The present invention relates to administration of sweet whey protein (SWP) for promoting the enteric neuronal development in infants, especially preterm, low birth, very low and extremely low birth weight infants as well as in young children up until the age of six. Administration of the SWP according to the invention prevents and treats disorders associated with an immature or impaired enteric nervous system. The disorders are, notably, dysfunctional gastrointestinal motility manifested as slow intestinal transit, intestinal discomfort, hard stools, constipation and/or gastrointestinal reflux, gut barrier dysfunction, food intolerance or necrotizing enterocolitis.