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Want a healthy gut? Exposures in first year of life have long-lasting effects

A healthy gut microbiome will help keep harmful diseases at bay.
Michael DeForge for NPR
A healthy gut microbiome will help keep harmful diseases at bay.

When a baby is born, their gut microbiome — the bacteria, viruses, fungi, protists and other single-celled organisms that live in the intestines and the stomach — is quite similar to the next infant’s.

It’s not until they hit three months of age that gut bacteria begin to differ from one child to the next. And those differences often run along racial and ethnic lines. That’s according to a new study by Liz Mallott, an assistant professor of biology at Washington University.

“Something happens, either at three months or shortly after, where you do start to see a slight divergence in the gut microbiome between Black, white, Asian Pacific Islander kids, Hispanic and non-Hispanic kids,” she said. “The taxa that diverge are taxa we know we acquire from the environment. They aren't bacteria species that are inherited from your mom … so it really is something in the external environment that must be driving the change.”

Differences in gut microbiomes early in life can have a lasting effect. Poor gut health leaves people at risk of developing Type 2 diabetes, severe asthma or other lung illnesses.

“[Microbes] are also involved in regulating our blood sugar and our blood pressure. They can increase or decrease inflammation. And they also protect us from pathogens,” Mallott said.

Pinpointing when young kids develop unique gut bacteria is important because it helps researchers determine what social and environmental factors might cause such differences.

“There are things like exposure to pollution, whether or not a kid is in day care or is cared for by family members or has a nanny, the introduction of different foods early in life — all of those could be driving these differences,” Mallott said.

Uncovering specific environmental factors is the next major research question. For now, Mallott advises that parents of newborns and young children expose their kids to as many different situations — and yes, germs — as possible.

Liz Mallott
Emily Woodbury
Liz Mallott is an assistant professor of biology at Washington University.

“It sounds cliché, but [make] sure your child gets a lot of time outside, playing in the dirt so they're exposed to a lot of different microbes, as well as having a lot of different social contacts. Interacting with a lot of different friends and family seems to be really important,” she said. “There are some studies coming out that were done during the pandemic that showed that having fewer social contacts is really detrimental to the microbiome.”

To learn more about Mallott’s work and what you can do to promote a healthy gut microbiome, listen to St. Louis on the Air on Apple Podcast, Spotify or Google Podcast, or by clicking the play button below.

Liz Mallott joins "St. Louis on the Air"

St. Louis on the Air” brings you the stories of St. Louis and the people who live, work and create in our region. The show is produced by Miya Norfleet, Emily Woodbury, Danny Wicentowski, Elaine Cha and Alex Heuer. Ulaa Kuziez is our production intern. The audio engineer is Aaron Doerr. Send questions and comments about this story to talk@stlpr.org.

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Emily is the senior producer for "St. Louis on the Air" at St. Louis Public Radio.