Vitamin D deficiency in Crohn's disease and healthy controls: A prospective case–control study in the Netherlands

Vitamin D deficiency has been observed in a wide range of medical conditions including Crohn's disease (CD). We aimed to assess whether CD patients have lower vitamin D levels than healthy controls, and to determine risk factors for vitamin D deficiency. 25(OH)D was measured by chemiluminescent immunoassay in serum obtained from 101 CD patients and 41 controls. Demographics, sunlight exposure, dietary vitamin D intake, comorbidities and medication were recorded using validated questionnaires. In CD patients the Harvey–Bradshaw index, Montreal classification and surgical resections were also evaluated. 25(OH)D levels of >75nmol/L, between 50 and 75nmol/L and