Effects of the Use of Curcumin on Ulcerative Colitis and Crohn's Disease: A Systematic Review

Inflammatory bowel disease (IBD) is an umbrella term used to describe chronic inflammatory disorders related to a substantial reduction in the quality of life of patients. Some patients with Crohn's disease (CD) and ulcerative colitis (UC) are refractory to conventional therapies, and Curcuma longa derivatives have been considered as adjuvants. Owing to the anti-inflammatory and antioxidant effects, some clinical trials used this plant in the therapeutic approach of IBD, and some meta-analyses evaluated the outcomes found in these studies. Owing to controversial findings, our systematic review aimed to evaluate these studies to show whether C. longa compounds can still be considered in the therapeutic approach of patients with CD and UC. MEDLINE-PubMed, EMBASE, and Cochrane were searched, and Preferred Reporting Items for a Systematic Review and Meta-Analysis guidelines were followed. The results of the randomized clinical trials (RCTs) showed promising results with the use of curcumin in the therapeutic approach of both UC and CD patients. Some meta-analyses show controversial results, possibly due to the presence of bias in the included studies. The actions of curcumin are achieved by several mechanisms, such as reducing the expression of interleukin (IL)-1, IL-6, IL-12, and tumor necrosis factor-alpha. Moreover, it reduces the levels of reactive oxygen species, such as superoxide anions and malondialdehyde. The results of using curcumin in CD and UC patients are challenging to be evaluated because RCTs are variable in the dose and the formulations of curcumin, in the time of treatment, and the route of administration. The number of patients in the samples is also usually small.