Translational investigations of turmeric supplements for arthritis treatment: A review of lessons learned

Objective: Turmeric rhizome has been used for centuries to combat inflammation, including joint inflammation in arthritis. However, scientific evidence of efficacy and mechanism of action and a systematic evaluation of the biological activity of turmeric components for the treatment of inflammation have been lacking. Additionally, as is often the case in the study of botanicals, the scant existing research examining possible anti-inflammatory effects of turmeric products is compromised by the use of extracts that are not well characterized or described. Methods: Turmeric extracts were isolated and chemically and biologically characterized prior to in vivo testing to determine anti-arthritic efficacy and mechanism of action using an animal model of rheumatoid arthritis, streptococcal cell wall-induced arthritis in female Lewis rats [1, 2]. Composition and biological activity of experimental extracts were compared to those of commercially-available turmeric dietary supplements and rhizome accessions grown under controlled conditions. Results: A turmeric fraction depleted of essential oils, similar in composition to commercial turmeric dietary supplements, profoundly inhibited joint swelling in a dose-dependent fashion. Periarticular destruction of cartilage and bone was also prevented by turmeric treatment. Mechanistic studies revealed that in vivo turmeric treatment inhibited local NF-κB activation and the subsequent expression of key NF-κB-regulated mediators of joint inflammation and destruction, including chemokines, cyclooxygenase 2, and receptor activator of NF-κB ligand (RANKL). Conclusions: These translational studies demonstrate in vivo efficacy and identify a mechanism of action for a well-characterized turmeric extract that supports further clinical evaluation of turmeric dietary supplements in the treatment of rheumatoid arthritis.

Acknowledgements: National Institutes of Health Office of Dietary Supplements and the National Center for Complementary and Alternative Medicine (Grant 5 P50 AT000474) and Janet L. Funk, Department of Medicine, University of Arizona.

References: 1. Funk, JL. et al. (2006)J Nat Prod 69:351–355.

2. Funk, JL. et al. (2006) Arthritis Rheum 54:3452–3464.