Human milk oligosaccharides (HMOs) establish and select for a strong population of beneficial bacteria in the infant gut.

“Role of HMO's in infant gut microbiome”

“So this is the baby's diet and diet we know is the basically, one of the major levers to control this community. So babies that are fed formula, their mircrobiota looks very different than breast mil. Actually, what we see is breast milk has a component of it, one of the major component of breast milk is this type of carbohydrate called human milk oligosaccharides or HMOs. For a long time it was really a mystery why those molecules where there because we knew that humans can digest human milk olisaccharides. So why would a mother put so much effort into creating these compounds and putting them in our milk if her baby can't even digest it. Well come to find out it's actually the gut microbes that are digesting these HMOs. So in breast milk there's just not food for the baby in form of lactose and fat, but these HMOs that are food for the baby's growing microbiota so the mother's feeding the baby and also her baby's growing microbiota.”

“these hmos are very specific for human milk and so far have not been able to be replicated in formula and so that we think is a large reason why the communities are so different”

“they aren't there to feed the baby instead hmos have a very special purpose which is setting up and feeding and ultimately creating the conditions to select for a strong population of commensal in other words healthful bacteria in the infant gut”

“these good bacteria then go on to help set up the immune system through the production of various signaling molecules such as short chain fatty acids which are metabolites produced from the gut bacteria after they metabolize the hmos these substances prevent colonization of pathogenic bacteria in the gut”

“the second largest concentration of carbohydrates in human breast milk are non-nutritive components called human milk oligosaccharides or hmos for short so let's talk about hmos a fascinating part of the story of breast milk hmos are complex indigestible sugars more than 200 different hmos have been identified in breast milk making them the third most abundant factor in human breast milk after lactose in fat these things are super abundant but here's the surprising part they aren't there to feed the baby instead hmos have a very special purpose which is setting up and feeding and ultimately creating the conditions to select for a strong population of commensal in other words healthful bacteria in the infant gut”