Something in Breast Milk Helps Protect Babies Against Allergies

Medscape Staff

January 26, 2023

Tiny molecules of microribonucleic acids (miRNAs) found in breast milk can help protect babies from developing allergic conditions like atopic dermatitis and food allergies, according to a new study by Penn State College of Medicine.

What to Know

  • Atopic conditions, like food allergies, asthma, and atopic dermatitis, occur in approximately one third of children because of inappropriate activation of the immune system to environmental exposures.

  • miRNAs are tiny molecules that regulate gene expression throughout the body. Four of the nearly 1000 kinds of miRNAs in human breast milk could protect against infant allergies.

  • Infants who did not develop allergic diseases such as allergic rhinitis, asthma, and atopic dermatitis consumed greater amounts, on average, of miRNA-375-3p (miR-375) in their mothers' breast milk than infants who developed atopy.

  • miR-375 is present in more than 99% of human milk samples, and it accounts for just under 1% of all miRNAs in breast milk. The greatest increase of miR-375 occurs in the first month following birth, but the upward trend continues from months 1 to 4.

  • The composition of the miRNAs found in mothers' milk varies because of maternal characteristics, such as weight, diet, and genetics, A lower body mass index was associated with a higher concentration of miR-375 in mothers' breast milk.

This is a summary of the article, "Infant Consumption of microRNA miR-375 in Human Milk Lipids Is Associated With Protection From Atopy," published in The American Journal of Clinical Nutrition on September 27, 2022. The full article can be found on

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