Vitamin D improves inflammatory bowel disease outcomes:Basic science and clinical review

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 antiinflammatory 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.