Implications of infant feeding practices on the development of the oral microbiome

Aside from the gut, the oral microbiome is the most diversified bacterial ecosystem in the human body and contributes to oral and systemic health. Disruptions in the oral microbiome have been linked to dental caries, periodontal disease, and systemic diseases such as diabetes. The development of the oral microbiome happens early in life, so analyzing the feeding practices of infants is important in understanding how they contribute to development. Environmental factors, tooth eruption, and diet also contribute to the health of the oral microbiome.

The World Health Organization recommends breast milk as the sole food source in early infancy. The nutritive benefits of breast milk include beneficial microbes, human milk oligosaccharides (HMOs), operational taxonomic units (OTUs), and antimicrobial proteins, all of which are necessary in developing a healthy gut.¹ Do infants fed with breast milk have an advantage over formula-fed infants in developing a healthy oral microbiome?

Comparing breastfed and formula-fed infants

Authors Arishi et al. evaluated evidence from several scientific publications to understand the development of the oral microbiome centering on how breastfeeding and early infant diet can affect the development process.¹ Breastfeeding was found to be a major determining factor in the development of the oral microbiome. The difference between breastfed infants and formula-fed infants can be seen within the first 24–48 hours of life. Infants who are exclusively breastfed foster a more diverse bacterial profile than infants who receive formula or a combination of breast milk and formula. This can be attributed to breast milk containing a million bacterial cells that breastfed infants are exposed to, many of which colonize in the oral cavity.

Breast milk is not only rich in bacteria, but it also contains HMOs, which are complex glycans that have prebiotic properties and can act as decoy receptors for pathogens. Also found in breast milk are short-chain fatty acids (SCFAs) and antimicrobial proteins. SCFAs are impactful to host health in several ways. They provide energy for colonocytes, helping maintain colon health, as well as regulate glucose homeostasis and have antitumor and anti-inflammatory effects. Antimicrobial proteins such as lactoferrin exhibit antibacterial, antiviral, and antifungal properties. They are effective in breaking down the cell wall of gram-negative bacteria and combating oral conditions such as halitosis, gingivitis, xerostomia, and even alveolar bone damage.

The oral microbiome of an infant who remained partially breastfed up to 24 months differed significantly from those who stopped breastfeeding by 12 months. Infants who stopped breastfeeding before 12 months harbored a greater abundance of Porphyromonas, known for its role in periodontitis, leading to gingival destruction and tooth loss. The difference in bacterial communities of breastfed infants was long-lasting and still detected at seven years of age.¹

Authors Neyraud et al. conducted a longitudinal analysis spanning the first year of an infant’s life, studying the effects breast milk and formula had on salivary metabolome.² They split 32 analyzed samples into two groups: 19 infants who were strictly breastfed, and 13 who had formula only or a combination of formula and breast milk. Results showed a difference between metabolites at different collection stages but not between the two groups. The authors speculate that these results were attributed to other oral events occurring during these stages, such as tooth eruption and the introduction of solid foods. Another contributing factor is the age of the participants. A previous study showed the largest difference in oral bacterial composition between breastfed and formula-fed infants was found between 24 months and 7 years of age. Little difference was seen between three and 12 months, which was the span of this study. Authors concluded that between the two feeding types, no significant difference in metabolites was shown, but they noted that due to the individual variability in breastfeeding and solid food practices, the possible impact of feeding type could not be excluded.

Breastfeeding and the oral microbiome

The studies presented focused on infant feeding practices and their impact on the oral cavity. Solid foods were found to have a significant contribution to the oral microbiome, but infants who were breastfed were found to have a more diverse bacterial profile. While the authors could not control all variables of the mother’s or the infant’s diets, they agreed that breastfeeding has an advantage when the oral microbiome is formed.

Oral microbiome and systemic health

In conclusion, having a healthy oral microbiome is paramount to the overall well-being of an individual. The direct link of the oral microbiome to the gut microbiome suggests that the health of one of these ecosystems has a direct effect on the other. Evidence supports that human breast milk is rich in bacteria, HMOs, OTUs, fatty acids, and antimicrobial proteins. All of these contribute to healthy oral and gut microbiomes. As it stands, breastfeeding is the recommended feeding method by the World Health Organization. Dental hygienists should be prepared to discuss the benefits of breastfeeding and its impact on the oral and gut microbiomes with expecting parents.

References

1. Arishi RA, Lai CT, Geddes DT, Stinson LF. Impact of breastfeeding and other early-life factors on the development of the oral microbiome. Front Microbiol. 2023;14:1236601. doi:10.3389/fmicb.2023.1236601
2. Neyraud E, Schwartz C, Brignot H, et al. Longitudinal analysis of the salivary metabolome of breast-fed and formula-fed infants over the first year of life. Metabolomics. 2020;16(3):37. doi:10.1007/s11306-020-01661-7