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

Improved methods for mare milk analysis: Extraction and quantification of mare milk carbohydrates and assessment of FTIR-based macronutrient quantification

Accurately determining the macronutrient profile of mare milk is a precursor to studying how milk composition affects foals' growth and development. This study optimized and validated an extraction and quantification method for mare milk oligosaccharides, which make up a portion of the carbohydrate fraction of mare milk. Mare milk was extracted with chloroform and methanol, and oligosaccharides were selectively isolated from the carbohydrate fraction using porous-graphitized carbon solid-phase-extraction (SPE). Good recovery rates for milk oligosaccharides (between 70 and 100%) were achieved with the optimized method. This study also compared the use of Fourier-Transform infrared (FTIR) spectroscopy versus wet chemistry quantification methods for protein, fat, and lactose. The FTIR method produced statistically equivalent protein contents to the wet chemistry method, along with substantial savings in both analyst time and consumable consumption. FTIR analysis slightly underestimated the fat content of mare milk relative to the official wet chemistry method, with the difference between the methods increasing at higher fat contents. FTIR also overestimated the lactose content of mare milk and appeared to generate "lactose" values that included the milk oligosaccharides and thus represented the total carbohydrate (lactose and milk oligosaccharides) content of mare milk.

Targeted fortification with human milk analysis: An opportunity for innovation

Human milk's variable macronutrient composition is a necessary consideration when caring for very low birthweight infants. Targeted fortification is the practice of fortifying human milk using its known composition from human milk analysis, rather than its assumed macronutrient values. Utilization of human milk analyzers to measure the protein, fat, lactose, and energy composition within human milk samples has allowed the translation of this practice into the clinical setting. This review discusses the rationale of why targeted fortification is an important practice, what barriers exist in its implementation in the clinical setting, and what research gaps remain to be addressed.

Human Milk Fortification: A Practical Analysis of Current Evidence

Human milk (HM) with appropriate fortification is the recommended nutrition for very low birth weight (VLBW) infants. Fortification provides additional nutrients, vitamins, and minerals to support the growing preterm infant during critical periods of development. This article discusses the variability of HM including differences between maternal and pasteurized donor human milk (DHM), fortification of HM through the use of single- and multi-nutrient fortifiers, and clinical controversies including the timing of fortification, volume of feedings, and future innovations in HM fortification.

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.

Determinants of fatty acid content and composition of human milk fed to infants born weighing <1250 g

BACKGROUND

Infants born at very low birth weight (VLBW) are vulnerable to deficits in fatty acids (FAs) but little is known of factors that influence the intakes or composition of their human milk feeds.

OBJECTIVES

We aimed to identify sources of variability in the fat composition of human milk fed to VLBW infants and examine the impact of milk source (mother's own or donor) on fat and FA intakes.

METHODS

Serial samples of mother's milk (n = 476) and donor milk (n = 53) fed to infants born weighing <1250 g (n = 114 infants from 100 mothers) were collected [Optimizing Mothers' Milk for Preterm Infants (OptiMoM) randomized clinical trial]. Fat and FA were analyzed using a mid-infrared human milk analyzer and GC with flame ionization detection.

RESULTS

At full enteral feeding, donor milk is estimated to provide 1.3 g · kg-1 · d-1 less total fat than mature mother's milk (recommended intake: 4.8 g · kg-1 · d-1), and 5-9 mg · kg-1 · d-1 less DHA (22:6n-3) and arachidonic acid (20:4n-6) (estimated average requirement: 55-60 and 35-45 mg · kg-1 · d-1, respectively) than colostrum or transitional milk. Similar deficits were observed in measured intakes of a subset of OptiMoM infants. In multivariable-adjusted models, maternal ethnicity had medium to large [≥0.5 SD score (SDS)] effects on DHA, SFAs, and MUFAs. Mothers with prepregnancy BMI in overweight and obese categories had higher milk total fat (β: 0.35; 95% CI: 0.10, 0.61 and β: 0.46; 95% CI: 0.16, 0.77 SDS, respectively). Those with BMI ≥30 in addition had higher proportions of SFAs (β: 0.61; 95% CI: 0.33, 0.89 SDS) and lower DHA (β: -0.54; 95% CI: -0.89, -0.20 SDS). Other factors, such as gestational age and income, were also associated with FA composition.

CONCLUSIONS

The fat and FA content of human milk fed to VLBW infants is variable. Care must be taken to ensure fat and FA intakes meet recommendations, particularly when feeding a high proportion of donor milk.This trial was registered at clinicaltrials.gov as NCT02137473.

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.

Use of near and mid infra-red spectroscopy for analysis of protein, fat, lactose and total solids in raw cow and camel milk

Milk samples (150 cow and 217 camel milk samples) were analyzed for protein, fat, lactose and total solids by near and mid-infrared transmission spectroscopy. Excellent positive correlations between the two methods were obtained for both types of milk (p < 0.001); for protein (r ≥ 0.96), fat (r ≥ 0.99), lactose (r = 0.82) and total solids (r = 0.90). The mean of the relative difference ((MIR values - NIR values)/0.5 (MIR values + NIR values) × 100%) for cow and camel milk were, for protein (+8.2 & +13.4%), fat (-9.3 & +0.9%), lactose (-5.4 &-0.7%) and total solids (-2.2 &-3.4%), respectively. The difference between the two methods may be due to the effects of differences in milk homogeneity, especially with respect to casein micelles and fat globules.

The Nutritional Composition and Energy Content of Donor Human Milk: A Systematic Review

The American Academy of Pediatrics recommends donor human milk (DHM) as the preferred feeding strategy for preterm infants when the milk of the mother is unavailable, based on conclusive evidence of lower rates of necrotizing enterocolitis with DHM feedings compared with preterm infant formula. The nutritional composition of DHM may differ from maternal milk for many reasons including differences in maternal characteristics, milk collection methods, and the impact of donor milk banking practices. The purpose of this systematic review is to examine the literature regarding research on the fat, protein, carbohydrate, vitamin, and mineral composition of DHM obtained through nonprofit milk banks or commercial entities. PubMed, CINAHL, and Scopus databases were searched for articles published between 1985 and 30 April, 2019. In total, 164 abstracts were screened independently by 2 investigators, and 14 studies met all inclusion criteria. Studies were predominantly small (<50 samples) and measured macronutrients. Few studies assessed vitamins and minerals. Information bias was prevalent due to the use of a variety of analytical methods which influence accuracy and cross-study comparisons. Other sources of information bias included missing information regarding methods for protein and calorie assessment. Despite these limitations, existing research suggests the potential for 2-fold and greater differences in the fat, protein, and energy composition of DHM, with mean values for energy and fat often below clinical reference values expected for human milk. Further research is warranted regarding the nutritional composition of DHM, with a prioritization on measuring macronutrients and micronutrients using established reference methods.

Targeted Breast Milk Fortification for Very Low Birth Weight (VLBW) Infants: Nutritional Intake, Growth Outcome and Body Composition

Despite improvements in nutritional management, preterm infants continue to face high rates of postnatal growth restriction. Because variability in breast milk composition may result in protein and energy deficits, targeted fortification has been advocated. We conducted an interventional study to compare body composition and growth outcomes of very low birth weight infants fed targeted protein-fortified human milk (HM) with those fed standard fortified HM. If mother’s own milk was not available, donor milk was used. Weekly analysis of HM with mid-infrared spectroscopy was conducted and additional protein was added to the fortified HM to ensure a protein intake of 4 g/kg/day. Weekly anthropometric measurements were done. Prior to discharge or at 37 weeks, corrected age skinfold thickness (SFT) measurements as well as body composition measurement using air displacement plethysmography were done. Among 36 preterm infants enrolled, those in the targeted group (n = 17) received more protein and had a larger flank SFT at study end than those in the standard group (n = 19). A pilot post-hoc analysis of subjects having at least 30 intervention days showed a 3% higher fat-free mass in the targeted group. Use of a targeted fortification strategy resulted in a higher protein intake and fat-free mass among those receiving longer intervention.

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.

Maternal body mass index, parity and smoking are associated with human milk macronutrient content after preterm delivery

BACKGROUND

Maternal characteristics may be associated with human milk macronutrients but no definite conclusions have been made to date.

AIM

This study aimed to determine the relationship of maternal-associated factors on the content of macronutrients in human milk for the first six weeks after preterm delivery.

STUDY DESIGN

Prospective observational cohort study.

SUBJECTS

Milk samples were collected from mothers after premature birth between 24 + 0-35 + 6 weeks.

OUTCOME MEASURES

Macronutrients and energy content were analyzed by mid-infrared transmission spectroscopy. Demographic and anthropometric data from mothers were systematically recorded.

RESULTS

A total 1.558 human milk samples from 192 mothers were analyzed. Colostrum: higher protein (p = 0.001) and lower carbohydrate content (p = 0.003) were present in primiparous compared to multiparous milk. Vaginal birth was associated with increased carbohydrate content (p = 0.021). Fat and energy content in colostrum was not related to any maternal characteristics. Mature human milk: similarly to colostrum, higher protein content (p = 0.001) and lower carbohydrates content (p = 0.022) were observed in primiparous compared to multiparous milk. The mode of delivery was found to be another factor possibly influencing protein and carbohydrate levels (p = 0.036, p = 0.003, respectively). Pre-pregnancy obesity was associated with increased fat (p = 0.030) and energy content (p = 0.020) in human milk. On the contrary, smoking had a negative relationship to fat and energy content (p = 0.026, p = 0.007, respectively).

CONCLUSION

Human milk macronutrient concentration after preterm delivery is associated with pre-pregnancy obesity, parity, mode of delivery and smoking. The impact of maternal factors on human milk composition should be taken into account in a strategy of feeding in premature infants.

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.