Major clinical outcomes of vitamin D deficiency in inflammatory bowel diseases: a systematic and integrative review

Introduction: Clinical studies have proven the direct correlation of vitamin D deficiency in patients suffering from inflammatory bowel diseases, such as Crohn's disease, with an average age of 41 years and more frequently in women. Vitamin D seems to interact with the immune system through its action on the regulation and differentiation of cells such as lymphocytes, macrophages, and natural killer (NK) cells, in addition to interfering with the production of cytokines. Objective: It was to present, through a systematic review, the main clinical outcomes of the correlation of vitamin D deficiency and inflammatory bowel diseases, highlighting Crohn's disease. Methods: The systematic review rules of the PRISMA Platform were followed. The research was carried out from August to October 2022 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 207 articles were found, and 142 articles were evaluated and 117 were included in this systematic review. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 20 studies with a high risk of bias and 28 studies that did not meet GRADE. Most studies showed homogeneity in their results, with R2 =95.7% >50%. It was shown that the highest prevalence of low serum levels of vitamin D is among patients suffering from Crohn's disease and other inflammatory bowel diseases when compared to a control group. However, more comprehensive studies are still needed, especially those that aim to evaluate serum vitamin D in values related to clinical treatment and also the effects of vitamin D supplementation on disease activity and mucosal healing. Thus, it will be possible to evaluate in a relevant way, the replacement of vitamin D in the remission of Crohn's disease, optimizing the treatment of patients and corroborating the improvement in quality of life.