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Breast milk and infant formula both encourage the growth of similar types of bacteria in a baby’s digestive system, but the bacteria from the two forms of food work differently, researchers report.
These differences could have health effects that are currently unclear, according to the researchers.
Good bacteria in the digestive tract play an important role in health by crowding out disease-causing bacteria, influencing metabolism and synthesizing many vitamins and amino acids, the building blocks of proteins.
“Formula makers are continually tweaking their ingredients, and they’ve been very successful in eliciting the right mix of bacteria,” said study senior author Gautam Dantas, a professor of pathology and immunology at Washington University School of Medicine in St. Louis.
“But almost all the studies to date have looked at the identity of the bacteria, not what they’re doing. What we found here is that the bacteria might look the same, but they’re not doing the same thing,” he said in a university news release.
For their study, the researchers analyzed the DNA of gut bacteria from 30 sets of twins born in the St. Louis area. They did this monthly from when the babies were born until they were 8 months old.
“The goal of all formulas is to look breast milk-like, and they’re not achieving that,” Dantas said. “In terms of which bacteria are there, they look similar, but in terms of what they have the genetic potential to do, it’s not the same. Different doesn’t mean bad, but different does mean different, and we have to understand what the health consequences are.”