Xiang Study: an association of breastmilk composition with maternal body mass index and infant growth during the first 3 month of life

Maternal adiposity moderates associations between dietary, serum, and human milk n-3 and n-6 PUFA

Overweight and obesity can alter the composition of human milk, including the fatty acid (FA) profile into more proinflammatory state. It is uncertain whether this is due to poor diet quality or the negative effects of obesity on FA metabolism. We examined the associations between dietary, serum, and human milk FA in mothers with normal and excessive body weight and investigated whether adiposity moderates the observed associations. A case-control study was conducted among 40 mothers (20 healthy weight (HW), 20 overweight/obese (OW/OB) 15.5 ± 1.2 weeks postpartum, matched by lactation duration and age. Dietary intake was analyzed based on 3-day food records, and adiposity was assessed by dual-energy X-ray absorptiometry (DXA), serum and human milk FA analyzed by gas chromatography (GC). Overweight/obese mothers had higher dietary and serum trans FA but lower serum arachidonic acid (AA) and human milk docosahexaenoic acid (DHA) compared to normal-weight mothers. Mediation analysis indicated that serum partially mediated the effect of dietary linoleic acid (LA), polyunsaturated fatty acid (PUFA) n-3, and alpha-linolenic acid (ALA) on human milk FA. Adiposity were found to negatively impact the dietary-to-human milk FA association but positively impact serum-to-human milk association. The obesity-related differences in human milk FA profile were not due to dietary differences. Our results suggest human milk PUFA levels may be influenced more by long-term diet than short-term intake, indicating a need for specific dietary guidelines for mothers with higher adiposity to minimze proinflammatory alterations in human milk composition.

Breast Milk Macronutrient Content and Its Effects on Infant Anthropometric Measurements in the First 6 Months: A Systematic Review and Meta-Analysis

PURPOSE

The aim of the study is to determine the effect of the macronutrient content of breast milk on the anthropometric measurements of infants in the first 6 months.

BACKGROUND

Breast milk contains essential macro- and micronutrients needed in the early stages of an infant's development. Current literature highlights the importance of understanding how breast milk's macronutrient content influences infant growth.

METHODS

The study protocol has been published in PROSPERO (CRD42023425550). This study adheres to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guideline. Studies published between January 1, 2016, and June 2, 2023, were reviewed across 6 databases. The Joanna Briggs Institute Cohort Studies checklist was used to assess methodological quality. Effect sizes were calculated using both fixed-effects and random-effects models.

RESULTS

Six studies were included in the systematic review and meta-analysis. The meta-analysis indicated a significant relationship between lactose content in breast milk and infant weight gain, length growth, and head circumference, as well as between fat-lipid content and infant weight gain within the first 6 months (P < .05). No significant relationship was found between protein or carbohydrate content of milk and anthropometric measurements of infants in the first 6 months (P > .05).

CONCLUSION AND IMPLICATIONS

The findings suggest that macronutrient concentrations in breast milk are important determinants of infant growth. Further research with high level of evidence and standard methodological protocols is recommended to elucidate the relationships between breast milk content and infant growth.

Maternal Nutrition and Human Milk Nutrients: A Scoping Review

PURPOSE

To explore the influence of maternal nutrition factors, including body mass index, nutritional supplementation, and dietary intake during the breastfeeding period, on macro and micronutrient composition in human milk.

STUDY DESIGN AND METHODS

We conducted a scoping review using the PRISMA-ScR checklist, initially identifying 5,984 original studies published in the English language from PubMed, Scopus, and Web of Science that presented findings on the association of maternal nutritional factors on human milk nutrient composition. After screening the title and abstract, we selected 69 studies for full review, including 3 studies found through checking reference lists. After full review, we included 23 studies in this scoping review.

RESULTS

Most studies found maternal body mass index and supplement consumption affected human milk macro and micronutrient composition, whereas inconsistent results were found on the relationship between maternal diet and human milk nutrients. Methodologies varied substantially across studies, especially for milk sample collection methods and maternal nutrition assessments.

CLINICAL IMPLICATIONS

Maternal nutrition factors may affect levels of human milk nutrients, requiring maternal nutrition monitoring during breastfeeding. However, given the considerable variability in the results between studies and methodological approaches, further studies should use standardized and validated procedures to strengthen the findings on this topic.

The association between maternal body mass index and breast milk composition: a systematic review

CONTEXT

Breast milk composition is influenced by many factors, ranging from maternal nutritional status to infant sex. Previous studies have explored the relationship between maternal body mass index (BMI) and breast milk composition; however, the findings have been inconsistent and controversial.

OBJECTIVE

To systematically review the evidence on the association of maternal weight and BMI with breast milk composition.

DATA SOURCES

The PubMed and Scopus databases were searched up to May 3, 2023, using the following search strategy: ("maternal weight" OR "maternal BMI" OR "mother's weight" OR "mother's BMI") AND ("maternal milk" OR "human milk" OR "breast milk").

DATA EXTRACTION

A total of 83 publications, involving data from more than 11 310 lactating women, were identified. All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

Overall, maternal BMI was associated with higher levels of leptin and insulin, and the ratio of omega-6 to omega-3 polyunsaturated fatty acids in breast milk. However, no conclusive associations were found between maternal BMI and the levels of energy, macronutrients, micronutrients, and other components of breast milk.

CONCLUSIONS

This systematic review provides robust evidence supporting a positive correlation between maternal BMI and breast milk concentrations of leptin, insulin, and the omega-6 to omega-3 polyunsaturated fatty acid ratio. Nevertheless, disparities in findings are noticeable for other constituents of breast milk. To comprehensively grasp the influence of maternal weight and BMI on breast milk composition, further research endeavors are imperative.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023458667.

Metagenomic assessment of the bacterial breastfeeding microbiome in mature milk across lactation

Introduction

Research has illustrated the presence of a diverse range of microbiota in human milk. The composition of the milk microbiome varies across different stages of lactation, emphasizing the need to consider the lactation stage when studying its composition. Additionally, the transfer of both milk and skin microbiota during breastfeeding is crucial for understanding their collective impact on infant health and development. Further exploration of the complete breastfeeding microbiome is necessary to unravel the role these organisms play in infant development. We aim to longitudinally assess the bacterial breastfeeding microbiome across stages of lactation. This includes all the bacteria that infants are exposed to during breastfeeding, such as bacteria found within human milk and any bacteria found on the breast and nipple.

Methods

Forty-six human milk samples were collected from 15 women at 1, 4, 7, and 10 months postpartum. Metagenomic analysis of the bacterial microbiome for these samples was performed by CosmosID (Rockville, MD) via deep sequencing.

Results

Staphylococcus epidermidis and Propionibacteriaceae species are the most abundant bacterial species from these samples. Samples collected at 10 months showed higher abundances of Proteobacteria, Streptococcaceae, Lactobacillales, Streptococcus, and Neisseria mucosa compared to other timepoints. Alpha diversity varied greatly between participants but did not change significantly over time.

Discussion

As the bacterial breastfeeding microbiome continues to be studied, bacterial contributions could be used to predict and reduce health risks, optimize infant outcomes, and design effective management strategies, such as altering the maternal flora, to mitigate adverse health concerns.

An expert panel on the adequacy of safety data and physiological roles of dietary bovine osteopontin in infancy

Human milk, due to its unique composition, is the optimal standard for infant nutrition. Osteopontin (OPN) is abundant in human milk but not bovine milk. The addition of bovine milk osteopontin (bmOPN) to formula may replicate OPN's concentration and function in human milk. To address safety concerns, we convened an expert panel to assess the adequacy of safety data and physiological roles of dietary bmOPN in infancy. The exposure of breastfed infants to human milk OPN (hmOPN) has been well-characterized and decreases markedly over the first 6 months of lactation. Dietary bmOPN is resistant to gastric and intestinal digestion, absorbed and cleared from circulation within 8-24 h, and represents a small portion (<5%) of total plasma OPN. Label studies on hmOPN suggest that after 3 h, intact or digested OPN is absorbed into carcass (62%), small intestine (23%), stomach (5%), and small intestinal perfusate (4%), with <2% each found in the cecum, liver, brain, heart, and spleen. Although the results are heterogenous with respect to bmOPN's physiologic impact, no adverse impacts have been reported across growth, gastrointestinal, immune, or brain-related outcomes. Recombinant bovine and human forms demonstrate similar absorption in plasma as bmOPN, as well as effects on cognition and immunity. The panel recommended prioritization of trials measuring a comprehensive set of clinically relevant outcomes on immunity and cognition to confirm the safety of bmOPN over that of further research on its absorption, distribution, metabolism, and excretion. This review offers expert consensus on the adequacy of data available to assess the safety of bmOPN for use in infant formula, aiding evidence-based decisions on the formulation of infant formula.

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.