Protein Content Of Human Milk Research Articles

Influences of human milk proteins on the release of human milk odors: Non-covalent interactions between α-lactalbumin and key odor skeleton compounds

Human milk (HM) provides optimal nutrition for infants, but infant formula (IF) serves as a potential alternative to HM when breastfeeding is not an option. However, IF possesses a more intense aroma than HM, and it is often challenging to reduce this disparity due to its stringent production regulations. Therefore, investigating the interaction between HM proteins and odor molecules is essential for comprehending the distinct odor characteristics of HM and guiding improvements in IF to mimic the aroma of HM. This research aims to characterize the HM odor and explore the influence of HM α-lactalbumin (HMLB) on the release of HM odor skeleton compounds (OSC) using a combination of computer simulation, human perceptions, and instrumental analyses. A total of 20 OSCs were identified. Notably, the release of most of these compounds was negatively correlated with the HM protein content, with the strongest negative correlations being observed for hexanal, nonanal, and decanal (|R| ≥ 0.7, P < 0.01). The molecular docking simulations demonstrated that HMLB inhibited the volatilization of hexanal, nonanal, and decanal, thereby increasing the odor threshold of these odor compounds (61.94 %, 241.5 %, and 198.6 %). This inhibition was mainly achieved through the formation of hydrogen bonding and hydrophobic interactions, a finding corroborated by multi-spectroscopic analysis. Overall, the experimental results provide valuable insights into the odor mechanism of HM and contribute to the development of IF that mimics the HM odor.

Breastfeeding Impact on Kidney Functions: A Systematic Review

IntroductionBreast milk depict a huge maternal and pediatric benefits, including a long-term impact on cardiovascular and metabolic health. We conducted a systematic review to explore the relevant sudies exploring the link between breastfeeding and future renal outcome Material and MethodsA systematic search was carried out on Medline* through PubMed* (with adapted filters) via the query: (breastfeeding[Title/Abstract] OR breastfeeding[MeSH Terms]) AND (kidney[MeSH Terms] OR kidney[Title/Abstract]) ResultsWe retrieved 12 articles, including only 3 investigational studies: - In 2017, the European Childhood Obesity Project Group found that either protein intakes or formula types modulated the infant calciuria. The authors proposed new cut-off values of calciuria based on infant feeding types - In a 2015 Dutch study encompassing more than 5000 children, breastfeeding in the first 4 months was associated with larger combined kidney volume and lower eGFR (both P<0.05) - A 2010 European multicenter clinical trial found that a higher protein content of the infant formula increases kidney size at 6 months of life, whereas a lower protein supply achieves kidney size indistinguishable from that of healthy breastfed infants, highliting the potential harm of early protein overdose. DiscussionFew papers explored the potential impact of breastfeeding on kidney health. The low protein content of human milk seems beneficial with positive subclinical changes in kidney volume and function in childhood. ConclusionBreastfeeding would have favorable kidney outcome in childhood, but data is sparse. Further investigations are needed to better understand the potential impact of breastfeeding on the future renal prognosis

A computational approach to nutrition science reveals the dynamics of the protein content of human milk

To study the computational aspects of collecting available data in a systematically organized database is becoming a matter of urgency in Nutrition & Food Science. Indeed, major projects on developing big datasets have attempted to fill this gap, but so far with limitations on important facets of food composition such as its temporal variation and uncertainty quantification. The need for methodological data processing, from data acquisition, digital storage, statistics and visualization, via pattern recognition and modelling to prediction and optimization is key to make objective and knowledge-based decisions on scientific and technological issues for food industry, academy and regulation. This study aims to demonstrate the use of a recently developed database on the composition of human milk, the first and easily the most complex food in one's life. We show that the purpose-built ontology of the database, with novelties like considering the food composition as a temporal and stochastic response, can help to recognize patterns in the variation of its protein content. Industrial relevance textThis study highlights the need (i) for introducing ISO-like standards how to digitize food composition data; (ii) for computational methods to explore and utilize such databases to their full potentials.

The levels of osteopontin in human milk of Chinese mothers and its associations with maternal body composition

ObjectiveThis study explored the content and change trend of osteopontin (OPN) in breast milk and analyzed the relationship between OPN in breast milk and maternal body composition. MethodsBreast-feeding mothers were recruited in Xinhua Hospital to collect breast milk and provide pertinent information. The content of OPN in breast milk was determined by enzyme-linked immunosorbent assay (ELISA). Determination of protein content in human milk was performed via the BCA method. The maternal body composition was determined by the bioelectrical impedance method. Serum glucocorticoid receptor α, adiponectin, insulin, and leptin were determined by ELISA. SPSS 25 was used for statistical analysis. ResultsIn the longitudinal cohort, 106 mothers provided 318 milk samples at different lactation periods. The results indicate that the OPN showed dynamic changes. OPN levels were (343.2 ± 163.5) mg/L during 114 days postpartum, (228.4 ± 121.5) mg/L during 24 months postpartum, and (204.8 ± 100.6) mg/L during 57 months postpartum. The content of OPN was very high in the first 114 days postpartum and then decreased. Compared with early postpartum milk, the OPN content of mature milk showed a significant relationship with maternal weight-related parameters. Additional body composition analysis was performed in 88 women at the mature milk phase. The results show that the OPN in milk is related to the mother’s body composition, especially the content of skeletal muscle mass, but not to relevant humoral factors. ConclusionsThe levels of OPN in human milk of Chinese mothers showed dynamic changes with the extension of lactation time. The OPN in human milk was related to the mother’s body composition but not related to related humoral factors.

Breast Milk Protein Percentiles According to Gestational and Postnatal Age: Could It Be Used as a New Alternative in Guided Fortification?

Human milk is the first choice for infant nutrition but it must be multinutrient fortified for optimum growth and neurodevelopment in preterm infants. However, there is no consensus on ideal fortification method. The authors aimed to generate the human-milk protein content percentiles during the first five postnatal weeks in four preterm groups (n = 108) with median gestational age of 32 (23-36) wk, who were fed adjustably fortified breast milk in the NICU between October 2011 and June 2013. Total 540 breast milk samples of mothers of 108 infants were weekly analyzed for protein intake. It was observed that the median human-milk protein levels decreased throughout the five postnatal weeks in all groups. None of the preterm infants was able to take the recommended daily protein intake with the fortification protocol of the authors' unit. Preterm human-milk protein charts can be used as a new practical individualized fortification guiding method instead of laborious targeted or adjustable approaches currently in use.

The ultrafiltration molecular weight cut-off has a limited effect on the concentration and protein profile during preparation of human milk protein concentrates

Optimizing protein intake for very low birth weight (<1,500 g) infants is fundamental to prevent faltering postnatal growth with the potential association of impaired neurodevelopment. The protein content of human milk is not sufficient to support the growth of very low birth weight infants. To meet their elevated protein requirements, human milk is currently fortified using typically bovine milk-based protein isolates (>85% on a dry basis). However, these products have several limitations for use in this vulnerable population. To overcome the shortcomings of bovine milk-based protein supplement, a human milk protein concentrate (HMPC) was developed. In preliminary attempts using 10 kDa ultrafiltration (UF) membranes, it was not possible to reach the protein content of commercial protein isolates, presumably due to the retention of human milk oligosaccharides (HMO). Consequently, it was hypothesized that the use of a UF membrane with a higher molecular weight cut-off (50 kDa rather than 10 kDa) could improve the transmission of carbohydrates, including HMO, in the permeate, thus increasing the protein purity of the subsequent HMPC. The results showed that permeate fluxes during the concentration step were similar to either UF molecular weight cut-off, but the 50-kDa membrane had a higher permeate flux during the diafiltration sequence. However, it was not sufficient to increase the protein purity of the human milk retentate, as both membranes generated HMPC with similar protein contents of 48.8% (10 kDa) and 50% (50 kDa) on a dry basis. This result was related to the high retention of HMO, mainly during the concentration step, although the diafiltration step was efficient to decrease their content in the HMPC. As the major bioactive proteins (lactoferrin, lysozyme, bile salt stimulated lipase, and α1-antitrypsin) in human milk were detected in both HMPC, the 50-kDa membrane seems the most appropriate to the preparation of HMPC in terms of permeation flux values. However, improving the separation of HMO from proteins is essential to increase the protein purity of HMPC.

High-pressure homogenization and high hydrostatic pressure processing of human milk: Preservation of immunological components for human milk banks

Human milk (HM) constitutes the first immunological barrier and the main source of nutrients and bioactive components for newborns. Immune factors comprise up to 10% of the protein content in HM, where antibodies are the major components (mainly IgA, IgG, and IgM). In addition, antibacterial enzymes such as lysozyme and immunoregulatory factors such as soluble cluster of differentiation 14 (sCD14) and transforming growth factor β2 (TGF-β2) are also present and play important roles in the protection of the infant's health. Donor milk processed in HM banks by Holder pasteurization (HoP; 62.5°C, 30 min) is a safe and valuable resource for preterm newborns that are hospitalized, but is reduced in major immunological components due to thermal inactivation. We hypothesized that high hydrostatic pressure (HHP) and high-pressure homogenization (HPH) are 2 processes that can be used on HM to reduce total bacteria counts while retaining immunological components. We studied the effects of HHP (400, 450, and 500 MPa for 5 min applied at 20°C) and HPH (200, 250, and 300 MPa, milk inlet temperature of 20°C) applied to mature HM, on microbiological and immunological markers (IgA, IgG, IgM, sCD14, and TGF-β2), and compared them with those of traditional HoP in HM samples from healthy donors. The HHP processing between 400 and 500 MPa at 20°C reduced counts of coliform and total aerobic bacteria to undetectable levels (<1.0 log cfu/mL) while achieving approximately 100% of immunological component retention. In particular, comparing median percentages of retention of immunological components for 450 MPa versus HoP, we found 101.5 versus 50.5% for IgA, 89.5 versus 26.0% for IgM, 104.5 versus 75.5% for IgG, 125.0 versus 72.5% for lysozyme, 50.6 versus 0.1% for sCD14, and 88.5 versus 61.1% for TGF-β2, respectively. Regarding HPH processing, at a pressure of 250 MPa and inlet temperature of 20°C, the process showed good potential to reduce coliforms to undetectable levels and total aerobic bacteria to levels slightly above those obtained by HoP. The median percentages of retention of immunological markers for HPH versus HoP were 71.5 versus 52.0%, 71.0 versus 27.0%, 104.0 versus 66.5%, and 30.9 versus 0.2%, for IgA, IgM, IgG, and sCD14, respectively; results did not significantly differ for lysozyme and TGF-β2. The HPH at 300 MPa produced higher inactivation of immunological components, similar to values achieved with HoP.

Diagnostic accuracy of biochemical markers for diagnosis polycystic ovary syndrome in reproductive women

Proteins in human milk (HM) are diverse and contribute to varied nutritional and biological functions for a neonate. HM proteins provide the building blocks including indispensable amino acids required to support infant growth and development and have a range of biological activities that help to preserve infant health in short and long terms. Like other components in HM, protein content is influenced by multitude of maternal and infant-related factors. The methodology used to collect, store, and analyze HM samples may also play a role in protein content variability and can be an important source of bias when different studies are compared. This chapter reviews in detail the average concentrations of protein content in HM and discusses factors that influence its composition. Finally, it highlights the gaps and proposes future research areas to focus on the advancement of proteins of HM.

Variation in the Protein Composition of Human Milk during Extended Lactation: A Narrative Review.

The aim of this review is to evaluate changes in protein parameters in the second year postpartum. There is considerable agreement among authors about the declining trend of human milk protein concentrations, but most research on protein content in breast milk focuses on the first year of life and comes from developed countries. Whereas this is the case for exclusive breastfeeding or for breastfeeding into the first year of life, the opposite applies to weaning or extended breastfeeding. This review is predominantly based on observational epidemiological evidence and on comparative research linking breast milk composition with cutting down on breastfeeding. Studies dating back several decades have shown an increase in the proportion of immunoglobulins, lactoferrin, and serum albumin during weaning. According to the limited data available, it seems likely that the regulation of milk protein composition during involution can be ascribed to alterations in tight junctions. In studies on humans and other mammalian species, offspring suckle more from mothers that produce more dilute milk and the increase in milk protein concentration is positively correlated to a decrease in suckling frequency during weaning. High milk protein contents were first reported in nonindustrial communities where breastfeeding is sustained the longest, but recent papers from urbanized communities have taken credit for rediscovering the increase in protein content of human milk that becomes evident with prolonged breastfeeding. This review presents an overview of the changes in breast milk protein parameters in the second year postpartum to enable milk banks’ practitioners to make informed nutritional decisions on preterm infants.

Excessive Leucine-mTORC1-Signalling of Cow Milk-Based Infant Formula: The Missing Link to Understand Early Childhood Obesity.

Increased protein supply by feeding cow-milk-based infant formula in comparison to lower protein content of human milk is a well-recognized major risk factor of childhood obesity. However, there is yet no conclusive biochemical concept explaining the mechanisms of formula-induced childhood obesity. It is the intention of this article to provide the biochemical link between leucine-mediated signalling of mammalian milk proteins and adipogenesis as well as early adipogenic programming. Leucine has been identified as the predominant signal transducer of mammalian milk, which stimulates the nutrient-sensitive kinase mammalian target of rapamycin complex 1 (mTORC1). Leucine thus functions as a maternal-neonatal relay for mTORC1-dependent neonatal β-cell proliferation and insulin secretion. The mTORC1 target S6K1 plays a pivotal role in stimulation of mesenchymal stem cells to differentiate into adipocytes and to induce insulin resistance. It is of most critical concern that infant formulas provide higher amounts of leucine in comparison to human milk. Exaggerated leucine-mediated mTORC1-S6K1 signalling induced by infant formulas may thus explain increased adipogenesis and generation of lifelong elevated adipocyte numbers. Attenuation of mTORC1 signalling of infant formula by leucine restriction to physiologic lower levels of human milk offers a great chance for the prevention of childhood obesity and obesity-related metabolic diseases.

Effect of two pasteurization methods on the protein content of human milk

The Holder method is the recommended pasteurization method for human milk banks, as it ensures the microbiological safety of human milk (HM). The loss of some biologically active milk components, due to the heat treatment, is a main limit to the diffusion of donor HM. High-temperature short-time (HTST) pasteurization may be an alternative to maintain the nutritional and immunological quality of HM. The aim of the present study was to compare the impact of Holder and HTST pasteurization on the HM protein profile. The protein patterns of HTST-treated milk and raw milk were similar. The Holder method modified bile salt-stimulated lipase, lactoferrin and components of the immune system. The HTST method preserved the integrity of bile salt-stimulated lipase, lactoferrin and, to some extent, of IgAs. Holder pasteurization decreased the amount of bile salt-stimulated lipase and inactivated the remaining molecules, while the HTST method did not alter its activity. Pasteurization increased the bioavailable lysine quantity. HTST pasteurization seems to better retain the protein profile and some of the key active components of donor HM.

Amino acid composition of lactating mothers' milk and confinement diet in rural North China.

This study was designed to investigate the amino acids composition of lactating mothers' milk and their confinement diet in a town in Northern China, as well as to assess the relation of amino acids content in human milk and diet. Forty lactating mothers age 19 to 35 years participated in the study. They were 4 to 180 days postpartum. A 24-hour dietary recall was done and amino acids content of maternal milk was analyzed. The main findings are as follows: (1) The protein content of human milk is 1.58 g/dL and the ratio of EAA to NEAA is about 1:2. The most abundant amino acids in human milk are GLU (16.0%), PRO (10.2%), LEU (8.67%) and the lowest two are MET (1.76%) and TRP (0.91%). (2)The diet contains enough energy and protein, but lacks vitamins A, B and C, indicating that it is a characteristic confinement diet. Grain and eggs are the main source of protein, and soy and fish were consumed less frequently. (3) Amino acids composition in diet and milk are similar; and the correlation of the amino acids patterns between diet and milk is 0.989, demonstrating that the amino acid composition of diet is the foundation of that in human milk. However, almost no relation is found between the amino acids concentration in maternal diet and milk, suggesting that the amino acids content of the diet does not have a direct relation with that of human milk.

Protein Content and Fortification of Human Milk Influence Gastroesophageal Reflux in Preterm Infants

: Preterm human milk (HM) may provide insufficient energy and nutrients and thus may need to be fortified. Our aim was to determine whether fat content, protein content, and osmolality of HM before and after fortification may affect gastroesophageal reflux (GER) in symptomatic preterm infants. : Gastroesophageal reflux was evaluated in 17 symptomatic preterm newborns fed naïve and fortified HM by combined pH/intraluminal-impedance monitoring (pH-MII). Human milk fat and protein content was analysed by a near-infrared reflectance analysis. Human milk osmolality was tested before and after fortification. Gastroesophageal reflux indexes measured before and after fortification were compared and were also related to HM fat and protein content and osmolality before and after fortification. : An inverse correlation was found between naïve HM protein content and acid reflux index (RIpH: P = 0.041, rho =-0.501). After fortification, osmolality often exceeded the values recommended for infant feeds; furthermore, a statistically significant (P < 0.05) increase in nonacid reflux indexes was observed. : Protein content of naïve HM may influence acid GER in preterm infants. A standard fortification of HM may worsen nonacid GER indexes and, due to the extreme variability in HM composition, may overcome both recommended protein intake and HM osmolality. Thus, an individualised fortification, based on the analysis of the composition of naïve HM, could optimise both nutrient intake and feeding tolerance.

Can infant feeding choices modulate later obesity risk?

Since the concept of lasting programming effects on disease risk in human adults by the action of hormones, metabolites, and neurotransmitters during sensitive periods of early development was proposed >3 decades ago, ample supporting evidence has evolved from epidemiologic and experimental studies and clinical trials. For example, numerous studies have reported programming effects of infant feeding choices on later obesity. Three meta-analyses of observational studies found that obesity risk at school age was reduced by 15–25% with early breastfeeding compared with formula feeding. We proposed that breastfeeding protects against later obesity by reducing the occurrence of high weight gain in infancy and that one causative factor is the lower protein content of human milk compared with most infant formula (the early protein hypothesis). We are testing this hypothesis in the European Childhood Obesity Project, a double-blind, randomized clinical trial that includes >1000 infants in 5 countries (Belgium, Germany, Italy, Poland, and Spain). We randomly assigned healthy infants who were born at term to receive for the first year infant formula and follow-on formula with higher or lower protein contents, respectively. The follow-up data obtained at age 2 y indicate that feeding formula with reduced protein content normalizes early growth relative to a breastfed reference group and the new World Health Organization growth standard, which may furnish a significant long-term protection against later obesity. We conclude that infant feeding practice has a high potential for long-term health effects, and the results obtained should stimulate the review of recommendations and policies for infant formula composition.

Effect of two pasteurization methods on the protein content of human milk

Effect of two pasteurization methods on the protein content of human milk

Available lysine content in human milk: Stability during manipulation prior to ingestion

Available lysine content is an indicator of protein quality and nutritional value of milk. Many studies have examined the effects of extraction, treatment and storage of human milk upon its components, though no references are found regarding the possible changes in milk quality as defined by its content in essential amino acids such as lysine. The present study investigates the available lysine content in human milk and the variations in lysine resulting from milk manipulation as follows: (a) Cold storage (refrigeration at 4 degrees C for 48 hours, and frozen for 15 days at -20 degrees C); (b) Thermal treatment under conditions of low (Holder)(63 degrees C/30 minutes) and high pasteurization (75 degrees C/15 seconds). The results obtained show a decrease in milk lysine concentration after storage in both refrigerated and frozen samples. Pasteurization causes a highly significant loss of available lysine. The lysine losses were greater on applying low pasteurization versus the more gentle conditions of high pasteurization. While manipulation through cold storage or thermal treatment does not affect the protein content of human milk, its protein quality is modified. When human milk must be subjected to hygienization, it is preferable to apply high temperature treatment (75 degrees C, 15 seconds) than habitual pasteurization (63 degrees C, 30 minutes).

How much protein is safe?

Since breastfeeding and human milk seem to prevent, while high dietary proteins in the first 2 y of life seem to promote, later overweight, questions have been raised on the safe levels of proteins in the early years. How much protein (as a percentage of total calorie intake) is safe? Revision of available data on the protein content of human milk, protein intake in the first 2 y of life and their association with body mass development. We should move from the figure of 7-8% in the 4-month exclusively breastfed infants up to the maximum acceptable levels of 14% in 12-24-month-old infants. When protein supply represents less than 6% and energy is limited, fully breastfed infants are likely to enter a status of negative nutrient balance. Over the limit of 14% energy from proteins in the 6-24 months period, some mechanisms may begin to operate, leading young children towards an early adiposity rebound and overweight development, beyond any genetic predisposition. Preliminary data seem to indicate a causal role for whole cow's milk proteins. We suggest maintaining breastfeeding as long as possible, and, in case human milk is insufficient, to introduce infant formulas, appropriate for age, up to 18-24 months, in order to keep protein intakes in the safe range of 8-12% within a diet adequate in energy and balanced as far as macronutrients.

164 Insulin-Like Growth Factors and Their Binding Proteins in Early Milk from Mothers of Preterm and Term Infants and Thei Biological Relevance

Background: Breast fed preterm infants often show a better neurological outcome than formula-fed. The benefit of human milk is partly ascribed to it's content of the growth promoting insulin-like growth factors (IGFs). The aim of this study was to investigate, whether the content of IGFs und Their binding proteins (IGFBPs) is higher in human milk from mothers of preterm infants than of term infants and to test their biological relevance.Methods: In a prospective study we investigated the concentrations of IGF-I, IGF-II and their binding proteins IGFBP-2 and IGFBP-3 in human milk from mothers of 30 preterm infants (<31 SSW) and of 19 term infants (>37 SSW) at day 7 and 21 after birth by means of an RIA, and the protein content of human milk by the Bichinonic acid (BCA) method. We analyzed the specific proteolysis of IGFBP-2 in human milk and the stability of 125I-IGF-I and 125IGFBP-2 in the presence of gastric juice from neonates.Results: Mean concentrations (±SD) of IGF-I(2,8 ± 0,2 vs. 2,3 ± 0,1 ng/ml), IGF-II (12,0 ± 0,4 vs. 12,2 ± 0,5 ng/ml) and IGFBP-3 (100,0 ± 5,1 vs. 80,0 ± 5,8 ng/ml) did not differ in human milk of preterm versus term infants on day 7. The content of IGFBP-2 (3144 ± 172 vs. 2428 ± 188 ng/ml) was higher in preterm human milk (p<0,05). IGF-I, IGF-II and IGFBP-2 did slightly change until day 21. IGFBP-3 decreased from day 7 to day 21 by 41%/ 27% in human milk of preterm/ term infants (p<0,05). The protein content in human milk of preterm infants was on day 7 (2,5 ± 0,1 g/dl) higher than on day 21 (p<0,05). On day 21 the protein content was equal to term infants (1,9 ± 0,1 g/dl). Preterm human milk contained about 42% more IGFBP-2- fragments of 14 und 25 kDa (p< 0,05). Incubation with gastric juice led to a complete digestion of 125IGFBP-2 and a partial digestion of 125I-IGF-II, while complexation with each other protected IGF-II and IGFBP-2 from cleavage.Conclusion: We suggest that IGF-II and IGFBP-2 play a role in the nutrition of preterm infants. Both are found in a constant level in human milk and IGF-2 showed a higher concentration in preterm than in term human milk for the first 3 weeks. IGFBP-2/IGF-II-complexes can partly pass the stomach and may exert their promotive effects in the intestine. Taken together it can be concluded that preterm infants profits best from breast milk of it's own mother.

Early protein intakes and adiposity: reloaded or downloaded?

It has been hypothesized that feeding human milk through the first year of life may have a protective effect towards a later adiposity development, in contrast with formula feeding. The low protein content of human milk has been hypothesized as a plausible biological hypothesis. Regardless, it is often underscored that feeding human milk is associated with a higher rate of weight gain in the first two months of life. In our opinion, it seems that the protective effect of human milk, if any, on adiposity development is far more complex, and tightly bound to the peculiarity of human milk composition and breastfeeding practice.

Faecal chymotrypsin in small for gestational age infants: effects of nucleotides and breast feeding

The effect of diet on pancreatic exocrine function, measured by faecal chymotrypsin activity (FCA), was studied longitudinally in three groups of small for gestational age (SGA) infants in the first...