Human Breast Milk miRNAs: Investigation of Association Between Breastfeeding Children and Maternal Obesity in Obesity Development in Offspring

Abstract

Background/Objectives: Human breast milk is a mammary gland secretion with a dynamic composition, containing important bioactive factors for infant growth. Epigenetic factors, like microRNAs, are found in breast milk and can regulate gene expression and, thus, infant growth. Obesity is, among others, a major global health concern with long-term consequences, making its prevention during early life a public health priority. Maternal lifestyle factors, including diet and body weight status, may influence infant growth patterns and susceptibility to obesity. The aim of this review is to explore the hypothesis that miRNA content in breast milk might be influenced by maternal obesity, eventually affecting the obesity risk in offspring. Methods: This systematic review was carried out in line with the PRISMA 2020 statement and included observational (cohort) studies that met the inclusion criteria and compare the expression of miRNAs in OW/OB lactating mothers and associate this to the obesity development in the offspring. Results: According to the included studies, the most common miRNAs are miR-148a, miR-30 family, and miR-let7 family, with miR-30b and miR-let7a among the most discussed that participate in adipogenesis. Some of these miRNAs secreted in breast milk pass on a genetic predisposition for obesity to the next generation, while others provide a protective role against obesity in the offspring. Conclusions: Eventually, even though individual miRNAs may fluctuate, the overall miRNA profile remains stable. The findings underscore the importance of balanced maternal nutrition and optimal health during lactation, both for supporting healthy infant development and for potentially reducing the risk of obesity later in life.