Summary

The incidence of inflammatory bowel diseases (IBD: comprising ulcerative colitis and Crohn’s disease) has increased in children and adolescents in the Western world over the last decades. The disease constitutes a long term burden for the patient, with impaired quality of life, health and reduced life expectancy. For the society and health care system, early disability and costs for treatment and follow-up are substantial. Environmental risk factors influencing the rising incidence remain to be determined, though some evidence supports the notion that the composition of the early gut microbiome is important. Consequently, exposure to antibiotics early in life is associated with increased risk. Existing knowledge on diet and dietary supplements is very limited, through pathways potentially affecting the development of the gut microbiome. Prospective cohorts with repeated collection of data and biobank samples starting in pregnancy provide unique possibilities to identify new environmental risk factors. In a Scandinavian collaboration, we aim to explore existing resources to extend the knowledge and potential environmental risk factors for IBD at a young age. The proposal builds on previous research experience utilizing these cohorts to study immune-mediated diseases starting in childhood and adolescence. The overall aim of the study is to identify new and modifiable factors for future prevention of IBD.

We hypothesize that:

1. Maternal diet during pregnancy and dietary patterns in early life is associated with the risk of IBD.
2. Iron intake during pregnancy and early childhood and iron biomarkers in cord blood predict IBD.
3. Vitamin D intake during pregnancy and early childhood and vitamin D levels in cord blood predict IBD.
4. Infections and use of antibiotics/antipyretics during early life is associated with the risk of IBD.
5. Socioeconomic factors including smoking exposure and psychological stress is associated with the risk of IBD.