When a baby is first born, its digestive tract is nearly virgin territory. They haven’t interacted with the outside world having been fed through an umbilical cord and protected by amniotic fluid. But that changes quickly, as trillions of bacteria move in to set up shop, coming primarily from contact with the mother’s skin, birth canal and gut. And unsurprisingly, it’s now been confirmed that the baby’s first food, breast milk, can play a big role in how that colonization plays out.
Establishing healthy cultures in your gut
We depend on bacteria in our digestive systems to help eat our food as well as keep us healthy by either consuming or blocking less-helpful pathogens from taking root in our guts and making us sick. Bifidobacteria is one such species that protects us from nastier microbes, lowering the pH level in our gut to make it less habitable for unwanted bacteria. It’s also commonly one of the first microbes to take up residence in infant digestive tracts, largely thanks to breast milk.
Feeding the baby and the bacteria
Breast milk is a complex formula, with a recipe that is different for every mother making it. A variety of genes play a role in shaping it, and one, FUT2, has now been isolated as making a particular sugar that encourages Bifidobacteria growth. It appears to be critical to this process, as mothers with mutations to FUT2 that lead to less sugar production had babies with less Bifidobacteria in their guts.
The babies often did acquire more Bifidobacteria later on, so it’s not clear if this is necessarily a key to being a healthy infant. But it does help decipher some of the ingredients in human milk and what role they play in infant health.
Source: Bundle Of Joyful Microbes: Mom's DNA Alters Baby's Gut Bacteria by Michaeleen Doucleff, Shots