Evaluation of a mid-infrared analyzer for the determination of the macronutrient composition of human milk

Human milk variation is shaped by maternal genetics and impacts the infant gut microbiome

Human milk is a complex mix of nutritional and bioactive components that provide complete nourishment for the infant. However, we lack a systematic knowledge of the factors shaping milk composition and how milk variation influences infant health. Here, we characterize relationships between maternal genetics, milk gene expression, milk composition, and the infant fecal microbiome in up to 310 exclusively breastfeeding mother-infant pairs. We identified 482 genetic loci associated with milk gene expression unique to the lactating mammary gland and link these loci to breast cancer risk and human milk oligosaccharide concentration. Integrative analyses uncovered connections between milk gene expression and infant gut microbiome, including an association between the expression of inflammation-related genes with milk interleukin-6 (IL-6) concentration and the abundance of Bifidobacterium and Escherichia in the infant gut. Our results show how an improved understanding of the genetics and genomics of human milk connects lactation biology with maternal and infant health.

Comparative analysis of different methods for protein quantification in donated human milk

Background

Human milk is the best option for feeding newborns, especially premature infants. In the absence of breast milk, milk from a human milk bank can be a suitable alternative. However, the nutritional content of human milk may be insufficient to meet these high requirements and milk fortification is needed. To facilitate the implementation of simpler and faster analyzers in neonatal healthcare facilities, this study focuses on the concordance analysis of two different analyzers, one based on mid-infrared and the other on ultrasound, in comparison to the Bradford method for determining protein concentration in human milk.

Methods

Mature milk samples from donor mothers were collected and pasteurized at the Human Milk Bank of Barcelona and protein quantification was performed using mid-infrared (MIRIS-HMA), ultrasound (MilkoScope Julie27), and the classical Bradford reference methods. The intraclass correlation coefficient (ICC) with 95% confidence interval and Bland-Altman plots were used to assess the agreement between methods.

Results

The mean protein concentration of 142 milk samples calculated using MIRIS-HMA, MilkoScope, and the Bradford assay were 1.38, 1.15, and 1.19 g/100 ml, respectively. The ICC was 0.70 for MIRIS-HMA vs. Bradford and 0.37 for MilkoScope vs. Bradford.

Conclusion

MIRIS-HMA obtained a better agreement with the Bradford technique and is a promising method for developing new devices based on MIR transmission spectroscopy principles. This study confirms how MIRIS-HMA can be used to accurately calculate the protein concentration of human milk.

Breast size in lactating women and the content of macronutrients in human milk

INTRODUCTION

Although the primary function of a woman's breast is milk synthesis, only a few studies have evaluated the relationship between breast size and human milk composition, showing equivocal results. This study aims to test if breast size during fully established lactation is related to energy density and content of macronutrients in human milk.

MATERIALS AND METHODS

Mothers of healthy, born-on-term infants at stage III of lactogenesis (N = 137) provided breast milk samples. Milk composition was analyzed using midinfrared transmission spectroscopy. The breast size index was calculated by dividing the breast by the circumference below the breast.

RESULTS

Stepwise forward linear regression showed a negative association between breast size index and lactose concentration in breast milk (β = -.242, p = .003). The final model, which includes breast size index, feeding frequency, and maternal energy intake together explained around 13% of the variance in breast milk lactose content (R2 adj = .126, p < .001). No statistically significant relationship was found between breast size index and milk's energy density, protein, and fat content.

CONCLUSION

This is the first study that shows a negative relationship between breast size during fully established lactation and lactose concentration in milk in a large sample size. No relationship between other macronutrients and breast size indicates that large breast size is not necessary for adequate milk production; however, it may contribute to an altered lactose concentration.

Lipid Peroxidation and Antioxidative Capacity Are Unaltered in Transitional Breast Milk Exposed to Light from Women Giving Birth to Preterm Infants before 32 Weeks of Gestation

Breast milk (BM) is the primary nutrition for infants and has a high content of lipids. Preterm infants receive expressed BM via tube feeding, and they are frequently treated with phototherapy. When parenteral nutrition (PN) is exposed to light and/or phototherapy, lipid peroxidation (LPO) increases. By light-protecting PN, morbidity and mortality are reduced in preterm infants through the reduction of oxidative stress. We aimed to investigate whether light-protecting breast milk could reduce LPO. Twelve mothers giving birth to a preterm infants of less than 32 weeks of gestational age were included. Transitional BM was collected and divided into three study groups; light-protected, ward light and phototherapy light. Baseline samples were collected after expression and the exposures started within one hour. Feeding syringe samples were exposed to light for 30 up to 360 min. Nasogastric tube samples were run through a tube under the same light conditions. Samples were stored in -80 °C until analyses of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE) and total antioxidant capacity (TAC). There were no significant differences in MDA, 4-HNE or TAC levels observed between the different study groups. This study indicates that the light exposure of expressed transitional BM does not affect LPO and the levels of MDA, 4-HNE or TAC.

Relationships between the Intakes of Human Milk Components and Body Composition of Breastfed Infants: A Systematic Review

Human milk provides all of the elements necessary for infant growth and development. Previous studies have reported associations between breastfeeding and a reduced risk of developing obesity and late-onset metabolic disorders; however, the underlying mechanisms are poorly understood. Recently, intakes of human milk components have been associated with infant body composition, which is likely partially implicated in the reduced risk of developing childhood obesity among breastfed infants. In this systematic review, we searched electronic bibliographic databases for studies that explored relationships between the 24 h intakes of human milk macronutrients and bioactive components and infant body composition and/or growth parameters. Of 13 eligible studies, 10 assessed relationships of infant body composition and growth outcomes with human milk macronutrients, while 8 studies assessed relationships with human milk bioactive components. Significant time-dependent relationships with infant anthropometrics and body composition were found for intakes and no relationships for concentrations of several human milk components, such as lactose, total protein, and human milk oligosaccharides, suggesting that measuring concentrations of human milk components without quantifying the intake by the infant may provide a limited understanding. Future studies investigating the effect of human milk components on infant growth and body composition outcomes should consider measuring the actual intake of components and employ standardised methods for measuring milk intake.

Pooling Strategies to Modify Macronutrient Content of Pasteurized Donor Human Milk

Background: Donor human milk (DHM) is the recommended feeding for preterm infants when mother's own milk is unavailable or insufficient. DHM macronutrient's variability may have significant implications on preterm growth. Different pooling strategies could be used to improve the macronutrient content, facilitating the achievement of nutritional requirements of preterm. Objective: The aim was to compare the impact of random pooling (RP) and target pooling (TP) strategies on the macronutrient content of DHM and to identify which RP practice allows the achievement of a macronutrient composition as similar as possible to that achievable with TP. Methods: The macronutrient content of 1,169 single-donor pools was analyzed, and a TP strategy combining 2,3,4, or 5 single-donor pools was adopted. On the bases of single-donor pools' analyses, a simulation of 10,000 randomly selected pools for each configuration of donor considered and for different milk volume proportions was performed. Results: Regardless of the type of strategy and milk volume, as the number of donor per pool increases, the percentage of pools with a macronutrient content equal or higher than the reference values for human milk increases. Conclusion: When a TP strategy is not feasible, a RP strategy combining at least five donors should be performed to obtain a better macronutrient content of DHM.

Human Milk Calorie Guide: A Novel Color-Based Tool to Estimate the Calorie Content of Human Milk for Preterm Infants

Fixed-dose fortification of human milk (HM) is insufficient to meet the nutrient requirements of preterm infants. Commercial human milk analyzers (HMA) to individually fortify HM are unavailable in most centers. We describe the development and validation of a bedside color-based tool called the 'human milk calorie guide'(HMCG) for differentiating low-calorie HM using commercial HMA as the gold standard. Mothers of preterm babies (birth weight ≤ 1500 g or gestation ≤ 34 weeks) were enrolled. The final color tool had nine color shades arranged as three rows of three shades each (rows A, B, and C). We hypothesized that calorie values for HM samples would increase with increasing 'yellowness' predictably from row A to C. One hundred thirty-one mother's own milk (MOM) and 136 donor human milk (DHM) samples (total n = 267) were color matched and analyzed for macronutrients. The HMCG tool performed best in DHM samples for predicting lower calories (<55 kcal/dL) (AUC 0.87 for category A DHM) with modest accuracy for >70 kcal/dL (AUC 0.77 for category C DHM). For MOM, its diagnostic performance was poor. The tool showed good inter-rater reliability (Krippendorff's alpha = 0.80). The HMCG was reliable in predicting lower calorie ranges for DHM and has the potential for improving donor HM fortification practices.

Human milk variation is shaped by maternal genetics and impacts the infant gut microbiome

Human milk is a complex mix of nutritional and bioactive components that provide complete nutrition for the infant. However, we lack a systematic knowledge of the factors shaping milk composition and how milk variation influences infant health. Here, we used multi-omic profiling to characterize interactions between maternal genetics, milk gene expression, milk composition, and the infant fecal microbiome in 242 exclusively breastfeeding mother-infant pairs. We identified 487 genetic loci associated with milk gene expression unique to the lactating mammary gland, including loci that impacted breast cancer risk and human milk oligosaccharide concentration. Integrative analyses uncovered connections between milk gene expression and infant gut microbiome, including an association between the expression of inflammation-related genes with IL-6 concentration in milk and the abundance of Bifidobacteria in the infant gut. Our results show how an improved understanding of the genetics and genomics of human milk connects lactation biology with maternal and infant health.

Evaluation of Breast Milk Macronutrient Content in Preeclamptic Mothers

Background: Preeclampsia remains among the leading causes of maternal and perinatal morbidity and mortality worldwide. This study aimed to evaluate the macronutrient content of colostrum in mothers with preeclampsia. Materials and Methods: Women who delivered by cesarean section at ≤37 weeks of gestation were included in the study. Fresh colostrum samples were collected by manual expression on postpartum days 2 and 4 and were analyzed using a mid-infrared human milk analyzer. Demographic characteristics of the patients were recorded. The protein, fat, carbohydrate, and energy composition of the milk samples were compared between mothers with and without preeclampsia. Results: A total of 58 colostrum samples (25 preeclampsia, 33 nonpreeclampsia) were analyzed. The median gestational age of the infants was similar in both groups (32 versus 33 weeks; p > 0.05). There were also no differences between the groups in terms of maternal age, maternal body mass index, maternal weight gain during pregnancy, and infant gender. Median protein, fat, and carbohydrate levels in the colostrum of the preeclamptic mothers were 2.2, 2.1, and 6.3 g/dL, respectively, compared with 1.8, 2.4, and 6.2 g/dL in the nonpreeclamptic mothers, respectively. Although the colostrum of preeclamptic mothers had higher protein content and lower fat content, the difference was not statistically significant. Carbohydrate and energy contents were similar in both groups. Conclusions: The presence of preeclampsia does not cause a significant change in the macronutrient composition of mother's milk. Analyses of micronutrients at different lactation stages in larger samples are needed.

Testing the effects of processing on donor human Milk: Analytical methods

Holder pasteurization is the current recommended method for donor human milk treatment. This method effectively eliminates most life-threatening contaminants in donor milk, but it also greatly reduces some of its biological properties. Consequently, there is a growing interest for developing novel processing methods that can ensure both microbial inactivation and a higher retention of the functional components of donor milk. Our aim was to offer a comprehensive overview of the analytical techniques available for the evaluation of such methods. To suggest an efficient workflow for the analysis of processed donor milk, a safety analytical panel as well as a nutritional value and functionality analytical panel are discussed, together with the principles, benefits, and drawbacks of the available techniques. Concluding on the suitability of a novel method requires a multifactorial approach which can be achieved by a combination of analytical targets and by using complementary assays to cross-validate the obtained results.

Macronutrient analysis of human milk and factors associated with its composition in mothers of preterm infants ≤ 32 weeks

We conducted an exploratory longitudinal study to evaluate the macronutrient composition of human milk in mothers delivering very preterm infants ≤ 32 weeks over the first 4 weeks of lactation and the association of human milk composition with maternal and neonatal factors A total of 213 human milk samples collected in the morning between 8 am and 12 pm from 60 eligible mothers were analyzed on 7 (n = 60), 14 (n = 60), 21 (n = 52), and 28 (n = 41) days of lactation by infrared transmission spectroscopy. The true protein content decreased significantly over 4 weeks (mean difference (95% confidence interval)) (MD (95% CI)) week 1 and week 4 = 0.2 g (0.037 to 0.363, P = 0.009)). On the contrary, the mean fat and calorie content showed significant increase over time (MD (95% CI)) = - 1.03 g (- 1.719 to - 0.343, P = 0.001) and - 9.0 kcal/dl (- 15.170 to - 2.830, P = 0.001), respectively). There was no difference in the carbohydrate content of human milk over 4 weeks. Macronutrient composition was independent of maternal parity, mode of delivery, pre-pregnancy body mass index, umbilical artery Doppler flows, previous breast feeding experience, neonatal centile status, gestation, and infant's weight at birth. Multiple regression analysis of human milk composition with mother's dietary components showed no significant association. CONCLUSION : We conclude that in mothers who deliver very preterm infants ≤ 32 weeks, true protein content decreased, fat and calorie content increased, and carbohydrate content remained stable in human milk during first 4 weeks of lactation. Human milk macronutrient composition was independent of various maternal and neonatal factors including maternal body mass index and dietary intake. TRIAL REGISTRATION : CTRI/2017/02/007895 What is Known: • Preterm human milk has high temporal and inter-individual variation in the macronutrient composition. What is New: • In mothers who deliver very preterm infants < 32 weeks, true protein content decreases, fat and calorie content increases, and carbohydrate content remains stable in human milk during first 4 weeks of lactation. • Human milk macronutrient composition is independent of various maternal and neonatal factors including maternal body mass index and dietary intake.

Using Nature to Nurture: Breast Milk Analysis and Fortification to Improve Growth and Neurodevelopmental Outcomes in Preterm Infants

Premature infants are born prior to a critical window of rapid placental nutrient transfer and fetal growth-particularly brain development-that occurs during the third trimester of pregnancy. Subsequently, a large proportion of preterm neonates experience extrauterine growth failure and associated neurodevelopmental impairments. Human milk (maternal or donor breast milk) is the recommended source of enteral nutrition for preterm infants, but requires additional fortification of macronutrient, micronutrient, and energy content to meet the nutritional demands of the preterm infant in attempts at replicating in utero nutrient accretion and growth rates. Traditional standardized fortification practices that add a fixed amount of multicomponent fortifier based on assumed breast milk composition do not take into account the considerable variations in breast milk content or individual neonatal metabolism. Emerging methods of individualized fortification-including targeted and adjusted fortification-show promise in improving postnatal growth and neurodevelopmental outcomes in preterm infants.

Exploring Innovations in Human Milk Analysis in the Neonatal Intensive Care Unit: A Survey of the United States

Introduction: Human milk (HM) is the ideal enteral feeding for nearly all infants and offers unique benefits to the very low birthweight (VLBW) infant population. It is a challenge to meet the high nutrient requirements of VLBW infants due to the known variability of HM composition. Human milk analysis (HMA) assesses the composition of HM and allows for individualized fortification. Due to recent U.S. Food and Drug Administration (FDA) approval, it has relatively recent availability for clinical use in the US.

Aim: To identify current practices of HMA and individualized fortification in neonatal intensive care units (NICUs) across the United States (US) and to inform future translational research efforts implementing this nutrition management method.

Methods: An institutional review board (IRB) approved survey was created and collected data on the following subjects such as NICU demographics, feeding practices, HM usage, HM fortification practices, and HMA practices. It was distributed from 10/30–12/21/2020 via online pediatric nutrition groups and listservs selected to reach the intended audience of NICU dietitians and other clinical staff. Each response was assessed prior to inclusion, and descriptive analysis was performed.

Results: About 225 survey responses were recorded during the survey period with 119 entries included in the analysis. This represented 36 states and Washington D.C., primarily from level III and IV NICUs. HMA was reported in 11.8% of responding NICUs. The most commonly owned technology for HMA is the Creamatocrit Plus TM (EKF Diagnostics), followed by the HM Analyzer by Miris (Uppsala, Sweden). In NICUs practicing HMA, 84.6% are doing so clinically.

Discussion: Feeding guidelines and fortification of HM remain standard of care, and interest in HMA was common in this survey. Despite the interest, very few NICUs are performing HMA and individualized fortification. Barriers identified include determining who should receive individualized fortification and how often, collecting a representative sample, and the cost and personnel required.

Conclusions: Human milk analysis and individualized fortification are emerging practices within NICUs in the US. Few are using it in the clinical setting with large variation in execution among respondents and many logistical concerns regarding implementation. Future research may be beneficial to evaluate how practices change as HMA and individualized fortification gain popularity and become more commonly used in the clinical setting.

Corrected fortification approach improves the protein and energy content of preterm human milk compared with standard fixed-dose fortification

OBJECTIVE

To evaluate whether a pragmatic corrected fortification (CF) model achieves recommended target protein and calorie content of human milk (HM) for preterm infants when compared with standard fixed-dose fortification (SF).

DESIGN

In this prospective non-interventional study, we enrolled mothers of infants with birth weight ≤1500 g fed exclusive HM. Infants with chromosomal or intestinal disorders were excluded. A total of 405 HM samples from 29 mothers and 45 donor milk samples were analysed for macronutrient content using a real-time HM analyser. A stepwise CF model was derived based on published data on HM calorie and protein content corrected for lactation stage and milk type. We applied both models to the measured protein and calorie content for all HM samples and compared the proportion of samples achieving target nutrient requirement in each group.

RESULTS

Target protein and calorie content of feed was achieved in 68% of HM samples with CF, compared with 5% samples with SF model (p<0.0001). For mother's own milk, none of the samples met the target macronutrient range with SF fortification during later lactation periods (≥week 5). With SF, over 40% of infants had poor growth (decline in weight z-score ≥0.8 SD) by 8 weeks. The final feed osmolality was acceptable for all fortification steps of the CF model.

CONCLUSION

The proposed CF model significantly improved the final protein and calorie content of HM with acceptable osmolality. It provides a proactive option to improve nutrient intake in premature infants.

Changes in macronutrients of human milk after bolus feeding: a simulation study

BACKGROUND

Enteral nutrition supply to preterm infants requires feeding through a feeding tube. The aim of this study was to evaluate changes in macronutrient composition of human milk (HM) while passing through a gastric feeding tube.

METHODS

Simulated real-life practice tube feeding was performed by using an infusion pump connected to a feeding tube. A human milk analyzer was used to compare the pre infusion and post infusion macronutrient contents of HM.

RESULT

There was a significant decrease in fat (from 4.06 ± 0.6 g/100 ml to 3.95 ± 0.6 g/100 ml), carbohydrates (from 7.51 ± 0.4 g/100 ml to 7.33 ± 0.5 g/100 ml), and energy content (from 70.77 ± 5.4 kcal/100 ml to 69.72 ± 0.5 kcal/100 ml) after passing through the feeding tube (P < 0.001).

CONCLUSION

A simulated real-life bolus tube feeding model demonstrated small but significant decreases in fat, carbohydrate, and energy content. The biological significance of our results to the very low birth weight infants should be further studied.

Influence of different breast expression techniques on human colostrum macronutrient concentrations

OBJECTIVE

To evaluate the effects of breast expression methods on macronutrient and caloric concentrations in human colostrum.

STUDY DESIGN

A cross-sectional study in which colostrum samples were collected simultaneously from each breast using different milk expression methods, including manual expression or electric pumping, assigned by simple randomization. Macronutrients were measured by infrared spectroscopy, and their concentrations were compared by the Wilcoxon test.

RESULTS

Ninety-six samples from each breast of selected donors were evaluated. There were no differences in carbohydrate (6.1 vs. 6.1 g/dL; p: 0.218) and protein (2.1 vs. 2.1 g/dL; p: 0.772) concentrations between the samples collected by manual expression and electric pumping. However, in those collected by manual expression, lipid concentrations (2.6 vs. 2.2 g/dL; p < 0.001) and caloric content (60 vs. 57 Kcal/dL; p = 0.001) were higher.

CONCLUSIONS

Colostrum collected by hand expression had a higher lipid concentration and caloric content than that collected by an electric pump.

Significant Loss of Macronutrients During Passage Through Feeding Tube: An Observational Study

Feeding infants born before week 34 of gestation is based mainly on providing nutrition directly to the gastrointestinal tract through a nasogastric tube. Little is known about the impact of formulas passage through nasogastric tube on their macronutrient content. The aim of our study was to evaluate changes in macronutrient content of various formulas after transfer through a feeding tube.

Methods

Eleven frequently used formulas were chosen. Ten consecutive measurements were performed for each formula. Simulated real-life practice tube feeding was performed by using an infusion pump connected to a feeding tube. A Human Milk Analyzer, using an infrared spectroscopy method, was used to compare the preinfusion and postinfusion macronutrient contents of the different formulas.

Results

A total of 220 measurements were performed. Variations in at least one macronutrient were observed in 5 out of 10 formulas. Fat and energy content were modified in 1 preterm formula.

Conclusions

Changes in the macronutrient content after tube feeding transfer were observed for some infant formulas, including those designed for very low birth weight infants. These alterations might relate to specific formulation of each formula. The biological significance of our results to the very low birth weight infants should be studied further.

Human milk pasteurisation reduces pre-lipolysis but not digestive lipolysis and moderately decreases intestinal lipid uptake in a combination of preterm infant in vitro models

Donor human milk, pasteurised for safety reasons, is the first alternative for feeding preterm infants when mothers' own milk is unavailable. Breastmilk pasteurisation impact on lipid digestion and absorption was evaluated by a static in vitro digestion model for preterm infants coupled with intestinal absorption using Caco-2/TC7 cells. Lipid absorption was quantified by digital image analysis of lipid droplets, by measurement of basolateral triglyceride concentration and by analysing the expression of major genes involved. After in vitro digestion, lipolysis extent was 13% lower in pasteurised human milk (PHM) than in raw human milk (RHM). In Caco-2/TC7 cells, the number of lipid droplets was identical for both milk types, while the mean droplet area was 17% smaller with PHM. Altogether, pasteurisation decreased the pre-lipolysis of human milk. This initial difference in free fatty acid amount was only partially buffered by the subsequent processes of in vitro digestion and cellular lipid absorption.

Nutritional and Non-nutritional Composition of Human Milk Is Modulated by Maternal, Infant, and Methodological Factors

Human milk (HM) is dynamic and shows a high inter- and intra-individual variability. To characterize HM with precision, it is necessary to understand the factors that modulate its composition. The objective of this narrative review is to summarize the maternal, infant and methodological factors that affect HM composition. We searched SCOPUS and PubMed databases for articles related to factors that are known to or could potentially influence HM composition and volume across lactation periods. Our comprehensive review encompasses various maternal-, infant-related, and methodological factors that modulate aspects of HM composition including macro- and micronutrients, vitamins and minerals, as well as volume. The most profound changes were observed in HM lipids and lipophiles. Evidence exists for many of the infant-related factors known to affect the nutritive and non-nutritive components of HM (e.g., birth weight, gestational age, infant age/stage of lactation). In contrast, less is known with respect to maternal factors; where there is either limited research or conflicting evidence (e.g., maternal lifestyle, obstetric history, medical conditions), except for the mother's diet, for which there is a relatively well-established understanding. Equally, although many of the methodological factors (e.g., HM sampling, handling and analytics) are known to impact HM composition, few studies have investigated this as a primary outcome, making it an important area of future research in HM. Here we propose a systematic capture of numerous maternal- and infant-related characteristics to facilitate associative comparisons of HM data within and across studies. Additionally, it would be prudent to standardize the methodological aspects known to affect HM composition in analytics, not only for HM lipids and lipophiles, but also for those nutrients whose variability is yet less well-understood. Defining the factors determining HM composition with accuracy will open perspectives for maternal intervention to optimize milk composition for specific needs of infants.

Infrared analyzers for the measurement of breastmilk macronutrient content in the clinical setting

INTRODUCTION

There is growing interest in the possibility of measuring the macronutrient content of human milk. Several studies that intend to validate commercially available human milk analyzers have been published with inconsistent results. This review will focus on currently available, verified methodologies for analyzing macronutrients in human milk.

AREAS COVERED

A literature search was conducted in the PubMed database. Five milk analyzers were chosen to be included in this review: MIRIS (Uppsala, Sweden) (seven articles found), Calais (Cleveland, United States) (four articles), SpectraStar (Brookfield, United States) (four articles), MilkoScan (Hillerdo, Denmark) (two articles), and Delta LactoScope (Stockholm, Sweden) (one article). The following information was extracted from published manuscripts: measuring device, sample preparation, purpose of the study, type of macronutrients studied, results, and conclusions.

EXPERT OPINION

Infrared spectroscopy can be an accurate and reliable technology for assessing the macronutrient content of human milk, specifically crude protein, and total fat. However, an optimal handling of samples, the development of standardized quality-control protocols, and an improvement in calibration procedures are required before the full implementation of infrared technology in neonatal units.

Impact of Maternal Anxiety on Human Milk Macronutrients Content: A Prospective Observational Study

Objective: The impact of maternal anxiety on the macronutrients content of human milk (HM) is unknown. We hypothesized that maternal stress generated by her infant's hospitalization will affect the mother's breast milk's macronutrients content. Materials and Methods: HM samples (2-3 mL) were collected from 21 mothers whose infants were hospitalized for 2-3 days between August 2016 and November 2017 due to neonatal fever. Samples were provided at three time points: first day of admission, second day of admission, and 1 week after discharge. The maternal anxiety level was measured by the State-Trait Anxiety Inventory (STAI). Milk analyses for macronutrients were performed by infrared transmission spectroscopy. Results: Fat and energy contents of HM on day 7 were significantly higher compared with the day of admission (p = 0.019 and p = 0.022, respectively), whereas they were similar to values on day 2. The maternal anxiety level (STAI) at the time of infant admission was significantly higher than at 1 week after discharge (p < 0.001). There was no significant correlation between the changes in fat content and changes in the STAI score between admission and 1 week after discharge. Conclusion: Short infant hospitalization is associated with a significant rise in maternal stress; however, macronutrients content of HM remained unaffected.

The Effect of Processing Donor Milk on Its Nutrient and Energy Content

Background: The pasteurization is a mandatory step to inactivate pathogenic microorganisms of bank milk. For storage, freezing and thawing are necessary. The concentration of macronutrients and energy of bank milk could be influenced by these procedures which are routinely used in human milk bank. Research Aim: The aim of this study is to analyze the effect of bank milk processing (pasteurization and freezing/thawing) on the macronutrients (fat, protein, and carbohydrate) concentration and energy content. Materials and Methods: The samples of donor milk were collected and studied before/after pasteurization and after frozen for 3 months. Total 100 samples of bank milk were tested using an infrared analyzer. The measurements of fat, protein, carbohydrate, and energy were statistically analyzed by SPSS. Results: There was a prominent reduction of fat mean concentration following pasteurization and frozen (20.5% and 6.5%, respectively). The processing did not cause significant changes in protein content, but there were significant increase after pasteurization and decrease after frozen in carbohydrate (p < 0.05). Overall (postpasteurization and frozen storage), a 9.6% decrease was observed for energy content. Conclusion: This study revealed that the processing of bank milk (including Holder Pasteurization and frozen storage) decreased fat and energy content of human milk significantly, and this could not meet the specific needs of preterm infants.

Impact of Infant and Maternal Factors on Energy and Macronutrient Composition of Human Milk

The present study investigates the influence of selected infant and maternal factors on the energy and macronutrient composition of mature human milk (HM). The study enrolled 77 mothers at 4-8 weeks postpartum. Each mother provided 1 sample of HM. Each extracted HM sample was formed by mixing four subsamples of HM, each of which were obtained in one predefined 6-h periods of the day. Among maternal factors, the analysis included: anthropometric data before and after pregnancy; weight gain in pregnancy; body composition, assessed using the Maltron BioScan 920-II to analyze bioimpedance; and dietary intake, assessed with three-day dietary records. Among the neonatal factors, birth weight and length, number of daily feedings and type of delivery were included. The composition of HM, including energy content, protein, fat and carbohydrate concentrations, was analyzed using the Miris human milk analyzer. Pearson's and Spearman's correlation coefficients and multivariable logistic regression models were used to analyze the association between the selected maternal and infant factors and HM milk composition. It was found that total protein content of HM was correlated with pre-pregnancy BMI (Spearman rho = 0.238; p = 0.037), current lean body mass (Spearman rho = -0.293, p = 0.01) and total water content (Spearman rho = -0.315, p = 0.005). Carbohydrates were the only macronutrients whose composition was significantly affected by the infant factors. It was reported that higher carbohydrate content was associated with male sex (OR = 4.52, p = 0.049). Our results show that maternal and infant factors, especially maternal pre-pregnancy and current nutritional status and infant sex, interact and affect HM composition, suggesting that macronutrient and energy content in HM may be determined in pregnancy and may have unique compositional profile for every mother-infant dyad.

Macro- and Micronutrients in Milk from Healthy Cambodian Mothers: Status and Interrelations

BACKGROUND

Except for low thiamin content, little is known about vitamins or macronutrients in milk from Cambodian mothers, and associations among milk nutrients.

OBJECTIVES

We measured fat-soluble vitamins (FSVs) and water-soluble vitamins (WSVs), and macronutrients, and explored internutrient associations in milk from Cambodian mothers.

METHODS

Milk from women (aged 18-45 y, 3-27 wk postpartum, n = 68) who participated in a thiamin-fortification trial were analyzed for vitamins B-2 (riboflavin, FAD), B-3 (nicotinamide), B-5, B-6 (pyridoxal, pyridoxine), B-7, B-12, A, E [α-tocopherol and γ-tocopherol (γ-TPH)], carotenoids, carbohydrate (CHO), fat, and protein. Milk vitamin B-1 [thiamin, thiamin monophosphate (TMP), thiamin pyrophosphate (TPP)] was previously assessed for fortification effects. Milk nutrient concentrations were compared with the Adequate Intake (AI) values for infants aged 0-6 mo. Pearson correlation was used to examine internutrient associations after excluding nutrients affected by fortification.

RESULTS

Fortification increased thiamin and B-1 and decreased γ-TPH. Less than 40% of milk samples met the AIs for all vitamins, and 10 samples did not reach any AI values for the analyzed nutrients. CHO, fat, and energy values were met in 1.5-11.8%, and protein in 48.5%, of the samples. Whereas fat, protein, and energy were related (all r < 0.5; P < 0.001) and associated with FSVs and WSVs, CHO correlated only with some WSVs. TPP was not correlated with B-1 vitamers, but with other WSVs (r = 0.28-0.58; P < 0.019). All FSVs, except α-carotene, were correlated with each other (r = 0.42-0.98; P < 0.002). TPP, FAD, B-2, and B-3 were associated with almost all FSVs (r = 0.24-0.63; P < 0.044).

CONCLUSIONS

Cambodian women might not provide sufficient nutrients to their exclusively breastfeeding infants. Besides thiamin, all other vitamins measured were much lower than the AI. There were many strong correlations among macronutrients and vitamins; the extent to which these are explained by maternal diet, milk volume, maternal physiology, or genetics requires additional exploration.

Circadian changes in the composition of human milk macronutrients depending on pregnancy duration: a cross-sectional study

Background

The purpose of this study was to evaluate the circadian variation of human milk macronutrients and energy content depending upon pregnancy duration.

Methods

One hundred eighty fresh human milk samples from 45 mothers (27 of preterm and 18 of full-term newborns) were collected on a single day chosen between the 14th to 16th day after delivery. The samples were taken four times per day at 12 PM, 6 PM, 12 AM and 6 AM. Only lactating women, who could not breastfeed their hospitalized newborns and expressed milk by breast pump, were enrolled in the study. Human milk macronutrient composition and energy count were evaluated by mid-infrared spectrophotometry.

Results

Significant differences in macronutrient content were observed between 6 AM and 12 PM for mean protein content (t = − 4.62, df = 44, p < 0.001), for mean fat content (t = − 2.10, df = 44, p = 0.04) and for mean energy content (t = − 2.24, df = 44, p = 0.03); between 6 AM and 6 PM for mean protein content (t = − 2.41, df = 43, p = 0.02), for mean fat content (t = − 3.76, df = 43, p = 0.001) and for mean energy content (t = − 3.85, df = 43, p < 0.001); between 12 PM and 12 AM for mean protein content (Wilcoxon test V = 75.5, p = 0.001), for mean fat content (t = 2.50, df = 44, p = 0.02) and for mean energy content (t = 2.74, df = 44, p = 0.01); between 6 PM and 12 AM for mean protein content (V = 229, p = 0.02), for mean fat content (t = 4.39, df = 43, p < 0.001) and for mean energy content (t = − 4.57, df = 43, p < 0.001). The average content of carbohydrates did not change significantly during the 24 h. The samples of preterm newborns’ mothers had more apparent diurnal fluctuations in macronutrient content.

Conclusions

Our study revealed significant diurnal variations in protein and fat in human milk, and these circadian fluctuations were more apparent in the milk of mothers of preterm infants.

Effect of Target Fortification on Osmolality and Microbiological Safety of Human Milk Over Time

OBJECTIVES

The fortification of human milk can result in increased osmolality, which may be associated with adverse effects for preterm infants. To evaluate the effect of target fortification on the osmolality and microbiological safety of donor human milk and raw mature milk during the first 72 hours of storage.

METHODS

We performed target fortification of 63 pasteurized donor human milk (PDHM) and 54 raw mature milk (RMM) samples in a laminar flow hood. Osmolality (mOsm/kg) was evaluated before fortification (T0), immediately after fortification (T1), at 6 (T2), 24 (T3), 48 (T4), and 72 hours (T5) after fortification. Microbiological analysis was performed at T0, T4, and T5. During the study, all samples were stored at 4°C.

RESULTS

Mean osmolality at each study point for PDHM and RMM were, respectively: T0: 291.4 ± 11.0 versus 288.4 ± 5.6 (P = 0.06); T1: 384.8 ± 16.7 versus 398.3 ± 23.7; T2: 393.9 ± 17.7 versus 410.1 ± 27.0; T3: 397.8 ± 17.6 versus 417.9 ± 26.1; T4: 400.0 ± 16.5 versus 420.2 ± 24.9; T5: 399.6 ± 16.5 versus 425.2 ± 25.8 (P < 0.001 from T1 to T5). Microbiological analyses were negative at each study points for PDHM. At T0 16.1% of RMM samples had positive cultures, whereas the bacterial count remained stable thought the study.

CONCLUSIONS

PDHM's osmolality increases during the first 6 hours after fortification and remains stable and safe until 72 hours. RMM's osmolality increases during the first 24 hours and remains stable and safe until 72 hours. The storage at 4°C and the manipulation of PDHM and RMM samples in a laminar flow hood seem to be safe and preserve the microbiological safety of fortified pasteurized human milk until 72 hours.

Successful Full Lactation Achieved by Mothers of Preterm Infants Using Exclusive Pumping

Background: Some mothers of preterm infants suffer from difficulties in initiating and maintaining adequate milk production. This study was designed to investigate the milk production in mothers of preterm infants using hospital-grade breast pumps and to study the nutrient content of their milk. Methods: This was an observational prospective study. Mothers of preterm infants with gestational age < 32 weeks or birth weight < 1,500 g who were admitted to our hospital from August 2016 to December 2017 were recruited. A pumping diary and a questionnaire were completed by mothers (n = 30). Milk samples from before, during, and after each pumping session on days 7 and 14 postpartum were analyzed. Results: The median time to onset of lactogenesis II was 75.4 h. Mean milk output increased gradually, meeting key thresholds of 350 g/d on day 6, 500 g/d on day 8, and close to 750 g/d on day 14. Then, all mean milk outputs were over 750 g/d. The mean milk output exceeded the mean feeding volume on days 7, 14, 21, 28, 35, and 42. Mothers using hospital-grade breast pumps had more cumulative milk production compared with mothers using hand expression. The milk yield on days 7 and 14 were positively correlated to that on days 21, 28, 35, and 42. Milk outputs on days 7, 14, and 42 of mothers with a pumping frequency of ≥ 6 times/d were greater than mothers with a pumping frequency of < 6 times/d. Threshold values for milk output on day 7 (cut-off, 406.8 g/d; sensitivity, 68.2%; specificity, 100%) and day 14 (cut-off, 518.0 g/d; sensitivity, 81.8%; specificity, 100%) were identified as predicting a milk output of more than 750 g/d on day 42. Fat and energy levels were higher in hind-milk than fore- or mixed-milk on days 7 and 14. Those who pumped ≥ 6 times/d had higher levels of fat, carbohydrate, and energy in their milk on day 7. Conclusion: Most preterm infants' mothers using a hospital-grade pump with a pumping frequency of ≥ 6 times/d can reach full lactation successfully. Nutrient analysis of the human milk should be performed.

Comparison of Changes in Breast Milk Macronutrient Content During the First Month in Preterm and Term Infants

Purpose: This study aims to achieve a better understanding of the trend of maternal milk macronutrient levels by analyzing protein, lipid, carbohydrate, and energy content of the breast milk and investigate the possible confounders of macronutrient content during the first 4 weeks of lactation to meet the specific needs of babies, guide optimum fortification of maternal milk. Patients and Methods: Breast milk from 39 mothers who had delivered preterm infants and 21 mothers of term infants were collected longitudinally for the first 4 weeks of lactation. Fresh milk samples were obtained on day 3, 7, 14, and 28 of lactation. The samples are analyzed using mid-infrared milk analyzer (MIRIS Human Milk Analyzer, HMA; Miris AB, Uppsala, Sweden). Results: Colostral milk protein concentrations of mothers of both preterm and term infants were significantly higher and the protein content of the samples decreased in time, according to the week of lactation during the study period. In contrast, fat, carbohydrate, and energy content were lowest in the colostral milk in both groups. When preterm and term milks were compared, fat and carbohydrate levels on 28th day and energy levels on 14th and 28th days were significantly higher in term milks, whereas no difference in protein contents were observed between the two groups on each time period. Mode of delivery was found to have statistically significant correlation with protein content of the milk. Conclusion: This longitudinal study revealed significant changes in analyzed macronutrient contents of mother's milk over the first 4 week period.

Accuracy and Reliability of Infrared Analyzers for Measuring Human Milk Macronutrients in a Milk Bank Setting

BACKGROUND

Infrared (IR) analysis is an emerging technology that may be a useful tool for milk banks to manage the nutrient variability in donor human milk.

OBJECTIVE

To evaluate the accuracy, reliability, and comparability of commercial infrared analyzers for measuring human milk macronutrients in a milk bank setting.

METHODS

Three nonprofit milk banks received blinded test kits of human milk that had been assessed using reference methods. Four infrared instruments were used to measure macronutrients as follows: 1 filtered mid-IR, 2 Fourier-transformed full-spectra mid-IR, and 1 near-IR. Twenty-five unique samples were read concurrently for the accuracy arm. An identical sample was read daily for 1 mo for the reliability arm.

RESULTS

Values for R 2 describing relationships with reference methods for total fat, crude protein, and lactose, were as follows: filtered mid-IR, 0.98, 0.94, and 0.48; Fourier-transformed full-spectra mid-IR, 0.97, 0.93, and 0.36 for instrument 1 and 0.98, 0.98, and 0.31 for instrument 2; and near-IR 0.93, 0.93, and 0.12. There was no significant difference between instruments for crude protein and total fat measurements. There were significant differences in carbohydrate measurements between instruments. For 1 mo of daily measurements in the reliability arm, CVs for filtered mid-IR were ≤4.6%, for Fourier-transformed full spectra mid-IR were ≤1.7%, and for near-IR were ≤5.1%.

CONCLUSIONS

Infrared analysis is an accurate and reliable method for measuring crude protein and total fat in a milk bank setting. Carbohydrate measurements are less accurate and are significantly different between instruments, which will likely lead to differences in derived calorie values.

The Practicality of Feeding Defatted Human Milk in the Treatment of Congenital Chylothorax

Introduction: Congenital chylothorax (CC) is a rare and life-threating condition. Since its treatment is founded on the elimination of long-chain fatty acids from the diet, breastfeeding has been traditionally contraindicated. However, breast milk could be very beneficial due to its immunological and nutritional benefits. Only limited research has been published about the usage of modified-fat breast milk (MBM) in chylothorax treatment. Methods and Results: Systematic review methods were used by two independent reviewers. Only a few case report studies (quality assessment on the domains of the GRADE approach), two small controlled studies, a retrospective study, and some test-tube-based laboratory research met the inclusion criteria. Despite this, we have observed a widespread clinical adoption of this novel treatment in health institutions. Data suggest that modified-fat breast milk does facilitate the resolution of chylothoraces. Refrigerated centrifuge (2°C, 3,000 rpm for 15 minutes) and syringe fat removal methods were the most efficient options in terms of fat reduction. Conclusions: Feeding of human milk is advisable in CC and feasible by means of a simple milk defatting procedure. Open questions remain, related to length and degree of fat restriction and need for individualized fortification of defatted breast milk.

Effect of Pooling Practices and Time Postpartum of Milk Donations on the Energy, Macronutrient, and Zinc Concentrations of Resultant Donor Human Milk Pools

OBJECTIVE

To characterize the macronutrient, energy, and zinc composition of pasteurized donor human milk pools and evaluate how composition varies based on pooling practices and "time postpartum" (ie, elapsed time from parturition to expression date) of individual milk donations.

STUDY DESIGN

The Mothers' Milk Bank (Arvada, Colorado) donated 128 donor human milk pools. Caloric density was assessed via mid-infrared spectroscopy, and zinc concentration was measured by atomic absorption spectroscopy. Pool time postpartum was calculated as the unweighted average of the time postpartum of all milk donations included in any given pool.

RESULTS

Time postpartum of donor human milk pools ranged from 3 days to 9.8 months. The majority (91%) of donor human milk pools included milk from either 1 donor or 2 donors. Pool energy density ranged from 14.7 to 23.1 kcal/oz, and protein ranged from 0.52 to 1.43 g/dL. Milk zinc concentrations were higher in preterm pools and were negatively correlated with pool time postpartum. We present an equation that estimates donor human milk pool zinc content based on time postpartum and explains 49% of the variability in zinc concentrations (P < .0001). Including more donors in donor human milk pools decreased the variability in protein, but not zinc, concentrations.

CONCLUSIONS

Donor human milk pools were lower in calories than is normally assumed in standard human milk fortification practices. Zinc concentrations were related to donor human milk time postpartum and were on average insufficient to meet preterm and term infants' needs without fortification or supplementation.

Variation and Interdependencies of Human Milk Macronutrients, Fatty Acids, Adiponectin, Insulin, and IGF-II in the European PreventCD Cohort

Human milk composition is variable. The identification of influencing factors and interdependencies of components may help to understand the physiology of lactation. In this study, we analyzed linear trends in human milk composition over time, the variation across different European countries and the influence of maternal celiac disease. Within a multicenter European study exploring potential prevention of celiac disease in a high-risk population (PreventCD), 569 human milk samples were donated by women from five European countries between 16 and 163 days postpartum. Some 202 mothers provided two samples at different time points. Protein, carbohydrates, fat and fatty acids, insulin, adiponectin, and insulin-like growth factor II (IGF-II) were analyzed. Milk protein and n-6 long chain polyunsaturated fatty acids decreased during the first three months of lactation. Fatty acid composition was significantly influenced by the country of residence. IGF-II and adiponectin concentrations correlated with protein content (r = 0.24 and r = 0.35), and IGF-II also correlated with fat content (r = 0.36), suggesting a possible regulatory role of IGF in milk macronutrient synthesis. Regarding the impact of celiac disease, only the level in palmitic acid was influenced by this disease, suggesting that breastfeeding by celiac disease mothers should not be discouraged.

Evaluation of macronutrient content of fresh and frozen human milk over 6 months

AIM

In this study; we aimed to see the time-dependent changes in the macronutrient content of early frozen breast milk and also to compare it with fresh breast milk in the first 6 months.

MATERIALS AND METHOD

We evaluated the milk samples of 43 mothers who delivered at term. Milk samples after the first 15 days following delivery were expressed and collected dividing into seven aliquots to be stored frozen at -20 °C. Every month freshly collected new milk samples were analyzed together with one aliquot of the stored samples, up to 6 months. The energy, protein, lipid, and carbohydrate contents of samples were analyzed by Miris Human Milk Analyzer.

RESULTS

In the first 3 months, fresh milk had higher caloric and lipid content when compared to frozen samples. The protein content of fresh milk decreased after 2 months and became lower than frozen samples. The energy and lipid content of frozen milk decreased over time but protein and carbohydrate contents stayed stable. Carbohydrate content of fresh and frozen samples did not show major changes.

CONCLUSION

It may be more suitable to consume the frozen milk that was collected in the early weeks of delivery within first 2 months.

Macronutrient content of pooled donor human milk before and after Holder pasteurization

BACKGROUND

Donor human milk (DHM) is the best alternative for preterm infants when their own mother's milk is unavailable. DHM should be pasteurized to guarantee microbiological safety; however, this process can influence the macronutrient content. The aim of this study was to investigate the effect of Holder pasteurization (HoP) on DHM macronutrient content.

METHODS

Protein, lactose, lipids (g/100 ml) and energy (kcal/100 ml) of DHM pools were analysed before and after HoP (62.5 °C for 30 min) using mid-infrared spectroscopy (HM analyser Miris AB®). The mean macronutrient content before and after HoP was compared by paired t-test. The percentage decreases (Delta%) were calculated.

RESULTS

The change in macronutrient content of 460 pools was determined. Protein, lipids and lactose decreased significantly after HoP (0.88 ± 0.20 vs 0.86 ± 0.20 and 2.91 ± 0.89 vs 2.75 ± 0.84 and 7.19 ± 0.41 vs 7.11 ± 0.48 respectively). The Delta% values were - 2.51 ± 13.12, - 4.79 ± 9.47 and - 0.92 ± 5.92 for protein, lipids and lactose, respectively (p ≤ 0.001).

CONCLUSION

This study confirms that the macronutrient content of DHM, especially in terms of lipids and protein, is reduced after HoP. Therefore, in order to perform a tailored fortification of DHM, the clinicians need to be aware of the somewhat diminished nutrient content of DHM.

Comparison of macronutrient content in human milk measured by mid-infrared human milk analyzer and reference methods

OBJECTIVE

The study aims at evaluating mid-infrared human milk analyzer (HMA) accuracy and precision, in human milk (HM).

STUDY DESIGN

Röse-Gottlieb, high-performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD), Kjeldahl and amino acid analysis (AA) were selected as references for total fat, lactose and total protein determination.

RESULTS

No significant difference was observed in lactose content between HMA and HPAEC-PAD. Significant differences were observed in fat and protein content between HMA and reference methods. However, the difference in fat content was lower than 12%, and therefore within the variability declared by supplier. For protein determination, the BCA protein assay was selected. No significant differences were observed in total protein content measured by BCA assay, Kjeldahl and AA methods.

CONCLUSIONS

HMA was reliable for the quantification of total fat and lactose content, but not for total protein one. The latter was measured by BCA assay, which yielded comparable results to Kjeldahl and AA methods.

Transmission infrared spectroscopy for rapid quantification of fat, protein, and lactose concentrations in human milk

OBJECTIVE

To develop partial least squares regression (PLSR) calibration models in combination with transmission infrared (TIR) spectroscopy for rapid and optimal quantification of human milk macronutrient concentrations.

STUDY DESIGN

Human milk samples (n = 306) were characterized simultaneously by reference chemical analytical methods and TIR spectroscopy. Reference macronutrient concentrations were linked to pre-processed spectra and divided into two (training and test) sets. PLSR was used to develop trial calibration models using training set, and the test set was used to assess the accuracy of the trial analytical methods.

RESULTS

For the methods selected as optimal, the concordance correlation coefficients between reference and TIR-based methods were 0.93 for fat, 0.96 for protein, and 0.52 for lactose. The Bland-Altman plots showed no evidence of systematic bias between TIR and reference methods.

CONCLUSIONS

TIR spectroscopy provides the basis for accurate and rapid quantification of human milk fat and protein concentrations but is less accurate for measuring lactose concentration.

Maternal Nutrition and Body Composition During Breastfeeding: Association with Human Milk Composition

The composition of human milk is dynamic and can vary according to many maternal factors, such as diet and nutritional status. This study investigated the association of maternal nutrition and body composition with human milk composition. All measurements and analyses were done at three time points: during the first (n = 40), third (n = 22), and sixth (n = 15) month of lactation. Human milk was analyzed using the Miris human milk analyzer (HMA), body composition was measured with bioelectrical bioimpedance (BIA) using a Maltron BioScan 920-II, and the assessment of women's nutrition was based on a three-day dietary record. The correlation coefficient (Pearson's r) did not show a significant statistical relationship between human milk composition and nutrients in women's diet at three time points. For women in the third month postpartum, we observed moderate to strong significant correlations (r ranged from 0.47 to 0.64) between total protein content in milk and the majority of body composition measures as follows: positive correlations: % fat mass (r = 0.60; p = 0.003), fat-free mass expressed in kg (r = 0.63; p = 0.001), and muscle mass (r = 0.47; p = 0.027); and negative correlation: % total body water (r = -0.60; p = 0.003). The variance in milk fat content was related to the body mass index (BMI), with a significant positive correlation in the first month postpartum (r = 0.33; p = 0.048). These findings suggest that it is not diet, but rather the maternal body composition that may be associated with the nutritional value of human milk.

Human Milk Nutrient Composition in the United States: Current Knowledge, Challenges, and Research Needs

Human milk is considered to be the ideal food for infants. Accurate, representative, and up-to-date nutrient composition data of human milk are crucial for the management of infant feeding, assessment of infant and maternal nutritional needs, and as a guide for developing infant formula. Currently in the United States, the nutrient profiles of human milk can be found in the USDA National Nutrient Database for Standard Reference, and in books or review articles. Nonetheless, these resources all suffer major drawbacks, such as being outdated, incomplete profiles, limited sources of data, and uncertain data quality. Furthermore, no nutrient profile was developed specifically for the US population. The purposes of this review were to summarize the current knowledge of human milk nutrient composition from studies conducted in the United States and Canada, and to identify the knowledge gaps and research needs. The literature review was conducted to cover the years 1980-2017, and 28 research papers were found containing original data on macronutrients and micronutrients. Most of these 28 studies were published before 1990 and mainly examined samples from small groups of generally healthy lactating women. The experimental designs, including sampling, storage, and analytic methods, varied substantially between the different studies. Data of several components from these 28 studies showed some consistency for 1-6 mo postpartum, especially for protein, fat, lactose, energy, and certain minerals (e.g., calcium). The data for 7-12 mo postpartum and for other nutrients are very scarce. Comprehensive studies are required to provide current and complete nutrient information on human milk in the United States.

Bariatric Surgery Does Not Appear to Affect Women's Breast-Milk Composition

Background

The breast-milk composition in the first 6 wk postpartum of women who have undergone bariatric surgery (BS) is unknown.

Objective

The aim of this study was to examine 1) the breast-milk macronutrient and vitamin A composition in women who had and who had not undergone BS and 2) the impact of maternal diet on the breast-milk composition. We hypothesized that the milk of women who had undergone BS would be less energy dense and have a lower vitamin A concentration than that of other women.

Methods

A multicenter prospective substudy was conducted at 2 university hospitals. Breast-milk samples were collected from 24 normal-weight [NW; mean ± SD body mass index (BMI; kg/m2): 21.5 ± 1.7; mean ± SD age: 29 ± 6 y], 39 overweight (OW; BMI: 26.9 ± 1.5; aged 29 ± 5 y), and 12 obese women (BMI: 35.0 ± 5.7; aged 29 ± 5 y) as well as from 11 women who had undergone BS (BMI: 28.0 ± 4.4; aged 30 ± 4 y) from day 3 until week 6 of lactation. Milk energy and macronutrients (Human Milk Analyzer; Miris) and vitamin A concentrations (iCheck Fluoro; BioAnalyt) were determined at the end of each week. Maternal diet (food-frequency questionnaire) and physical activity (Kaiser Physical Activity Survey) were measured during the third trimester of pregnancy and on day 3 or 4 and during week 6 of lactation. Statistical analyses include 1-factor ANOVA, Spearman and Pearson correlations, and multiple linear regression.

Results

In all women, a weekly increase in milk energy, total fat, and total carbohydrates was seen, whereas a weekly decrease in proteins and vitamin A was found during the first 2 wk of lactation, followed by a stable concentration of all nutrients. At week 4, milk protein concentrations were higher in women who had undergone BS (14 g/L) compared with NW (8 g/L; P = 0.005) and OW (9 g/L; P = 0.019) women. At week 5, milk carbohydrate concentrations were higher in women who had undergone BS (74 g/L) compared with NW women (68 g/L; P = 0.042).

Conclusions

Breast milk of women who have undergone BS appears to be adequate in energy, macronutrients, and vitamin A during the first 6 wk of lactation. This supports the conclusion that breast feeding should not be discouraged in this group of women. This trial was registered at http://www.clinicaltrials.gov as NCT02515214.

The impact of human breast milk components on the infant metabolism

BACKGROUND & AIMS

Breastfeeding is beneficial for mothers and infants. Underlying mechanisms and biochemical mediators thus need to be investigated to develop and support improved infant nutrition practices promoting the child health. We analysed the relation between maternal breast milk composition and infant metabolism.

METHODS

196 pairs of mothers and infants from a European research project (PreventCD) were studied. Maternal milk samples collected at month 1 and month 4 after birth were analysed for macronutrient classes, hormone, and fatty acid (FA) content. Phospholipids, acylcarnitines, and amino acids were measured in serum samples of 4-month old infants. Associations between milk components and infant metabolites were analysed with spearman correlation and linear mixed effect models (LME). P-values were corrected for multiple testing (PLME).

RESULTS

Month 1 milk protein content was strongly associated with infant serum lyso-phosphatidylcholine (LPC) 14:0 (PLME = 0.009). Month 1 milk insulin was associated to infant acetylcarnitine (PLME = 0.01). There were no associations between milk protein content and serum amino acids and milk total fat content and serum polar lipids. Middle- and odd-chain FA% in breast milk at both ages were significantly related to serum LPC and sphingomyelins (SM) species in infant serum (all PLME<0.05), while FA% 20:5n-3 and 22:6n-3 percentages were significantly associated to serum LPC 22:6 (PLME = 1.91×10-4/7.93×10-5) in milk only at month 4. Other polyunsaturated fatty acids and hormones in milk showed only weak associations with infant serum metabolites.

CONCLUSIONS

Infant serum LPC are influenced by breast milk FA composition and, intriguingly, milk protein content in early but not late lactation. LPC 14:0, previously found positively associated with obesity risk, was the serum metabolite which was the most strongly associated to milk protein content. Thus, LPC 14:0 might be a key metabolite not only reflecting milk protein intake in infants, but also relating high protein content in milk or infant formula to childhood obesity risk.

Protein use and weight-gain quality in very-low-birth-weight preterm infants fed human milk or formula

Background

Nutritional management of preterm infants aims to approximate the tissue growth and body composition of a fetus of the same postmenstrual age. The adequacy of the quality of protein supply can influence the rate and the relative quality of weight gain.

Objective

We investigated the protein balance according to feeding regimen and the association between human milk feeding and fat-free mass content at the term-corrected age in very-low-birth-weight preterm infants.

Design

A prospective observational study was conducted. Inclusion criteria were as follows: healthy infants, gestational age ≤32 wk, birth weight <1500 g, stable clinical conditions, and feeding by mouth with human milk or formula at discharge. Infants were enrolled at hospital discharge. At enrollment, macronutrient intakes and protein balance were determined. Anthropometric measurements and body composition were also assessed. The nutritional composition of human milk was calculated by infrared spectroscopy. The protein balance was determined according to the nitrogen balance standard method. Body composition was assessed by an air-displacement plethysmography system. At the term-corrected age, anthropometry and body composition assessments were repeated.

Results

Seventeen preterm infants fed fortified human milk and 15 preterm infants fed formula were enrolled. At discharge, despite similar macronutrient intakes, infants fed fortified human milk showed a higher nitrogen balance (expressed as mg · kg-1 · d-1) compared with preterm formula-fed infants (mean ± SD: 488.3 ± 75 compared with 409.8 ± 85 mg · kg-1 · d-1, P = 0.009). At term-corrected age, growth was similar in the 2 groups, whereas fortified human milk-fed infants showed a higher percentage of fat-free mass (85.1% ± 2.8% compared with 80.8% ± 3.2%, P = 0.002). Moreover, at multiple linear regression, fat-free mass content was independently associated with being fed human milk (R2 = 0.93, P < 0.0001).

Conclusion

Our findings suggest that human milk feeding is associated with early fat-free mass deposition in healthy and stable preterm infants. This trial was registered at www.clinicaltrials.gov as NCT03013374.

The effect of maternal habitus on macronutrient content of human milk colostrum

OBJECTIVE

There is a paucity of studies on the impact of maternal body mass index (BMI) on macronutrient content of human milk colostrum (HMC). The objective of this study was to compare macronutrient content of HMC in healthy women of term infants in relation to their BMI. We hypothesized that mother habitus influences human milk colostrum content.

METHOD

Colostrum was collected from 109 healthy mothers of hospitalized healthy term infants divided into four prepregnancy BMI groups: 12 underweight, 59 normal weight, 20 overweight, and 18 obese women between 24 and 72 h after birth. Macronutrient content was measured using mid-infrared spectroscopy.

RESULTS

There were no significant differences in macronutrients between the BMI groups. We performed four separate stepwise backward multiple regression analyses taking into account fat, carbohydrate, protein or energy content as dependent variables and maternal BMI, parity, gestational age, infant gender, maternal age, maternal education, mode of delivery and time postdelivery. In these analyses, fat, carbohydrate and energy content were not related to maternal BMI, while protein content was significantly and positively correlated with BMI (P=0.008) and negatively correlated with gestational age (P=0.004) and time postdelivery (P<0.001). Colostrum carbohydrate content was positively correlated with parity. Colostrum fat and energy content were negatively correlated with maternal age and positively correlated with parity.

CONCLUSION

Most macronutrient and energy content of colostrum are unaffected by prepregnancy maternal BMI, with the exception of protein content that is positively related to maternal BMI.

Validation of mid-infrared spectroscopy for macronutrient analysis of human milk

OBJECTIVE

Human milk has considerable variation in its composition. Hence, the nutrient profile is only an estimate and can result in under- or over-estimation of the intake of preterm infants. Mid-infrared (MIR) spectroscopy is an evolving technique for analyzing human milk but needs validation before use in clinical practice.

STUDY DESIGN

Human milk samples from 35 mothers delivering at 35 weeks to term gestation were analyzed for macronutrients by MIR spectroscopy and by standard laboratory methods using Kjeldahl assay for protein, Mojonnier assay for fat and high-pressure liquid chromatography assay for lactose.

RESULTS

MIR analysis of the macronutrients in human milk correlated well with standard laboratory tests with intraclass correlation coefficients of 0.997 for fat, 0.839 for protein and 0.776 for lactose. Agreement between the two methods was excellent for fat, and moderate for protein and lactose (P<0.001).

CONCLUSIONS

This methodological paper provides evidence that MIR spectroscopy can be used to analyze macronutrient composition of human milk. Agreement between the methodologies varies by macronutrient.

Assessment of human milk composition using mid-infrared analyzers requires calibration adjustment

OBJECTIVE

Nutrient composition of human milk (HM) is highly variable. Targeted HM fortification has been proposed to address these variations and reduce the cumulative nutritional deficit in preterm infants. Near-infrared analysis is used to measure the protein and fat content in HM; however, the reliability of this technique has not been evaluated. The objective of this study is to evaluate the reproducibility and accuracy of two generations of HM analyzers (HMA1 and HMA2) in estimating protein and lipid contents.

STUDY DESIGN

Reproducibility was assessed by analyzing in duplicate 146 and 128 HM samples with HMA1 and HMA2 (Miris), respectively. To evaluate the accuracy, lipid and protein concentrations were assessed in 31 and 39 samples using HMA1 or HMA2, respectively. Values were compared with measurements obtained using reference methods and correction equations were calculated. After applying the correction equations on 12 HM samples, the performance of the two devices were compared and the equation was validated according to the reference methods.

RESULTS

The coefficients of variation for protein and lipid assessments were below 3% for both HMA1 and HMA2. Protein concentrations were significantly underestimated by HMA2 (-0.53±0.23 g dl^-1). Lipid content was significantly overestimated by both devices, but the error was greater with HMA1 (0.76±0.48 g dl^-1) than with HMA2 (0.36±0.33 g dl^-1). Correction equations were specific for each generation of HMA. Finally, after correction, both instruments provided similar and accurate results.

CONCLUSION

HMAs require calibration adjustment before their use in clinical practice, to avoid inappropriate HM fortification.

"Bed Side" Human Milk Analysis in the Neonatal Intensive Care Unit: A Systematic Review

Human milk analyzers can measure macronutrient content in native breast milk to tailor adequate supplementation with fortifiers. This article reviews all studies using milk analyzers, including (i) evaluation of devices, (ii) the impact of different conditions on the macronutrient analysis of human milk, and (iii) clinical trials to improve growth. Results lack consistency, potentially due to systematic errors in the validation of the device, or pre-analytical sample preparation errors like homogenization. It is crucial to introduce good laboratory and clinical practice when using these devices; otherwise a non-validated clinical usage can severely affect growth outcomes of infants.

Fortification of human milk for preterm infants

Human milk is the preferred feeding for all infants, including those of very low birth weight (<1500 g). It has both nutritional and anti-infective properties which are especially important for infants at risk for sepsis and necrotizing enterocolitis. When maternal milk is not available or the amount produced is not sufficient to meet daily needs, donor human milk may (should) be used in its place. However, donor human milk is generally term in quality and likely has insufficient protein to promote appropriate growth. Whether donor or mother's own milk, fortification of human milk is required to meet nutrient requirements for growth and development for these preterm infants who are at high risk for growth faltering during the hospital stay. There are multiple strategies and products that may be employed to support desired growth rates. The advent of human milk analyzers may be helpful in a more customized approach to fortification.