ABSTRACT
BACKGROUND: Human milk composition analysis seems essential to adapt human milk fortification for preterm neonates. The Miris human milk analyzer (HMA), based on mid-infrared methodology, is convenient for a unique determination of macronutrients. However, HMA measurements are not totally comparable with reference methods (RMs). OBJECTIVE: The primary aim of this study was to compare HMA results with results from biochemical RMs for a large range of protein, fat, and carbohydrate contents and to establish a calibration adjustment. METHODS: Human milk was fractionated in protein, fat, and skim milk by covering large ranges of protein (0-3 g/100 mL), fat (0-8 g/100 mL), and carbohydrate (5-8 g/100 mL). For each macronutrient, a calibration curve was plotted by linear regression using measurements obtained using HMA and RMs. RESULTS: For fat, 53 measurements were performed, and the linear regression equation was HMA = 0.79RM + 0.28 (R(2) = 0.92). For true protein (29 measurements), the linear regression equation was HMA = 0.9RM + 0.23 (R(2) = 0.98). For carbohydrate (15 measurements), the linear regression equation was HMA = 0.59RM + 1.86 (R(2) = 0.95). A homogenization step with a disruptor coupled to a sonication step was necessary to obtain better accuracy of the measurements. Good repeatability (coefficient of variation < 7%) and reproducibility (coefficient of variation < 17%) were obtained after calibration adjustment. CONCLUSION: New calibration curves were developed for the Miris HMA, allowing accurate measurements in large ranges of macronutrient content. This is necessary for reliable use of this device in individualizing nutrition for preterm newborns.
Subject(s)
Dietary Carbohydrates/analysis , Dietary Fats/analysis , Milk Proteins/analysis , Milk, Human/chemistry , Spectrophotometry, Infrared/standards , Calibration , Humans , Linear Models , Reference Standards , Reproducibility of Results , Spectrophotometry, Infrared/instrumentationABSTRACT
Perinatal undernutrition affects not only fetal and neonatal growth but also adult health outcome, as suggested by the metabolic imprinting concept. Although maternal milk is the only channel through which nutrients are transferred from mother to offspring during the postnatal period, the impact of maternal undernutrition on milk composition is poorly understood. The present study investigates, in a rat model of nutritional programming, the effects of feeding an isocaloric, low-protein diet throughout gestation and lactation on milk composition and its possible consequences on offspring's growth and metabolic status. We used an integrated methodological approach that combined targeted analyses of macronutrients, free amino acid and fatty acid content throughout lactation, with an untargeted mass-spectrometric-based metabolomic phenotyping. Whereas perinatal dietary protein restriction failed to alter milk protein content, it dramatically decreased the concentration of most free amino acids at the end of lactation. Interestingly, a decrease of several amino acids involved in insulin secretion or gluconeogenesis was observed, suggesting that maternal protein restriction during the perinatal period may impact the insulinotrophic effect of milk, which may, in turn, account for the slower growth of the suckled male offspring. Besides, the decrease in sulfur amino acids may alter redox status in the offspring. Maternal undernutrition was also associated with an increase in milk total fatty acid content, with modifications in their pattern. Altogether, our results show that milk composition is clearly influenced by maternal diet and suggest that alterations in milk composition may play a role in offspring growth and metabolic programming.
Subject(s)
Amino Acids/metabolism , Diet, Protein-Restricted/adverse effects , Fatty Acids/metabolism , Fetal Development , Lactation/metabolism , Maternal Nutritional Physiological Phenomena , Milk/metabolism , Adiposity , Animals , Animals, Suckling , Female , Growth Disorders/etiology , Male , Metabolic Diseases/etiology , Metabolomics/methods , Milk Proteins/administration & dosage , Milk Proteins/analysis , Milk Proteins/biosynthesis , Oxidative Stress , Pregnancy , Random Allocation , Rats, Sprague-DawleyABSTRACT
Although free amino acids (FAA) account for a small fraction of total nitrogen in mammalian milk, they are more abundant in human milk than in most formulas, and may serve as a readily available source of amino acids for protein synthesis, as well as fulfill specific physiologic roles. We used reversed phase Ultra Performance Liquid Chromatography (UPLC) coupled to electrospray ionization tandem mass spectrometry (ESI-MS/MS) technique for FAA profiling in milks from three species (human, rat and cow) with a simple and rapid sample preparation. The derivatization procedure chosen, combined with UPLC-ESI-MS/MS allowed the quantitation of 21 FAA using labeled amino acids (Internal Standards) over a 10 min run time in micro-samples of mammalian milk (50 µL). The low limit of quantitation was 0.05 pmol/µL for most FAA with good repeatability and reproducibility (mean CV of 5.1%). Higher levels of total FAA were found in human (3032 µM) and rat milk (3460 µM) than in bovine milk (240 µM), with wide differences in the abundances of specific FAA between species. This robust analytical method could be applied to monitor FAA profile in human breast milk, and open the way to individualized adjustment of FAA content for the nutritional management of infants.
