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Study: Breast milk helps babies develop immunity-boosting gut bacteria

Gut bacteria, the microorganisms that live in your digestive tract, are all the rage these days. Connected to everything from mood to asthma to waistlines, yogurt makers are adding them to products as “probiotics,” and one company has even turned them into a $1.9 billion business by trying to develop them into medicine.

Gut bacteria and the communities they form, called microbiota, are important for infants’ health too, and a new study in Science says that breast milk is part of the equation. Newborn infants are exposed to bacteria from a number of sources, which vary depending on everything from the kind of birth (Cesarean vs. vaginal) to the people and animals that the baby is exposed to, as well as what the baby is fed after it is born.

Understanding more about baby gut bacteria can have huge implications for infant health. For example, the right amount of Bifidobacterium, a “major member of the infant gut community” identified over 40 years ago, can give an infant the fuel she needs, build her immune system, or keep pathogens at bay. How much of that bacteria is found in a baby’s gut is linked to the level of oligosaccharides, a chain of simple sugars, in the mother’s breast milk, studies have found.

The Science study, however, recognizes how much work is left to be done on this front. While a prior study found that mothers from populations that are “Western, educated, industrialized, rich, [and] democratic” (“WEIRD”) have a gene that influences their oligosaccharides, it is still unclear, for example, how the baby’s own genes play into with that. And while preliminary studies have shown that babies being fed probiotics and breast milk have lower risks of neonatal mortality, the researchers call for further research into how the use of probiotics, prebiotics (carbohydrates that probiotics feed on) and breastmilk can improve babies’ gut bacteria, and therefore, their health.