Quantitative profiling of glycerides, glycerophosphatides and sphingolipids in Chinese human milk with ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry

Comprehensive lipidomic profiling of human milk from lactating women across varying lactation stages and gestational ages

An untargeted lipidomic analysis was conducted to investigate the lipid composition of human milk across different lactation stages and gestational ages systematically. A total of 25 lipid subclasses and 934 lipid species as well as 90 free fatty acids were identified. Dynamic changes of the lipids throughout lactation and gestational phases were highlighted. In general, lactation stages introduced more variations in the lipid composition of human milk than gestational ages. Most lipids decreased as the milk progressed from the colostral stage to the mature stage, with some reaching a peak at the transitional stage. Significant variations in lipid composition across gestational ages were predominantly evident during early lactation period. In mature milks, most of the lipids exhibited no discernible statistical differences among gestational ages. This elucidation offers valuable insights and guidance for tailoring precise nutritional strategies for infants with diverse health needs.

Human milk sphingomyelin: Function, metabolism, composition and mimicking

Human milk, which contains various nutrients, is the "gold standard" for infant nutrition. Healthy human milk meets all the nutritional needs of early infant development. Polar lipids mainly exist in the milk fat globule membrane, accounting for approximately 1-2% of human milk lipids; sphingomyelin (SM) accounts for approximately 21-24% of polar lipids. SM plays an important role in promoting the development of the brain and nervous system, regulating intestinal flora, and improving skin barriers. Though SM could be synthesized de novo, SM nutrition from dietary is also important for infants. The content and composition of SM in human milk has been reported, however, the molecular mechanisms of nutritional functions of SM for infants required further research. This review summarizes the functional mechanisms, metabolic pathways, and compositional, influencing factors, and mimicking of SM in human milk, and highlights the challenges of improving maternal and infant early/long-term nutrition.

Quercetin alleviates inflammation induced by porcine reproductive and respiratory syndrome virus in MARC-145 cells through the regulation of arachidonic acid and glutamine metabolism

BACKGROUND

Porcine reproductive and respiratory syndrome virus (PRRSV) infection causes severe inflammatory response, respiratory disease and sow reproductive failure. Quercetin is among the widely occurring polypheno found abundantly in nature. Quercetin has anti-inflammatory, anti-oxidative and anti-viral properties.

OBJECTIVES

This study aimed to explore the effect and mechanism of quercetin on PRRSV-induced inflammation in MARC-145 cells.

METHODS

Observing the cytopathic effect and measurements of inflammatory markers in MARC-145 cells collectively demonstrate that quercetin elicits a curative effect on PRRSV-induced inflammation. Liquid chromatography-mass spectrometry was further used for a non-targeted metabolic analysis of the role of quercetin in the metabolic regulation of PRRSV inflammation in MARC-145 cells.

RESULTS

It was shown that quercetin attenuated PRRSV-induced cytopathy in MARC-145 cells. Quercetin treatment inhibited PRRSV replication in MARC-145 cells in a dose-dependent manner. We also found that quercetin inhibited PRRSV-induced mRNA expression and secretion levels of tumour necrosis factor-α, interleukin 1β and interleukin 6. Metabolomics analysis revealed that quercetin ameliorated PRRSV-induced inflammation. Pathway analysis results revealed that PRRSV-induced pathways including arachidonic acid metabolism, linoleic acid, glycerophospholipid and alanine, aspartate and glutamate metabolism were suppressed by quercetin. Moreover, we confirmed that quercetin inhibited the activation of NF-κB/p65 pathway, probably by attenuating PLA2, ALOX and COX mRNA expression.

CONCLUSIONS

These results provide a crucial insight into the molecular mechanism of quercetin in alleviating PRRSV-induced inflammation.

Comparison of lipidome profiles in human milk from Chinese Han and Korean ethnic groups based on high-throughput lipidomic techniques

The composition of milk lipids varies across different ethnic sources. The lipidome profiles of Chinese Han human milk (HHM) and Chinese Korean human milk (KHM) were investigated in this study. A total of 741 lipids were identified in HHM and KHM. Twenty-eight differentially expressed lipids (DEL) were screened between the 2 milk groups; among these, 6 triacylglycerols (TG), 13 diacylglycerols (DG), 7 free fatty acids (FFA), and 1 monoglyceride (MG) were upregulated in KHM. Carnitine (CAR) was upregulated in HHM. Most DEL showed a single peak distribution in both groups. The correlations, related pathways and diseases of these DEL were further analyzed. The results demonstrated that DG, MG, and FFA showed highly positive correlations with each other (r > 0.8). The most enriched Kyoto Encyclopedia of Genes and Genomes (https://www.kegg.jp/kegg/) and Human Metabolome Database (http://www.hmdb.ca) pathways were inositol phosphate metabolism, and α-linolenic acid and linolenic acid metabolism, respectively. Major depressive disorder-related FFA (20:5) and FFA (22:6) were more abundant in KHM, whereas HHM showed more obesity-related CAR. These data potentially provide lipidome information regarding human milk from different ethnicities in China.

Impact of manufacturing processes on glycerolipid and polar lipid composition and ultrastructure in infant formula

The introduction of exogenous lipids in the production of infant formula induces significant alterations in milk lipid composition, content, and membrane structure, thus affecting the lipid digestion, absorption, and utilization. This study meticulously tracks these changes throughout the manufacturing process. Pasteurization has a significant effect on phosphatidylcholine and sphingomyelin in the outer membrane, decreasing their relative contents to total polar lipids from 12.52% and 17.34% to 7.72% and 12.59%, respectively. Subsequent processes, including bactericidal-concentration and spray-drying, demonstrate the thermal stability of sphingomyelin and ceramides, while glycerolipids with arachidonic acid/docosahexaenoic acid and glycerophospholipids, particularly phosphatidylethanolamine, diminish significantly. Polar lipids addition and freeze-drying technology significantly enhance the polar lipid content and improve microscopic morphology of infant formula. These findings reveal the diverse effects of technological processes on glycerolipid and polar lipid compositions, concentration, and ultrastructure in infant formulas, thus offering crucial insights for optimizing lipid content and structure within infant formula.

Progress in triacylglycerol isomer detection in milk lipids

In triacylglycerols (TAGs), position differences of fatty acids on the glycerol skeleton produce various TAG isomers. These TAG isomers have different pathways of digestion, absorption, and utilization in infants, thereby affecting TAG nutritional properties of TAGs. Here, we review the progress of research on methods for detecting TAG isomers, and identify direction and thought for improving these methods, including novel chromatographic combinations, perfect algorithm, and improved equipment. The ensuing optimization of these methods is expected to provide robust guarantee for the gradual improvement of milk-derived TAG isomer detection, and is an important prerequisite for infant formula to mimic the structured lipids of human milk.

Advances in the composition, efficacy, and mimicking of human milk phospholipids

Phospholipids are the essential components of human milk, contributing to the enhancement of cognitive development, regulation of immune functions, and mitigation of elevated cholesterol levels. Infant formulas supplemented with phospholipids can change the composition, content, and globule membrane structure of milk lipids, improving their digestive properties and nutritional value. However, mimicking phospholipids in infant formulas is currently limited, and the supplemented standards of phospholipid species and amounts in infant formulas are unknown. Consequently, there is a significant difference between the phospholipids in infant formulas and those in human milk. This article reviews the recent progress in human milk phospholipid research, aiming to describe the composition, content, and positive effects of human milk phospholipids, as well as summarises the dietary sources of phospholipid supplementation and the current state of human milk phospholipid mimicking in infant formulas. This review provides clear directions for research on mimicking human milk phospholipids and evaluating the nutritional functions of phospholipids in infants.

1,3-Dioleoyl-2-palmitoyl-glycerol and 1-oleoyl-2-palmitoyl-3-linoleoyl-glycerol: Structure-function relationship, triacylglycerols preparation, nutrition value

Based on multivariate statistics, this review compared major triacylglycerols (TAGs) in animal milk and human milk fat from China and other countries. Human milk fat differs from animal milk fat in that it has longer acyl chains and higher concentrations of 1,3-dioleoyl-2-palmitoyl-glycerol (O-P-O) and 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (O-P-L). O-P-L is a significant and distinct TAG in human milk fat, particularly in China. 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) is human milk's major triglyceride molecule of O-P-L, accounting for more than 70%. As a result, OPL has piqued the interest of Chinese academics. The synthesis process and nutritional outcomes of OPL have been studied, including changes in gut microbiota, serum lipid composition, improved fatty acid and calcium absorption, and increased total bile acid levels. However, current OPL research is limited. Therefore, this review discussed enzymatic preparation of 1,3-dioleoyl-2-palmitoyl-glycerol (OPO) and OPL and their nutritional and physiological activity to direct future research direction for sn-2 palmitate and OPL.

A combination of phospholipids and long chain polyunsaturated fatty acids supports neurodevelopmental outcomes in infants: a randomized, double-blind, controlled clinical trial

Phospholipids (PLs) and long-chain polyunsaturated fatty acids (LCPUFAs) are naturally present in breast milk and play important roles in promoting the growth of the infant. Several studies have investigated the effects of the combination of PLs and LCPUFAs on neurodevelopment. However, data on the effectiveness of infant formula containing both PLs and LCPUFAs on the neurodevelopment of infants is still scarce. This randomized, double-blind, controlled clinical study was designed to evaluate the effect of an infant formula enriched with PLs and LCPUFAs on growth parameters and neurodevelopmental outcomes in term infants up to 365 days of age. Infants were enrolled within 30 days of birth who were then randomly assigned to either a control group (n = 150) or an investigational group (n = 150). Both groups consist of cow's milk-based formula which were generally identical in terms of composition, except that the investigational formula was additionally supplemented with PLs and LCPUFAs. The infants were followed for the first year of life. Breastfed infants were the reference (n = 150). Bayley Scales of Infant Development [3rd edition (Bayley-III)], Carey Toddler Temperament Scales (TTS), MacArthur-Bates Communicative Development Inventories (CDI), Single Object Attention and Free Play Tasks were used to evaluate neurodevelopmental outcomes of infant at 365 days of age. In addition, Ages and Stages Questionnaires (ASQ) were also conducted at 120, 180, and 275 days of age. Compared to breastfeeding, both infant formulas were well-tolerated and provided adequate growth, with no adverse events being reported throughout the study. Infants of the investigational group showed higher mean scores in Bayley-III cognitive performance (104.3 vs. 99.0, p < 0.05), language (106.9 vs. 104.5, p < 0.05), and motor skills (109.2 vs. 103.9, p < 0.05) compared the control group. Similar results were being reported for other developmental scales including TTS and ASQ. Notably, the test scores of infants fed the investigational formula were similar to those who were breastfed. Our results indicate that PL and LCPUFA supplementation may be beneficial for neurodevelopment of infants throughout the first year of life. Further studies are needed to investigation long-term effects PL and LCPUFA on neurodevelopment in early life.

Pseudo-targeted lipidomics insights into lipid discrepancies between yak colostrum and mature milk based on UHPLC-Qtrap-MS

Yak milk is essential to maintain the normal physiological functions of herders in Tibetan areas of China. However, the lipid components of yak colostrum (YC) and mature milk (YM) have not been systematically studied. We employed a quantitative lipidomics to comprehensively describe the alterations in the milk lipid profile of lactating yaks. Herein, totally 851 lipids from 28 lipid subclasses in YC and YM were identified and screened for 43 significantly different lipids (SDLs; variable importance in projection > 1, fold change < 0.5 or > 2 with P < 0.05), with cholesterol ester (CE, 16:0) and triacylglycerol (TAG, 54:6 (20:5), 50:1 (16:0), 56:6 (20:5)) were the potential lipid biomarkers. Fourteen SDLs were modulated downwards, and 29 SDLs were modulated upwards in YM. Moreover, by analyzing lipid metabolic pathways in these SDLs, glycerophospholipid metabolism was the most critical. Our results furnish integral lipid details for evaluating yak milk's nutritional quality.

Concentration and composition of odd-chain fatty acids in phospholipids and triacylglycerols in Chinese human milk throughout lactation

Human milk represents the gold standard for infant nutrition, with approximately 50% of the energy in human milk derived from lipids. Odd-chain fatty acids (OCFAs) have been recognized as a category of bioactive milk fatty acids in recent research; however, limited data exist on OCFAs in human milk. This study collected human milk samples spanning the postpartum period from 0 to 400 days. Phospholipids containing OCFAs (PL-OCFAs) were determined in 486 human milk samples using hydrophilic liquid chromatography-electrospray ionization-triquadrupole-mass spectrometry. Triacylglycerols containing OCFAs (TAG-OCFAs) were analyzed in 296 human milk samples using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The average total concentration of PL-OCFA ranged from 30.89 ± 14.27 mg L-1 to 93.48 ± 36.55 mg L-1 during lactation, and the average total TAG-OCFA content ranged from 103.1 ± 147.15 mg L-1 to 965.41 ± 651.67 mg L-1. Despite the lower absolute concentration of PL-OCFA, its relative concentration (8.75%-11.75%) was significantly higher than that of TAG-OCFA (0.37%-1.85%) throughout lactation. PC-OCFA, SM-OCFA and PE-OCFA are major sub-classes of PL-OCFA. Furthermore, C17:0 was the major chain length in both PL-OCFA and TAG-OCFA, followed by C15:0. C17:1 was characteristic of TAG-OCFA, while long-chain fatty acids C19:0, C21:0 and C23:0 were characteristic of PL-OCFA. Our findings highlighted the importance of bioactive lipids in human milk, suggesting that OCFAs could be targeted in future studies in relation to the health and development of infants.

Comprehensive analysis of phospholipid in milk and their biological roles as nutrients and biomarkers

Phospholipids (PL) have garnered significant attention due to their physiological activities. Milk and other dairy products are important dietary sources for humans and have been extensively used to analyze the presence of PL by various analytical techniques. In this paper, the analysis techniques of PL were reviewed with the eight trigrams of phospholipidomics and a comprehensive fingerprint of 1295 PLs covering 8 subclasses in milk and other dairy products, especially. Technology is the primary productive force. Based on phospholipidomics technology, we further review the relationship between the composition of PL and factors that may be involved in processing and experimental operation, and emphasized the significance of the biological role played by PL in dietary supplements and biomarkers (production, processing and clinical research), and providing the future research directions.

Novel trends and challenges in fat modification of next-generation infant formula: Considering the structure of milk fat globules to improve lipid digestion and metabolism of infants

Differences in the composition and structure of lipid droplets in infant formula (IF) and human milk (HM) can affect the fat digestion of infants, leading to high risk of metabolic diseases during later stages of growth. Recently, interest in simulating HM fat (HMF) has gradually increased due to its beneficial functions for infants. Much research focuses on the simulation of fatty acids and triacylglycerols. Enzymatic combined with new technologies such as carbodiimide coupling immobilization enzymes, solvent-free synthesis, and microbial fermentation can improve the yield of simulated HMF. Furthermore, fat modification in next-generation IF requires attention to the impact on the structure and function of milk fat globules (MFG). This review also summarizes the latest reports on MFG structure simulation, mainly related to the addition method and sequence of membrane components, and other milk processing steps. Although some of the simulated HMF technologies and products have been applied to currently commercially available IF, the cost is still high. Furthermore, understanding the fat decomposition of simulated HMF during digestion and assessing its nutritional effects on infants later in life is also a huge challenge. New process development and more clinical studies are needed to construct and evaluate simulated HMF in the future.

Effects of lipids from multiple sources on glyceride composition, concentration, and structure of infant formulas benchmarked to human milk

The important parameters affecting the nutritional properties of lipids were analyzed and compared between human milk (HM), infant formulas (IFs), mammalian milk, and substitute fat, including molecular species, fatty acid composition, glyceride content, and important structural triacylglycerols (TAGs). The molecular species of triacylglycerols with functional fatty acids were significantly different between HM and IFs, and their contents in HM were significantly higher than those in IFs. Accordingly, the evaluation scores of fatty acid composition and glyceride content in IFs were less than 50 compared to HM. Although the introduction of vegetable oils effectively improved the unsaturation of IF lipid, the excessive addition of TAGs rich in oleic and linoleic acid resulted in an imbalance of TAG composition and structure. Only 36.84 % of IFs were supplemented with structured lipids, but those still lacked sn-2 palmitate TAGs. The adoption of multiple lipids and novel processing technologies is required for novel IFs to match the composition, content, positional structure and spherical membrane structure of HM as closely as possible.

Longitudinal changes in choline concentration and associated factors in human breast milk

BACKGROUND

Human breast milk is the primary source of choline and choline-containing compounds for infants at early stages of life. Choline data across lactation in Chinese human milk were limited.

OBJECTIVE

This study aimed to quantify the five choline compounds in Chinese human breast milk and explore associated factors.

METHODS

A total of 540 lactating mothers from the MUAI (Maternal Nutrition and Infant Investigation) study were included. The content of water-soluble choline (free choline, phosphocholine, glycerophosphocholine) and lipid-soluble choline (phosphatidylcholine, sphingomyelin) in 892 human milk samples collected from 0 to 400 days postpartum were examined, and associated factors were explored.

RESULTS

Choline concentrations in human milk varied from postpartum day 0-400 (92.06 ± 65.22 to 171.01 ± 47.84 mg/L). Water-soluble choline was the major component (88.6%-93.8%) in human milk and ranged from 793.03 (659.22) to 1544.43 (443.32) μmol/L. Its trajectory followed that of total choline, increasing from colostrum to transitional milk and then declining in mature milk. In contrast, lipid-soluble choline accounted for 6.2%-11.4% over lactation and had an opposite trajectory. Choline composition varied by delivery mode and parity history.

CONCLUSION

The concentrations of individual choline and choline-containing compounds during lactation in Chinese human breast milk were described for the first time. Our results address gaps in extant Chinese human milk choline data and support tailored dietary reference intakes for Chinese lactating women and infants. Our data describes the level and profile of choline from 0 to 400 days postpartum in Chinese human breast milk. This is the most updated data on choline and also the first report of water-soluble choline as the predominant type in Chinese human milk. Our results compensate for the deficiencies in data on choline in Chinese human milk.

CLINICAL TRIAL REGISTRATION

Clinical Trial Registry number: ChiCTR1800015387. Web link to study on registry: https://www.chictr.org.cn/index.aspx.

A new insight into the polar lipid composition in mature breast milk and ewe milk with comparative lipidomics analysis

Polar lipids play essential biological functions in energy storage, both as structural components of cell membranes and as signaling molecules. In this study, a comprehensive UHPLC-QTRAP-MS-based lipidomic analysis of mature breast milk (BM) and ewe milk (EM) was conducted. Through the analysis, a total of 362 polar lipid species from 14 subclasses were characterized, including 60 phosphatidylethanolamines (PEs), 59 phosphatidylcholines (PCs), 38 phosphatidylinositols (PIs), 35 sphingomyelins (SMs), and 34 ceramides (Cers). Of these, 139 lipid molecules were screened as significantly differentially expressed polar lipids (SDPLs) between the two kinds of milk based on the following criteria: a variable importance in projection (VIP) value > 1.0, a false discovery rate-adjusted P-value < 0.0001, and a fold change (FC) of either > 2.0 or < 0.5; these included 111 upregulated and 28 downregulated SDPLs in EM compared to BM. Among these SDPLs, the content of PE (16:1_18:0) was found to be significantly higher in EM compared to BM (FC = 69.5853, P < 0.0001). Moreover, sphingolipid metabolism and glycerophospholipid metabolism were determined to be vital metabolic pathways. This was derived from the finding that PE, PC, SM, and PI were key lipid metabolites in the two kinds of milk that were related to these two metabolic pathways. This study provides new insights into the characterization of SDPLs in mammalian milk, and also provides a theoretical basis for optimizing infant formula.

Comparison of phospholipid composition and microstructure of milk fat globules contained in human milk and infant formulae

Phospholipids play key roles in infant nutrition and cognitive development. It is hypothesized that infant formula (IF) has lower phospholipid species, content and milk fat globule (MFG) structural integrity than human milk (HM). Herein, we performed qualitative and quantitative analyses of phospholipids in six classes of IF and HM using ultra-performance liquid chromatography with mass spectrometry. The contents of phosphatidylethanolamine (15.81 ± 7.20 mg/L) and sphingomyelin (35.84 ± 15.56 mg/L) in IF were significantly lower than those in HM (30.74 ± 17.38 mg/L, 45.53 ± 16.04 mg/L, respectively). Among the six IF classes, cow's milk-based IF had the highest number of phospholipid species, and IF containing milk fat globular membrane had the highest phospholipid content. The size, zeta potential, and amount of MFGs in IF were significantly lower than those in HM. These results may prove useful for designing better IF that mimic HM.

Comparison and enrichment of sn-2 palmitoyl triacylglycerols (OPO/OPL) in fish oil for its potential application as human milk fat substitutes

Triacylglycerols (TAG) are differences in fatty acid distributions between infant formula and human milk. In this study, fish oil (Tilapia, Golden pompano, Tiger grouper, and Basa) showed the potential as the source of human milk fat substitutes by comparing TAG profiles with infant formula and human milk. The total lipids and TAG of fish were concentrated in the by-products of fish (head and viscera) and contained high levels of palmitic acid, oleic acid, and linoleic acid. Compared with infant formula, fish oil was closer to human milk in sn-2 fatty acid distribution, and sn-2 palmitic acid level in fish oil exceeded 52 % of total palmitic acid, Golden pompano head was the highest (64.46 %). Further research showed that the content of sn-2 palmitoyl TAG (OPO and OPL dominated) increased from 157.16 mg/g TAG to 305.18 mg/g TAG by isopropanol enrichment (solid-liquid ratio: 1:4, temperature: -12 °C, time: 4 h).

Comparison of glycerophospholipid and sphingolipid in mature milk from different sampled regions in the Chinese human milk project (CHMP) study

Milk phospholipids (PLs) are critical components of infant growth. This study aimed to discover PL in mature human milk (HM) from China (n = 201) and mainly assessed the effect caused by sampled regions. The average total PL concentration was quantified from 3.65 to 11.25 mg per g of lipid, and the major PL class identified was sphingomyelin (SM, 38.06-47.62 %), followed by phosphatidylcholine (PC, 29.61-34.39 %), and phosphatidylethanolamine (PE, 10.54-24.46 %). In addition, the 36:2 (18:0/18:2), 38:6 (16:0/22:6), 40:1 (d18:1/22:0), and 42:2 (d18:1/24:1) were the most abundant molecular species identified in glycerophospholipid and SM molecular species respectively. Some PL molecular species were strongly related with region of sampling, like lysophosphatidylinositol 18:1 was only detected in Beijing. In conclusion, those findings showed that the PL molecular species and concentration of HM had significant regional diversity, and it will give the Chinese human milk database more accurate PL data.

Profile of Human Milk Phospholipids at Different Lactation Stages with UPLC/Q-TOF-MS: Characterization, Distribution, and Differences

Human milk phospholipids are important for the regular growth and development of infants. Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was employed to qualitatively and quantitatively analyze 277 phospholipid molecular species in 112 human milk samples to obtain a detailed profile of human milk phospholipids along the lactation stage. MS/MS fragmentation patterns of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were characterized in detail. Phosphatidylcholine is the most dominant group, followed by sphingomyelin. PC(18:0/18:2), SM(d18:1/24:1), PE(18:0/18:0), PS(18:0/20:4), and PI(18:0/18:2) showed the highest average concentration among all of the phosphatidylcholine, sphingomyelin, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol molecular species, respectively. The fatty acids attached to the phospholipid molecules were mainly palmitic, stearic, oleic, and linoleic acids, and the plasmalogens decreased along the lactation stage. The increase of sphingomyelins and phosphatidylethanolamines and the decrease of phosphatidylcholines are the key changes from colostrum to transitional milk; the increase of lysophosphatidylcholines and lysophosphatidylethanolamines and the continuous decrease of phosphatidylcholines are the vital changes from transitional milk to mature milk.

Comparative Lipidomic Analysis Reveals the Lactational Changes in the Lipid Profiles of Chinese Human Milk

Human milk (HM) lipid plays a crucial role in infant development, whereas its complex lipid profiles and its dynamic changes during prolonged lactation have not been investigated yet. Comparative lipidomic analyses were employed in investigating the lipid profiles of breast milk covering all lactation stages herein. Results revealed significant differences between colostrum and the remaining lactations. A total of 237 species of glycerolipids (GLs) and 231 phospholipids (PLs) were identified. Colostrum had the most abundant lipid species and was enriched with triacylglycerols (TGs) with a high molecular weight. TG(17:1/18:1/24:1), TG(24:1/24:1/26:1), TG(24:0/24:1/26:1), and SM(d20:1/14:1) were characteristic lipids of colostrum. Differential lipid species which were responsible for distinguishing the adjacent lactations were also indicated. Our findings can help deepen the overall understanding of HM lipid profiles and its dynamic changes, which will facilitate the development of infant formulas suitable for Chinese babies in diverse age groups.

Interfacial composition in infant formulas powder modulate lipid digestion in simulated in-vitro infant gastrointestinal digestion

The interface structure and composition of fat globules are very important for the digestion and metabolism of fat and growth in infants. Interface composition of fat globules in infant formula (IF) supplemented with milk fat globule membranes (MFGM) and lecithin in different ways were analyzed and their effects on fat digestion properties were evaluated. The results showed that the distribution of phospholipids at the interface and structural of Concept IF1 and Concept IF2 that were more similar to those of human milk (HM) than that of conventionally processed IF3. Concept IF2 and IF3 supplemented with lecithin had larger initial particle size and more sphingomyelin (SM) (23.12 ± 0.26 %, 26.94 ± 0.34 %) than Concept IF1, and Concept IF2 had the smallest proportion of casein in the interfacial. Due to its interface composition, Concept IF2 had the highest degree of lipolysis (85.07 ± 0.76 %), the phospholipid ring structure can always be observed during gastric digestion, and a final fatty acid composition released that was more similar to HM. Concept IF1 and IF3 were different from HM and Concept IF2 in terms of structure and lipolysis rate, although superior to commercial IF4. These indicate that changes in the interfacial composition and structure of fat globules improve the digestive properties of fats in IF. Overall, the results reported herein are useful in designing new milk formulas that better simulate HM.

Lipid Profiles of Human Milk and Infant Formulas: A Comparative Lipidomics Study

Infant formulas (IFs) are prevalent alternatives for human milk (HM), although their comparative lipid profiles have not been fully investigated. We adopted lipidomics to analyze and compare in-depth the lipid patterns of HM and IFs. The results indicated that the distribution of fatty acids (FAs) and the structure of triacylglycerols varied substantially in the analyzed samples. A total number of 425 species were identified during the analysis. HM was abundant in triacylglycerols that contained unsaturated and long-chain FAs (>C13), while triacylglycerols in IFs were mainly comprised of saturated and medium-chain FAs (C8-C13). Higher levels of sphingomyelin were observed in HM. Furthermore, HM and IF1 contained 67 significantly differential lipids (SDLs), and 73 were identified between HM and IF2. These SDLs were closely associated with nine metabolic pathways, of which the most significant was the glycerophospholipid metabolism. The results shed light on the differences between the lipid profiles of human and infant formula milks, and provide support for designing Chinese infant formula.

Quantification of phospholipids and glycerides in human milk using ultra-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry

Human milk lipids, which are an important source of energy and affect growth and development of infants, require a comprehensive method for its qualitative and quantitative analysis. This work describes a method for the analysis of phospholipids, glycerides, free fatty acids and gangliosides in human milk by ultra-performance liquid chromatography using a C18 column with quadrupole-time-of-flight mass spectrometry (Q-TOF-MS). The lipids were extracted by liquid-liquid extraction and phospholipids were separated by solid phase extraction (SPE). The chromatographic columns with two different specifications (4.6 mm × 150 mm, and 3 mm × 50 mm) were used to detect phospholipids and glycerides in human milk, respectively. The sphingolipids and glycerides were analyzed in positive ion mode, and the glycerophospholipids and free fatty acids were analyzed in negative ion mode. Both internal and external standards were used for absolute quantification in this experiment. 483 species of lipids, including phospholipids, glycerides, free fatty acids and gangliosides, in human milk were analyzed using UPLC-Q-TOF-MS with high sensitivity and good linearity, with coefficient of correlation above 0.99, the relative standard deviation of accuracy and precision less than 10%. The results in a large number of human milk samples showed that this method was suitable for qualitative and quantitative analysis of lipids in human milk, even for other mammalian milk and infant formulae.

The Effects of Postpartum Yak Metabolism on Reproductive System Recovery

The goal of this study was to determine the metabolism of multiparous female yaks during the late perinatal period and identify its effects on reproductive recovery in order to explain the low reproduction rate of yaks. Eight multiparous female yaks were randomly selected as the sample, and serum was collected from the yaks every 7 days from the day of delivery until 28 days after the delivery (five time points). The presence of serum metabolic profiles and reproductive hormones was identified using ELISA. The key metabolites were identified using liquid chromatography-mass spectrometry, and a dynamic metabolic network representation was created using bioinformatics analysis. A total of 117 different metabolites were identified by calculating the fold change of the metabolite expression at each time point. The dynamic metabolic network was created to represent the activities of the key metabolites, metabolic indexes and reproductive hormones. The initial efficiency of the glucose metabolism in the late perinatal period was found to be low, but it increased during the final period. The initial efficiencies of the lipid and amino acid metabolisms were high but decreased during the final period. We inferred that there was a postpartum negative energy balance in female yaks and that the synthesis and secretion of estrogen were blocked due to an excessive fatty acid mobilization. As a result, the reproductive hormone synthesis and secretion were maintained at a low level in the late perinatal period, and this was the main reason for the delayed recovery of the reproductive function postpartum. However, the specific mechanism needs to be further verified.

Progress and perspectives of enzymatic preparation of human milk fat substitutes

Human milk fat substitutes (HMFS) with triacylglycerol profiles highly similar to those of human milk fat (HMF) play a crucial role in ensuring the supply in infant nutrition. The synthesis of HMFS as the source of lipids in infant formula has been drawing increasing interest in recent years, since the rate of breastfeeding is getting lower. Due to the mild reaction conditions and the exceptionally high selectivity of enzymes, lipase-mediated HMFS preparation is preferred over chemical catalysis especially for the production of lipids with desired nutritional and functional properties. In this article, recent researches regarding enzymatic production of HMFS are reviewed and specific attention is paid to different enzymatic synthetic route, such as one-step strategy, two-step catalysis and multi-step processes. The key factors influencing enzymatic preparation of HMFS including the specificities of lipase, acyl migration as well as solvent and water activity are presented. This review also highlights the challenges and opportunities for further development of HMFS through enzyme-mediated acylation reactions.

Medium- and long-chain triacylglycerols and di-unsaturated fatty acyl-palmitoyl-glycerols in Chinese human milk: Association with region during the lactation

The triacylglycerols (TAGs) of medium- and long-chain triacylglycerols (MLCT) and di-unsaturated fatty acyl-palmitoyl-glycerols (UPU) in human milk provide better nutritional effects, and should be prioritized as crucial focuses on neonatal nutrition research. However, little has been done on the influences of the lactation stage and regional diversity on MLCT and UPU. In this study, we collected 204 human milk samples during colostrum, 1st and 4th month from the north (Baotou), central (Beijing), east (Jinan), southwest (Kunming), southeast (Shenzhen), and northwest (Xining) regions of China. There were 122 species of TAGs detected with UPLC-Q-TOF-MS, including 60 kinds of MLCT and 15 kinds of UPU. The MLCT and UPU type TAGs in human milk were ~27 and ~38%, respectively. The sum content of MLCT and UPU in human milk was stable. Compared to the regional diversity, lactation stages showed more obvious influences on MLCT and UPU composition. Moreover, a summary of TAG studies indicated that Chinese human milk showed a higher ratio of O-P-L to O-P-O than in western countries.

MYBIOTA: A birth cohort on maternal and infant microbiota and its impact on infant health in Malaysia

Background

The microbiota plays a key role in early immunity maturation that affects infant health and is associated with the development of non-communicable diseases and allergies in later life.

Objective

The MYBIOTA is a prospective mother-infant cohort study in Malaysia aiming to determine the association between gut microbiota with infant health (temperament, gastrointestinal disorders, eczema, asthma, and developmental delays) in Selangor, Malaysia.

Methods

Pregnant mothers will be enrolled in their first trimester of pregnancy, and follow-ups will be done for infants during their first year of life. Maternal-infant biological samples (blood, feces, saliva, urine, and breast milk), anthropometric, dietary, and clinical information will be collected at different time points from early pregnancy to 12 months postpartum.

Discussion

This study could provide a better understanding of the colonization and development of the gut microbiome during early life and its impact on infant health.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT04919265.

Profiling of triacylglycerol composition in the breast milk of Chinese mothers at different lactation stages

Triacylglycerol (TAG) is the primary constituent of human milk fat and plays a vital role in the healthy development of infants. But few studies reported the sophisticated profile of TAG molecular species in human breast milk and its temporal changes during a prolonged lactation period. An efficient ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method was adopted to examine TAGs. A total of 128 TAGs in 296 human breast milk samples collected during postnatal 0 to 400 days were identified. The changes in the human milk TAG profile mainly took place in the early stages of lactation (postnatal 0-45 days), and the TAG profile became stable in mature milk after 200 days of lactation. Odd chain fatty acids (OC-FAs) may be important markers for identifying human breast milk of different lactation stages. This study could provide evidence for developing safe and efficacious human-milk substitutes for children without access to human breast milk.

Advances in analysis, metabolism and mimicking of human milk lipids

Human milk lipids differ from the milk lipids of other mammals in composition and positional distribution of fatty acids. Analysis and detection technology of lipids is key to understanding milk lipids, and thus the concentrations, compositions and distribution characteristics of milk lipids are discussed. Differences between human milk lipids and their substitutes in form, composition and structure affect their digestion, absorption and function in infants. Characteristics and mimicking of human milk lipids have been intensively studied with the objective of narrowing the gap between human milk and infant formulae. Based on the existing achievements, further progress may be made by improving detection techniques, deepening knowledge of metabolic pathways and perfecting fat substitutes. This review detailed the characteristics of human milk lipids and related detection technologies with a view towards providing a clear direction for research on mimicking human milk lipids in formulae to further improve infant nutrition.

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.

Lactational Changes of Phospholipids Content and Composition in Chinese Breast Milk

Phospholipids are pivotal polar lipids in human milk and essential for infants’ growth and development, especially in the brain and cognitive development. Its content and composition are affected by multiple factors and there exist discrepancies in different studies. In this study, we determined five major phospholipids classes (phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylcholine, and sphingomyelin) in 2270 human milk samples collected from 0 to 400 days postpartum in six regions of China. The high-performance liquid chromatography coupled with an evaporative light scattering detector (HPLC-ELSD) was performed to quantify the phospholipids. Total phospholipid median (IQR) content was in a range between 170.38 ± 96.52 mg/L to 195.69 ± 81.80 mg/L during lactation and was higher concentrated in colostrum milk and later stage of lactation (after 200 days postpartum) compared with that in the samples collected between 10 to 45 days postpartum. Variations in five major sub-class phospholipids content were also observed across lactation stages (phosphatidylethanolamine: 52.61 ± 29.05 to 59.95 ± 41.74 mg/L; phosphatidylinositol: 17.65 ± 10.68 to 20.38 ± 8.55 mg/L; phosphatidylserine: 15.98 ± 9.02 to 22.77 ± 11.17 mg/L; phosphatidylcholine: 34.13 ± 25.33 to 48.64 ± 19.73 mg/L; sphingomyelin: 41.35 ± 20.31 to 54.79 ± 35.26 mg/L). Phosphatidylethanolamine (29.18–32.52%), phosphatidylcholine (19.90–25.04%) and sphingomyelin (22.39–29.17%) were the dominant sub-class phospholipids in Chinese breast milk during the whole lactation period. These results updated phospholipids data in Chinese human milk and could provide evidence for better development of secure and effective human milk surrogates for infants without access to breast milk.