Abstract
Among all the body fluids, breast milk is one of the richest sources of microRNAs (miRNAs). MiRNAs packaged within the milk exosomes are bioavailable to breastfeeding infants. The role of miRNAs in determining infant growth and the impact of maternal overweight/obesity on human milk (HM) miRNAs is poorly understood. The objectives of this study were to examine the impact of maternal overweight/obesity on select miRNAs (miR-148a, miR-30b, miR-29a, miR-29b, miR-let-7a and miR-32) involved in adipogenesis and glucose metabolism and to examine the relationship of these miRNAs with measures of infant body composition in the first 6 months of life. Milk samples were collected from a cohort of 60 mothers (30 normal-weight [NW] and 30 overweight [OW]/obese [OB]) at 1-month and a subset of 48 of these at 3 months of lactation. Relative abundance of miRNA was determined using real-time PCR. The associations between the miRNAs of interest and infant weight and body composition at one, three, and six months were examined after adjusting for infant gestational age, birth weight, and sex. The abundance of miR-148a and miR-30b was lower by 30% and 42%, respectively, in the OW/OB group than in the NW group at 1 month. miR-148a was negatively associated with infant weight, fat mass, and fat free mass, while miR-30b was positively associated with infant weight, percent body fat, and fat mass at 1 month. Maternal obesity is negatively associated with the content of select miRNAs in human milk. An association of specific miRNAs with infant body composition was observed during the first month of life, suggesting a potential role in the infant’s adaptation to enteral nutrition.
Highlights
Breastfeeding is one of the most highly effective preventive measures that a mother can take to protect the health of her infant and herself (US Surgeon General, January 2011)
Though bioactive factors are being discovered in human milk (HM), the mechanisms by which breast milk plays a role in reducing risks of obesity and type 2 diabetes mellitus is unknown
The objectives of the study were [1] test the hypothesis that maternal obesity is associated with altered abundance of specific HM exosomal miRNAs involved in insulin signaling, glucose homeostasis, and adipogenesis, and [2] examine relationships between HM miRNA and infant anthropometrics and body composition during the first six months of life
Summary
Breastfeeding is one of the most highly effective preventive measures that a mother can take to protect the health of her infant and herself (US Surgeon General, January 2011). Exclusive and longer duration of breastfeeding plays a role in protecting against later obesity and type 2 diabetes mellitus, relative to formula [4,5,6]. There is growing evidence that human milk (HM) is a source of macronutrients, and of bioactive factors with the potential to influence the growth and body composition of the child [7,8]. Though bioactive factors are being discovered in HM, the mechanisms by which breast milk plays a role in reducing risks of obesity and type 2 diabetes mellitus is unknown. As an outgrowth of this work, we have begun to explore a novel mechanism involving the transfer of miRNAs via HM from the mother to the developing infant
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