Evaluation of Breast Milk and Breast Milk Substitutes on Growing Rats

Breast milk substitutes are used extensively in many countries of the world. They are generally based on milk protein, but formulas containing other protein sources are also marketed. The protein and amino acid adequacy of such formulas are ascertained by comparison with breast milk. Furthermore, the pediatric Committee on Nutrition1 recommends that the protein level of a breast milk substitute should not fall below 1.8 gm/100 kcal if the protein has a PER of at least 100% of casein. If the PER is below that of casein, the protein content of the formula should be increased accordingly, although proteins with PER below 70% of casein should not be used.</jats:p

Proteomic Characterization of Specific Minor Proteins in the Human Milk Casein Fraction

Human milk contains many bioactive proteins that are likely to support the early development of the newborn. The aim of this study was to identify whether there are specific minor proteins associated with the human milk casein micelle prepared by the acid precipitation method. Protein identification was performed by liquid chromatography tandem mass spectrometry analysis. Eighty-two proteins were identified in the casein micelle, 18 of which are not present in their whey compartment. Thirty-two of these proteins specifically associated with the casein micelle have not previously been identified in human milk or colostrum. Proteins involved in immune function comprised the major part (28%) of total proteins, and another significant part is involved in metabolism/energy production (22%). Most of the proteins were of extracellular or cytoplasmic origin (accounting for 50 and 29%, respectively). This study indicates that various soluble proteins should be considered as part of the casein compartment, prepared by the acid precipitation method. The data provide new insight not only into the proteomic profile of the human milk casein micelle and its physiological significance, but also into the proper proportion of casein and casein-associated proteins to use in infant formula

Growth of Breast-Fed and Formula-Fed Infants From 0 to 18 Months: The DARLING Study

Anthropometric data were collected monthly from birth to 18 months as part of the Davis Area Research on Lactation, Infant Nutrition and Growth study, which followed infants who were either breast-fed or formula-fed during the first 12 months. The two cohorts were matched for parental socioeconomic status, education, ethnic group, and anthropometric characteristics and for infant sex and birth weight, and neither group was given solid foods before 4 months. While mean weight of formula-fed infants remained at or above the National Center for Health Statistics median throughout the first 18 months, mean weight of breast-fed infants dropped below the median beginning at 6 to 8 months and was significantly lower than that of the formula-fed group between 6 and 18 months. In contrast, length and head circumference values were similar between groups. Weight-for-length z scores were significantly different between 4 and 18 months, suggesting that breast-fed infants were leaner. The groups had similar weight gain during the first 3 months, but breast-fed infants gained less rapidly during the remainder of the first year: cumulative weight gain in the first 12 months was 0.65 kg less in the breast-fed group. Length gain was similar between groups. These results indicate that weight patterns of breast-fed infants, even in a population of high socioeconomic status, differ from current reference data and from those of formula-fed infants. Thus, new growth charts based on breast-fed infants are needed.</jats:p

Formula Feeding Skews Immune Cell Composition toward Adaptive Immunity Compared to Breastfeeding

Abstract The ontogeny of the immune system and the effect thereon by type of infant feeding is incompletely understood. We analyzed frequencies and composition of immune cells in blood of breastfed (BF) and formula-fed (FF) infants at 1.5, 4, and 6 mo of age. Three formulas with the same protein concentration but with varying levels of α-lactalbumin and caseinoglycomacropeptide were compared. Twenty-nine exclusively BF infants served as reference, and 17 infants in each formula group completed the study. Whole blood and PBMCs were analyzed by flow cytometry and immunoflow cytometry, respectively. Leukocyte count of BF infants increased with time due to increased frequency of neutrophils. Lymphocyte count was high at 1.5 mo and was unchanged over time, as were the relative proportions of CD4+ αβT cells, CD8+ αβT cells, B cells, NK cells, and γδT cells. Most CD45R0+CD3+ cells were HLA-DR− and hence memory cells. Compared with breastfeeding, formula feeding resulted in a significant decrease in proportion of NK cells, but a significant increase in naive CD4+ αβT cells and an elevated CD4-to-CD8 ratio, that is, 3.3 in the combined FF groups compared with 2.6 in the BF group. No significant differences were found between the three groups of FF infants. In conclusion, blood cells of lymphoid lineage did not change significantly in frequencies or composition from 1.5 to 6 mo of age in BF infants. In contrast, FF infants displayed an ongoing maturation of adaptive immunity cells and a delayed recruitment of innate immunity cells as compared with BF infants.</jats:p

Comparative Proteomics of Human and Macaque Milk Reveals Species-Specific Nutrition during Postnatal Development

Milk has been well established as the optimal nutrition source for infants, yet there is still much to be understood about its molecular composition. Therefore, our objective was to develop and compare comprehensive milk proteomes for human and rhesus macaques to highlight differences in neonatal nutrition. We developed a milk proteomics technique that overcomes previous technical barriers including pervasive post-translational modifications and limited sample volume. We identified 1606 and 518 proteins in human and macaque milk, respectively. During analysis of detected protein orthologs, we identified 88 differentially abundant proteins. Of these, 93% exhibited increased abundance in human milk relative to macaque and include lactoferrin, polymeric immunoglobulin receptor, alpha-1 antichymotrypsin, vitamin D-binding protein, and haptocorrin. Furthermore, proteins more abundant in human milk compared with macaque are associated with development of the gastrointestinal tract, the immune system, and the brain. Overall, our novel proteomics method reveals the first comprehensive macaque milk proteome and 524 newly identified human milk proteins. The differentially abundant proteins observed are consistent with the perspective that human infants, compared with nonhuman primates, are born at a slightly earlier stage of somatic development and require additional support through higher quantities of specific proteins to nurture human infant maturation

Comparative Proteomics of Human and Macaque Milk Reveals Species-Specific Nutrition during Postnatal Development

Milk has been well established as the optimal nutrition source for infants, yet there is still much to be understood about its molecular composition. Therefore, our objective was to develop and compare comprehensive milk proteomes for human and rhesus macaques to highlight differences in neonatal nutrition. We developed a milk proteomics technique that overcomes previous technical barriers including pervasive post-translational modifications and limited sample volume. We identified 1606 and 518 proteins in human and macaque milk, respectively. During analysis of detected protein orthologs, we identified 88 differentially abundant proteins. Of these, 93% exhibited increased abundance in human milk relative to macaque and include lactoferrin, polymeric immunoglobulin receptor, alpha-1 antichymotrypsin, vitamin D-binding protein, and haptocorrin. Furthermore, proteins more abundant in human milk compared with macaque are associated with development of the gastrointestinal tract, the immune system, and the brain. Overall, our novel proteomics method reveals the first comprehensive macaque milk proteome and 524 newly identified human milk proteins. The differentially abundant proteins observed are consistent with the perspective that human infants, compared with nonhuman primates, are born at a slightly earlier stage of somatic development and require additional support through higher quantities of specific proteins to nurture human infant maturation