Scientists Link Baby's Brain Development to Their Gut Bacteria

The development of your baby's brain could be influenced by the microbes in their belly, scientists have found.

The trillions of microbes that live inside our guts play essential roles in a range of bodily processes, from digestion to mental health. The gut contains more than 100 million nerve cells—the highest concentration in any part of the body other than the brain. Now, we are also beginning to learn about the roles of these microbes in the earliest stages of our lives.

"The microbiome plays an important role in the early development of several systems, such as the nervous and immune system, as well as providing another layer of protection against pathogens [disease]," Sebastian Hunter, a researcher from the University of British Columbia who led a study on the subject published Wednesday in the scientific journal PLOS One, told Newsweek.

"During brain development, it has been observed that microbiome dysbiosis can be associated with major neurodevelopmental psychiatric disorders," Hunter said.

Your child's microbiome could be linked to their brain development, a new study found.TATYANA_TOMSICKOVA/GETTY

Dysbiosis refers to an imbalance in the microbial communities that make up our gut microbiome. This is often brought about by a reduction in the diversity of different "good" bacteria in the stomach, which allows more harmful bacteria to take over.

In the study, Hunter and his team analyzed data from 56 babies, aged between 4 and 6 months. Each infant underwent at least one of three tests to evaluate their cognitive abilities, and researchers were able to analyze their gut microbiomes from stool samples.

The team found that those children who performed well in a social attention test—which measures the child's ability to share focus on an object with another person—tended to have high levels of Bifidobacteria and bacteria in the genus Eggerthella. They also had lower levels of bacteria in the groups Hungatella and Streptococcus.

"From the microbes we found associations, Bifidobacterium is the one with the most known relevancy to brain development," Hunter said. "Some bacteria from this genus are considered probiotics with strong associations to the gut-brain axis and host immunity and can promote the formation of synapses and microglial function."

Bifidobacteria are one of the first types of microbes to grow in a baby's gut and play an important role in the digestion of the healthy sugars in breast milk. They also support the immune system and help produce important nutrients in the body like B vitamins and fatty acids. These fatty acids are also involved in brain health and development.

But where do these "healthy" microbes actually come from?

"The microbiome of infants is mostly acquired as an exchange of microbiota between the mother and the offspring, particularly during birth," Hunter said. "This newly established microbiota can be affected by several environmental and genetic factors, such as the mode of delivery, the use of antibiotics or by the diet given to the child (breastfeeding vs. formula feeding), among others."

Not everyone has a choice over whether they get a C-section or if they can breastfeed, but there are other ways to support your child's microbiome.

"Some of these are to reduce the use of nonessential antibiotics as they not only affect the pathogens but our normal [microbes]; to promote the proliferation of healthy microbes either by ingestion of nutrients such as dietary fibers or by consuming foods with beneficial bacteria such as fermented foods like yogurt; and by decreasing over-sanitization as the interaction with a wide variety of microbes is necessary for training our immune system to react accordingly," Hunter said.

"With C-section births, new procedures like vaginal seeding are being tested to expose the infants to the beneficial microbes of the mother, but more research is needed to prove its benefits and safety of the procedure."

Research into the gut microbiome is still in its infancy, and more research is needed to fully elucidate the associations between brain development and microbiome composition.

"Further research in bigger trials is needed to understand and establish the link between the microbiota and brain development, and caution should be taken in over-interpreting the results, as the relatively small sample size of the pilot limits the interpretation of the results due to the low statistical power," Hunter said.