Nov. 5, 2025 — The secret to raising a more emotionally resilient kid might start in an unexpected place: their gut.
A new study in Nature Communications linked children’s gut bacteria from birth to age 2 with their risk of developing anxiety and depression symptoms up to five years later.
“There is a growing body of evidence that links early life gut microbiome development to many aspects of health, both in infancy and into adulthood,” said Christopher Stewart, PhD, professor of human microbiome research at Newcastle University in the U.K., who was not involved with the study.
Here’s what to know about the link between gut bugs and emotional health in kids.
Gut Clues to Emotional Health
Researchers analyzed data from a long-term study of 55 children that recorded stool samples at age 2, brain scans at age 6, and behavior surveys at age 7.5.
They found that 2-year-olds with more of certain kinds of gut bacteria — from the clostridiales order and lachnospiraceae family — were more likely to have emotional symptoms like feeling withdrawn, anxious, or sad several years later.
“Having a lot of internalizing symptoms early in life [is strongly correlated with] anxiety disorders later in development,” said study author Bridget Callaghan, PhD, associate professor of psychology at UCLA.
The study builds on previous research linking these bacterial groups — which include hundreds of species — to anxiety, depression, and inflammatory conditions such as inflammatory bowel disease. The brain scans showed that clostridiales and lachnospiraceae were associated with altered connectivity in emotion-related brain regions such as the amygdala, orbitofrontal cortex, and medial temporal lobe, said Callaghan.
The study doesn’t prove causation, just an association between gut bugs and brain connectivity, said Callaghan. Still, earlier research in animals suggests a direct link is possible. Gut bacteria create byproducts that can travel to the brain and influence how it functions.
“The gut microbiome is like a big chemical kitchen creating all these different metabolites and products,” Callaghan said. These include “neuroactive chemicals” — like short-chain fatty acids, hormones, and neurotransmitters — that can influence brain development and communication. Some cross the blood-brain barrier, a layer of cells that protects the brain from toxins, while others send messages to the brain via the bloodstream, nerves, or immune system.
The gut-brain connection affects people of all ages, but it may be especially important in early childhood, when both the microbiome and brain are developing quickly.
“The gut microbiome and the brain have these sensitive periods that overlap,” she said. During these periods, “they may be particularly important for shaping one another and shaping the type of connectivity that they have.”
How Anxiety Affects the Gut
The gut-brain connection goes both ways. If your kid gets a stomachache when they’re dealing with tough emotions, pay attention. Anxiety or unexplained stomach issues in children may stem from stress or environmental factors, not just a medical gastrointestinal problem, though it’s still important to have serious issues checked, Callaghan said.
Fear and worry can be normal. But if internalizing symptoms or anxiety affects your child’s ability to function, early intervention is key.
“If we can get children the help that they need, usually through therapy at this age, then that can be really quite transformative in the life of the child,” said Callaghan.
How to Optimize a Kid’s Microbiome
More research is needed to uncover which clostridiales and lachnospiraceae species do what. And it’s too early to target specific bugs For now, focusing on building a healthy community of gut bugs is key, said Callaghan. Here’s what can help:
Breastfeed your baby. Breast milk contains sugars that help beneficial gut bacteria thrive, Callaghan said. The ideal is exclusive breastfeeding for at least six months, followed by a combination of solids and breast milk, says Stewart. The American Academy of Pediatrics recommends continuing breastfeeding as long as mother and baby desire, for two years or beyond.
If breastfeeding isn’t possible, don’t stress — your health and happiness are important for your child’s well-being, too. “All these recommendations are in the best-case scenario,” Callaghan said. “But really, it is a tradeoff between the number of things that we know impact an infant’s health, and part of that is mom's wellness.”
Introduce fruits and vegetables early and often. Pregnant mothers who eat more fruits and vegetables tend to have infants with healthier gut microbiomes and lower counts of clostridiales and lachnospiraceae, research suggests.
When your child starts solid foods, emphasize a variety of fiber-rich fruits and vegetables. “Trying to expose them to a diverse diet is really helpful,” said Callaghan. For picky eaters, she suggests blending leafy greens into foods they like.
Let your kid play in the dirt. “Encourage regular exercise and lots of time outdoors, including playing in the mud and getting dirty,” said Stewart. Outdoor play has been linked to lower stress and anger in preschoolers and a healthier gut microbiome. Exposure to bacteria in nature may promote growth of gut bugs that produce serotonin, a neurotransmitter involved in mood regulation.
Keep junk food to a minimum. Sugary, ultra-processed foods have been linked to gut bacteria changes associated with mood disorders such as anxiety and depression.
Don’t rely on supplements. While it’s “plausible” that probiotic supplements could help young kids optimize their gut microbiome for mental health, there is no one-size-fits-all product. “We are still a long way from knowing what the best probiotics would be for the right person, in the right amount, at the right time,” said Stewart. “In the meantime, I would be wary of any product claiming otherwise.”
What’s Next
Researchers have more questions to explore. “We're still really scratching the surface of what there is to know about the way that the microbiome is associated with emotional health and the brain,” said Callaghan.
And while gut bacteria appear to play a role, tried-and-true techniques for supporting children’s mental health, such as modeling coping skills and setting routines, remain critical.
“The microbiome is one piece of a very large puzzle that is human mental health,” said Callaghan. “Overemphasizing the microbiome alone is not the right way for the field to go, but it is a helpful piece of the puzzle. Any kind of traction we can get in understanding mental health is important.”
