Review
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World J Gastroenterol. May 7, 2014; 20(17): 4934-4947
Published online May 7, 2014. doi: 10.3748/wjg.v20.i17.4934
Vitamin D improves inflammatory bowel disease outcomes: Basic science and clinical review
Krista M Reich, Richard N Fedorak, Karen Madsen, Karen I Kroeker
Krista M Reich, Richard N Fedorak, Karen Madsen, Karen I Kroeker, Division of Gastroenterology, University of Alberta, Edmonton, Alberta T6G 2X8, Canada
Author contributions: Reich KM developed and wrote the manuscript; Fedorak RN, Madsen K and Kroeker KI contributed to the design and editing of the paper; all authors approve the final version for submission.
Supported by A graduate studentship from the Center of Excellence for Gastrointestinal and Immunity Research (CEGIIR) and the Alberta Innovates-Health Solutions Inflammatory Bowel Disease Consortium to Reich KM
Correspondence to: Karen I Kroeker, MD, FRCPC, Assistant Professor, Division of Gastroenterology, University of Alberta, 2-40 Zeidler Ledcor Centre, 130 University Campus, Edmonton, Alberta T6G 2X8, Canada. karen.kroeker@ualberta.ca
Telephone: +1-780-2481433-3 Fax: +1-780-4928121
Received: September 27, 2013
Revised: November 13, 2013
Accepted: December 12, 2013
Published online: May 7, 2014
Processing time: 222 Days and 7.8 Hours
Abstract

Vitamin D deficiency is commonly diagnosed among patients with inflammatory bowel disease (IBD). Patients with IBD are at risk of low bone density and increased fractures due to low vitamin D levels, long standing disease, and frequent steroid exposures; as a result, it is well established that vitamin D supplementation in this population is important. There is increasing support for the role of vitamin D in strengthening the innate immune system by acting as an immunomodulator and reducing inflammation in experimental and human IBD. The active form of vitamin D, 1,25(OH)D3, acts on T cells to promote T helper (Th)2/regulatory T responses over Th1/Th17 responses; suppresses dendritic cell inflammatory activity; induces antibacterial activity; and regulates cytokine production in favor of an anti-inflammatory response. Murine and human IBD studies support a therapeutic role of vitamin D in IBD. Risk factors for vitamin D deficiency in this population include decreased sunlight exposure, disease duration, smoking, and genetics. Vitamin D normalization is associated with reduced risk of relapse, reduced risk of IBD-related surgeries, and improvement in quality of life. Vitamin D is an inexpensive supplement which has been shown to improve IBD outcomes. However, further research is required to determine optimal serum vitamin D levels which will achieve beneficial immune effects, and stronger evidence is needed to support the role of vitamin D in inducing disease response and remission, as well as maintaining this improvement in patients’ disease states.

Keywords: Vitamin D; Inflammatory bowel disease; Immune response; Inflammation; Cytokines; Supplementation

Core tip: There is support for the importance of maintaining normal vitamin D levels in inflammatory bowel disease (IBD) patients, demonstrated by its anti-inflammatory actions in the gut. A randomized controlled trial examined the impact of vitamin D supplementation on IBD outcomes and demonstrated a reduced risk of relapse in vitamin D-treated Crohn’s disease patients. Furthermore, vitamin D3 and active vitamin D have been shown to reduce clinical disease activity and improve quality of life in IBD patients. Normalization of vitamin D levels is also associated with a decreased risk for IBD-related surgery. This vitamin has therapeutic benefit in IBD patients.