Three recent publications from Professor Gideon Lack have fundamentally changed our understanding of how to prevent food allergy. His team has shown that early introduction of allergenic foods may prevent food allergy in most but not all high-risk children. Various allergy and paediatric societies around the world are changing their recommendations based on these three studies. It appears there is a window of opportunity to safely introduce allergenic foods to high-risk children. This has resource implications, as some of these children will need testing and food challenges.