Tiny molecules in breast milk may prevent infants from developing allergies

Nov. 15, 2022
The researchers said the discovery could lead to strategies for mothers to help lower the odds of their babies developing allergies.

Breastfed babies are believed to suffer fewer allergic conditions, like eczema and food allergies, than formula-fed babies; yet the reason has not been well understood. Now, a new study by Penn State College of Medicine finds that small molecules found in most humans’ breast milk may reduce the likelihood of infants developing allergic conditions like atopic dermatitis and food allergies.

The researchers followed 163 mothers who planned to breastfeed for at least four months and their infants from birth through 12 months. They tracked how long each baby breastfed, and measured the miRNA composition of each mother’s breast milk over the course of lactation (0, 4 and 16 weeks). The team calculated the amount of specific miRNAs infants consumed based on reported breastfeeding patterns and the concentration of certain miRNAs in mothers’ milk samples. The researchers evaluated infants for atopic dermatitis, food allergies and wheezing throughout the study.

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 results were published in The American Journal of Clinical Nutrition on September 27.

Penn State Health release