1. Department of Pediatrics, Gastroenterology, Hepatology, Nutrition, Allergology and Pulmonology, Medical University of Bialystok, 15-274 Bialystok, Poland
2. Department of Pediatrics and Gastroenterology, Medical University of Lublin, 20-059 Lublin, Poland
3. Department of Pediatric Gastroenterology and Nutrition, Medical University of Warsaw, 02-091 Warsaw, Poland
4. Department of Gastroenterology, Allergology and Pediatrics, Polish Mother’s Memorial Hospital-Research Institute, 93-338 Lodz, Poland
5. Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznan, Poland
6. 2nd Clinical Department of Pediatrics, Gastroenterology and Nutrition, Medical University of Wroclaw, 50-369 Wroclaw, Poland