The impact of turmeric or its curcumin extract on nonalcoholic fatty liver disease: a systematic review of clinical trials

Abstract

Background: Turmeric and its curcumin extract have been evaluated in patients with nonalcoholic fatty liver disease (NAFLD), a common ailment that can lead to irreparable liver damage. Objective: To identify the evidence supporting the use of turmeric or curcumin therapy in NAFLD. Methods: We searched PubMed, EMBASE, and Cochrane Central from the earliest possible date to 12/17/18 including terms for turmeric, curcumin, and NAFLD. We assessed the impact of turmeric or its curcumin extract on alanine transaminase (ALT), aspartate transaminase (AST), and NAFLD severity via ultrasound. Results: Five trials assessed the comparative efficacy of curcumin/turmeric in NAFLD. One trial was single armed with comparisons only versus baseline and another trial was only available in abstract form. All of the trials had small sample sizes, 4 of 5 trials had limited durations of follow-up, and all trials had methodological limitations that negatively impacted the strength and applicability of evidence. Clinical and methodological heterogeneity precluded statistical pooling. Three of the 4 trials with evaluable data for turmeric or curcumin versus their own baseline demonstrated significant reductions in ALT, AST, and NAFLD severity grade. Two of the 4 placebo controlled trials had significant mean difference reductions in ALT and AST for turmeric or curcumin versus placebo while 2 of 3 of these trials found significant reductions in NAFLD severity grade. Among these trials, only one used turmeric instead of a curcumin extract and this turmeric trial did not demonstrate any differences in ALT, AST, or NAFLD severity between the turmeric and placebo groups. Conclusions: Curcumin extract is a promising, but not proven, treatment for NAFLD while the role for turmeric is less clear. The general findings are that ALT, AST and NAFLD severity are reduced with the use of curcumin.