The gut microbiome has been getting a lot of attention in the past decade. It is made up of bacteria, archaea, and fungi which all play a critical role in the body’s immune system. Specific diets and medications have been used to boost the bacteria in the gut. In cancer research it has been shown that certain bacteria in the gut can dictate response to therapy and there is currently research being conducted to pair specific gut microbiomes with immunotherapy.
Mammals have evolved to provide nutrients to their offspring through breast milk. It is critical for babies to receive these nutrients in one form or the other. Breast milk also contains hormones, enzymes, antimicrobials, and growth factors, all needed to properly develop. Many proteins necessary for proper energy and nutrients are in breast milk including casein and milk fat globule membrane proteins. These proteins also help stimulate immunity in the context of preclinical conditions. While we know how beneficial these nutrients are for newborns, it is unclear the beneficial extent of these proteins. It is now suggested that immunity-boosting nutrients in breast milk might have two superior functions: stimulating the immune system directly and indirectly through gut microbe regulation.
Researchers lead by Dr. Ignatius Man-Yau Szeto at the Yili Maternal and Infant Nutrition Institute in Beijing, China recently reported evidence of immune-regulating function of breast milk proteins. For the first time, researchers have shown a varied composition of proteins in breast milk with key microbes beneficial to the gut in babies, recently published in Frontiers in Microbiology. This composition further suggests that these proteins have a regulatory role in immune function critical for early immunity and metabolic development.
Szeto and colleagues analyzed the protein composition in breast milk of 23 women and in the stool of their newborn babies. They focused on nine proteins including osteopontin, lactalbumin, and k-casein due to their roles in newborn development. However, their complete roles and functional mechanisms have not been completely identified, which Szeto and their team are currently working to discover.
The protein concentration in breast milk was 1.6% 42 days after delivery compared to 1.2% 3-months after delivery. The most abundant proteins included casein, α-lactalbumin, and lactoferrin. Most proteins were reduced between 42 days and 3 months after delivery or post-partum. They additionally found that the microbiome in babies were composed of bacterial genera Bifidobacterium, Escherichia, Streptococcus, and Enterobacter. Interestingly, researchers found strong correlations between breast milk protein concentrations and two beneficial bacteria known to be rare in newborn babies: Clostridium butyricum and Parabacteroides distasonis, which are both used as human probiotics.
Szeto and colleagues demonstrated that varied composition of proteins in breast milk can influence specific gut microbes in newborn babies that play a key role in early immunity. This research can inform physicians which protein are necessary for a healthy gut in humans. Additionally, it has the potential to inform companies which proteins to include in formula for mothers that cannot breast feed their children. Overall, this work helps better inform both physicians and mothers which nutrients are critical for healthy human development.
Reported, Yili Maternal and Infant Nutrition Institute, Frontiers in Microbiology