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Anisa Arsenault
Associate Editor

The Anatomy of Baby Poop Is Changing—And That Might Not Be a Good Thing

Researchers are attributing it to three modern-day factors.
PUBLISHED ON 03/09/2018

If you’ve been a parent for literally a day, you already know that baby poop is crazy. Meconium—what is that?! And breastfed-baby poop—why does it smell sweet? There’s a ton of different types of baby poop, but a new study says one thing is consistent across the board: The pH of baby poop has changed a lot over the years.

Researchers with Evolve BioSystems say when the scientific community began publishing studies regarding the bacteria of infant feces in 1926, baby poop ranked at a 5.0 on the pH scale. That scale, which ranges from 0 to 14, measures how acidic or alkaline something is, with 0 being the most acidic and 14 being the most basic, or alkaline. Today, a 5 is still the norm in many countries worldwide, but in the US, it’s jumped to 6.5, brining it close to a neutral pH.

That might be a problem.

As the study, published in the journal mSphere, explains, an infant’s colon needs to be on the acidic side to promote the growth of good gut bacteria and inhibit the growth of pathogenic bacteria. Above all, today’s infants are probably low on Bifidobacterium, a group of good bacteria that breaks down milk and produces acids. As a result, there’s an increase in potentially harmful bacteria such as E. coli and Clostridia.

This rising imbalance in a baby’s gut microbiome can lead to health issues like digestive problems, colic, eczema, allergies, diabetes and obesity.

Why is this happening to babies in the United States? In a press release, study co-author Jennifer Smilowitz, PhD, Associate Director of the Human Studies Research Program for the Foods for Health Institute at UC Davis, explains the team’s theory.

“These alarming changes to the infant gut microbiome and thus, gut environment, may be due to modern medical practices like antibiotics, c-sections, and formula feeding,” she says. “These are all potentially life-saving medical practices, but have unintended consequences on the infant gut microbiome.”

In fact, after looking at 14 studies of breastfed babies published between 1926 and 2017, researchers were able to map out the periods of time when the pH of baby poop jumped the most: the 1940s and 1950s, when antibiotic use increased, and the 1980s, when c-section rates rose.

Photo: Evolve BioSystems

So what are we supposed to do about it? We’re not going to avoid antibiotics or c-sections when they’re medically necessary. Based on the results of a 2017 clinical trial, Evolve BioSystems suggests that administering baby a dietary version of B. infantis EVC001 (a particular species of Bifidobacteria) can stabilize a baby’s gut microbiome, bringing that poop pH back closer to 5.0. And its effects last for 30 days as long as the baby is breastfed. This dietary supplement currently exists in the form of an infant probiotic.

PHOTO: iStock