More than 40 percent of arthritis sufferers in the U.S. report using complementary and alternative medicine, including dietary supplements, and the use of alternative remedies has increased since the FDA issued health warnings about anti-inflammatory drugs such as Celebrex. However, the effectiveness of many supplement ingredients has not been adequately studied. To complicate the matter, over-the-counter supplements are not regulated in the same way as drugs and their composition can vary widely. A new study published in the November 2006 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis) examined the effect and mechanism of turmeric (a botanical supplement long thought to have anti-inflammatory properties) on arthritis.
Led Janet L. Funk and Barbara N. Timmermann (currently at the University of Kansas), researchers at the University of Arizona in Tucson, AZ had already shown in an earlier study that turmeric can prevent joint inflammation in rats. In the current study, they expanded their research to compare the chemical composition of an experimental turmeric extract with those of commercially available over the counter turmeric dietary supplements. They also examined the dosage of the experimental version on joint inflammation and destruction, determined its effect on inflammation markers, and ascertained the mechanism by which turmeric protects joints in arthritis.
Initial results showed that a version of turmeric extract that was free of essential oils had a significant impact on arthritis and most closely matched the composition of commercially available supplements. This version was used in subsequent experiments and was shown to prevent acute and chronic arthritis, even when it was administered after arthritis had been induced. In addition, turmeric significantly inhibited joint destruction due to arthritis, and inhibited NF-B, a protein that controls the gene expression of substances that produce an inflammatory response. Turmeric also altered the expression of hundreds of genes involved in joint swelling and destruction and prevented an increase in osteoclasts (cells that break down bone) in joints.
The current research, which was funded by the Office of Dietary Supplements and National Center for Complementary and Alternative Medicine of the National Institutes of Healthis the first study to document the composition of a turmeric-containing compound that is similar to commercially available products and to document the mechanisms by which it reduces the effects of arthritis. The authors were able to find an effective dose in rats that would be equivalent in humans to 1.5 milligrams per day of a portion of the turmeric root that makes up 3% of dried turmeric powder. The inhibition of NF-B and of key inflammatory genes directly or indirectly activated by NF-B suggests that inhibition of this protein may be an important mechanism in turmeric's anti-arthritic effects. In fact, the authors state that "it would appear that turmeric dietary supplements share the same mechanism of action as antiarthritic pharmaceuticals currently under development that target NF-B." It is also possible that turmeric blocks other inflammatory pathways, given its chemical complexity. Turmeric seems to block early inflammatory responses, as evidenced by the fact that it was effective when started 3 days but not 8 days after arthritis was induced, the authors note.
"In summary," the authors state, "just as the willow bark provided relief for arthritis patients before the advent of aspirin, it would appear that the underground stem (rhizome) of a tropical plant [turmeric] may also hold promise for the treatment of joint inflammation and destruction." They note that the anti-inflammatory effects of botanicals can only be utilized if their chemical content is analyzed. The authors conclude: "Finally, before turmeric supplements can be recommended for medicinal use, clinical trials are clearly needed to verify/determine whether treatment with adequate doses of well-characterized turmeric extracts can indeed prevent/suppress disease flares in RA [rheumatoid arthritis] patients, as well as to explore any potential benefits of turmeric dietary supplements in the prevention or treatment of more common forms of arthritis in the general population."
Article: "Efficacy and Mechanism of Action of Turmeric Supplements in the Treatment of Experimental Arthritis," Janet L. Funk, Jennifer B. Frye, Janice N. Oyarzo, Nesrin Kuscuoglu, Jonathan Wilson, Gwen McCaffrey, Gregory Stafford, Guanjie Chen, R. Clark Lantz, Shivanand D. Jolad, Aniko M. Sólyom, Pawel R. Kiela, Barbara N. Timmermann, Arthritis & Rheumatism, November 2006; 54:11; pp. 3452-3464; (DOI: 10.1002/art.22180).
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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