Inflammatory bowel diseases (IBD) are a chronic immunologically mediated inflammatory condition of the gastrointestinal tract comprising two clinical entities: ulcerative colitis and Crohn's disease. Genetic,environmental and microbial factors, and the immune responses play an important role in the disease development. The incidence and prevalence of IBD have increased in the past 50 years in the Western world and are increasing in developing countries. Faecal calprotectin is a reliable biomarker for functional quantitative measurement of intestinal inflammation in IBD. Faecal calprotectin test is recognized to be reliable in clinical practice for the assessment of endoscopic activity and remission. Vitamin D or cholecalciferol is a prohormone classified as a fat-soluble vitamin. The organism can produce the substance itself in the skin during summer time. The importance of vitamin D for the regulation of calcium metabolism, for bone formation, for the treatment of osteoporosis and for the prevention of falls and associated fractures is generally recognized. Vitamin D seems to play a role in the pathogenesis of many diseases,including IBD. Several observational studies showed an inverse correlation between 25(OH)D and disease activity. Vitamin D deficiency is common among patients with IBD. The relapse rate in patients with Crohn' disease and 25(OH)D <50 nmol/l is almost doubled. There is a significant inverse correlation between serum 25(OH)D levels and the specific inflammatory marker faecal calprotectin. The lowest serum 25(OH)D levels have been reported in patients with a more severe disease progression or previous ileum resection. Low 25(OH)D serum concentrations are associated with more frequent IBDassociated surgeries and hospitalisations. However, no intervention studies have been conducted to date that have investigated the influence of vitamin D on inflammation in adult IBD patients. An intervention study with subjects aged 5-18 years nevertheless showed a statistically significant inverse correlation between 25(OH)D serum concentration and the inflammation marker calprotectin.~The FOPH Expert Commission recommends a daily intake of 600 IU for adults aged 19-59 years, 800 IU for >60 years. The maximum tolerable intake for all age groups is 4'000 IU daily, with daily or cumulative intermittent, weekly or monthly, administration being considered. Adherence is, however, better with intermittent intake. In this study, the administration to patients with monthly supplementation represents one capsule per month, corresponding to 800 IU cholecalciferol daily. The administration to patients with weekly supplementation is one capsule per week, corresponding to 3,500 IU cholecalciferol daily. The cumulative administration of 24'000 IU per week does not exceed the upper limit of 4'000 IU per day or 28'000 IU per week. Insufficient adherence to IBD medication has been identified as responsible for therapy escalation with more expensive regimens, disease complication or hospitalization, that all drive substantial costs. In a systematic review including 93'998 patients with IBD, adherence rate to prescribed biologics ranged from 37% to 96%. Difficulties with medication adherence can be identified with indirect methods such as questionnaires. To monitor adherence, questionnaires and pill-count are the most frequently used methods. However, more robust methods are recommended such as electronic methods. One option is the use of a e-pill bottles with electronic caps. The opening of the e-pill-bottle that corresponds to the withdrawal of a medicine from the container is registered with a time stamp, a method currently in development in our research group.
In this research project, the investigators want to find out whether the additional intake of vitamin D further reduces the inflammatory events in the intestines of IBD patients. There are three groups of subjects: the 1st group takes a capsule of 24,000 IU per week, the 2nd group takes 24,000 IU per month, the 3rd group is the control group. The intake extends over 6 months during the autumn and winter period.