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

Human milk proteins differentiate over the sex of newborns and across stages of lactation

BACKGROUND & AIMS

Human milk (HM) is a complete food that meets the nutritional and energy demands of the newborns. It contains numerous bioactive components, including functional proteins. Variations in HM energy and lipid content have already been reported related to the newborn's sex, but differences between protein profiles are still scarce. This work aimed to identify differences between HM proteins produced by mothers of female and male newborns, in the lactation stages of colostrum and mature milk, and the metabolic pathways involved.

METHODS

A total of 98 HM samples were collected from 39 lactating women and classified according to the newborn's sex, stages of lactation, and three mothers' age groups, and evaluated about protein concentration and one-dimensional electrophoretic profile. Next, to assess samples with the greatest differences, the HM proteins regarding the newborn's sex and the stages of lactation were compared using nano-LC-MS/MS, in 24 HM samples randomly rearranged into four groups: female and male infants, and colostrum and mature milk. Functional classification, metabolic pathways, and protein interaction networks were analyzed by Gene Ontology, KEGG, and STRING, respectively.

RESULTS

The soluble protein content of HM decreased throughout lactation, with differences regarding isolated factors, such as mothers' age group, child's sex and stages of lactation, and also in terms of their interactions. A total of 146 proteins were identified, 42 of which showed different abundances over the sexes of newborns and 53 between the stages of lactation. In general, proteins related to metabolic processes were up-regulated for mothers of male infants and in the mature stage of lactation, while proteins related to defense were up-regulated in mothers of female infants and in the colostrum phase.

CONCLUSION

This study indicated that there are differentiated and specific nutritional and defense needs of newborns, by sex and by lactation phase, which is highly relevant for a more appropriate supply of food to infants receiving HM from donor mothers.

Characterisation of the protein quality and composition of water kefir-fermented casein

This study aimed to assess the technique of natural fermentation by applying water kefir to the casein protein. The diverse microorganisms and their enzymes found naturally in the water kefir can influence casein's characteristics. The fermented casein's protein quality (digestibility and secondary protein structure) and composition (total soluble solids and nutritive and non-nutritive substances) were investigated. Our findings revealed that the fermented casein's protein digestibility and total phenolic content increased from 82.46 to 88.60 % and 7.6 to 8.0 mg gallic acid equivalent/100 g, respectively. In addition, their surface charge and hydrophobicity changed from -30.06 to -34.93 mV and 286.9 to 213.7, respectively. Furthermore, the fermented casein's secondary protein components, α-helix (decreased from 13.66 to 8.21 %) and random coil (increased from 16.88 to 19.61 %), were also altered during the fermentation. Based on these findings, the water kefir fermentation approach could be an effective, practical, non-thermal approach for improving casein's protein quality and composition.

Science and Faith to Understand Milk Bioactivity for Infants

Milk bioactivity refers to the specific health effects of milk components beyond nutrition. The science of milk bioactivity involves the systematic study of these components and their health effects, as verified by empirical data, controlled experiments, and logical arguments. Conversely, 'faith in milk bioactivity' can be defined as personal opinion, meaning, value, trust, and hope for health effects that are beyond investigation by natural, social, or human sciences. Faith can be strictly secular, but also influenced by spirituality or religion. The aim of this paper is to show that scientific knowledge is frequently supplemented with faith convictions to establish personal and public understanding of milk bioactivity. Mammalian milk is an immensely complex fluid containing myriad proteins, carbohydrates, lipids, and micronutrients with multiple functions across species, genetics, ages, environments, and cultures. Human health includes not only physical health, but also social, mental, and spiritual health, requiring widely different fields of science to prove the relevance, safety, and efficacy of milk interventions. These complex relationships between milk feeding and health outcomes prevent firm conclusions based on science and logic alone. Current beliefs in and understanding of the value of breast milk, colostrum, infant formula, or isolated milk proteins (e.g., immunoglobulins, α-lactalbumin, lactoferrin, and growth factors) show that both science and faith contribute to understand, stimulate, or restrict the use of milk bioactivity. The benefits of breastfeeding for infants are beyond doubt, but the strong beliefs in its health effects rely not only on science, and mechanisms are unclear. Likewise, fear of, or trust in, infant formula may rely on both science and faith. Knowledge from science safeguards individuals and society against 'milk bioactivity superstition'. Conversely, wisdom from faith-based convictions may protect science from unrealistic 'milk bioactivity scientism'. Honesty and transparency about the potentials and limitations of both scientific knowledge and faith convictions are important when informing individuals and society about the nutritious and bioactive qualities of milk.

Optimizing ARA and DHA in infant formula: A systematic review of global trends, regional disparities, and considerations for precision nutrition

In the context of precision nutrition, the addition of ARA and DHA in infant formula needs to consider more factors. This study conducted a comprehensive literature review, including 112 relevant Chinese and English articles, to summarize and analyze the global levels of ARA, DHA, and the ARA/DHA ratio in breast milk. The data were correlated with local aquatic products intake and children's IQ. The results indicated that the average level of DHA in breast milk across regions is lower than that of ARA. Variations in DHA content were identified as a primary factor influencing ARA/DHA ratio fluctuations. Breast milk ARA and DHA levels decrease with prolonged lactation periods but increase over the past 22 years. Correlation analysis revealed a significant positive relationship between aquatic products intake and breast milk DHA levels (r = 0.64, p < 0.05). Breast milk DHA levels also showed a significant positive correlation with children's IQ (r = 0.67, p < 0.01). Stable breast milk ARA content did not exhibit significant correlations with aquatic products intake or children's IQ (r = 0, p > 0.05). Among 22 infant formula products available in China, only 5 had ARA levels within the range of breast milk. Most formula products had higher ARA levels than DHA, resulting in ARA/DHA ratios generally exceeding 1. The temporal and spatial variability in breast milk ARA and DHA levels may lead to diverse health outcomes in infants. Therefore, the addition of ARA and DHA in infant formula should consider this variability, including the molecular forms and positional isomerism of the added ARA and DHA. Additionally, considering the impact of different cognitive development tests and infant's gene expression on formula assessment results, there is a need to establish a more comprehensive infant health assessment system to guide the addition of ARA and DHA in formula.

3-Monochloropropane-1,2-diol reduced bioaccessibility of sn-2 palmitate via binding with pancreatic lipase in infant formula during gastrointestinal digestion

Infant formula contains 3-monochloropropane-1,2-diol esters (3-MCPDE), which are formed during the deodorization step of vegetable oil refining. The European Food Safety Authority stated that 3-MCPDE can be hydrolyzed in the gastrointestinal tract to free-form 3-monochloropropane-1,2-diol (3-MCPD), which has potential toxicity and can be rapidly absorbed. Evaluating the effect of 3-MCPD on nutrition absorption is a prerequisite for establishing effective management strategies. A total of 66 crucial lipid molecules associated with 3-MCPD were identified based on debiased sparse partial correlation analysis. 3-MCPD affected triglyceride hydrolyzation and increased the concentration of undigested sn-2 palmitate (9.57 to 17.06 mg kg-1). 3-Monochloropropane-1,2-diol reduced the bioaccessibility of fatty acids, and more short- (31.42 to 58.02 mg kg-1) and medium-chain fatty acids (17.03 to 26.43 mg kg-1) remained unabsorbed. Lipidomic profiles of infant formula models spiked with different 3-MCPDE levels were investigated, and the results were consistent with the experiments with the commercial formula indicating lipid alteration was mainly affected by the digestive 3-MCPD. The formation of 3-MCPD ester-pancreatic lipase with the binding energy of -4.9 kcal mol-1 was more stable than triglyceride-pancreatic lipase (-4.0 kcal mol-1), affecting triglyceride hydrolyzation. 3-Monochloropropane-1,2-diol was bound to Glu13 and Asp331 residues of the pancreatic lipase via hydrogen bonds, which resulted in a conformational change of pancreatic lipase and spatial shielding effect. The existence of the spatial-shielding effect reduced the accessibility of pancreatic lipase and further affected triglyceride hydrolyzation. These findings indicated that 3-MCPD obstructed nutrient acquisition and laid the foundation for the subsequent nutrition enhancement design.