[1] Univ Hosp N Staffordshire, Dept Gastroenterol, Stoke On Trent, Staffs, England
[2] Keele Univ, Ctr Hlth Planning & Management, Keele, Staffs, England
[3] Chelsea & Westminster Hosp, Dept Dietet, London, England
[4] Cent Middlesex Hosp, Dept Gastroenterol & Nutr, London NW10 7NS, England
[5] Keele Univ, Dept Math, Keele, Staffs, England
[6] Nutr Clin Care, Trowbridge, Wilts, England