Grape consumption improves joint flexibility and reduces pain associated with knee osteoarthritis

Osteoarthritis (OA) is the most common disease of joints, with a complex etiology. Pain and stiffness lead to loss of mobility that often requires invasive therapies. A growing interest in natural treatments suggests a role in OA therapy for foods with bioactive compounds. Grape polyphenols have anti-inflammatory properties that may influence OA outcomes. The purpose of this study was to assess the effect of grape consumption on self-reported pain, joint range-of-motion (ROM) and biochemical markers of inflammation (C-reactive protein [CRP]) and cartilage metabolism (insulinlike growth factor-1 [IGF-1], human cartilage glycoprotein 30 [YKL-40]) in individuals with self-reported knee OA. Using convenience sampling, 72 men and women with knee OA were recruited through local orthopedic clinics, primary care physicians, a senior recreation facility, the Texas Woman’s University campus, and other locations in the community. The treatment group (n =35, 27 female) consumed 47 g of freeze-dried grape powder (FDGP) daily for four months. The placebo group (n = 37, 28 female) consumed a comparable placebo. The FDGP group had a significant decrease in pain related to activity from baseline to end of treatment in comparison to placebo (-5.3 vs. - 2.1, p <0 .05). At midpoint, both groups had a significant reduction in total knee symptoms and impact on quality of life (QOL) that was only evident in the FDGP group at the end of study. Furthermore, this improvement benefitted female participants more so than males. FDGP consumption resulted in gender specific changes in IGF-1 compared to the placebo group. Males in the FDGP group had a significant increase in IGF-1 from baseline compared to males in the placebo group (1.6 and 19.9 ng/mL in FDGP; 6.8 and 2.0 ng/mL in placebo for baseline and final, respectively), and females in both FDGP and placebo group (5.1 and 3.2 ng/mL FDGP; 4.9 and 8.9 ng/mL placebo for female baseline and final, respectively), p <0.05). There was no change in overall ROM, CRP, or YKL-40 between FDGP and placebo groups. These results suggest consumption of whole grapes with their bioactive constituents may be a natural alternative to reducing pain and improving symptoms associated with OA.