M O’Sullivan, Proc Nutr Soc. 2015 Feb;74(1):5-12
Low levels of vitamin D have been reported as a potential risk factor for several immune mediated inflammatory conditions such as rheumatoid arthritis, cancers, diabetes and also in IBD. IBD is more common in countries of northern latitude where sunlight exposure is less than more tropical latitudes. Exposure to sunlight is important in the way the body makes and uses Vitamin D and researchers have therefore made the link between Vitamin D and chronic inflammatory conditions. In recent years, there has been a growing scientific interest in vitamin D as a treatment alongside other medicines in IBD.
This journal article is a review of the cumulative scientific evidence for the role of vitamin D in the onset, course and disease modification in IBD. Vitamin D deficiency is common in IBD affecting at least 35% of patients, particularly those with Crohn’s disease. Even in healthy individuals, there is a high background vitamin D deficiency due to lack of sunlight exposure and poor dietary intake. For those with Crohn’s disease, there are additional risk factors for deficiency including poor absorption, intestinal inflammation, surgical removal of a bowel segment, and steroid usage. This article described several studies indicating the relationship between vitamin D levels in blood and the disease activity/severity in Crohn’s. Some studies suggested that low levels were associated with more active and severe disease, however these studies were unable to address the issue of ‘cause and effect’. The authors also described studies investigating the role of vitamin D supplementation to prevent relapse or induce remission in CD. The scientific evidence was suggestive, however not compelling enough to be recommended as a routine anti-inflammatory therapy.
Treatment with vitamin D is simple and may be helpful in IBD. However in order to understand the relationship between vitamin D and IBD, large-scale studies would be needed to draw up the evidence.
Many of you may have had blood tests to measure your Vitamin D level; these results are often lower over winter due to reduced sun exposure and better in the summer. However, you doctor may offer you a daily supplement if your Vitamin D level is persistently low. Many children without IBD receive the same treatment.