Introduction:
Human milk consists of various useful microorganisms that benefit the infant's gastrointestinal tract. Many factors, such as genetics, maternal health and nutrition, delivery method, nursing, lactation stage, and geography, may affect the human milk microbiome. However, recent studies showed that the pumping of breast milk may also affect the composition of the human milk microbiome. Indirect breastfeeding using pumped milk may reduce the amount of good oral bacteria and sometimes may increase the amount of pathogenic or disease-causing microbes.
What Are the Organisms Present in the Human Milk Microbiome?
Initially, it was believed that the presence of bacteria in milk resulted from contamination, either from the newborn being exposed to the vagina or from the mother's skin coming into contact with the infant's mouth. Utilizing common visual and biochemical traits for species identification, bacterial culture techniques have been employed to analyze human milk microbiota composition. The majority of conducted investigations have determined that the most often and consistently found genera in human milk are Staphylococcus and Streptococcus. It's interesting to note that breastfed infants have higher levels of staphylococcus in their feces than formula-fed infants.
Staphylococcus and Streptococcus use oxygen when developing in the gut, fostering a favorable environment for the growth of advantageous anaerobic bacteria. Bifidobacterium, Faecalibacterium, and Akkermansia are a few anaerobes that have been found in human milk as well. They may lower the risk of disorders linked to dysbiosis by producing short-chain fatty acids.
What Are the Factors Affecting the Human Milk Microbiome?
Numerous bioactive components found in human milk, including bacteria, oligosaccharides, and other chemicals, play an important part in host-microbe interactions and the health of infants. Although the makeup of the milk microbiota has been better-understood thanks to new methods, little is known about the biological functions of bioactive substances in newborns. While several factors, such as genetics, maternal health and nutrition, delivery method, nursing, lactation stage, and geography, may have an impact on the human milk microbiome.
The enteric nervous system's cytokine production is controlled by microbes found in human milk, and mucosal immune functions are maintained. Maternal BMI (Body Mass Index) is one of the variable factors that can affect the microbiota composition of milk. The colostrum and mature milk of obese mothers have higher concentrations of Lactobacillus spp., Staphylococcus spp., and Akkermansia spp., respectively, with correspondingly lower concentrations of taxa from the phylum Bacteroidetes, Proteobacteria, and Firmicutes. Furthermore, a mother's diet may affect her gut microbiota, which in turn may affect the microorganisms in her milk and their vertical transmission to the infant.
While ingestion of polyunsaturated fatty acids and linoleic acid increases the number of bacteria of the Bifidobacterium genus, vitamin C is linked to an increase in Staphylococcus bacteria. B1, B2, and B9 vitamin ingestion can also affect the makeup of the bacteria in breast milk. Pregnant women who consume a lot of food high in calories have been demonstrated to have an increase in Firmicutes phylum organisms. There hasn't been much conclusive research on how probiotics and/or antibiotic use during pregnancy affect the makeup of the human milk microbiome.
Does Pumping Affect the Human Milk Microbiome?
Studies found that in comparison to direct breastfeeding, indirect breastfeeding via pumped milk is linked to the loss of oral bacteria and a greater quantity of possible pathogens. Even though it was once thought to be sterile, breastmilk currently has low bacteria. This complex community of bacteria in breast milk may aid in establishing the child's gut microbiota. However, the exact mechanisms by which the maternal microbiota influences the infant microbiota are yet to be understood. This process could be disturbed, changing the infant's microbiota and increasing the risk of obesity, allergies, and other chronic disorders. The determinants of milk microbiota are still largely understood, despite recent studies on human milk microbiota suggesting that various variables might influence it.
Indirect breastfeeding was linked to a higher number of potential opportunistic infections, such as Stenotrophomonas and Pseudomonadaceae. Indirect breastfeeding is defined as at least one serve of pumped milk in the two weeks prior. Increased contact with possible microorganisms in breast milk may raise the infant's risk of developing a respiratory infection, which may help to explain why babies who get pumped milk have a higher risk of developing pediatric asthma than babies who are breastfed exclusively.
Direct breastfeeding without using a pump was linked to greater levels of bacterial richness and diversity overall and microorganisms commonly seen in the mouth. Whereas indirect breastfeeding results in bacterial enrichment from the environment (associated with the pump), direct breastfeeding enhances newborns' oral microbiota acquisition.
Conclusion:
The composition of the human milk microbiota and the microorganisms that are transmitted to the infant through breastfeeding are influenced by several variables, including maternal health status and diet, gestational age, infant gender, mode of delivery, lactation stage, mode of feeding, geographic location, and social network density. However, studies suggest that the pumping of breast milk can also alter the composition of the human milk microbiome.
