So we all know that our guts are home to billyuns and billyuns of helpful microorganisms, which help us do stuff like, say, digest food. My question is: how do they get there? Are we born with them, or do we acquire them through the food we eat? And if the latter, how does our body ensure that only the “good” ones survive and we don’t get some awful intestinal infection instead? Or am I labouring under some sort of misconception?
Our guts are sterile when we are born. The bacteria that colonize there come in with the food we eat.
They do not help digest the food we eat, BTW. All the food is digested by the small intestine before it gets to the large intestine. The bacteria work only on undigested food, whether it’s fiber or lactose or oligosaccharides or whatever else doesn’t get digested by the normal intestinal enzymes.
The good bacteria get a long head start because babies are unlikely to eat any foods that contain harmful bacteria. Mother’s milk won’t contain any nor will modern day formulas.
Most foods don’t contain harmful bacteria in the first place, if one is eating a normal diet. And even if one does, there’s a big difference between eating them and having them colonize the colon.
Its the intestinal fauna that I worry about.
Don’t infants also get beneficial bacteria from mother’s milk? I had heard this is one reason breast-fed babies may be healthier, but it is hard to wade through the pro- and anti- breastfeeding propoganda out there, some of it pretty militant.
Antibodies, not bacteria. The might pick up some skin bacteria from the nipple area.