Therapeutic Effect of Curcumin on Metabolic Diseases: Evidence from Clinical Studies

Abstract

Metabolic diseases have become a serious threat to human health worldwide. It is crucial to look for effective drugs from natural products to treat metabolic diseases. Curcumin, a natural polyphenolic compound, is mainly obtained from the rhizomes of the genus Curcuma. In recent years, clinical trials using curcumin for the treatment of metabolic diseases have been increasing. In this review, we provide a timely and comprehensive summary of the clinical progress of curcumin in the treatment of three metabolic diseases, namely type 2 diabetes mellitus (T2DM), obesity and non-alcoholic fatty liver disease (NAFLD). The therapeutic effects and underlying mechanisms of curcumin on these three diseases are presented categorically. Accumulating clinical evidence demonstrates that curcumin has good therapeutic potential and a low number of side effects for the three metabolic diseases. It can lower blood glucose and lipid levels, improve insulin resistance and reduce inflammation and oxidative stress. Overall, curcumin may be an effective drug for the treatment of T2DM, obesity and NAFLD. However, more high-quality clinical trials are still required in the future to verify its efficacy and determine its molecular mechanisms and targets.

Keywords: clinical evidence; curcumin; diabetes; non-alcoholic fatty liver disease; obesity.

Figure 1

Chemical structure (A) of curcumin and its main plant sources ((B) Curcuma wenyujin Y.H. Chenet C. Ling; (C) Curcuma longa L.; (D) Curcuma phaeocaulis VaL.; (E) Curcuma kwangsiensis S.G. Lee et C.F. Liang). The pictures are from the website: http://www.iplant.cn/frps, accessed on 21 September 2022.

Figure 2

The therapeutic effects and potential mechanisms of curcumin on T2DM. ↑ indicates increase and ↓ indicates decrease. Specifically, curcumin can lower blood glucose and lipid levels and improve insulin resistance. Moreover, curcumin alleviates inflammation by decreasing the levels of IL-6, TNF-α and hs-CRP, and increasing the anti-inflammatory cytokine adiponectin. Curcumin alleviates oxidative stress by decreasing the levels of MDA and increasing the expression of antioxidants, including SOD, GSH and TAC.

Figure 3

The therapeutic effects and potential mechanisms of curcumin on obesity. ↑ indicates increase and ↓ indicates decrease. Specifically, curcumin can alleviate inflammation by decreasing the levels of IL-1β, IL-6, TNF-α and hs-CRP. Curcumin alleviates oxidative stress by decreasing the levels of MDA and PAB and increasing the expression of the antioxidant’s TAC.

Figure 4

The therapeutic effects and potential mechanisms of curcumin on NAFLD. ↑ indicates increase and ↓ indicates decrease. Specifically, curcumin can improve liver function and hepatic steatosis and lower blood lipid levels. Moreover, curcumin alleviates inflammation by decreasing the levels of IL-6, TNF-α, hs-CRP and MCP-1, and increasing the anti-inflammatory cytokine adiponectin. Curcumin alleviates oxidative stress by decreasing the expression of 8-OHdG and CML.