1. Department of Paediatric Allergology, Gastroenterology and Nutrition, Medical University of Lodz, Łódź, Poland
2. Department of Paediatrics, Medical University of Warsaw, Warsaw, Poland
3. Department of Paediatrics, Gastroenterology, Allergology and Paediatric Nutrition, Medical University of Gdańsk, Gdańsk, Poland
4. Department of Paediatrics, Nutrition and Metabolic Diseases, Children’s Memorial Health Institute, Warsaw, Poland
5. Department of Paediatrics, Gastroenterology, Hepatology, Nutrition, Allergology and Pulmonology, Medical University of Bialystok, Białystok, Poland