Department of Paediatrics, Zuyderland Medical Center, Sittard, Netherlands. Electronic address: n.bevers@zuyderland.nl. Department of Paediatric Gastroenterology, Hepatology and Nutrition, Antwerp University Hospital, Edegem, Belgium. Department of Paediatrics, Zuyderland Medical Center, Sittard, Netherlands. Maastricht University Medical Center [MUMC], Department of NUTRIM, Maastricht, The Netherlands. Department of Paediatrics, Zuyderland Medical Centre, Sittard-Geleen, Netherlands. Department of Paediatrics, Catharina Hospital, the Netherlands. Department of Paediatrics, Maxima Medical Centre, Veldhoven, the Netherlands. Department of Paediatrics, Jeroen Bosch Medical Centre, Den Bosch, the Netherlands. Erasmus Medical Center, Children's Hospital Department of Paediatric Gastroenterology, Rotterdam, The Netherlands. Department of Paediatrics, Gelre Hospital, Apeldoorn, the Netherlands. department of Paediatrics, Isala Hospitals, Zwolle, the Netherlands. Ghent University Hospital, Ghent University, Ghent, Belgium. Department of Methodology and Statistics, Maastricht University, Maastricht, Netherlands. Laboratory of Clinical Chemistry and Haematology, Zuyderland Medical Centre, Heerlen, Limburg, The Netherlands. Department of Paediatrics and NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands. Division of Gastroenterology-Hepatology and NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands. University of Groningen, University Medical Centre Groningen - Beatrix Children's Hospital, Department of Paediatric Gastroenterology Hepatology and Nutrition, Groningen, The Netherlands.