Vitamin D supplementation in inflammatory bowel disease: a narrative review

Inflammatory bowel disease is a chronic disorder characterized by exacerbation and remission periods, and its worldwide incidence has increased in recent decades. Vitamin D is involved in immune regulation and improves barrier functions and intestinal microbiota. Studies have observed that high vitamin D levels decrease relapses and improve the clinical course of inflammatory bowel disease. The objective of this review was to analyze the evidence on vitamin D supplementation in adult patients with inflammatory bowel disease. Among inactive patients, the studies administrating less than 2000 international units per day of vitamin D did not find any beneficial effects. However, those supplementing 2000 international units of vitamin D per day increased serum levels and reduced disease activity. In patients with active disease, doses between 5000 to 10 000 international units per day reduced symptomatology. This review showed that vitamin D supplementation above 2000 international units per day among inactive patients with inflammatory bowel disease, and between 5000 to 10 000 international units per day among those in the active stage, shows potential benefits on the disease.