Human Milk Micronutrients and Child Growth and Body Composition in the First 2 years: A Systematic Review.

Human milk (HM) provides a plethora of nutritional and non-nutritional compounds that support infant development. For many compounds, concentrations vary substantially among mothers and across lactation, and their impact on infant growth is poorly understood. We systematically searched MEDLINE, Embase, the Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born infants. Outcomes included weight-for-length, length-for-age, weight-for-age, body mass index (in kg/m2)-for-age, and growth velocity. From 9992 abstracts screened, 144 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Micronutrients (vitamins and minerals) are reported here, based on 28 articles involving 2526 mother-infant dyads. Studies varied markedly in their designs, sampling times, geographic and socioeconomic settings, reporting practices, and the HM analytes and infant anthropometrics measured. Meta-analysis was not possible because data were sparse for most micronutrients. The most-studied minerals were zinc (15 articles, 1423 dyads) and calcium (7 articles, 714 dyads). HM iodine, manganese, calcium, and zinc concentrations were positively associated with several outcomes (each in ≥2 studies), whereas magnesium (in a single study) was negatively associated with linear growth during early lactation. However, few studies measured HM intake, adjusted for confounders, provided adequate information about complementary and formula feeding, or adequately described HM collection protocols. Only 4 studies (17%) had high overall quality scores. The biological functions of individual HM micronutrients are likely influenced by other HM components; yet, only 1 study analyzed data from multiple micronutrients simultaneously, and few addressed other HM components. Thus, available evidence on this topic is largely inconclusive and fails to address the complex composition of HM. High-quality research employing chronobiology and systems biology approaches is required to understand how HM components work independently and together to influence infant growth and to identify new avenues for future maternal, newborn, or infant nutritional interventions.

Human Milk Macronutrients and Child Growth and Body Composition in the First Two Years: A Systematic Review.

Among exclusively breastfed infants, human milk (HM) provides complete nutrition in the first mo of life and remains an important energy source as long as breastfeeding continues. Consisting of digestible carbohydrates, proteins, and amino acids, as well as fats and fatty acids, macronutrients in human milk have been well studied; however, many aspects related to their relationship to growth in early life are still not well understood. We systematically searched Medline, EMBASE, the Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born healthy infants. From 9992 abstracts screened, 57 articles reporting observations from 5979 dyads were included and categorized based on their reporting of HM macronutrients and infant growth. There was substantial heterogeneity in anthropometric outcome measurement, milk collection timelines, and HM sampling strategies; thus, meta-analysis was not possible. In general, digestible carbohydrates were positively associated with infant weight outcomes. Protein was positively associated with infant length, but no associations were reported for infant weight. Finally, HM fat was not consistently associated with any infant growth metrics, though various associations were reported in single studies. Fatty acid intakes were generally positively associated with head circumference, except for docosahexaenoic acid. Our synthesis of the literature was limited by differences in milk collection strategies, heterogeneity in anthropometric outcomes and analytical methodologies, and by insufficient reporting of results. Moving forward, HM researchers should accurately record and account for breastfeeding exclusivity, use consistent sampling protocols that account for the temporal variation in HM macronutrients, and use reliable, sensitive, and accurate techniques for HM macronutrient analysis.

Human Milk Bioactive Components and Child Growth and Body Composition in the First 2 Years: A Systematic Review.

Human milk (HM) contains macronutrients, micronutrients, and a multitude of other bioactive factors, which can have a long-term impact on infant growth and development. We systematically searched MEDLINE, EMBASE, Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born infants. From 9992 abstracts screened, 141 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Bioactives including hormones, HM oligosaccharides (HMOs), and immunomodulatory components are reported here, based on 75 articles from 69 unique studies reporting observations from 9980 dyads. Research designs, milk collection strategies, sampling times, geographic and socioeconomic settings, reporting practices, and outcomes varied considerably. Meta-analyses were not possible because data collection times and reporting were inconsistent among the studies included. Few measured infant HM intake, adjusted for confounders, precisely captured breastfeeding exclusivity, or adequately described HM collection protocols. Only 5 studies (6%) had high overall quality scores. Hormones were the most extensively examined bioactive with 46 articles (n = 6773 dyads), compared with 13 (n = 2640 dyads) for HMOs and 12 (n = 1422 dyads) for immunomodulatory components. Two studies conducted untargeted metabolomics. Leptin and adiponectin demonstrated inverse associations with infant growth, although several studies found no associations. No consistent associations were found between individual HMOs and infant growth outcomes. Among immunomodulatory components in HM, IL-6 demonstrated inverse relationships with infant growth. Current research on HM bioactives is largely inconclusive and is insufficient to address the complex composition of HM. Future research should ideally capture HM intake, use biologically relevant anthropometrics, and integrate components across categories, embracing a systems biology approach to better understand how HM components work independently and synergistically to influence infant growth.

The Impact of Homogenization on Donor Human Milk and Human Milk-Based Fortifiers and Implications for Preterm Infant Health.

An exclusive human milk diet (EHMD) has been shown to reduce health complications of prematurity in infants born weighing ≤1250 g compared with cow milk-based diets. Accordingly, the number of available human milk (HM)-based nutritional products continues to increase. Newly available products, and those reportedly soon to enter the market, include homogenized donor HM and homogenized HM-based fortifiers. Existing literature demonstrating the benefits of an EHMD, however, is limited to non-homogenized HM-based products. Herein, we summarize existing evidence on the impact of homogenization on HM, with a particular focus on changes to the macromolecular structure of the milk fat globule and the subsequent impact on digestion kinetics. We use these published data to create a conceptual framework for the potential implications of homogenized HM-based nutritional products on preterm infant health. Importantly, we underscore that the safety and efficacy of homogenized HM-based products warrant investigation.

Pumping supplies alter the microbiome of pumped human milk: An in-home, randomized, crossover trial.

BACKGROUND: The human milk microbiome may contribute to the benefits of breastfeeding by providing bacteria to the infant gastrointestinal tract. Many women pump their milk, but the effect of pumping on the milk microbiome is unknown. OBJECTIVES: Our objective was to determine the effects of pumping supplies on the pumped human milk microbiome. METHODS: This was an in-home, randomized, crossover trial of 2 collection methods. Women (n = 52) pumped twice within 3.5 h, once with their own breast pumps and milk collection supplies (OWN SUPP) and once with a hospital-grade pump and sterile collection supplies (STER SUPP). Pumping order was randomized. The milk microbiome was characterized by aerobic culturing and 16S ribosomal RNA gene sequencing. RESULTS: Milk collected with OWN SUPP yielded more total aerobic and gram-negative bacteria than milk collected with STER SUPP, reflecting a 6.6 (adjusted OR; 95% CI: 1.7, 25; P = 0.006) higher odds of containing >104 total aerobic CFU/mL and 19 (adjusted OR; 95% CI: 4.1, 88; P < 0.0001) higher odds of yielding culturable gram-negative bacteria. Milk collected with OWN SUPP yielded more Proteobacterias , including higher relative abundances of Acinetobacter and Stenotrophomonas, compared to milk collected with STER SUPP. Results were consistent across pumping-order groups. CONCLUSIONS: We demonstrated that pumping supplies altered the milk microbiome. On average, milk collected with OWN SUPP resulted in elevated levels of culturable total and gram-negative bacteria and proteobacterial DNA compared to milk collected with STER SUPP. More research is needed to assess implications for infant health.

Genome Sequences of Four Strains of Acinetobacter bereziniae Isolated from Human Milk Pumped with a Personal Breast Pump and Hand-Washed Milk Collection Supplies.

Acinetobacter bereziniae, formerly Acinetobacter genomospecies 10, is an opportunistic pathogen possessing resistance to multiple antibiotics, and it has been reported to be responsible for hospital-associated infections in immunocompromised individuals. We report the draft genome sequences of four Acinetobacter bereziniae strains that were isolated from a single human milk sample collected with a personal breast pump and a hand-washed milk collection kit.