromatograms. Fifty-five percent of the mothers were secretors and 45% were non-secretors. Infant sex affected HMO levels depending on the maternal secretor status. Secretor mothers to boys had higher levels of FUT2-dependent OS and higher levels of disialyllacto-N-tetraose in the milk of mothers to girls, whereas non-secretor mothers to girls had higher levels of 3'-sialyllactose. In addition, the season at which the human milk samples were obtained affected the levels of some HMOs, resulting in significantly lower levels in the summer. Our findings provide novel information on the irregularity in the HMO profile among Israeli lactating women and identify several factors contributing to this variability.

Human Milk Oligosaccharides Are Associated with Lactation Stage and Lewis Phenotype in a Chinese Population

Background: Human milk oligosaccharides (HMOs) are the third most abundant component of human milk. Various factors may affect the concentration of HMOs, such as the lactation period, Lewis blood type, and the maternal secretor gene status. Objectives: The purpose of this study is to investigate factors associated with HMO concentrations in Chinese populations. Methods: A sub-sample of 481 was randomly selected from a large cross-sectional study in China (n = 6481) conducted in eight provinces (Beijing, Heilongjiang, Shanghai, Yunnan, Gansu, Guangdong, Zhejiang, and Shandong) between 2011 and 2013. HMO concentrations were determined by a high-throughput UPLC-MRM method. Various factors were collected through face-to-face interviews. Anthropometric measurement was conducted by trained staff. Results: Median total HMO concentration was 13.6 g/L, 10.7 g/L, and 6.0 g/L for colostrum, transitional milk, and mature milk, respectively. HMO concentration decreased significantly as the lactation period increased (p < 0.0001). There were significant differences of average total HMO concentration between secretor mothers and non-secretor mothers (secretor 11.3 g/L vs. non-secretor 5.8 g/L, p < 0.0001). There were significant differences of average total HMO concentrations among three Lewis blood types (p = 0.003). Comparing with the concentration of total oligosaccharides of Le+ (a−b+), average of total oligosaccharides concentrations increased by 3.9 (Le+ (a+b−), p = 0.004) and 1.1 g/L (Le− (a−b−), p = 0.049). The volume of breast milk expressed and the province the mother came from affected the concentration of total oligosaccharides (all p < 0.0001). Maternal BMI (p = 0.151), age (p = 0.630), prematurity (p = 0.850), mode of delivery (p = 0.486), infants’ gender (p = 0.685), maternal education level (p = 0.989), maternal occupation (p = 0.568), maternal allergic history (p = 0.370), maternal anemia (p = 0.625), pregnancy-induced hypertension (p = 0.739), gestational diabetes (p = 0.514), and parity (p = 0.098) were not significantly correlated with the concentration of milk oligosaccharides. The concentrations of 2′-fucosyllactose (2′-FL), lacto-N-neotetraose (LNnT), sialyllacto-N-tetraose c (LSTc), lacto-N-fucopentaose I (LNFP-I), disialylated lacto-N-tetraose (DSLNT), difucosyl-para-lacto-N-neohexaose (DFpLNnH), difucosyl-lacto-N-hexaose (DFLNH[a]), and 3-sialyllactose (3′-SL) showed a gradual downward trend, while the concentration of 3-fucosyllactose (3-FL) showed a gradual upward trend among three lactation stages (p < 0.05). Conclusions: The concentration of HMOs changes throughout lactation, and it varies between different HMOs. HMO concentrations differed between lactation stage, maternal secretor gene status, Lewis blood type, volume of breast milk expressed, and the province the mother came from. Prematurity, mode of delivery, parity, infants’ gender, and maternal characteristics did not affect the HMO concentration. Geographical region may be not associated with HMOs concentration in human milk. There may be a mechanism for co-regulation of the secretion of some of the oligosaccharides such as 2′FL vs. 3FL, 2′FL vs. LNnT, and lacto-N-tetraose (LNT).

Associations between Maternal Diet, Human Milk Macronutrients, and Breast-Fed Infant Growth during the First Month of Life in the SMILE Iwamizawa in Japan

Maternal diet may affect human milk macronutrients, but it remains to be elucidated whether this is also influential in infant growth. This study aimed to examine (1) how maternal diet influences human milk macronutrients, and (2) to what extent the variation in milk macronutrients affects infant growth during the first month of life. In 71 Japanese lactating women, maternal dietary information was collected from the brief-type self-administered diet history questionnaire, and anthropometry of mother-infant dyads was collected from medical records. Macronutrients in milk were analyzed by a Human Milk Analyzer. Maternal retinol intake was associated with the carbohydrate content in human milk at 1-month postpartum (standardized β coefficient: 0.287; p = 0.038). Moreover, the energy content in human milk was associated with an increase in the weight standard deviation score based on the WHO growth standard at 1 month of age (standardized β coefficient: 0.399; p = 0.046). Nevertheless, the milk macronutrient was not associated with the risk of infant growth abnormalities. In conclusion, a part of the maternal diet impacts macronutrient contents in human milk, but milk macronutrients have a limited effect on infant growth only within the normal growth curve during the first month of life.

Recent advances on human milk oligosaccharide antimicrobial activity

Over the past century, human health has been enhanced by antimicrobial development. Following the deployment of the first antibiotics in the 1940s, bacterial resistance evolved and has increasingly outmaneuvered even the most promising antimicrobial agents. Accordingly, increased interest has been placed on alternative methods to circumvent antimicrobial resistance evolution. In the enclosed short review, we discuss the antimicrobial properties of human breast milk with a special emphasis on human milk oligosaccharides (HMOs). We recount studies across gram-negative and gram-positive pathogens, highlighting the usage of HMOs in promoting human health and wellness.

Comparison of twelve human milk oligosaccharides in mature milk from different areas in China in the Chinese Human Milk Project (CHMP) study

Human milk oligosaccharides (HMOs) act as a vital role in the development of infant's gut microbiome and immune function. This study aimed to measure 12 oligosaccharides in milk from Chinese donors (n = 203), and evaluated the influences of multiple factors on the HMOs profiles. The results indicated that concentrations of 6'-sialyllactose were the highest among 12 oligosaccharides (2.31 ± 0.81 g/L). HMOs concentrations varied depending on geographical location. Latitude was observed to be related to concentrations of Lacto-N-neohexaose, lacto-N-fucopentaose III, 3'-sialyllactose (r = -0.67, r = +0.63 and r = +0.50, respectively). Environmental factors like seasons correlated with lacto-N-difucohexaose Ⅱ, Lacto-N-neohexaose and 2'-fucosyllactose (r = -0.47, r = -0.4, r = -0.35, respectively). Several HMOs concentrations were correlated with maternal diet. As a consequence, the HMOs profiles measured were influenced by geographical, environmental, maternal anthropometric as well as dietary factors.

Exploring the Potential of Human Milk and Formula Milk on Infants’ Gut and Health

Early-life gut microbiota plays a role in determining the health and risk of developing diseases in later life. Various perinatal factors have been shown to contribute to the development and establishment of infant gut microbiota. One of the important factors influencing the infant gut microbial colonization and composition is the mode of infant feeding. While infant formula milk has been designed to resemble human milk as much as possible, the gut microbiome of infants who receive formula milk differs from that of infants who are fed human milk. A diverse microbial population in human milk and the microbes seed the infant gut microbiome. Human milk contains nutritional components that promote infant growth and bioactive components, such as human milk oligosaccharides, lactoferrin, and immunoglobulins, which contribute to immunological development. In an attempt to encourage the formation of a healthy gut microbiome comparable to that of a breastfed infant, manufacturers often supplement infant formula with prebiotics or probiotics, which are known to have a bifidogenic effect and can modulate the immune system. This review aims to elucidate the roles of human milk and formula milk on infants’ gut and health.

Development of high-throughput UPLC-MS/MS using multiple reaction monitoring for quantitation of complex human milk oligosaccharides and application to large population survey of secretor status and Lewis blood group

Human milk oligosaccharides (HMOs) have attracted increasing attention due to the emerging evidence of their positive roles for infant's health. A high-throughput method for absolute quantitation of the complex HMOs including multiple isomeric structures is important but very challenging, due to the highly divers nature and wide variation in content of HMOs from different individuals. Here we used UPLC-MS-MRM in the negative-ion mode for accurate quantitation of 23 complex HMOs in just 15 min. The selected oligosaccharides are in their native forms and include neutral and sialylated, fucosylated and non-fucosylated, linear and branched, and secretor and Lewis phenotype indicators. The well validated method with good sensitivity, recovery and reproducibility was then applied to a large population quantitative survey of 251 Chinese mothers from five different ethnic groups (Han, Zhuang, Hui, Mongolian and Tibetan) living in different geographical regions for their secretor's status and Lewis phenotypes.

Effects of Antioxidants in Human Milk on Bronchopulmonary Dysplasia Prevention and Treatment: A Review

Bronchopulmonary dysplasia (BPD) is a severe chronic lung illness that affects neonates, particularly premature infants. It has far-reaching consequences for infant health and their families due to intractable short- and long-term repercussions. Premature infant survival and long-term quality of life are severely harmed by BPD, which is characterized by alveolarization arrest and hypoplasia of pulmonary microvascular cells. BPD can be caused by various factors, with oxidative stress (OS) being the most common. Premature infants frequently require breathing support, which results in a hyperoxic environment in the developing lung and obstructs lung growth. OS can damage the lungs of infants by inducing cell death, inhibiting alveolarization, inducing inflammation, and impairing pulmonary angiogenesis. Therefore, antioxidant therapy for BPD relieves OS and lung injury in preterm newborns. Many antioxidants have been found in human milk, including superoxide dismutase, glutathione peroxidase, glutathione, vitamins, melatonin, short-chain fatty acids, and phytochemicals. Human milk oligosaccharides, milk fat globule membrane, and lactoferrin, all unique to human milk, also have antioxidant properties. Hence, human milk may help prevent OS injury and improve BPD prognosis in premature infants. In this review, we explored the role of OS in the pathophysiology of BPD and related signaling pathways. Furthermore, we examined antioxidants in human milk and how they could play a role in BPD to understand whether human milk could prevent and treat BPD.

In silico analysis of the human milk oligosaccharide glycome reveals key enzymes of their biosynthesis

Human milk oligosaccharides (HMOs) form the third most abundant component of human milk and are known to convey several benefits to the neonate, including protection from viral and bacterial pathogens, training of the immune system, and influencing the gut microbiome. As HMO production during lactation is driven by enzymes that are common to other glycosylation processes, we adapted a model of mucin-type GalNAc-linked glycosylation enzymes to act on free lactose. We identified a subset of 11 enzyme activities that can account for 206 of 226 distinct HMOs isolated from human milk and constructed a biosynthetic reaction network that identifies 5 new core HMO structures. A comparison of monosaccharide compositions demonstrated that the model was able to discriminate between two possible groups of intermediates between major subnetworks, and to assign possible structures to several previously uncharacterised HMOs. The effect of enzyme knockouts is presented, identifying β-1,4-galactosyltransferase and β-1,3-N-acetylglucosaminyltransferase as key enzyme activities involved in the generation of the observed HMO glycosylation patterns. The model also provides a synthesis chassis for the most common HMOs found in lactating mothers.

Current Advances in Structure-Function Relationships and Dose-Dependent Effects of Human Milk Oligosaccharides

HMOs (human milk oligosaccharides) are the third most important nutrient in breast milk. As complex glycans, HMOs play an important role in regulating neonatal intestinal immunity, resisting viral and bacterial infections, displaying anti-inflammatory characteristics, and promoting brain development. Although there have been some previous reports of HMOs, a detailed literature review summarizing the structure-activity relationships and dose-dependent effects of HMOs is lacking. Hence, after introducing the structures and synthetic pathways of HMOs, this review summarizes and categorizes identified structure-function relationships of HMOs. Differential mechanisms of different structural HMOs utilization by microorganisms are summarized. This review also emphasizes the recent advances in the interactions between different health benefits and the variance of dosage effect based on in vitro cell tests, animal experiments, and human intervention studies. The potential relationships between the chemical structure, the dosage selection, and the physiological properties of HMOs as functional foods are vital for further understanding of HMOs and their future applications.

Carotenoid Profile in Maternal/Cord Plasma and Changes in Breast Milk along Lactation and Its Association with Dietary Intake: A Longitudinal Study in a Coastal City in Southern China

In this study, changes of carotenoids in breast milk were observed longitudinally for up to one year. Our study aimed to analyze the profile of carotenoids in breast milk and maternal/cord plasma and its correlation with dietary intake in Guangzhou. Plasma and breast milk samples of five stages during lactation (i.e., colostrum; transitional milk; and early, medium, and late mature milk) were collected from lactating mothers. The food frequency questionnaire (FFQ) was used for collecting data on dietary intake in the corresponding stages. Levels of lutein, zeaxanthin, β-cryptoxanthin, β-carotene, and lycopene were analyzed by high-performance liquid chromatography. We found that the total carotenoid level decreased gradually with the extension of lactation and eventually stabilized. Among them, the content of lutein increased from colostrum to transitional milk and decreased thereafter until it plateaued in the mature milk. Furthermore, lutein was reported as the dominant nutrient in maternal plasma, cord plasma, transitional milk, and mature milk at up to 400 days postpartum, while beta-carotene was predominant in colostrum. The content of β-carotenoid in middle and late mature breast milk was related to dietary intake (r = 1.690, p < 0.05). Carotenoid level in cord blood was lower than that in the mother’s plasma and was related to the carotenoid intake in the mother’s diet. Correlation of carotenoids between maternal and umbilical cord blood, breast milk, and maternal blood could well reflect the transport of carotenoids. These findings may help to guide mothers’ diets during breastfeeding.

Profile of Twenty-Three Human Milk Oligosaccharides in Han Chinese Mothers throughout Postpartum 1 year

Human milk oligosaccharides (HMOs) are multifunctional carbohydrates in breast milk, which are composed by a variety of structures. This study aimed to identified HMOs concentration profile, milk microbiota composition, and the associations with major maternal characteristics in Han Chinese mothers in the one-year lactation period. Seventeen healthy mothers aged from 28 to 36 years, who gave birth to healthy term infants, were recruited. Carbohydrates were detected using the MIRIS human milk analyzer (HMA), and twenty-three HMOs were quantified using ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS). Results showed that carbohydrates were relatively stable, while total HMO concentrations ranged from 1.74 to 9.72 g/L and decreased gradually over lactation in breast milk. Based on the structure, seven sialylated HMOs concentration showed the significant decline ( $p<0.05$ ) after three months in lactation. In addition, the relationships between maternal factors, containing the lactation period, genetic status, delivery mode, parity, and milk microbiota profile, and the HMO composition in healthy women, which still need further investigations, were observed.

Recent understanding of human milk oligosaccharides in establishing infant gut microbiome and roles in immune system

Human milk oligosaccharides (HMOs) are complex sugars with distinctive structural diversity present in breast milk. HMOs have various functional roles to play in infant development starting from establishing the gut microbiome and immune system to take it up to the mature phase. It has been a major energy source for human gut microbes that confer positive benefits on infant health by directly interacting through intestinal cells and generating short-chain fatty acids. It has recently become evident that each species of Bifidobacterium and other genera which are resident of the infant gut employ distinct molecular mechanisms to capture and digest diverse structural HMOs to avoid competition among themselves and successfully maintain gut homeostasis. HMOs also directly modulate gut immune responses and can decoy receptors of pathogenic bacteria and viruses, inhibiting their binding on intestinal cells, thus preventing the emergence of a disease. This review provides a critical understanding of how different gut bacteria capture and utilize selective sugars from the HMO pool and how different structural HMOs protect infants from infectious diseases.

Development of the digestive system in early infancy and nutritional management of digestive problems in breastfed and formula-fed infants

Food digestion and absorption in infants are closely related to early growth and long-term health. Human milk and infant formula are the main food sources for 0-6 month-old infants. Due...

A one-year study of human milk oligosaccharide profiles in the milk of healthy UK mothers and their relationship to maternal FUT2 genotype

Human milk oligosaccharides (HMOs) are indigestible carbohydrates with prebiotic, pathogen decoy and immunomodulatory activities that are theorized to substantially impact infant health. The objective of this study was to monitor HMO concentrations over 1 year to develop a long-term longitudinal dataset. HMO concentrations in the breast milk of healthy lactating mothers of the Cambridge Baby Growth and Breastfeeding Study (CBGS-BF) were measured at birth, 2 weeks, 6 weeks, 3 months, 6 months and 12 months postpartum. HMO quantification was conducted by high-performance anion-exchange chromatography with pulsed amperometric detection using a newly validated "dilute-and-shoot" method. This technique minimizes sample losses and expedites throughput, making it particularly suitable for the analysis of large sample sets. Varying patterns of individual HMO concentrations were observed with changes in lactation timepoint and maternal secretor status, with the most prominent temporal changes occurring during the first 3 months. These data provide valuable information for the development of human milk banks in view of targeted distribution of donor milk based on infant age. Maternal FUT2 genotype was determined based on identification at single-nucleotide polymorphism rs516246 and compared with the genotype expected based on phenotypic markers in the HMO profile. Surprisingly, two mothers genotyped as secretors produced milk that displayed very low levels of 2'-fucosylated moieties. This unexpected discrepancy between genotype and phenotype suggests that differential enzyme expression may cause substantial variation in HMO profiles between genotypically similar mothers, and current genotypic methods of secretor status determination may require validation with HMO markers from milk analysis.

Six Oligosaccharides' Variation in Breast Milk: A Study in South China from 0 to 400 Days Postpartum

This study investigated the variation in oligosaccharide levels in the breast milk of south Chinese mothers in a prolonged breastfeeding period of up to 400 days postpartum. A total of 488 breast milk samples were collected from 335 healthy mothers at five different time points: 0–5 days, 10–15 days, 40–45 days, 200–240 days, and 300–400 days postpartum. A high-performance anion-exchange chromatography-pulsed amperometric detector (HPAEC-PAD) was used to quantify 2′-fucosyllactose (2′-FL), 3-fucosyllactose (3-FL), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT), 3′-sialyllactose (3′-SL) and 6′-sialyllactose (6′-SL). In this study, we found six oligosaccharides that were present in breast milk from 0 to 400 days postpartum. The median value ranges of individual oligosaccharide components in this study were 1013–2891 mg/L 2′-FL, 193–1421 mg/L 3-FL, 314–1478 mg/L LNT, 44–255 mg/L LNnT, 111–241 mg/L 3′-SL, and 23–602 mg/L6′-SL. HMO levels decreased over the lactation periods, except for 3-FL, which increased throughout lactation. The predominant fucosylated and sialylated HMOs were 2′-FL and 6′-SL at 40–45 days postpartum and changed to 3-FL and 3′-SL at 200–240 days postpartum. Results from this study showed that lactating women continue to provide their offspring with a high level of 2′-FL one year after delivery, suggesting that 2′-FL may play an important role for infants in early life. Our findings also provide further evidence in support of breastfeeding after one-year postpartum.

Dynamic Changes in Human Milk Oligosaccharides in Chinese Population: A Systematic Review and Meta-Analysis

The aim of this systematic review was to summarize concentrations of human milk oligosaccharides (HMOs) in the Chinese population. We searched articles originally published in both Chinese and English. When compiling data, lactation was categorized into five stages. We found that 6′-sialyllactose, lacto-N-tetraose, and lacto-N-neotetraose decreased over lactation. Conversely, 3′-fucosyllactose increased over lactation. Our study represents the first systematic review to summarize HMO concentrations in Chinese population. Our findings not only provide data on HMO profiles in Chinese population but suggest future directions in the study of the metabolism of HMOs.

Extraction and Quantitative Analysis of Goat Milk Oligosaccharides: Composition, Variation, Associations, and 2'-FL Variability

Human milk oligosaccharides (hMOS) are associated with health benefits for newborns. We studied the composition of goat MOS (gMOS) from colostrum up to the 9th month of lactation to conceive an overview of the structures present and their fate. Potential correlations with factors such as age, parity, and lifetime milk production were examined. An effective method for gMOS extraction and ultra-high-performance liquid chromatography coupled to fluorescence detection (UPLC-FLD) analysis was established, following 2-aminobenzamide gMOS labeling. Considerable biological variability was highlighted among the 12 quantified gMOS and the 9 non-quantified structures in the individual milk samples. Most characteristic, 2'-fucosyllactose was present in 73.7% of the milk samples analyzed, suggesting the possibility of a secretor/non-secretor goat genotype, similar to humans. Contributing factors to the observed biological variability were goat age, parity, lifetime milk production, and the kids' sex. The results significantly contribute to the current understanding of (variations in) gMOS composition.

Presence and Levels of Galactosyllactoses and Other Oligosaccharides in Human Milk and Their Variation during Lactation and According to Maternal Phenotype

Among the human milk oligosaccharides (HMOS), the galactosyllactoses (GLs) are only limitedly studied. This study aims to describe the presence and relative levels of HMOS, including GLs, in human milk (HM) according to maternal Secretor and Lewis (SeLe) phenotype and lactation stage. Relative levels of 19 HMOS were measured in 715 HM samples collected in the first 4 months postpartum from 371 donors participating in the PreventCD study. From a subset of 24 Dutch women (171 HM samples), samples were collected monthly up to 12 months postpartum and were additionally analyzed for relative and absolute levels of β6′-GL, β3′-GL and α3′-GL. Maternal SeLe phenotype or HM group was assigned based on the presence of specific fucosylated HMOS. Most HMOS, including β6′- and β3′-GL, were present in the vast majority (≥75%) of HM samples, whereas others (e.g., LNDFH II, 2′-F-LNH and α3′-GL) only occurred in a low number (<25%) of samples. Clear differences were observed between the presence and relative levels of the HMOS according to the maternal phenotype and lactation stage. Absolute concentrations of β6′-GL and β3′-GL were higher in HM group IV samples compared to samples of the other three HM groups. β3′-GL was also higher in HM group II samples compared to HM group I samples. β3′-GL and β6′-GL were stable over lactation stages. In conclusion, presence and levels of HMOS vary according to HM group and lactation stage. Not all HMOS behave similarly: some HMOS depend strongly on maternal phenotype and/or lactation stage, whereas others do not. β3′-GL and β6′-GL were present in low concentrations in over 75% of the analyzed HM samples and showed differences between HM groups, but not between the lactation stages.

Recent advance in infant nutrition: Human milk oligosaccharides

Breast feeding and human milk are the standards for infant feeding and nutrition. Human milk oligosaccharides (HMOs) are the third most abundant solid component in human milk. To date, more than 200 structural different HMOs have been identified and some can be synthesized by the food industry. HMOs are one of the major differences between human milk and formula milk, and current evidence demonstrates their various beneficial effects toward infants' health: acting as anti-adhesive antimicrobials, immune modulators, and intestinal cell response modulators, as well as providing prebiotics effect and neurodevelopment and cognition effects. HMOs compositions vary among mothers, influenced by the stage of lactation, duration of pregnancy and maternal genetic factors. However, there are still some unknown factors affecting the compositions of HMOs and requiring further research for clarification. A combination of preclinical and clinical cohort studies may help to identify whether an individual HMO contributes to disease protection. In recent years, 2'-fucosyllactose (2'-FL) and lacto-N-neotetraose (LNnT) have been approved as food ingredients by official authorities. Infant formulae supplemented with these HMOs are well-tolerated. However, more prospective clinical studies are warranted to elucidate HMOs' significance in infant nutrition. Breast milk feeding remains the best option for infants nutrition and development. Whenever breast milk is not adequate or unavailable, infant formula supplemented with HMOs might be considered as an alternative.

Changes in HMO Concentrations throughout Lactation: Influencing Factors, Health Effects and Opportunities

Human milk oligosaccharides (HMOs) are important functional biomolecules in human breast milk. Understanding the factors influencing differences in HMO composition and changes in their concentration over lactation can help to design feeding strategies that are well-adapted to infant's needs. This review summarises the total and individual concentration of HMOs from data published from 1999 to 2019. Studies show that the HMO concentrations are highest in colostrum (average 9-22 g/L), followed by slightly lower concentrations in transitional milk (average 8-19 g/L), with a gradual decline in mature milk as lactation progresses, from 6-15 g/L in breast milk collected within one month of birth, to 4-6 g/L after 6 months. Significant differences in HMO composition have been described between countries. Different HMOs were shown to be predominant over the course of lactation, e.g., 3-fucosyllactose increased over lactation, whereas 2'-fucosyllactose decreased. Recent clinical studies on infant formula supplemented with 2'-fucosyllactose in combination with other oligosaccharides showed its limited beneficial effect on infant health.

Combining HPAEC-PAD, PGC-LC-MS, and 1D 1H NMR to Investigate Metabolic Fates of Human Milk Oligosaccharides in 1-Month-Old Infants: a Pilot Study

A solid-phase extraction procedure was optimized to extract 3-fucosyllactose and other human milk oligosaccharides (HMOs) from human milk samples separately, followed by absolute quantitation using high-performance anion-exchange chromatography-pulsed amperometric detection and porous graphitized carbon-liquid chromatography-mass spectrometry, respectively. The approach developed was applied on a pilot sample set of 20 human milk samples and paired infant feces collected at around 1 month postpartum. One-dimensional 1H nuclear magnetic resonance spectroscopy was employed on the same samples to determine the relative levels of fucosylated epitopes and sialylated (Neu5Ac) structural elements. Based on different HMO consumption patterns in the gastrointestinal tract, the infants were assigned to three clusters as follows: complete consumption; specific consumption of non-fucosylated HMOs; and, considerable levels of HMOs still present with consumption showing no specific preference. The consumption of HMOs by infant microbiota also showed structure specificity, with HMO core structures and Neu5Ac(α2-3)-decorated HMOs being most prone to degradation. The degree and position of fucosylation impacted HMO metabolization differently.

The clinical impact of maternal weight on offspring health: lights and shadows in breast milk metabolome

INTRODUCTION

Pre-pregnancy overweight and obesity, depending on maternal nutrition and metabolic state, can influence fetal, neonatal and long-term offspring health, regarding cardio-metabolic, respiratory, immunological and cognitive outcomes. Thus, maternal weight can act, through mechanisms that are not full understood, on the physiology and metabolism of some fetal organs and tissues, to adapt themselves to the intrauterine environment and nutritional reserves. These effects could occur by modulating gene expression, neonatal microbiome, and through breastfeeding.

AREAS COVERED

In this paper, we investigated the potential effects of metabolites found altered in breast milk (BM) of overweight/obese mothers, through an extensive review of metabolomics studies, and the potential short- and long-term clinical effects in the offspring, especially regarding overweight, glucose homeostasis, insulin resistance, oxidative stress, infections, immune processes, and neurodevelopment.

EXPERT OPINION

Metabolomics seems the ideal tool to investigate BM variation depending on maternal or fetal/neonatal factors. In particular, BM metabolome alterations according to maternal conditions were recently pointed out in cases of gestational diabetes, preeclampsia, intrauterine growth restriction and maternal overweight/obesity. In our opinion, even if BM is the food of choice in neonatal nutrition, the deepest comprehension of its composition in overweight/obese mothers could allow targeted supplementation, to improve offspring health and metabolic homeostasis.

Structure-Specific and Individual-Dependent Metabolization of Human Milk Oligosaccharides in Infants: A Longitudinal Birth Cohort Study

To follow human milk oligosaccharide (HMO) biosynthesis and in vivometabolization, mother milk and infant feces from 68 mother-infant dyads at 2, 6, and 12 weeks postpartum were analyzed, with 18 major HMOs quantitated. Fucosylated and neutral core HMO levels in milk were dependent on mothers' Lewis/Secretor status, whereas most sialylated HMO levels were independent. Infant fecal excretion of HMOs gradually declined with age, especially for neutral core structures. Although decreasing in absolute concentrations in milk during lactation, the relative abundance of total fucosylated HMOs increased in both milk and feces. Mono-fucosylated HMOs were more consumed than those decorated with two fucose moieties. More (α2-3)-sialylated HMOs were degraded than (α2-6)-sialylated HMOs. The transition speed of HMO metabolization from nonspecific or structure-specific consumption stage to the complete consumption stage was individual-dependent. Variation was associated with mode and place of delivery, where caesarean section or early exposure to hospital environment delayed the transition.

Human Milk Oligosaccharide Profiles over 12 Months of Lactation: The Ulm SPATZ Health Study

Human milk oligosaccharides (HMOs) have specific dose-dependent effects on child health outcomes. The HMO profile differs across mothers and is largely dependent on gene expression of specific transferase enzymes in the lactocytes. This study investigated the trajectories of absolute HMO concentrations at three time points during lactation, using a more accurate, robust, and extensively validated method for HMO quantification. We analyzed human milk sampled at 6 weeks (n = 682), 6 months (n = 448), and 12 months (n = 73) of lactation in a birth cohort study conducted in south Germany, using label-free targeted liquid chromatography mass spectrometry (LC-MS²). We assessed trajectories of HMO concentrations over time and used linear mixed models to explore the effect of secretor status and milk group on these trajectories. Generalized linear model-based analysis was used to examine associations between HMOs measured at 6 weeks of lactation and maternal characteristics. Results: Overall, 74%, 18%, 7%, and 1% of human milk samples were attributed to milk groups I, II, III, and IV, respectively. Most HMO concentrations declined over lactation, but some increased. Cross-sectionally, HMOs presented high variations within milk groups and secretor groups. The trajectories of HMO concentrations during lactation were largely attributed to the milk group and secretor status. None of the other maternal characteristics were associated with the HMO concentrations. The observed changes in the HMO concentrations at different time points during lactation and variations of HMOs between milk groups warrant further investigation of their potential impact on child health outcomes. These results will aid in the evaluation and determination of adequate nutrient intakes, as well as further (or future) investigation of the dose-dependent impact of these biological components on infant and child health outcomes.

Maternal and Infant Factors Influencing Human Milk Oligosaccharide Composition: Beyond Maternal Genetics

Maternal genetics is a key determinant of human milk oligosaccharide (HMO) composition in human milk. Beyond genetic status, other factors influencing the HMO profile are poorly defined. Thus, we aimed to review the existing evidence on the associations between nongenetic maternal and infant factors and HMO composition. A systematic search was performed on PubMed and Web of Science (without a time restriction) to identify any relevant studies published. In total, 1056 results were obtained, of which 29 articles were selected to be included in this review. The range of factors investigated include lactation stage, maternal pre-pregnancy BMI (ppBMI), maternal age, parity, maternal diet, mode of delivery, infant gestational age, and infant sex. The data suggest that, beyond maternal genetics, HMO composition seems to be influenced by all these factors, but the underlining mechanisms remain speculative. The published evidence is discussed in this review, along with potential implications for infant growth and development. For example, 2'-fucosyllactose, which was reportedly increased in mothers with higher ppBMIs, was also associated with increased infant weight and height. In addition, greater levels of sialylated HMOs after preterm birth may support brain development in these infants.

Gold standard for nutrition: a review of human milk oligosaccharide and its effects on infant gut microbiota

Human milk is the gold standard for nutrition of infant growth, whose nutritional value is mainly attributed to human milk oligosaccharides (HMOs). HMOs, the third most abundant component of human milk after lactose and lipids, are complex sugars with unique structural diversity which are indigestible by the infant. Acting as prebiotics, multiple beneficial functions of HMO are believed to be exerted through interactions with the gut microbiota either directly or indirectly, such as supporting beneficial bacteria growth, anti-pathogenic effects, and modulation of intestinal epithelial cell response. Recent studies have highlighted that HMOs can boost infants health and reduce disease risk, revealing potential of HMOs in food additive and therapeutics. The present paper discusses recent research in respect to the impact of HMO on the infant gut microbiome, with emphasis on the molecular basis of mechanism underlying beneficial effects of HMOs.

Impact of dietary fibers in infant formulas on gut microbiota and the intestinal immune barrier

Human milk (HM) is the gold standard for the nutrition of infants. An important component of HM is human milk oligosaccharides (hMOs), which play an important role in gut microbiota colonization and gut immune barrier establishment, and thereby contribute to the maturation of the immune system in early life. Guiding these processes is important as disturbances have life-long health effects and can lead to the development of allergic diseases. Unfortunately, not all infants can be exclusively fed with HM. These infants are routinely fed with infant formulas that contain hMO analogs and other non-digestible carbohydrates (NDCs) to mimic the effects of hMOs. Currently, the hMO analogs 2'-fucosyllactose (2'-FL), galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), and pectins are added to infant formulas; however, these NDCs cannot mimic all hMO functions and therefore new NDCs and NDC mixtures need to become available for specific groups of neonates like preterm and disease-prone neonates. In this review, we discuss human data on the beneficial effects of infant formula supplements such as the specific hMO analog 2'-FL and NDCs as well as their mechanism of effects like stimulation of microbiota development, maturation of different parts of the gut immune barrier and anti-pathogenic effects. Insights into the structure-specific mechanisms by which hMOs and NDCs exert their beneficial functions might contribute to the development of new tailored NDCs and NDC mixtures. We also describe the needs for new in vitro systems that can be used for research on hMOs and NDCs. The current data suggest that "tailored infant formulas" for infants of different ages and healthy statuses are needed to ensure a healthy development of the microbiota and the gut immune system of infants.

Bioactive Compounds in Infant Formula and Their Effects on Infant Nutrition and Health: A Systematic Literature Review

Infant formulas are an alternative to replace or supplement human milk when breastfeeding is not possible. The knowledge of human milk's bioactive compounds and their beneficial effects has attracted the interest of researchers in the field of infant nutrition, as well as researchers of technology and food sciences that seek to improve the nutritional characteristics of infant formulas. Several scientific studies evaluate the optimization of infant formula composition. The bioactive compound inclusion has been used to upgrade the quality and nutrition of infant formulas. In this context, the purpose of this systematic literature review is to assess the scientific evidence of bioactive compounds present in infant formulas (α-lactalbumin, lactoferrin, taurine, milk fat globule membrane, folates, polyamines, long-chain polyunsaturated fatty acids, prebiotics, and probiotics) and their effects on infant nutrition and health. Through previously determined criteria, studies published in the last fifteen years from five different databases were included to identify the advances in the optimization of infant formula composition. Over the last few years, there has been optimization of the infant formula composition, not only to increase the similarities in their content of macro and micronutrients but also to include novel bioactive ingredients with potential health benefits for infants. Although the infant food industry has advanced in the last years, there is no consensus on whether novel bioactive ingredients added to infant formulas have the same functional effects as the compounds found in human milk. Thus, further studies about the impact of bioactive compounds in infant nutrition are fundamental to infant health.

The Effects of Human Milk Oligosaccharide Supplementation During Critical Periods of Development on the Mesolimbic Dopamine System

Human milk oligosaccharides (HMO)s are a key component in human milk and represent an important dietary modulator of infant gut microbiota composition and associated gut-brain axis development and homeostasis. The brain reward system, specifically the mesolimbic dopamine (DA) projections from the ventral tegmental area (VTA) to nucleus accumbens (NAc) is involved in the motivation and preference for food. The objective of the present study was to determine if HMO fortified diets given during the critical period of reward system development (p21) could affect the structure of the reward system. At weaning (p21), Sprague-Dawley rats were randomized to one of four fortified diet groups: Control, 3'sialyllactose (3'FL), 2'-fucosyllactose (2'FL), or a combination of 3'SL and 2'FL (3'SL + 2'FL). Messenger RNA (mRNA) expression was quantified for DA and appetite associated markers in the VTA and NAc and western blots measured the immediate early gene FosB and its isoform ΔFosB. Females fed the 3'SL + 2'FL fortified diet displayed a decrease in DAT expression in the VTA and an increase in leptin expression in the NAc. Females displayed an overall lower expression of NAc D2, VTA ghrelinR, and VTA leptin. In males, VTA DAT and FosB were negatively correlated with body weight and systemic leptin. Sex differences in the expression of DA markers underscore the need to investigate this phenomenon and understand the functional significance in preventing or treating obesity. This study highlights sex differences in response to HMO supplementation and the need for further investigations into the functional significance of nutritional interventions during DA system development.