1. In this longitudinal cohort study, infants who did not develop atopic disease consumed breast milk containing higher concentrations of the micro-RNAs (miRNAs) miR-375-3p and miR-148-3p compared to those who developed atopic disease.

2. Additionally, the concentration of miR-375-3p in breast milk increased throughout the lactation period and was inversely proportional to maternal body mass index (BMI).

Evidence Rating Level: 2 (Good)

Food allergies, asthma, and atopic dermatitis are common childhood atopic diseases that arise from inappropriate immune activation to non-noxious stimuli. Previously, it has been shown that infants who are breastfed beyond 3 months of age have a lower risk of developing atopic conditions. Although, the mechanisms behind this risk reduction are unclear, it has been suggested that micro-RNAs (miRNA) in breast milk may play a role. Therefore, the aim of the present longitudinal cohort study was to investigate whether certain miRNAs present in human breast milk may be linked with reduced risk of atopic conditions.

This cohort study examined 163 mother-infant dyads from birth to 12 months of age. Infants who were born at term and breastfed beyond 4 months were included. Dyads were excluded if there were plans for adoption, they were non-English speaking, or if either the mother or infant had co-morbid medical conditions that would prevent breast-feeding. The concentrations of 4 human miRNAs (miR-146b-5p, miR-148b-3p, miR-21-5p, and miR-375-3p) and the number of feeds were measured in the first 6 months to determine miRNA consumption. The primary outcome was presence of atopic disease in the first year of life, as reported by parent questionnaires.

The results found that 73 infants developed atopic disease. It was found that infants who did not develop atopy consumed higher concentrations of miR-375-3p and miR-148-3p. Furthermore, regression analyses showed that the consumption of miR-375-3p was associated with reduced risk of developing atopy. The concentration of miR-375-3p in breast milk increased over the course of lactation and was inversely associated with maternal body mass index (BMI). However, the study was limited by the high dropout rate (24%), which may have impacted the findings. Nonetheless, these results demonstrated the potential role of miRNAs in reducing infant risk of atopic disease.

Click to read the study in The American Journal of Clinical Nutrition

Image: PD

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