April 24, 2023 – Parents of newborns know that the contents of their babies’ diapers have a story to tell, such as how the latest meal went over or if the baby is getting enough to drink. Scientists in Denmark wanted to know more about what may cause people to develop diseases, so they, too, turned to the diapers.

The researchers found 10,000 stories, in the form of viruses, many of which had never before been identified.

“Specifically we are trying to decipher how having certain gut bacteria in infancy can protect you from developing chronic disease later in life,” said researcher Shiraz Shah, PhD,  in a blog post describing the study, which was published this month in Nature Microbiology.

Shah and his colleagues at the Copenhagen Prospective Studies for Asthma in Childhood recruited mothers during pregnancy, who agreed to enroll their babies in the study after birth. The diapers were collected when the babies were 1 year old, and the children are now 12 years old. The diaper analysis was the first step in the study, which has a long-term goal of identifying causes of chronic inflammatory diseases such as asthma, eczema, and allergies.

The researchers were surprised by the sheer number of viruses that they found.

“Our current working hypothesis is that viral loads are elevated in the infant gut because the immune system is still maturing,” Shah wrote.

The next analysis will examine diapers from when the babies were 1 week and 1 month old to see if the 10,000 virus types were present at those young ages. Later analyses will look at whether certain viruses were able to protect children from getting diseases such as asthma or ADHD.

The children in the study will continue to contribute information, and the researchers will keep watching for connections between the gut and serious diseases.

“We do believe that many chronic diseases begin in early childhood even if symptoms appear much later. Our setup allows us to test this,” Shah wrote. “For now, at least we know that having a gut teeming with viruses must be a natural part of being a baby.”

As for what to call those new viruses that had never been seen before? The researchers named them after the babies who contributed diapers to the study.