Research continues to connect the dots between the relationship of the intestinal microbiome and health. Pediatric longitudinal studies, where participants are followed over time, allow a better understanding of how microbes play a role in this. Imbalances in intestinal bacteria, known as dysbiosis, are linked to the etiology of various neurological, immune, and metabolic disorders [1].
One factor that influences microbes during infancy is nutrition source. Breast milk plays a crucial role in establishing the makeup of the microbiome and reducing susceptibility to certain diseases [2]. Although there may be times when breast milk is not an option, the positive correlation with health prompts serious consideration of providing it to infants when possible.
Human Milk Oligosaccharides
Human milk oligosaccharides (HMOs) are complex sugars found in breast milk [3]. They contribute to developing an infant’s microbiome by serving as a prebiotic source for beneficial bacteria such as bifidobacteria. HMOs are resistant to the low PH found in an infant’s stomach. They are unique in their ability to reach the small intestine and colon intact, where they help shape microbial groups. They serve various beneficial roles by exerting antimicrobial effects, competing with pathogens, disrupting parasitic adhesion, and reducing the risk of bacterial-acquired diarrhea [3]. Whether or not an infant receives breast milk plays a role in the variability of bacteria within the microbiome and susceptibility to disease [4].
Breast Milk or Formula – What’s the Difference?
Breast milk contains many immune-enhancing components including HMOs, secretory immunoglobulin A, and lactoferrin [5]. These are not only critical for immune resiliency but also neurocognitive development. Formula manufacturers try to mirror the nutrients found in breast milk, however, factors such as shelf-life stability and bioavailability make this difficult. Due to the structural difference in formula, bacterial strains associated with positive health benefits such as bifidobacteria are less abundant in formula-fed infants [2]. Specifically, the Bifidobacterium genus is involved in immune resiliency, intestinal mucosa integrity, and protection from infection [3].
Infant Microbiome and Health
Imbalances in gut flora are often affiliated with various childhood ailments to include autism, helicobacter pylori infection, failure to thrive, nutritional disorders, and inflammatory bowel conditions [6]. Dysbiosis can also play a role in the development of various diseases such as atopic dermatitis and asthma in children [7]. Aside from nutrition (breast milk or formula), factors such as the method of delivery and antibiotic exposure early in life also play a role in shaping the microbiome and susceptibility to disease [8],[9], [10].
Summary
The study of the microbiome is a complex topic that continues to evolve. There is a much greater appreciation for how our microbial composition influences health. Breast milk, among other factors, plays an influential role in laying a foundation for a healthy infant microbiome and susceptibility to developing various illnesses.
References
1. Donaldson, G P et al. “Gut microbiota utilize immunoglobulin A for mucosal colonization.” Science (New York, N.Y.) vol. 360,6390 (2018): 795-800. doi:10.1126/science.aaq0926
2. Bäckhed, Fredrik et al. “Dynamics and Stabilization of the Human Gut Microbiome during the First Year of Life.” Cell host & microbe vol. 17,5 (2015): 690-703. doi:10.1016/j.chom.2015.04.004
3. Milani, Christian et al. “The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota.” Microbiology and molecular biology reviews : MMBR vol. 81,4 e00036-17. 8 Nov. 2017, doi:10.1128/MMBR.00036-17
4. Roswall, Josefine et al. “Developmental trajectory of the healthy human gut microbiota during the first 5 years of life.” Cell host & microbe vol. 29,5 (2021): 765-776.e3. doi:10.1016/j.chom.2021.02.021
5. Institute of Medicine (US) Committee on the Evaluation of the Addition of Ingredients New to Infant Formula. Infant Formula: Evaluating the Safety of New Ingredients. Washington (DC): National Academies Press (US); 2004. 3, Comparing Infant Formulas with Human Milk. Available from: https://www.ncbi.nlm.nih.gov/books/NBK215837/
6. Saeed, Nermin Kamal et al. “Gut microbiota in various childhood disorders: Implication and indications.” World journal of gastroenterology vol. 28,18 (2022): 1875-1901. doi:10.3748/wjg.v28.i18.1875
7. Shao, Yan et al. “Stunted microbiota and opportunistic pathogen colonization in caesarean-section birth.” Nature vol. 574,7776 (2019): 117-121. doi:10.1038/s41586-019-1560-1
8. Bokulich, Nicholas A et al. “Antibiotics, birth mode, and diet shape microbiome maturation during early life.” Science translational medicine vol. 8,343 (2016): 343ra82. doi:10.1126/scitranslmed.aad7121
9. Stokholm, Jakob et al. “Cesarean section changes neonatal gut colonization.” The Journal of allergy and clinical immunology vol. 138,3 (2016): 881-889.e2. doi:10.1016/j.jaci.2016.01.028
10. Yassour, Moran et al. “Natural history of the infant gut microbiome and impact of antibiotic treatment on bacterial strain diversity and stability.” Science translational medicine vol. 8,343 (2016): 343ra81. doi:10.1126/scitranslmed.aad0917
11. News Medical Life Sciences. (2024). The Microbiome of a Newborn. [Photograph]. Received from https://www.news-medical.net/health/The-microbiome-of-a-newborn.aspx Assessed and Endorsed by the MedReport Medical Review Board