First Year Of Lactation Research Articles

Effect of Holder Pasteurization, Mode of Delivery, and Infant's Gender on Fatty Acid Composition of Donor Breast Milk.

Breast milk (BM) plays a crucial role in providing essential fatty acids (FA) and energy for the growing infant. When the mother's own BM is not available, nutritional recommendations suggest donor milk (DM) in clinical and home practices. BM was collected from a variety of donor mothers in different lactation stages. Holder pasteurization (HoP) eliminates potential contaminants to ensure safety. FA content of BM samples from the Breast Milk Collection Center of Pécs, Hungary, were analyzed before and after HoP. HoP decreases the level of C6:0, C8:0, C14:1n-5c, C18:1n-9c, C18:3n-6c, C18:3n-3c, and C20:4n-6c in BM, while C14:0, C16:0, C18:1n-9t, C22:0, C22:1n-9c, C24:0, C24:1n-9c, and C22:6n-3c were found in elevated concentration after HoP. We did not detect time-dependent concentration changes in FAs in the first year of lactation. BM produced for girl infants contains higher C20:2n-6c levels. In the BM of mothers who delivered via cesarean section, C12:0, C15:0, C16:0, C17:0, C18:0, C18:1n-9t, C22:1n-9c levels were higher, while C18:2n-6c, C22:0, C24:0, and C22:6n-3c concentrations were lower compared to mothers who gave birth spontaneously. FAs in BM are constant during the first year of lactation. Although HoP modifies the concentration of different FAs, pasteurized DM provides essential FAs to the developing infant. Current data providing information about the FA profile of BM gives origination to supplementation guidelines.

The Concentration of Lactoferrin in Breast Milk Correlates with Maternal Body Mass Index and Parity.

Background: Lactoferrin (LF) is a multifunctional glycoprotein found in human milk and body fluids, which has been shown to play a vital role in regulating the immunity and supporting the intestinal health of infants. Aim: This study evaluated the association between maternal/parturient factors and LF concentration in the breast milk of Chinese mothers. Methods: 207 breast milk samples were collected from healthy mothers with in the first year of lactation. Maternal and parturient information was collected for these participants through questionnaires. The content of lactoferrin in breast milk was detected by liquid chromatography, and macronutrient concentration in breast milk was measured by human milk analyzer in only 109 samples. Results: Our findings demonstrated that the LF content was much higher within the first month of lactation than it was after that period (p < 0.05). When compared with normal and lean mothers, the LF content of obese mothers was considerably higher (p < 0.05). The parity and LF content showed a favorable correlation. The proportion of LF to total protein tended to decrease as lactation progressed. Protein, fat, dry matter, and energy content were significantly positively correlated with LF content (p < 0.001). Conclusion: Early breast milk tends to have a higher level of LF, and the change of LF concentration in breast milk is associated with the parity and body mass index of the mother.

Human Milk Macronutrients and Bioactive Molecules and Development of Regional Fat Depots in Western Australian Infants during the First 12 Months of Lactation.

We investigated associations between intakes of human milk (HM) components (macronutrients and biologically active molecules) and regional fat depots development in healthy term infants (n = 20) across the first year of lactation. Infant limb (mid-arm and mid-thigh) lean and fat areas were assessed by ultrasound imaging at 2, 5, 9 and 12 months of age. Concentrations of HM total protein, whey protein, casein, adiponectin, leptin, lysozyme, lactoferrin, secretory IGA, total carbohydrates, lactose, HM oligosaccharides (total HMO, calculated) and infant 24-h milk intake were measured, and infant calculated daily intakes (CDI) of HM components were determined. This pilot study shows higher 24-h milk intake was associated with a larger mid-arm fat area (p = 0.024), higher breastfeeding frequency was associated with larger mid-arm (p = 0.008) and mid-thigh (p < 0.001) fat areas. Lysozyme (p = 0.001) and HMO CDI (p = 0.004) were time-dependently associated with the mid-arm fat area. Intakes of HM components and breastfeeding parameters may modulate infant limb fat depots development during the first year of age and potentially promote favorable developmental programming of infant body composition; however, further studies are needed to confirm these findings.

Microbiological Quality of Milk Donated to the Regional Human Milk Bank in Warsaw in the First Four Years of Activity.

As the survival rate for preterm infants increases, more emphasis is placed on improving health-related quality of life through optimal nutritional management. Human Milk Banks (HMBs) provide bioactive nutrients and probiotic microorganisms to premature newborns, especially in the first year of life. Donated milk screening and selection of potential donors ensures the quality and microbiological safety of the donated milk. Therefore we reviewed the basic characteristics of donors and the amounts and contamination of breast milk donated to the Regional Human Milk Bank (RHMB) in Warsaw. In four years, the RHMB collected 1445.59 L of milk, of which 96.60% was distributed among hospitalised infants. Additionally, breastmilk from donor candidates (139 samples from 96 women) was tested at least once in the first year of lactation. First analyses showed that 18 women’s milk samples were microbiologically pure, and 78 samples had one or more species of commensal and/or potentially pathogenic bacteria. In human milk samples from 10 women, the bacteria level was above the standard required by the RHMB; therefore, donors were re-educated, and further samples were tested. Most women followed the recommendations on hygienic expression and storage of milk before transfer to the RHMB. Our analysis will help to increase the accessibility and quality of raw donor milk and to meet the needs of more newborns.

Development of Visceral and Subcutaneous-Abdominal Adipose Tissue in Breastfed Infants during First Year of Lactation.

This study aimed to investigate relationships between infant abdominal visceral and subcutaneous adiposity and human milk (HM) components and maternal body composition (BC) during first year of lactation. Subcutaneous-abdominal depth (SAD), subcutaneous-abdominal fat area (SFA), visceral depth (VD) and preperitoneal fat area of 20 breastfed infants were assessed at 2, 5, 9 and 12 months using ultrasound. Maternal BC was determined with bioimpedance spectroscopy. HM macronutrients and bioactive components concentrations and infant 24-h milk intake were measured and calculated daily intakes (CDI) determined. Maternal adiposity associated with infant SFA (negatively at 2, 5, 12, positively at 9 months, all overall p < 0.05). 24-h milk intake positively associated with infant SAD (p = 0.007) and VD (p = 0.013). CDI of total protein (p = 0.013), total carbohydrates (p = 0.004) and lactose (p = 0.013) positively associated with SFA. Lactoferrin concentration associated with infant VD (negatively at 2, 12, positively at 5, 9 months, overall p = 0.003). CDI of HM components and maternal adiposity have differential effects on development of infant visceral and subcutaneous abdominal adiposity. Maintaining healthy maternal BC and continuing breastfeeding to 12 months and beyond may facilitate favourable BC development reducing risk of obesity.

Proteomic analysis of hypoxia and non-hypoxia secretome mesenchymal stem-like cells from human breastmilk.

IntroductionBreastmilk contains proteins and cells which have stem cell properties. The human breastmilk stem cell mimick mesenchymal stem cells and expresses pluripotency genes. The protein level of breastmilk is high in colostrum and gradually subsides in the first year of lactation. The mesenchymal stem cells from breastmilk can be an alternative source of stem cells that can potentially affect cardiovascular therapy. This study aimed to identify the proteomic analysis of secretome mesenchymal stem-like cells under hypoxia compared to non-hypoxia from human breastmilk stem cells.Material and methodsThe human breastmilk was collected from six healthy breastfeeding women and transported to the laboratory under aseptic conditions. The breastmilk cells were isolated then cultured. After 72 h, the human breastmilk stem cells reached confluence then cleaned up and isolated in serum-free media (spheroid) to allow serial passaging every 48 h. The acquisition stem cell was made with flow cytometry. The cells were divided into hBSC secretomes under hypoxia (A) and non-hypoxia (B) and analyzed for LC-MS to identify the peptide structure.ResultsThe human breastmilk cells contained several mesenchymal stem-like cells in density 2.4 × 106 cell/mL for hypoxia and 2 × 106 cell/mL for non-hypoxia conditions. The human breastmilk stem cell surface markers derived from the third cell passage process were 93.77% for CD44, 98.69% for CD73, 88.45% for CD90, and 96.30% for CD105. The protein level of secretome mesenchymal stem -like cells under hypoxia was measured at 5.56 μg/mL and 4.28 μg/mL for non-hypoxia. The liquid chromatography-mass spectrometry analysis identified 130 and 59 peptides from hypoxia and non-hypoxia of the human breastmilk stem cell secretome sequentially. Some important proteomics structures were found in the hypoxic human breastmilk stem cell secretome, such as transforming growth factor-β, VE-cadherin, and caspase.ConclusionThe human breastmilk cells contain mesenchymal stem-like cells and a high concentration of CD44, CD73, CD90, and CD105 as surface markers at third passage culture. The hypoxic hBSC secretome produces a higher protein level compare to non-hypoxia. The transforming growth factor -β was found in the hypoxic hBSC secretome as a modulator of VEGF-mediated angiogenesis.

Time of Lactation and Maternal Fucosyltransferase Genetic Polymorphisms Determine the Variability in Human Milk Oligosaccharides.

Rationale: Human milk oligosaccharides (HMOs) vary among mothers and genetic factors contribute to this variability. We assessed changes in HMO concentrations during the first year of lactation and the relationship with FUT2 Secretor group and FUT3 Lewis group defining genetic polymorphisms.Methods: Milk samples were collected from lactating mothers participating in the LIFE Child cohort in Leipzig, Germany. The concentrations of 24 HMOs in milk samples collected at 3 months (N = 156), 6 months (N = 122), and 12 months (N = 28) were measured using liquid chromatography. Concentrations of HMOs were compared at all time-points and were tested for their associations with FUT2 and FUT3 genetic variations by sPLS regression.Results: FUT2 SNP rs601338 was found to predominantly define the Secretor status Se-: 11.8% and it was highly correlated with 2′-fucosyllactose (2′FL, p < 0.001) and lacto-N-fucosylpentaose-I (LNFP-I, p < 0.001). FUT3 SNPs rs28362459 and rs812936 were found to define Lewis status (Le-: 5.9%) and correlated with lacto-N-fucosylpentaose-II (LNFP-II, p < 0.001). A polygenic score predicted the abundance of 2′FL levels within Secretors' milk (adj. R2 = 0.58, p < 0.001). Mean concentrations of most of the individual HMOs, as well as the sums of the measured HMOs, the fucosylated HMOs, and the neutral HMOs were lower at 6 and 12 months compared to 3 months (p < 0.001).Conclusions: Secretor and Lewis status defined by specific FUT2 and FUT3 SNPs are confirmed to be good proxies for specific individual HMOs and milk group variabilities. The polygenic score developed here is an opportunity for clinicians to predict 2′FL levels in milk of future mothers. These results show opportunities to strengthen our understanding of factors controlling FUT2 and FUT3 functionality, the temporal changes and variability of HMO composition during lactation and eventually their significance for infant development.

Human milk immunomodulatory proteins are related to development of infant body composition during the first year of lactation.

To investigate relationships between infant body composition (BC) and human milk (HM) immunomodulatory proteins (IMPs) during the first 12 months of lactation. BC of breastfeeding dyads (n = 20) was measured with ultrasound skinfolds (infants) and bioimpedance spectroscopy (infants/mothers) at 2, 5, 9, and/or 12 months post partum. Breastfeeding frequency, 24-h milk intake, and IMP concentrations (lactoferrin, lysozyme, secretory immunoglobulin A (sIgA)) were measured, and calculated daily intakes (CDIs) were determined. We used linear regression/mixed-effects models and adjusted results for multiple comparisons. No associations were seen between maternal characteristics and IMP concentrations/CDIs or between IMP concentrations and infant BC. Lactoferrin CDI was negatively associated with infant fat-free mass index (P = 0.002); lysozyme CDI was positively associated with infant fat mass (P = 0.004) and fat mass index (P = 0.004) measured with ultrasound skinfolds. In this small cohort of infants breastfed on demand during first year of life, we report differential associations of HM IMPs with infant BC, showing that in addition to their critical role in shaping infant immunity, lactoferrin, and lysozyme also influence development of infant BC, highlighting the importance of breastfeeding for 12 months and beyond. HM IMPs (concentrations and, most importantly, daily intakes) time-dependently and differentially associate with development of infant lean mass and adiposity during first 12 months of lactation. There is no information on how intakes and concentrations of these components affect development of infant BC. HM contains IMPs-lactoferrin, lysozyme, and sIgA, which not only play a critical role in shaping infant's immunity, but also influence infant growth and development of BC, highlighting the importance of breastfeeding for 12 months and beyond and warranting careful consideration of the dose effects of supplemented formula.

Immune profiling of breast milk from mothers with treated celiac disease.

The protective effect of breastfeeding on celiac disease (CD) onset is controversial. We studied a wide range of milk components in milk produced by celiac mothers following long-term gluten-free diet (GFD) in comparison to milk produced by healthy mothers. Breast-milk samples from celiac (n = 33) and healthy (n = 41) mothers were obtained during the first year of lactation. A panel of bioactive components was analyzed by enzyme-linked immunosorbent assay in the aqueous fraction. We studied molecules involved in defenses, immunoregulation, and strengthening of the gut-epithelial barrier. During late lactation (from 6 to 12 months after delivery), the content of total immunoglobulin A (IgA) and IgM was significantly lower in the milk produced by celiac patients. Nevertheless, gliadin (GFD)-specific IgA relative contribution was higher in this group, in contrast to tetanus toxoid-specific antibodies. The balance between pro-inflammatory and anti-inflammatory molecules was different. While interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 were most frequently found in samples from celiac mothers, soluble Toll-like receptor-2 prevalence was lower. We describe differences between the innate and adaptive immune profile of milk produced by celiac and healthy mothers. These results might explain previous controversial reports about breastfeeding and CD protection. In spite of a long-term adherence to GFD, the milk produced by mothers with CD exhibit a different immune profile, in relation with some immunoregulatory factors and antibody content. This work shows a more comprehensive characterization of milk from celiac mothers, including macronutrients, lysozymes, growth factors, and immunoregulatory components that had not been studied before. The present study widens the available data regarding the characteristics of human milk of celiac mothers following GFD. Further follow-up studies of the health of children who were breastfed by celiac mothers will be necessary in order to also estimate the impact of the present results therein.

Imaging of Pregnancy Associated Breast Cancer

AbstractBackground: Pregnancy-Associated Breast Cancer (PABC) is breast cancer presenting either during pregnancy or in the first postpartum year.Aim of Study: The purpose of this study was to calculate the incidence of pregnancy associated breast cancer in patients presenting with clinically palpable masses during pregnancy or first postpartum year and to evaluate the role of sonomam-mography in the diagnosis of pregnancy associated breast cancer.Patients and Methods: The study included 100 female patients with clinically palpable breast masses discovered during pregnancy and first year of lactation. All patients were evaluated by Ultrasound. Mammography was only performed on 23 patients. Mammographic and sonographic findings were evaluated retrospectively. No further diagnostic evaluation was done in case of benign radiological findings, yet biopsy was the next step performed if findings were suspicious.Results: In total, 100 women were enrolled in this study; the mean age of this study population was 29 years. Among the studied cases only 15 cases (n=15/100, 15%) were malig-nant, their age ranged from 26 years to 40 years with average 34.6, four of them (n=4/15) were presented by right breast palpable lumps and 11 (n=11/15) by left breast palpable lumps. Ultrasound helped to classify 2 cases (n=2/15) as BIRADS 4 and the rest (n=13/15) as BIRADS 5. Ultrasound guided biopsy was then performed for the 15 patients confirming their malignant nature.Conclusion: Even though the majority of the pregnancy-associated breast masses are benign; a strict evaluation of any lesion is still required to exclude malignancy.

Developmental changes in the endocrine stress response in orangutans (Pongo pygmaeus)

Non-invasive measures of stress are crucial for captive and conservation management programs. The adrenal hormone dehydroepiandrosterone-sulfate (DHEAS) has recently been adopted as a stress marker, but there is little investigation of its relationship to glucocorticoids (GC), well-known indicators of stress. This study examined the influence of age, reproductive state and environment on GC and DHEAS levels in orangutans, to test whether the GC/DHEAS ratio can provide an index of stress response in primates. We measured fecal GC (fGC) and fecal DHEAS (fDHEAS) concentrations in 7 captive orangutans from zoological parks in Japan and 22 wild orangutans from Danum Valley Conservation Area, Malaysia. We found that in a stressful condition (transportation), fDHEAS levels increased 2days after the fGC response, which occurred 1day after the stressor. One pregnant female had elevated levels of both hormones, and a higher fGC/fDHEAS ratio than baseline. Females in the first year of lactation had fGC levels and the fGC/fDHEAS ratio significantly higher than both baseline and females in the second and subsequent years of lactation. There was no effect of age on fGC levels, but the fGC/fDHEAS ratio was higher in infants than adults and adolescents. fDHEAS concentrations were lower in infants than juveniles, adolescents and adults, a phenomenon known as adrenarche, shared with humans and other great apes. We suggest that changes in DHEAS during orangutan life history are associated with changes in the dynamics of maintaining homeostasis that vary with age and reproductive state. The GC/DHEAS ratio index is useful to evaluate age-related abilities of responding to stressful challenges.

Absolute Quantification of Human Milk Caseins and the Whey/Casein Ratio during the First Year of Lactation.

Whey proteins and caseins in breast milk provide bioactivities and also have different amino acid composition. Accurate determination of these two major protein classes provides a better understanding of human milk composition and function, and further aids in developing improved infant formulas based on bovine whey proteins and caseins. In this study, we implemented a LC-MS/MS quantitative analysis based on iBAQ label-free quantitation, to estimate absolute concentrations of α-casein, β-casein, and κ-casein in human milk samples (n = 88) collected between day 1 and day 360 postpartum. Total protein concentration ranged from 2.03 to 17.52 with a mean of 9.37 ± 3.65 g/L. Casein subunits ranged from 0.04 to 1.68 g/L (α-), 0.04 to 4.42 g/L (β-), and 0.10 to 1.72 g/L (α-), with β-casein having the highest average concentration among the three subunits. Calculated whey/casein ratio ranged from 45:55 to 97:3. Linear regression analyses show significant decreases in total protein, β-casein, κ-casein, total casein, and a significant increase of whey/casein ratio during the course of lactation. Our study presents a novel and accurate quantitative analysis of human milk casein content, demonstrating a lower casein content than earlier believed, which has implications for improved infants formulas.

Longitudinal study of pesticide residues in human milk from Western Australian women during the first year of lactation

Longitudinal study of pesticide residues in human milk from Western Australian women during the first year of lactation

Associations between Maternal Body Composition and Appetite Hormones and Macronutrients in Human Milk.

Human milk (HM) appetite hormones and macronutrients may mediate satiety in breastfed infants. This study investigated associations between maternal adiposity and concentrations of HM leptin, adiponectin, protein and lactose, and whether these concentrations and the relationship between body mass index and percentage fat mass (%FM) in a breastfeeding population change over the first year of lactation. Lactating women (n = 59) provided milk samples (n = 283) at the 2nd, 5th, 9th and/or 12th month of lactation. Concentrations of leptin, adiponectin, total protein and lactose were measured. Maternal %FM was measured using bioimpedance spectroscopy. Higher maternal %FM was associated with higher leptin concentrations in both whole (0.006 ± 0.002 ng/mL, p = 0.008) and skim HM (0.005 ± 0.002 ng/mL, p = 0.007), and protein (0.16 ± 0.07 g/L, p = 0.028) concentrations. Adiponectin and lactose concentrations were not associated with %FM (0.01 ± 0.06 ng/mL, p = 0.81; 0.08 ± 0.11 g/L, p = 0.48, respectively). Whole milk concentrations of adiponectin and leptin did not differ significantly over the first year of lactation. These findings suggest that the level of maternal adiposity during lactation may influence the early appetite programming of breastfed infants by modulating concentrations of HM components.

Longitudinal study of pesticide residue levels in human milk from Western Australia during 12 months of lactation: Exposure assessment for infants.

The presence of pesticides in human milk (HM) is of great concern due to the potential health effects for the breastfed infant. To determine the relationships between HM pesticides and infant growth and development, a longitudinal study was conducted. HM samples (n = 99) from 16 mothers were collected at 2, 5, 9 and 12 months of lactation. A validated QuEChERS method and Gas chromatography-tandem mass spectrometry (GC-MS/MS) were used for the analysis of 88 pesticides in HM. Only p,p’-DDE, p,p’-DDT and β-HCH were detected with a mean concentration (±SD) of 52.25 ± 49.88 ng/g fat, 27.67 ± 20.96 ng/g fat and 48.00 ± 22.46 ng/g fat respectively. The concentrations of the detected pesticides decreased significantly throughout the first year of lactation. No significant relationships between HM p,p’-DDE and infant growth outcomes: weight, length, head circumference and percentage fat mass were detected. The actual daily intake (ADI) of total DDTs in this cohort was 14–1000 times lower than the threshold reference and significantly lower than the estimated daily intake (EDI). Further, the ADI decreased significantly throughout the first 12 months of lactation.

A longitudinal study of human milk composition in the second year postpartum: implications for human milk banking.

While the composition of human milk has been studied extensively in the first year of lactation, there is a paucity of data regarding human milk composition beyond one year postpartum. Policies vary at milk banks around the world regarding how long lactating women are eligible to donate their milk. The primary purpose of this study is to describe longitudinal changes in human milk composition in the second year postpartum to support the development of evidence based guidelines regarding how long lactating women can donate human milk to a milk bank. Nineteen lactating women in North Carolina provided monthly milk samples from 11 months to 17 months postpartum (N = 131), and two non-profit milk banks provided (N = 33) pooled, unpasteurized milk samples from 51 approved donors less than one year postpartum. There was a significant increase (P < 0.05) in the concentration of total protein, lactoferrin, lysozyme, Immunoglobulin A, oligosaccharides and sodium in longitudinal samples of mother's milk between 11 and 17 months postpartum, while zinc and calcium concentrations declined, and no changes were observed in lactose, fat, iron and potassium. Human milk in the second year postpartum contained significantly higher concentrations of total protein, lactoferrin, lysozyme and Immunoglobulin A, than milk bank samples, and significantly lower concentrations of zinc, calcium, iron and oligosaccharides. Accepting milk bank donations beyond one year postpartum is a potential strategy for increasing the supply of donor milk, but may require mineral fortification.

Protein Evolution of Human Milk.

Given the documented short- and long-term advantages of breastfeeding, human milk (HM) as a sole source of nutrition for the first few months of newborn life is considered a normative standard. Each macroconstituent of HM plays a crucial role in the growth and development of the baby. Lipids are largely responsible for providing more than 50% of the energy as well as providing essential fatty acids and minor lipids that are integral to all cell membranes. Carbohydrates can be broadly divided into lactose and oligosaccharides, which are a readily digestible source of glucose and indigestible nonnutritive components, respectively. Proteins in HM provide essential amino acids indispensable for the growth of infants. What is more interesting is that protein concentration profoundly changes from colostrum to mature milk. In this report, we share data from an observatory, single-center, longitudinal trial assessing the constituents of HM collected 30, 60 and 120 days postpartum from 50 mothers (singleton deliveries: 25 male and 25 female infants). The protein content decreased with evolving stages of lactation from an average of 1.45 to 1.38 g/100 ml. The data did not show any gender differences as it was reported for lipid content at 120 days postpartum by our group. Additionally, we also share consolidated literature data on protein evolution of HM during the first year of lactation.

The Total Amino Acid Profile of Human Milk is Stable Over the First Year of Lactation and Consistent Across Geographical Populations: a GEHM Study

The amino acid composition of human milk is thought to be critical in the development of breastfed infants. Part of the Global Exploration of Human Milk (GEHM) study examines variability in amino acid profiles over the course of lactation, both between individual mothers and across geographical populations. Total and free amino acid profiles, determined using specialized ion exchange chromatography followed by post column derivitization, are reported for longitudinal samples collected from three global cohorts (Mexico, China, and USA) at 4, 13, 26, and 52 weeks lactation. This study focused on utilization of rigorously controlled sample collection techniques as well as statistically monitored process control during analysis to ensure the accuracy of generated results. Although the amino acid profiles of human milk have been reported previously, these extra control measures as well as the integration of numerous samples from different geographical populations provides additional insights into amino acids in human milk. While the free amino acid profiles exhibit higher variability amongst individuals, these findings suggest that the total amino acid profiles remain remarkably consistent even when investigated in distinct geographical locations, amongst multiple donors, and across lactation. This characteristic pattern, observed in all amino acids, can be illustrated by the essential amino acid Threonine (Thr), which has a variability of 55% for free Thr and 4% for total Thr. Support for this research was provided by Mead Johnson Pediatric Nutrition Institute.

Determination of 12 Minerals in Human Milk by Inductively Coupled Plasma ‐ Mass Spectrometry: a GEHM Study of Three Global Cohorts through the First Year of Lactation

Elemental composition of human milk may be influenced by several factors, including dietary intake and genetic background, though variation in milk content over lactation and by geographic region has not been well characterized. A newly validated simultaneous method allows rapid and accurate determination of concentrations for 12 elements, P, Na, K, Ca, Mg, Mn, Cu, Zn, Fe, Mo, Cr, and Se, in human milk via inductively coupled plasma‐mass spectrometry (ICP‐MS). As part of the Global Exploration of Human Milk (GEHM) collaboration, human milk collected during the first year of lactation from three global cohorts (Mexico City, Mexico, Shanghai, China, and Cincinnati, United States) was analyzed at 4, 26 and 52 weeks lactation. Samples underwent acidic microwave digestion followed by ICP‐MS quantification, and analysis included suppression of known polyatomic interferences using collision cell technology. Milk from distinct geographic regions exhibited similar mineral concentrations as well as temporal patterns between 4 and 52 weeks of lactation. Among several observations, some elements showed consistent decreases in concentration between 4 and 52 weeks postpartum, including Ca (295 to 220 µg/mL, ↓25%), K (545 to 431 µg/mL, ↓21%), P (163 to 130 µg/mL, ↓20%), Cu (416 to 140 ng/mL, ↓66%) and Zn (2520 to 617 ng/mL, ↓76%), while Fe and Mn remained fairly stable with 蠄10% change in concentration over the course of lactation. This research was supported by Mead Johnson Pediatric Nutrition Institute.

Developing human mammary‐gland functions during the first year of lactation (II) (622.7)

Proteomic analysis of human milk provides a non‐invasive means to explore the physiology of lactating mammary gland. We applied quantitative milk proteomic analysis (TMT labeling) over one year of lactation (n =10 women with samples at 1 week, 1, 3, 6, 9 and 12 months) as probes for the developing mammary‐gland function. Proteins involved in the processes of endoplasmic reticulum‐assisted degradation and proteasomal degradation are, in general, upregulated over lactation, suggesting increased activities in protein catabolism. Rab GTPases that control intracellular membrane trafficking in various endocytosis and secretion processes are typically present at highest abundance at 6 months of lactation. The extracellular domain of intercellular adhesion molecule 1 (ICAM‐1) is upregulated over lactation. The increased proteolytic shedding of ICAM‐1 may represent a means to suppress leukocyte recruitment into milk as lactation progresses. In contrast, the shedding of E‐cadherin decreases over lactation, suggesting increasing barrier integrity at the adherens junctions in lactating human mammary epithelium. These insights combining in‐depth determination of protein content in milk with bioinformatic analysis illustrate the large potential for advancing our understanding of the lactating mammary gland.