They don’t make baby poop like they did in 1926, that’s for sure. Here’s why scientists care.

Our stool is a window into the health of our guts.

By Claire Maldarelli

Most of us do our best not to think too much about baby poop. But, as it turns out, stool has a lot more power than we think—and not just in terms of its pungent smell. Our poops can say a lot about our health, and that’s true from the first time we soil a diaper.

Recently, researchers have found that the bacteria that live inside our guts—known as the microbiome—are crucial to keeping us healthy. But understanding which bacteria help and which hurt—and how we can maintain a gut full of “healthy bacteria”—is still something that scientists are figuring out. Studying an infant’s stool might be a key way to do so.

During the first year of life, as a baby is growing, their intestines are fostering a nursery of bacteria. Those microbes are important in that they help to digest food and create a healthy immune system. But our microbiomes may not be as healthy as they once were. Back in December of last year, a group of researchers investigated whether they could replace a key species of good bacteria known as Bifidobacterium infantis in the guts of babies who lacked them. They could, but found that when they did so the pH of those infants’ stools changed drastically, becoming more acidic. Adding those bifidobacterium back made the infants’ guts more normal, so the researchers presumed that a lower stool pH might indicate a gut full of the right microbes.

To figure that out, the researchers looked back at studies from 1926 to 2017 that had analyzed the pH of infant stool (apparently, scientists have been interested in the pH of infant stool for a while) to see if they could identify any trends. The results, published last week in the journal mSphere, show that over the past 100 years, infant stool pH has gone up (meaning that it has become more basic)—changing from an average reading of 5.0 to 6.5. (For reference, the more acidic something is, the lower its pH and the more basic, the higher the pH. Pure water is a neutral 7.0).

That seems like a small increase, but it’s actually quite significant for a scale that only goes from zero to 14. But okay, our babies’ poop pH has gone up. Is that such a big deal?

The researchers think that this change in pH could be because we have slowly lost that specific strain of bacteria, Bifidobacterium, from our guts. Since mothers pass their gut microbiomes on to their babies when they are born, its disappearance in an adult can lead to a brood of bifidobacterium-less kids...Read more on Popular Science