Researchers find the molecules in breast milk that may protect infants from developing allergies

16-Nov-2022 - Last updated on 16-Nov-2022 at 16:21 GMT

Image: Getty/Jose Luis Pelaez Inc

Scientists have identified the specific molecules in breast milk which if added to formula may help address the disparity that formula-fed babies are more sensitive to allergens.

In research that has potentially hugely significant implications for baby formula, researchers have pinpointed the molecules in breast milk that may reduce the likelihood of infants developing allergic conditions like atopic dermatitis and food allergies.

Breastfed babies are believed to suffer fewer allergic conditions, such as eczema and food allergies, than formula-fed babies; yet the reason has not been well understood. If the molecules identified by the research could be put in formula, it may therefore help lower the odds of babies developing allergies, the scientists said.

Atopic conditions, like food allergies, asthma and a skin condition called atopic dermatitis occur in approximately one-third of children as a result of inappropriate activation of the immune system to environmental exposures.

“Infants who breastfeed beyond three months may have a lower risk for these conditions, but we don’t fully understand the biology behind this,” explained Dr. Steven Hicks, associate professor of pediatrics and pediatrician at Penn State Health Children’s Hospital.

Hicks' prior studies have demonstrated how micro‑ribonucleic acids (miRNAs), or tiny molecules that can regulate gene expression throughout the body, can be used to diagnose certain health conditions like concussion or autism.

There are nearly 1,000 different kinds of miRNAs in human breast milk and composition varies due to maternal characteristics like weight, diet and genetics. Hicks and his team therefore hypothesized that four of these miRNAs could have a protective effect against infant allergies.

Of the infants studied, 41 (25%) developed atopic dermatitis, 33 (20%) developed a food allergy and 10 (6%) had wheezing. Infants who did not develop atopy consumed greater amounts, on average, of miRNA-375-3p (miR-375) in their mothers’ breastmilk, than infants who developed atopy. There were no other differences in maternal traits, infant traits or environmental exposures between infants with atopy and infants without atopy. The researchers also found that levels of this miRNA increased throughout lactation and that mothers with a lower body mass index tended to have a higher concentration of miR-375.

“The fact that miR-375 content increased during the course of lactation may explain why sustained breastfeeding has been associated with reduced atopy in certain studies,” Hicks said. He noted that the greatest increase of miR-375 happened in the first month following birth, but that the upward trend continued between months one and four. “In contrast with formula, which does not contain human miRNAs, miR-375 is present in more than 99% of human milk samples, and it accounts for just under 1% of all miRNAs in breastmilk.”

According to Hicks, the findings from this study could lead to new interventions to help prevent infants from developing allergies, such as attempting to boost miR-375 levels in maternal breast milk.

Hicks also said that with further research miR-375 might one day be added to formula, which currently contains no miRNAs, to help address the disparity that formula-fed babies are more likely to develop atopic conditions.

"Other studies measuring miRNA content in formula have not been able to identify measurable amounts of human miRNA," he explained to FoodNavigator. "However, research by our team and others have shown that human milk contains robust quantities of miRNAs.

"The technology to incorporate miRNAs into formula already exists," he added. "But, before adding miRNAs to formula we need to verify that 1) specific miRNAs do indeed confer protection from specific diseases (such as allergies); and 2) including miRNAs does not cause unexpected side effects. So, there are still several steps required before we can apply this information in formula production."