Inflammatory biomarkers response to two dosages of vitamin D supplementation in patients with ulcerative colitis: A randomized, double-blind, placebo-controlled pilot study

Background: This study was designed to determine the effects of two dosages of vitamin D supplementation on inflammatory biomarkers in patients with ulcerative colitis (UC). Methods: Fifty mild to moderate active UC patients were randomly assigned to consume either 2000 or 1000 IU/day vitamin D for 12 weeks. Inflammatory biomarkers, disease activity, quality of life, anthropometric indices, dietary intakes, and physical activity were measured at the beginning and the end of the study. Results: Serum level of hs-CRP decreased in both groups at the end of study, but the changes were not significantly different within and between groups. Serum level of TNF-alpha in the high dose group was reduced at the end of the study non-significantly (P-value = 0.289). In the low dose group, a significant increase in serum TNF-alpha concentration was observed (p <= 0.001). The changes in serum TNF-alpha were significantly different between two groups (p = 0.005); however, after adjusting for the effect of confounders, the significance effect was disappeared (p = 0.162). Activity of NF-kB increased in both groups while this increase was significant in the low dose group compared to the baseline (p <= 0.001), and to high dose group (p = 0.006). After adjustment for confounders, the difference between groups remained statistically significant (p = 0.002). Conclusion: Our results indicate that 12 weeks supplementation with 2000 IU/day vitamin D prevents from systematic inflammation, while decreasing disease activity in patients with mild to moderate active UC. Further studies are needed to find the optimum dosage and duration of supplementation. (C) 2020 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.