Researchers continue to shed new light on the mysterious world of microorganisms that influences our health and development in more ways than you might realize. But it's not just adults that can benefit from this research – a new study has now found that a healthier gut microbiome can help premature babies grow faster, reducing or potentially preventing a lifetime of chronic health problems.

In recent years, the gut microbiome has emerged as one of the key areas of medical research, with studies revealing how these hitchhiking organisms influence a person's risk of diabetes, autoimmune diseases and even Alzheimer's. In future, manipulating the amounts of certain species that call us home could open up new treatments for weight loss or even cancer prevention.

But this important ecosystem has mostly been studied in adults. A team of pediatricians and microbiologists at the University of Rochester Medical Center set out to investigate how the gut microbiome could be affecting the health of some of the most at-risk people – premature babies.

To get a closer look at their microbiomes, the team collected stool samples from 95 premature infants, born at around 29 weeks on average. These samples were taken once a week for as long as the baby was in the intensive care unit, which was anywhere from a few weeks to up to six months. The researchers kept an eye on the populations of different bacteria over time, the type and amount of nutrients they were being fed, and how the baby was growing.

The team found that infants with higher levels of good bacteria in their guts generally grew faster than those with less healthy microbiomes. The dominant species also seemed to change over time – a beneficial bug known as Bacilli often ruled the roost for the first stage of life, before a species called Gammaproteobacteria rose up over time.

Ideally, doctors would be able to study stool samples of infants in order to tailor the nutrients and feeding patterns to exactly what they – and their good gut bacteria – need.

"We have a sense of what types of calories to give, like fats, proteins, and carbohydrates, and an idea of how we should balance these calories," says Kristin Scheible, an author of the study. "But, even when we push babies above the recommended level of caloric intake many of them still don't grow. The hope is that by adjusting the calories to both the baby and their microbiome we can nourish the system in a way that optimizes growth and allows for development of all the organ systems that are premature. Ultimately, we want to feed the right organisms to help feed and grow the baby."

Unfortunately, it's not practical to take stool samples of all infants in neonatal intensive care. But the team found that the change in bacteria populations tended to line up with clear stages in development. For the first few days infants expel a kind of stool known as meconium, which is made up of amniotic fluid and other materials ingested while in the womb. Bacilli is the most common bacteria in meconium, but loses the crown to Gammaproteobacteria as the baby transitions over to normal feces.

Since it's much easier to look out for changes in stool types, the team says this could be a good start. Certain nutrients could be given while the infant is excreting meconium, and the formula could swap over when normal stool begins to appear.

The next step for the team is to investigate how these bacteria use the nutrients the baby is given, which could influence the formula given.

The research was published in the journal Microbiome.