Nutrition plays a critical role during different stages of infancy. Did you know that prematurity, for example, can be considered as a nutritional emergency? Dr. Senterre describes in this issue of the Nest how optimized nutritional support in the preterm improves postnatal growth and may reduce adverse outcomes. Early vs. late introduction of complementary foods in children at risk to develop allergies is controversially discussed amongst health care professionals. Prof. Smith summarizes the latest scientific evidence introducing the concept of ‘Window of Opportunity for Tolerance’ where foods could be introduced at lower risk of developing allergy. A large data set is available on the evidence of benefits of probiotics and somewhat less on prebiotics. Prof. Lifschitz reviewed the scientific findings and highlights that several probiotics have been shown to be effective in preventing and treating certain illnesses in adults and children.