[1] Univ Edinburgh, Dept Child Life & Hlth, 20 Sylvan Pl, Edinburgh EH9 1UW, Midlothian, Scotland
[2] Univ Aberdeen, Royal Aberdeen Childrens Hosp, Aberdeen AB9 1FX, Scotland
[3] Royal Hosp Sick Children, Dept Paediat Gastroenterol, Glasgow G3 8SJ, Lanark, Scotland
[4] Univ Glasgow, Acad Unit Life Course Nutr & Hlth, Coll Med Vet & Life Sci, Div Dev Med,Human Nutr Sect, Glasgow, Lanark, Scotland
[5] Royal Hosp Sick Children, Dept Paediat Gastroenterol & Nutr, Edinburgh EH9 1LF, Midlothian, Scotland
[6] Royal Aberdeen Childrens Hosp, Dept Paediat Gastroenterol, Aberdeen, Scotland
[7] Victoria Hosp, Dept Internal Med & Geriatr, Kirkcaldy, Fife, Scotland
[8] Univ Edinburgh, Gastrointestinal Unit, Mol Med Ctr, Edinburgh EH9 1UW, Midlothian, Scotland
[9] Univ Edinburgh, Sch Med, Ctr Populat Hlth Sci, Edinburgh EH9 1UW, Midlothian, Scotland
[10] Univ Toronto, Hosp Sick Children, Div Paediat Gastroenterol Hepatol & Nutr, Toronto, ON M5G 1X8, Canada