Marked regional variations in the prevalence of inflammatory bowel disease in a limited geographical region are not associated with compounds in the drinking water

Abstract

Objective: The incidence of autoimmune diseases, especially inflammatory bowel disease (IBD), has increased substantially. Globally, there are vast differences varying from 0.2/105 in some Asian countries to over 80/105 in the Faroe Islands. Environmental factors have been suggested as triggers. The aim was to investigate the incidence and prevalence of IBD in the 33 municipalities in the county Scania in Southern Sweden, an area comprising 100 × 100 km with 1,274,069 inhabitants. Furthermore, we wanted to explore whether compounds in the drinking water could contribute to IBD; one report from Norway has suggested that iron in drinking water could contribute to UC. Methods: Patients with CD and UC were identified through the ICD-10 diagnosis database during the period 2000–2013. Water analyses for pH, alkaline, nitrate, sulphate, iron, magnesium and calcium were based on established methods and compared with the prevalence of IBD using Student’s t-test. Results: A total number of 8925 patients were identified. The incidence for CD and UC were high (mean 16.4/105, range 13.6–17.9 and 25.3/105, range 21.3–28.0, respectively). The prevalence varied substantially (p