Objective: Osteoarthritis (OA) is a degenerative joint disease associated with inflammation. The present study aimed to determine changes in serum levels of inflammatory biomarkers in OA patients whose clinical symptoms were improved as a result of supplementation with curcuminoids.

Methods: This study was a randomized double-blind placebo-control parallel-group clinical trial in which 40 subjects with mild-to-moderate degree knee OA were randomly allocated to receive either pure curcuminoids (1,500 mg/day in 3 divided doses; n=19) or matched placebo (n=21) for 6 weeks. In order to enhance the bioavailability of curcuminoids, piperine (15 mg/day) was added to the treatment regimen. Serum levels of interleukins 4 (IL-4) and 6 (IL-6), tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β) and high-sensitivity C-reactive protein (hs-CRP), together with erythrocyte sedimentation rate (ESR) were determined at baseline as well as at the end of trial.

Results: Serum concentrations of IL-4 (p=0.001), IL-6 (p=0.006) and hs-CRP (p=0.004) were significantly reduced in the curcuminoid group whilst serum levels of TNF-α and TGF-β and mean ESR remained unaltered by the end of trial (p>0.05). In the placebo group, serum concentrations of IL-4 (p=0.001), IL-6 (p=0.003), TNF-α (p=0.003) and TGF-β (p=0.005) were significantly reduced but mean hs-CRP and ESR values remained statistically unchanged (p>0.05). Comparison of the magnitude of changes in the evaluated inflammatory biomarkers did not indicate any significant difference between the study groups (p>0.05).

Conclusion: Significant improvement in clinical symptoms of OA in curcuminoid-treated subjects cannot be attributed to the systemic anti-inflammatory effects of these phytochemicals.