Vitamin D deficiency in inflammatory bowel disease.

Vitamin D is required for bone health and importantly, vitamin D deficiency has been found to be associated with cardiovascular disease, diabetes, cancer and autoimmune diseases. Vitamin D deficiency is defined as a serum 25-hydroxyvitamin D (25-OH D) level of ≤ 20 ng/ml while insufficiency is defined as a 25-OH D level of 21 - 29 ng/ml. The prevalence of vitamin D deficiency and insufficiency in the general population varies greatly but ranges from 1-9% and 8 - 36%. In patients with Crohn's disease (CD), the prevalence of deficiency varies from 8% to 71% and insufficiency ranges from 22 - 65%. In patients with ulcerative colitis (UC), the prevalence of vitamin D deficiency is 15 - 28%. Risk factors for vitamin D deficiency in IBD include malnutrition, ileal resection, and disease activity. Seasonal variation in vitamin D levels, with deficiency noted during winter months, suggests a lack of sun exposure a cause of deficiency. Despite the known prevalence of vitamin D deficiency and insufficiency, there are no recommendations for screening in patients with IBD.