Low-Protein Formulas with Alpha-Lactalbumin-Enriched or Glycomacropeptide-Reduced Whey: Effects on Growth, Nutrient Intake and Protein Metabolism during Early Infancy: A Randomized, Double-Blinded Controlled Trial

Human milk oligosaccharide secretion dynamics during breastfeeding and its antimicrobial role: A systematic review

BACKGROUND

Human milk oligosaccharides (HMOs) are bioactive components of breast milk with diverse health benefits, including shaping the gut microbiota, modulating the immune system, and protecting against infections. HMOs exhibit dynamic secretion patterns during lactation, influenced by maternal genetics and environmental factors. Their direct and indirect antimicrobial properties have garnered significant research interest. However, a comprehensive understanding of the secretion dynamics of HMOs and their correlation with antimicrobial efficacy remains underexplored.

AIM

To synthesize current evidence on the secretion dynamics of HMOs during lactation and evaluate their antimicrobial roles against bacterial, viral, and protozoal pathogens.

METHODS

A systematic search of PubMed, Scopus, Web of Science, and Cochrane Library focused on studies investigating natural and synthetic HMOs, their secretion dynamics, and antimicrobial properties. Studies involving human, animal, and in vitro models were included. Data on HMO composition, temporal secretion patterns, and mechanisms of antimicrobial action were extracted. Quality assessment was performed using validated tools appropriate for study design.

RESULTS

A total of 44 studies were included, encompassing human, animal, and in vitro research. HMOs exhibited dynamic secretion patterns, with 2′-fucosyllactose (2′-FL) and lacto-N-tetraose peaking in early lactation and declining over time, while 3-fucosyllactose (3-FL) increased during later stages. HMOs demonstrated significant antimicrobial properties through pathogen adhesion inhibition, biofilm disruption, and enzymatic activity impairment. Synthetic HMOs, including bioengineered 2′-FL and 3-FL, were structurally and functionally comparable to natural HMOs, effectively inhibiting pathogens such as Pseudomonas aeruginosa , Escherichia coli , and Campylobacter jejuni . Additionally, HMOs exhibited synergistic effects with antibiotics, enhancing their efficacy against resistant pathogens.

CONCLUSION

HMOs are vital in antimicrobial defense, supporting infant health by targeting various pathogens. Both natural and synthetic HMOs hold significant potential for therapeutic applications, particularly in infant nutrition and as adjuncts to antibiotics. Further research, including clinical trials, is essential to address gaps in knowledge, validate findings, and explore the broader applicability of HMOs in improving maternal and neonatal health.

Ethanol-Inducible Bioproduction of Human α-Lactalbumin in Komagataella phaffii

α-Lactalbumin (α-LA) is the most abundant whey protein in human milk. Microbially expressed α-LA serves as a potential additive in infant formula to improve the protein composition and amino acid profile, enhancing the deep simulation of human milk. Komagataella phaffii is widely recognized for its ability to achieve high-density fermentation and robust secretion of heterologous proteins, making it ideal for large-scale production with relatively simple fermentation conditions. At present, the expression of human α-LA in K. phaffii remains challenged by the potential toxicity of using methanol as an inducer and inefficient bioproduction. In this study, we first employed the ethanol-transcriptional signal amplification device system in K. phaffii to express human α-LA, achieving a titer of 7.39 mg·L-1 in shake flask fermentation. Next, through hybrid optimization of the native α-factor signal peptide and multicopy integration of the target gene, the α-LA titer was further increased to 16.52 mg·L-1 in the shake flask. Finally, by addressing acetic acid accumulation in bioreactor fermentation, the engineered production strain achieved a titer of 0.60 g·L-1 in a 3 L bioreactor. This work represents the first demonstration of high-efficiency methanol-free production of human α-LA in K. phaffii and provides strategies for the efficient expression and secretion of recombinant proteins in this host organism.

Impact of formula protein quantity and source on infant metabolism: serum, urine, and fecal metabolomes of a randomized controlled study

BACKGROUND

Human milk offers significant health benefits for infants; however, when not feasible, infant formula serves as an alternative. The higher protein content in infant formula is thought to contribute to the distinct metabolic profiles observed in formula-fed infants compared with those fed human milk.

OBJECTIVES

This study investigates the impact of formula protein quantity and whey protein types on the serum, urine, and fecal metabolomes of infants.

METHODS

A secondary analysis was performed on a random subset of 200 well-characterized per-protocol infants who completed a prospective, randomized, double-blind controlled trial. Infants were randomly assigned to 1 of 3 groups: standard formula, protein-reduced formula with α-lactalbumin-enriched whey, or protein-reduced formula with casein glycomacropeptide-reduced whey, along with an observational reference group of exclusively breastfed infants. Serum, urine, and fecal metabolites were quantified using 1H nuclear magnetic resonance spectroscopy at baseline (1-2 mo), 4, and 6 mo of age. Dietary intake was assessed monthly ≤6 mo of age.

RESULTS

Formula protein content and type of whey protein used significantly influenced the amino acid profile and associated catabolic markers in serum and urine but had minimal impact on the fecal metabolome. Reduced protein formulas yielded metabolome profiles closer to those of breastfed infants compared with standard formula. Despite these improvements, infants fed human milk still demonstrated enhanced branched-chain amino acid (BCAA) oxidation and a greater capacity to eliminate catabolic waste products from BCAA metabolism over infants consuming protein-reduced formulas.

CONCLUSIONS

Comprehensive metabolomics profiling of serum, urine, and feces captures molecular-level changes and informs potential strategies for formula optimization. Both the quantity and source of protein significantly influenced the metabolic profiles of formula-fed infants. However, modifications in protein alone cannot fully resolve the metabolic differences between formula-fed and breastfed infants, highlighting the complexity of mimicking the human milk feeding-associated metabolic profile. This study was registered at clinicaltrials.gov as NCT02410057.

Low-protein diet supplemented with isomalto-oligosaccharide reduces diarrhea rate of weaned piglets by regulating intestinal function

Excess protein in infant formula can harm the health of infants. Isomalto-oligosaccharide (IMO), a prebiotic, can be incorporated into infant formula. This study employed weaned piglets as a model to establish varying protein levels, investigating the impact of IMO in low-protein diets on the intestinal health. A total of 192 weaned piglets were randomly assigned to four groups, with each group containing six pens of eight piglets each. The control group was fed a diet containing 19% crude protein (CP), while the other three experimental groups were supplemented with 0.2% IMO, with CP levels of 19%, 18%, and 17%, respectively. The experiment lasted 28 days, with one piglet from each pen slaughtered at the end. There were no differences in growth performance among the groups. Nonetheless, the diarrhea rate in an 18% protein diet supplemented with IMO (18CP + IMO group) was reduced during d1-21 and 1-28 (p < 0.05). The diarrhea rate and the apparent total tract digestibility (ATTD) of acid detergent fiber (ADF) showed a quadratic correlation (p < 0.05). Meanwhile, 18CP + IMO group showed that the ATTD of dry matter and ADF increased (p < 0.05); the crypt depth of the jejunum decreased (p < 0.05), while the expression of intestinal barrier (ZO-1) and intestinal development (CDX2) related genes increased (p < 0.05); the abundance of beneficial bacteria (Bifidobacterium) increased (p = 0.06). Compared with 19CP group, the other three groups had lower contents of indole and skatole (p < 0.05). Our results showed that supplementing an 18% CP diet with 0.2% IMO decreased diarrhea incidence in weaned piglets, enhanced nutrient digestibility, intestinal barrier and microbiota, and reduced harmful metabolite production.

Infant growth and tolerance with a formula based on novel native demineralized whey: A randomized double-blind pilot study

OBJECTIVES

The aim of the study was to evaluate the effects on infant growth and tolerance of a Test infant formula based on a novel whey extraction and demineralization process, compared to a Standard formula and a breastfed reference arm.

METHODS

Healthy term infants (n = 61) aged up to 21 days were randomized to Test or Control formula. A breastfed group (n = 39) served as a reference. Growth, tolerance, adverse events, and sleep were evaluated every month until 6 months of age. Plasma amino-acid concentrations at 3 months of age were measured in a subgroup population.

RESULTS

Growth curves of all infants globally agreed with World Health Organization standards across the 6-month period study. Regarding tolerance, no difference between the formula-fed groups was observed on daily number of crying episodes, intensity or time to onset of regurgitations, and stool frequency or consistency, except at 5 months with infants in the Control group having more watery stools. Plasma concentration of some amino acids differed between the groups, especially tryptophan concentration which was higher in infants fed with the Test formula. In parallel, total sleep duration was longer in these infants at 2, 3, and 5 months of age, corresponding to an increase in daytime sleep.

CONCLUSIONS

Test formula supported an adequate infant growth from birth to 6 months of age and was well-tolerated by all infants. An increase in total sleep at several months was also observed with the Test formula.

Diet Supplemented with Special Formula Milk Powder Promotes the Growth of the Brain in Rats

This investigation was to study the effects of different formula components on the brain growth of rats. Fifty male SD rats were randomly divided into five groups: a basic diet group; a 20% ordinary milk powder group; a 20% special milk powder group; a 30% ordinary milk powder group; and a 30% special milk powder group by weight. LC-MS was used to detect brain lipidomics. After 28 days of feeding, compared with the basic diet group, the brain/body weights of rats in the 30% ordinary milk powder group were increased. The serum levels of 5-HIAA in the 30% ordinary milk powder group were lower than in the 20% ordinary milk powder group. Compared with the basic diet group, the expressions of DLCL, MePC, PI, and GM1 were higher in the groups with added special milk powder, while the expressions of LPE, LdMePE, SM, and MGTG were higher in the groups with added ordinary milk powder. The expression of MBP was significantly higher in the 20% ordinary group. This study found that different formula components of infant milk powder could affect brain growth in SD rats. The addition of special formula infant milk powder may have beneficial effects on rat brains by regulating brain lipid expression.

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.

Low-Protein Infant Formula Enriched with Alpha-Lactalbumin during Early Infancy May Reduce Insulin Resistance at 12 Months: A Follow-Up of a Randomized Controlled Trial

High protein intake during infancy results in accelerated early weight gain and potentially later obesity. The aim of this follow-up study at 12 months was to evaluate if modified low-protein formulas fed during early infancy have long-term effects on growth and metabolism. In a double-blinded RCT, the ALFoNS study, 245 healthy-term infants received low-protein formulas with either alpha-lactalbumin-enriched whey (α-lac-EW; 1.75 g protein/100 kcal), casein glycomacropeptide-reduced whey (CGMP-RW; 1.76 g protein/100 kcal), or standard infant formula (SF; 2.2 g protein/100 kcal) between 2 and 6 months of age. Breastfed (BF) infants served as a reference. At 12 months, anthropometrics and dietary intake were assessed, and serum was analyzed for insulin, C-peptide, and insulin-like growth factor 1 (IGF-1). Weight gain between 6 and 12 months and BMI at 12 months were higher in the SF than in the BF infants (p = 0.019; p < 0.001, respectively), but were not significantly different between the low-protein formula groups and the BF group. S-insulin and C-peptide were higher in the SF than in the BF group (p < 0.001; p = 0.003, respectively), but more alike in the low-protein formula groups and the BF group. Serum IGF-1 at 12 months was similar in all study groups. Conclusion: Feeding modified low-protein formula during early infancy seems to reduce insulin resistance, resulting in more similar growth, serum insulin, and C-peptide concentrations to BF infants at 6-months post intervention. Feeding modified low-protein formula during early infancy results in more similar growth, serum insulin, and C-peptide concentrations to BF infants 6-months post intervention, probably due to reduced insulin resistance in the low-protein groups.