The effect of a garlic supplement on the pro-inflammatory adipocytokines, resistin and tumor necrosis factor-alpha, and on pain severity, in overweight or obese women with knee osteoarthritis

Background: Osteoarthritis (OA) is a prevalent degenerative joint disease, which is associated with chronic and disabling pain. The adipocytokines, resistin and tumor necrosis factor-alpha (TNF-alpha), might play a role in OA pathogenesis and outcomes. Purpose: The aim of this study was, therefore, to assess the anti-inflammatory and analgesic effects of a garlic supplement on serum resistin and TNF-alpha concentrations and on pain severity in overweight or obese women with knee OA. Study design: Randomized, double-blind, placebo-controlled, parallel-design trial. Methods: In this study, 80 post-menopausal overweight or obese women (25 <= BMI <= 40 kg/m(2), age 50-75 years) with mild to moderate knee OA were enrolled. Patients were randomly divided into two groups to receive twice-daily either garlic tablets (total: 1000 mg) or placebo for 12 weeks. The primary outcome measures were fasting serum concentrations of resistin and TNF-alpha, and pain severity (assessed using 0-10 point visual analogue scale (VAS)). Results: At week 12, resistin concentrations were significantly decreased in the garlic group (6.41 +/- 2.40 to 5.56 +/- 2.16 ng/ml; P = 0.008). Serum TNF-alpha levels did not change significantly within or between the two groups. Pain scores were significantly reduced in the garlic (6.8 +/- 2 to 5.3 +/- 2.3; P = 0.002), but not in the placebo (6.7 +/- 2.4 to 6.2 +/- 2.5; P = 0.674), group. Pain scores were also significantly lower in the garlic, compared with the placebo, group following supplementation (5.3 +/- 2.3 vs. 6.2 +/- 2.5; P = 0.043). Conclusions: The findings suggest that garlic supplementation for 12 weeks might reduce pain severity in overweight or obese women with knee OA, which may, at least in part, be mediated via a reduction in the pro-inflammatory adipocytokine, resistin.