Early exposure to antibiotics might increase a kid’s risk of asthma by altering their gut bacteria, a new mouse study finds.

Antibiotics could specifically lower gut production of indole propionic acid (IPA), a biochemical that's crucial to long-term protection against asthma, researchers reported July 15 in the journal Immunity.

“We have discovered that a consequence of antibiotic treatment is the depletion of bacteria that produce IPA, thus reducing a key molecule that has the potential to prevent asthma,” said lead researcher Ben Marsland, a professor of immunology with Monash University in Australia.

When given antibiotics in early life, lab mice became more susceptible to allergic reactions to dust mites, researchers found. Human asthma is commonly triggered by exposure to dust mites.

This susceptibility to dust mite allergens continued in the mice long-term, even after their gut microbiome and IPA levels returned to normal, researchers said.

That suggests that IPA’s function in establishing a healthy immune response is particularly important in early life, the researchers noted.

What’s more, when the mice had their diet supplemented with IPA early in life, they were effectively cured of dust mite allergies and asthma.

“The use of antibiotics in the first year of life can have the unintentional effect of reducing bacteria which promote health,” Marsland said in a university news release. “We now know from this research that antibiotics lead to reduced IPA, which we have found is critical early in life as our lung cells mature, making it a candidate for early life prevention of allergic airway inflammation. “

The findings reinforce the importance of developing a stable gut microbiome in children, Marsland said.

In addition, dietary supplements rich in IPA might help kids avoid asthma. However, this needs to be tested in humans, researchers said, since animal research doesn't always pan out in people.

“It is shaped first by food intake — both milk and solid foods — as well as genetics and environmental exposures,” Marsland said. “Infants at high risk of allergies and asthma have been shown to have a disrupted and delayed maturation of the gut microbiome.”