Benefits of breastfeeding in infant health: a role for milk signaling peptides

Abstract Breastfeeding represents optimal nutrition during immediate postnatal life. Besides ensuring traditionally considered essential nutrients, breastfeeding has been associated to a number of beneficial outcomes in later life, such as protection against obesity and diabetes. Emerging knowledge points toward health benefits of breast milk being related to specific bioactive components, particularly endogenously synthesized peptide hormones, which are not significantly present in infant formula. Among them, leptin appears as the most biologically relevant. There is direct cause-effect demonstration from animal studies of the critical role of oral intake of leptin during the early postnatal period in metabolic programming of neonates, and relevant evidence from human studies suggesting milk-borne leptin provides protection to infants from excess weight gain. Other hormones with a relevant function in energy metabolism, such as insulin, adiponectin, and ghrelin, may also play a role in infant growth and development, although the concrete function of breast milk components is still unknown.