Macronutrient Content Of Human Milk Research Articles

The Effect of Unadjusted Mineral Supplementation on Bone Health of Preterm Infants Fed Fortified Human Milk: An Exploratory Analysis

Background: In standard fortification of human milk (HM), the HM macronutrient content is assumed, and a fixed amount of a multinutrient fortifier is added to achieve recommended nutrient intakes. In target fortification, the HM macronutrient content is regularly measured, guiding the addition of modular macronutrient supplements to the fortified HM, to achieve the nutritional targets more precisely. Objective: The study aimed to investigate whether this addition of modular supplements, unaccompanied by mineral supplementation, predispose to metabolic bone disease (MBD). Methods: This is a secondary analysis of a larger study of infants born with <33 weeks gestational age. Fortifications based on the assumed (Group 1) or measured (Group 2) of the HM macronutrient content were compared, using low serum phosphate levels as an indicator of MBD, and length growth as a surrogate of bone growth. Results: Eighty-four infants were included, 35 in Group 1 and 49 in Group 2. During the exposure period, infants of Group 2 received higher mean fat (6.1 vs. 5.3 g/kg/day, P < 0.001) and carbohydrate (13.0 vs. 11.7 g/kg/day, P < 0.001) intakes; in addition, they exhibited lower mean serum phosphate (5.5 vs. 6.0 mg/dL, P = 0.022) and faster mean length velocity (1.06 vs. 0.89 cm/week, P = 0.003). Conclusions: These findings suggest that feeding fortified HM with extra fat and carbohydrate content, unaccompanied by mineral supplementation, promotes increased bone growth, as indicated by accelerated length growth, but with insufficiently mineralized osteoid, indicated by low serum phosphate levels. Intervention studies using direct biomarkers of bone mass content and mineral density are necessary to corroborate our findings.

PTFS05-07-23 The Association of Human Milk Macronutrient Content With Early Childhood Growth and Neurodevelopment in Rural Bangladesh

PTFS05-07-23 The Association of Human Milk Macronutrient Content With Early Childhood Growth and Neurodevelopment in Rural Bangladesh

Individualized Fortification Based on Measured Macronutrient Content of Human Milk Improves Growth and Body Composition in Infants Born Less than 33 Weeks: A Mixed-Cohort Study

The optimal method for human milk (HM) fortification has not yet been determined. This study assessed whether fortification relying on measured HM macronutrient content (Miris AB analyzer, Upsala, Sweden) composition is superior to fortification based on assumed HM macronutrient content, to optimize the nutrition support, growth, and body composition in infants born at <33 weeks' gestation. In a mixed-cohort study, 57 infants fed fortified HM based on its measured content were compared with 58 infants fed fortified HM based on its assumed content, for a median of 28 and 23 exposure days, respectively. The ESPGHAN 2010 guidelines for preterm enteral nutrition were followed. Growth assessment was based on body weight, length, and head circumference Δ z-scores, and the respective growth velocities until discharge. Body composition was assessed using air displacement plethysmography. Fortification based on measured HM content provided significantly higher energy, fat, and carbohydrate intakes, although with a lower protein intake in infants weighing ≥ 1 kg and lower protein-to-energy ratio in infants weighing < 1 kg. Infants fed fortified HM based on its measured content were discharged with significantly better weight gain, length, and head growth. These infants had significantly lower adiposity and greater lean mass near term-equivalent age, despite receiving higher in-hospital energy and fat intakes, with a mean fat intake higher than the maximum recommended and a median protein-to-energy ratio intake (in infants weighing < 1 kg) lower than the minimum recommended.

Maternal Diet Influences Human Milk Protein Concentration and Adipose Tissue Marker.

(1) Background: Adequate protein intake plays an essential role in growth and neurodevelopment, especially in preterm infants. We investigated the effects of maternal diet and body mass index (BMI) on human milk (HM) composition. (2) Methods: HM samples were obtained from 136 lactating mothers (BMI: 18.0−36.7 kg/m2), of which 93% gave birth to preterm infants. Macronutrient content in HM was measured by mid-infrared transmission spectroscopy. Leptin and adiponectin were analyzed using appropriate ELISAs. Maternal diet was determined by 24-h recall. (3) Results: Significant positive associations were found between protein, fat, carbohydrate and energy intake, and levels of corresponding macronutrients in HM, especially in protein concentrations (p < 0.001). An increased protein intake was positively correlated with adiponectin (p < 0.001) and leptin (p = 0.035) in HM. Maternal BMI was positively associated with a higher protein level in HM (p < 0.05), as well as with a higher dietary protein intake (p < 0.05). (4) Conclusions: Knowledge of maternal diet and BMI impacting HM composition is essential to optimize the feeding of newborn infants. This is especially relevant in the nutritional management of preterm infants; it can be utilized in approaches to improve growth rates and the appropriate development of infants and to prevent obesity.

Carbohydrate content of human milk is affected by seasonal variations: a retrospective observational study

The influence of seasonal variation upon human milk macronutrient content has not been elucidated. This study aimed to compare the macronutrient content of HM produced by lactating mothers during the winter and the summer seasons. Macronutrient content of colostrum milk samples collected from lactating mothers of healthy term infants between March 2012 and February 2016 was measured by mid-infrared spectroscopy and compared. The carbohydrate content of the colostrum was significantly higher in the summer season than in the winter season (6.2 ± 1.3 vs. 5.5 ± 1.4, p-value < 0.001). Protein, fat, and energy contents were similar in summer and winter in both groups (protein 2.7 ± 2.1 vs. 2.6 ± 2.2 g/100 ml, fat 2.6 ± 1.9 vs. 2.35 ± 1.9 g/100 ml, and energy 62 ± 19.1 vs. 60.5 ± 21 kcal/100 ml, respectively). The carbohydrate content in colostrum obtained from mothers of term infants was affected by seasonal variations.

Human Milk Bioactives: Future Perspective.

Human milk is a dynamic, complex fluid that offers much more than nutrition to infants. The macronutrient content of human milk has been well characterized and described. However, human milk is not a simple matrix of protein, carbohydrate, fat, and micronutrients. The National Institutes of Health have defined bioactives in food as elements that "affect biological processes or substrates and hence have an impact on body function or condition and ultimately health." Bioactives are cells, anti-infectious and anti-inflammatory agents, growth factors, and prebiotics that are naturally present in human milk. They may explain the differences in health outcomes observed between breastfed and non-breastfed infants. They influence the development of the immune and gastrointestinal systems, gut microbiota, neurodevelopment, metabolic health, and protection against infection. Human milk oligosaccharides are one bioactive that have been an increasingly popular area of research. This review provides a broad overview of some bioactive components that positively affect the immune system and touches on certain well-known growth factors present in human milk. Future research will look at the interplay of the multitude of bioactive components in human milk as a biological system and beyond singular compounds.

Investigation of the Effect of Human Milk Expression Techniques on Milk Content: A Systematic Review.

If the mother and infant cannot meet after birth, it is recommended to express milk and give it to the infant. There was evidence indicating that there might be decrease in essential nutrient values in human milk content depending on the expression technique in literature. The goal of this systematic review was to investigate the effect of human milk expression techniques on the macronutrient milk content and establish an evidence base for future studies. Studies investigating the effect of human milk expression techniques on milk content were reviewed without year limitations. A literature review was conducted in six electronic databases (MEDLINE, Web of Science, PubMed, ScienceDirect, CINAHL and Cochrane) until 30 May 2021, using the keywords of breast milk expression techniques, milk content and breast milk pumping. From 258 articles initially screened, we included 6 articles in the systematic review. The fat, protein and lactose content of human milk was analyzed in the studies reviewed. It was concluded that there was no significant effect on the protein (9.7-9.8 g/dl and 2.1-2.1 g/dl, respectively) and lactose (6.50-6.53% and 6.1-6.1 g/dl, respectively) content of milk. However, the fat (58.30, 48.81g/l; 2.6-2.2 g/dl) content was affected. This study investigated the effect of milk expression techniques on the macronutrient content of human milk, and it was concluded that there was no significant effect on the protein and carbohydrate content of milk. However, the fat content was affected. Limitation of this study is that some factors that might affect the content of human milk were not standardized sufficiently in the included studies.

Tandem Breastfeeding and Human Milk Macronutrients: A Prospective Observational Study.

Tandem breastfeeding is defined as two or more offspring of different ages who are breastfed by their mother at the same time. Breastfeeding during pregnancy and tandem breastfeeding have not been widely investigated. To determine the influence of tandem breastfeeding on the macronutrient content of human milk. This longitudinal study used a prospective and a retrospective group. Human milk samples from tandem-breastfeeding participants (n = 18) were compared to samples from non-tandem-breastfeeding participants (n = 31). Samples were collected during the last month of pregnancy (pregnancy milk), 72 hr after birth (colostrum) and 14-60 days post-delivery (mature milk). Macronutrients were measured by mid-infrared spectroscopy. Fat content in pregnancy milk was lower than in mature milk (p < .01). Protein content was higher in pregnancy milk than in colostrum and mature milk (p < .01 and p < .001, respectively). Inversely, carbohydrate content in pregnancy milk was lower than in colostrum and mature milk (p = .02 and p < .01, respectively). Fat and energy contents in pregnancy milk of tandem-breastfeeding participants were lower than in mature milk of non-tandem-breastfeeding participants (p < .001 and p < .01, respectively), and protein content was higher than in mature milk (p < .001). Carbohydrate content in colostrum and mature milk of tandem-breastfeeding participants was higher than that of non-tandem-breastfeeding participants (p < .001 for both). Human milk produced during pregnancy had different macronutrient content than human milk produced after delivery. Colostrum and mature milk of tandem-breastfeeding participants were similar to human milk produced by non-tandem-breastfeeding participants, with the exception of carbohydrate content.

The implications of routine milk fortification for the short and long-term health of preterm babies

Fortification refers to the practice of enriching human milk feeds for very preterm babies with macronutrients, minerals and vitamins. Though standard of care in some parts of the world, adoption of fortification is not universal. Fortification entered into use on the assumption that human milk macronutrient content, principally protein, is insufficient to support the growth and development of very preterm babies. However, because of the substantial variability in human milk composition, routine fortification risks exposing some babies to very high protein intakes, which may be dangerous. Some clinicians fear fortification with cow-milk derived products will increase the risk of necrotising enterocolitis, leading them to favour commercial fortifiers made from pooled human milk over cow milk based products, a practice that has additional ethical implications. Randomised controlled trials of multi-nutrient fortification to-date are inadequate. No trial has had power to detect important functional effects; the majority are methodologically weak and focus primarily upon short-term growth. Evidence to guide practice is inadequate. There is an urgent need for collaboration to conduct high-quality research to end these long-standing uncertainties.

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

ABSTRACT 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.

Macronutrient Intake from Human Milk, Infant Growth, and Body Composition at Term Equivalent Age: A Longitudinal Study of Hospitalized Very Preterm Infants

The variable macronutrient content of human milk may contribute to growth deficits among preterm infants in the neonatal intensive care unit (NICU). In a longitudinal study of 37 infants < 32 weeks gestation, we aimed to (1) determine the between-infant variation in macronutrient intake from human milk and (2) examine associations of macronutrient intake with growth outcomes. We analyzed 1626 human milk samples (median, 43 samples/infant) with mid infrared spectroscopy. Outcomes at term equivalent age were weight, length, head circumference, fat mass, and fat-free mass. Median (range) intakes from human milk were: protein 1.37 (0.88, 2.43) g/kg/day; fat 4.20 (3.19, 5.82) g/kg/day; carbohydrate 8.94 (7.72, 9.85) g/kg/day; and energy 82.5 (68.7, 99.3) kcal/kg/day. In median regression models adjusted for birth size and gestational age, and other covariates, greater intakes of fat and energy were associated with higher weight (0.61 z-scores per g/kg/day fat, 95% CI 0.21, 1.01; 0.69 z-scores per 10 kcal/kg/day, 95% CI 0.28, 1.10), whereas greater protein intake was associated with greater body length (0.84 z-scores per g/kg/day protein, 95% CI 0.09, 1.58). Higher fat intake was also associated with higher fat mass and fat-free mass. Macronutrient intakes from human milk were highly variable and associated with growth outcomes despite routine fortification.

The Effect of Physical Activity on Human Milk Macronutrient Content and Its Volume.

Objective: There are multiple health benefits associated with both breastfeeding and practicing physical activity (PA). Therefore, it is likely that many women might want to engage in both. We designed the current randomized clinical trial to examine the effect of moderate- to high-intensity PA on human milk (HM) volume and macronutrient contents. Methods and Study Design: In this prospective, randomized, crossover clinical trial, we recruited 31 healthy mothers who had been exclusively breastfeeding their infants. Mothers expressed HM twice each day on 2 consecutive days-a day with PA (1-hour before and 1-hour after PA) and a control day without PA (at the exact same hours of the day). The order of days (with/without PA) was determined randomly. Macronutrients and energy contents of HM were analyzed using the Human Milk Analyzer (Miris AB, Uppsala, Sweden). PA was graded according to the Borg Rating of Perceived Exertion scale (RPE scale). Results: A total 124 HM samples from 31 mothers were analyzed. Moderate- to high-intensity PA affected neither macronutrients (fat, carbohydrates, protein) nor energy content. Milk volume remained unaffected by PA as well. Conclusions: Maternal PA does not affect HM volume or its macronutrient contents. Lactating mothers can be reassured regarding their breast milk volume and composition while practicing PA of moderate to high intensity.

Role of Daily Milk Volume and Period of Lactation in Nutrient Content of Human Milk: Results from a Prospective Study.

Most studies assessing the macronutrient content of human milk are published retrospectively using analyzers that fail to determine sodium content and do not take into account the role of volume in milk composition. We aimed to describe macronutrient content and sodium content in human milk over time, observe any associations between them, and determine the factors associated with the evolution of milk composition. A prospective, longitudinal, monocentric study was undertaken. Contents of protein, fat, and lactose of 102 milk samples from 40 mothers were determined using a human milk analyzer and that of sodium with a flame spectrophotometer. Milk volumes along with clinical data were recorded. Protein content in the fourth quartile of volume was significantly lower than that in the first three, suggesting the existence of a volume threshold for protein content at approximately 445 mL. After multivariate analysis, it was found that maternal age, average volume, and lactation period remained significantly associated with protein content, maternal age remained significantly associated with fat content, and only average volume with sodium content. In consideration of previous findings along with our data, we suggest that extra care should be taken with fortification for feeding preterm infants when the mother’s milk volume is greater than 400–450 mL.

Macronutrient content of donor milk from a regional human milk bank: variation with donor mother-infant characteristics.

Better understanding of the variation in macronutrient content of human donor milk (HDM) potentiates targeted nutrition for preterm babies. The present study describes the relationship of maternal age, parity, monthly lactation stage estimate (LSEm), daily volume of milk expressed (Vd), sex, gestation and birth weight z scores with macronutrient content of HDM. Multilevel mother-infant pair ID random intercept models were performed using the predictor variables above on the outcome HDM macronutrient content determined using mid-IR spectroscopy. Mean macronutrient content was also compared by gestational age and small for gestational age (SGA) (z score<-1·28) or appropriate for gestational age (AGA) (z score≥-1·28) categories. A total of 2966 samples of donations from 1175 mother-infant pairs to the UK Northwest Human Milk Bank between 2011 and 2017 were analysed. Mean protein, fat, carbohydrate and calculated energy were 0·89 (SD 0·24)g/dl, 2·99 (SD 0·96)g/dl, 7·09 (SD 0·44)g/dl, and 60·37 (SD 8·41)kcal/dl (252·59 (SD 35·19) kJ/dl), respectively. Preterm SGA HDM was significantly higher in protein, fat and energy content than term AGA HDM and significantly lower in carbohydrate content than term AGA HDM after controlling for LSEm, Vd and between-subject effects. Degree of prematurity did not influence macronutrient content. Between-subject effects accounted for more of the variance in macronutrient content than the fixed effects in the model. Despite this, SGA status, as well as prematurity, may be an important determinant of macronutrient content in human milk. As bioavailability of macronutrients from HDM is uncertain, studies evaluating growth and body composition in preterm and SGA babies fed HDM are warranted.

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

BackgroundMaternal characteristics may be associated with human milk macronutrients but no definite conclusions have been made to date. AimThis 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 designProspective observational cohort study. SubjectsMilk samples were collected from mothers after premature birth between 24 + 0–35 + 6 weeks. Outcome measuresMacronutrients and energy content were analyzed by mid-infrared transmission spectroscopy. Demographic and anthropometric data from mothers were systematically recorded. ResultsA 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). ConclusionHuman 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.

Macronutrient and calorie content in preterm and term human milk at first three week after delivery

Background The macronutrients in human milk change dynamically and vary among mothers. Evaluation of macronutrient content in human milk is needed to improve nutritional management in preterm infants.&#x0D; Objective To measure the macronutrient content in preterm and full term human milk during three lactation periods in the first three weeks after delivery.&#x0D; Methods We conducted a prospective study among 80 mothers of infants who were hospitalized in the Department of Perinatology/NICU at Sardjito Hospital, Yogyakarta. Carbohydrate, fat, protein, and caloric content were measured using a MIRIS human milk analyzer, once per week for three consecutive weeks after delivery. A single, daytime human milk specimen was collected in the morning by directly expressing from the breast.&#x0D; Results Median protein, fat, carbohydrate, and caloric contents of mature milk in the preterm group were 1.40 (IQR 0.38), 3.25 (IQR 1.00), 5.70 (IQR 0.80) g/dL, and 60 kcal/dL, respectively. Median protein, fat, carbohydrate, and caloric contents of mature milk in the full term group were 1.40 (IQR 0.35), 3.30 (IQR 0.77), 5.80 (IQR 0.75) g/dL, and 62 kcal/dL, respectively, at the third week after delivery. In both groups, protein content in the first week was significantly higher than in the third week (P&lt;0.001) after delivery. In contrast, fat content in the first week was significantly lower than in the third week (P&lt; 0.05) after delivery, in both groups.&#x0D; Conclusions There are no significant differences in macronutrient and caloric content between preterm and full term human milk during the first three weeks after delivery. However, there are significant changes in fat and protein content in both preterm and full term human milk during early lactation, between the first and third weeks.

Macronutrient composition in human milk from mothers of preterm and term neonates is highly variable during the lactation period

ObjectiveTo investigate the macronutrient content of human milk during the first 28 days of lactation of mothers who delivered preterm infants, and to compare preterm to term milk. MethodsA prospective and longitudinal study of mothers at various stages of lactation was conducted in the Amiens-Picardie University Hospital (France). Fat, true protein, carbohydrate and energy contents were estimated in human milk collected from each participant. ResultsMacronutrients in human milk were: fat (g/100 mL), 3.36±1.01; true protein ( g/100 mL), 1.34±0.61; carbohydrate ( g/100 mL), 7.23±0.68; energy (kcal/100 mL), 72.97±9.21 for extremely preterm human milk; fat (g/100 mL), 3.47±1.14; true protein (g/100 mL) 1.32±0.63; carbohydrate g/100 mL), 7.28±1.10; energy (kcal/100 mL), 76.18±12.84 for very preterm human milk; fat (g/100 mL), 3.48±0.87; true protein (g/100 mL), 1.26±0.46; carbohydrate (g/100 mL), 7.36±0.47; energy (kcal/100 mL), 76.47±8.21 for moderate preterm human milk; fat (g/mL), 3.48±1.57; true protein (g/100 mL), 1.23±1.03; carbohydrate (g/100 mL), 7.36±0.63; energy (kcal/100 mL), 76.56±13.57 for term human milk. ConclusionMarked variations in macronutrient contents were observed between preterm and term human milk. The macronutrient score of extremely and moderate preterm human milk versus term human milk was significant, p=0.0001.

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

ObjectiveThe study aims at evaluating mid-infrared human milk analyzer (HMA) accuracy and precision, in human milk (HM).Study designRöse-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.ResultsNo 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.ConclusionsHMA 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.

Human Milk Analysis Using Mid-Infrared Spectroscopy.

The composition of human milk is known to vary with length of gestation, stage of lactation, and other factors. Human milk contains all nutrients required for infant health but requires fortification to meet the needs of low-birth-weight infants. Without a known nutrient profile of the mother's milk or donor milk fed to a baby, the composition of the fortified product is only an estimate. Human milk analysis has the potential to improve the nutrition care of high-risk newborns by increasing the information about human milk composition. Equipment to analyze human milk is available, and the technology is rapidly evolving. This pilot study compares mid-infrared (MIR) spectroscopy to reference laboratory milk analysis. After obtaining informed consent, we collected human milk samples from mothers of infants weighing <2 kg at birth. Duplicate samples were analyzed for macronutrients by MIR and by reference laboratory analysis including Kjeldahl for protein, Mojonnier for fat, and high-pressure liquid chromatography for lactose. Intraclass correlation coefficients, Bland-Altman scatter plots, and paired t tests were used to compare the two methods. No significant differences were detected between the macronutrient content of human milk obtained by MIR vs reference laboratory analysis. MIR analysis appears to provide an accurate assessment of macronutrient content in expressed human milk from mothers of preterm infants. The small sample size of this study limits confidence in the results. Measurement of lactose is confounded by the presence of oligosaccharides. Human milk analysis is a potentially useful tool for establishing an individualized fortification plan.

Macronutrient composition of human milk from Korean mothers of full term infants born at 37-42 gestational weeks.

BACKGROUND/OBJECTIVESBreast milk is the best available food for optimum growth and development of infants and the breastfeeding rate is increasing in Korea. The purpose of this study is to measure the concentrations of macronutrients and to evaluate their changes according to lactation period in breast milk from lactating Korean women.SUBJECTS/METHODSMilk samples were obtained from 2,632 healthy lactating women (mean age; 32.0 ± 3.3 years), where the lactating period was up to a period of 8 months, who also volunteered to participate in the Human Milk Macronutrient Analysis Research. Lactose, protein, fat and water content in the breast milk samples were analyzed with infrared spectrometry using MilkoScan FT-2.RESULTSThe mean macronutrient composition per 100 mL of mature breast milk was 7.1 g for lactose, 1.4 g for protein and 3.0 g for fat, and energy content was 61.1 kcal. The protein concentration was significantly lower in milk samples at 1-2 weeks (2.0 g/dL) to 2-3 months (1.4 g/dL) than those at 0-1 week (2.2 g/dL), but it was similar among samples from 3-4 months to 7-8 months (1.3 g/dL). Mean lipid levels varied among different lactational period groups (2.7-3.2 g/dL), but presented no significant difference. Lactose concentration in the milk samples did not differ with lactation period. Maternal body mass index was positively related to protein and lipid breast milk contents, but was negatively related to lactose content. General linear models examining the associations between maternal variables and milk macronutrient content revealed that lactation period had a major impact on protein and lipid, but not on lactose content in breast milk.CONCLUSIONSThese results warrant future studies to explore factors that may be associated with changes in macronutrient content in human milk.