April 29 (UPI) -- The composition of a baby's first poop helps predict whether they will develop food allergies during childhood, a study published Thursday by Cell Reports Medicine found.
After birth, usually within the first day of life, newborns typically produce a thick, dark green stool containing a substance called meconium, the researchers said.
Meconium is made up of a variety of materials ingested and excreted during development in the womb, including metabolites, or molecules that help the body turn food into energy.
However, babies whose meconium contains fewer types of these metabolites are more likely to develop allergies by age 1, according to the researchers.
When combined with a machine-learning algorithm, meconium analysis accurately identifies newborns who will later develop food allergies 76% of the time, they said.
"Now we have an opportunity to identify at-risk infants who could benefit from early interventions before they even begin to show signs and symptoms of allergies later in life," study co-author Dr. Charisse Petersen told UPI in an email.
"[Our study] shows that the development of a healthy immune system ... may actually start well before a child is born," said Petersen, a research associate in pediatrics at the University of British Columbia in Vancouver.
For this study, Petersen and her colleagues analyzed meconium samples from 100 infants and tracked the newborns for one year.
They worked under the theory that meconium is "like a time capsule" that can reveal what the infant was exposed to from their mother, before birth, including skin cells, amniotic fluid and metabolites, Petersen said.
The substance also becomes the initial food source for the earliest gut microbes, or "beneficial" bacteria in the digestive tract, known as the microbiota, that help in digestion and influence overall health.
The fewer different types of metabolites a baby's meconium contained, the greater the child's risk of developing allergies by age 1 year, the data showed.
In addition, a reduction in certain metabolites was associated with changes to key bacterial groups that play a critical role in the development and maturation of the microbiota.
The study findings have important implications for infants at risk for food allergies, researchers said.
About 8% of children in the United States have a food allergy, placing them at increased risk for developing asthma, according to the American Academy of Pediatrics.
"At the moment, the most effective means for combating allergies after a baby is born is through prevention during [the] early-life window, when the immune cells are most receptive to tolerant responses," Petersen said.
"Unfortunately, a lot of allergies aren't diagnosed until after this window closes, so our goal is to identify at-risk infants as early as possible to inform decisions [that] ... prioritize supporting a healthy infant microbiota when they have the best chance of prevent allergies," she said.