ABSTRACT & COMMENTARY
The Yellow Spice That Just Keeps on Giving: Turmeric and Arthritis
By David Kiefer, MD, Editor
- A polysaccharide component of turmeric
rhizome, in the form of the extract HR-INF-02, was studied in 120 people with moderate osteoarthritis in a placebo-controlled, four-arm, 42-day study.
- The group taking only turmeric had better improvements, when compared to placebo, in pain severity, the WOMAC index, and the Clinician Global Impression of Change.
- The turmeric group also experienced less side effects over the course of the research study.
A polysaccharide-rich extract of turmeric rhizome provided benefits in people with knee osteoarthritis.
Madhu K, et al. Safety and efficacy of Curcuma longa extract in the treatment of painful knee osteoarthritis: A randomized placebo-controlled trial. Inflammopharmacology 2013;21:129-136.
This was a randomized, single-blind (the study investigator was not blinded to the group assignment), placebo-controlled trial examining the effects of a curcuminoid-free extract of turmeric (Curcuma longa, Family Zingiberaceae) rhizome on adults with knee osteoarthritis (OA). The authors wished to expand on turmeric research by studying the polar, polysaccharide-rich fraction of this rhizome. Whole turmeric contains many phytochemicals, including curcuminoids and polysaccharides; the anti-inflammatory effects of turmeric may have its origins in a compound other than the oft-studied curcuminoids.
To be included in the trial, study participants had to be older than the age of 40 and have "clinical evidence" documenting knee OA, including pain on most days for the 6 months preceding the trial and radiological evidence of grade 2-3 OA (Kellgren and Lawrence OA rating system, from 1 [minimal] to 4 [severe] OA). Exclusion criteria were trauma or surgery to the affected knee(s), patellofemoral disesase, medical or arthritic conditions affecting knee evaluation (not specified), or any disease that may affect a participants ability to finish the trial (again, not specified).
The study participants were randomized to one of four groups (see Table 1). The doses for the turmeric and glucosamine were based on animal and human research as cited by the authors.
The researchers collected demographic, medication, and past medical history information. The primary outcome was OA pain severity as per the visual analog scale (VAS) rated 0-100 at baseline, day 21, and day 42. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) (24 questions, each rated 0-4, total possible 96) was used to assess pain, stiffness, and functional limitation of the affected joint. In addition, the Clinician Global Impression of Change (CGIC) on days 21 and 42 assessed the study participants’ overall condition. Participants were allowed acetaminophen up to 4 g daily as rescue medication, though not within 24 hours of an examination.
An intention-to-treat analysis of the 120 patients randomized in the trial found that all groups improved in VAS, WOMAC, and CGIC over the course of the 42 days (P < 0.01), but the turmeric only group fared better than placebo (P < 0.05) for all three scales. Turmeric alone was better than the combination for VAS and WOMAC (P < 0.05), and better than glucosamine only for CGIC (P < 0.05). Furthermore, only four participants in the turmeric group complained of joint pain at the end of the trial (compared to 29 at the beginning) and fewer participants in the turmeric group used rescue medication; both of these results were noted by the authors to be statistically different from the other groups (P < 0.01). The turmeric group and the combination group had less joint crepitus, and all treatment groups had less joint effusion and joint limitation when compared to placebo.
Thirteen mild adverse effects were reported, the least number (n = 2) being in the turmeric group. The authors did not run statistics on the adverse effect spread.
Commentary
Turmeric is becoming standard of care in the integrative medicine and nutraceutical worlds as a treatment for pain, including pain from osteoarthritis.1 Most plants have a variety of phytochemicals accounting for their physiological activity, and turmeric is no exception. A group of compounds in turmeric, the curcuminoids, including curcumin, have been studied for their anti-inflammatory effects,2 but the trial being reviewed here sheds light on similar anti-inflammatory, pain-relieving activity for the polysaccharide component delivered in the extract HR-INF-02.
Some questions surface upon further review of this article. Some of the results seem too good to be true. Turmeric was the best performer and the intervention with the least side effects. Was it due to the turmeric extract company’s involvement? The company donated the turmeric extract, but it does not seem to have been involved in the data collection or analysis. A statement to that effect would have been nice to see. Also, improvements in the three scales were seen at 21 and 42 days, not only for turmeric, but also for glucosamine, an intervention that normally takes longer before an effect is seen.3 Could some of these substantial effects be due to the single-blind nature of this trial? Possibly, as subtle interactions between staff and participants could lead to clinically relevant benefits. Corroboration with a longer, larger trial conducted in a double-blind fashion would do much to address these criticisms and bring this curcuminoid-free extract, or extracts that contain both curcuminoids and polysaccharides, into greater use.
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Table 1. Four Groups of Curcuma longa Research Study
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Group
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Substance
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Dose
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Number of Participants
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Placebo
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Microcrystalline cellulose
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400 mg twice daily
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30
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Turmeric
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Extract HR-INF-02 gelatin capsules containing 12.6% polysaccharides
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500 mg twice daily
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30
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Glucosamine
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Glucosamine sulfate
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750 mg twice daily
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30
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Glucosamine + Turmeric
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As above
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500 mg twice daily (turmeric) plus 750 mg twice daily
(glucosamine)
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30
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References
- Gregory PJ, et al. Dietary supplements for osteoarthritis. Am Fam Physician 2008;77:177-184.
- Henrotin Y, et al. Biological actions of curcumin on articular chondrocytes. Osteoarthritis Cartilage 2010;18:141-149.
- Dahmer S, Schiller RM. Glucosamine. Am Fam Physician 2008;78:471-476.
