Prevention of obesity is among the well-recognized beneficial effects that breastfeeding exerts on a variety of organs and systems. This effect seems to occur via various mechanisms: (1) a low content of proteins in human milk as opposed to the high content found in formula and cow’s milk that leads to obesogenic concentrations of insulin and insulin-like growth factor 1 in blood; (2) a good balance of other hormonal molecules that regulate the fat to lean body mass ratio or favor better recognition of satiety; (3) an optimal intestinal microbiota (IM) composition; and (4) food preferences later in life. However, the breastfeeding-obesity link has been questioned because of several confounding factors,1 including maternal habits during gestation and breastfeeding as well as the mother’s metabolic health status (obesity and diabetes), race, and ethnicity. The duration of breastfeeding is also an issue that should be considered in studies of breastfeeding and obesity. Indeed, a long duration of breastfeeding (>7 months) has been associated with a reduced risk of overweight and obesity,2 while a short duration (≤4 months) may not be sufficient to obtain the beneficial effects of breastfeeding.3 Another confounding factor is early exposure to antibiotics, which is increasing even for minor infections. Antibiotics were found to induce a growth-promoting effect in prepubertal children, possibly by altering their IM.4 The neonatal IM composition is influenced by prenatal and postnatal antibiotic exposure5 and other age-specific modifiers such as mode of delivery (natural birth vs cesarean delivery) and mother-to-infant transfer of bacterial strains and human milk oligosaccharides via breastfeeding. The latter are structurally diverse unconjugated glycans that are highly abundant in and unique to human milk; they can stimulate the growth and/or activity of healthy intestinal bacteria.
Paolella G, Vajro P. Childhood Obesity, Breastfeeding, Intestinal Microbiota, and Early Exposure to AntibioticsWhat Is the Link?. JAMA Pediatr. 2016;170(8):735-737. doi:10.1001/jamapediatrics.2016.0964