Breast milk is a living nutritional fluid containing antibodies, hormones and enzymes. Insulin is one of the key hormones in breast milk, found in concentrations nearly four-fold higher than in cow’s milk. What role does insulin play, and how can we capture its benefits for pre-term infants? Professor Raanan Shamir traces the path of insulin from breast milk into the infant gut, showing how this hormone affects gut maturation, histology and enzyme expression of the mucosal cells. Oral insulin has far-reaching effects that extend beyond the gut, modulating the levels of glucose and lipids in the blood.How can we apply this knowledge to optimize infant formula? Shamir outlines data from several pilot studies which tested oral insulin supplementation in premature infants, revealing encouraging findings on the benefits of insulin on weight gain, gut maturation and modulating the immune response. Shamir’s group has launched a randomized, controlled trial in premature infants to demonstrate the safety and efficacy of a novel insulin-supplemented infant formula.