The effect of freeze-dried grape powder on inflammatory markers and physical activity in adults with self-reported knee osteoarthritis
Osteoarthritis (OA) is the most common joint disease among US adults, leading to pain and disability. Treatment of OA is focused on symptom management since no cure has been found, and may involve expensive procedures including joint replacement and may lead many to seek natural dietary approaches. Grapes, rich in anti-inflammatory polyphenols may aid in management of OA symptoms. The purpose of this study was to assess the effect of daily consumption of freeze-dried grape powder on physical activity, and biochemical markers of inflammation and cartilage metabolism in individuals with self-reported knee osteoarthritis. A total of 72 men and women with knee OA were recruited and randomized into 2 groups. Group 1 (n=28, 21 female and 7 males) consumed 47 grams of freeze-dried grape powder (FDGP) daily for four months. Group 2 (n=28, 21 female and 7 males) consumed 47 grams of a comparable placebo. Serum specimens and self-reported physical activity were obtained at baseline and at four months. There was a significant decrease in very hard activity in the placebo group. However, an increase in moderate activity was seen for those <64 yr. in the placebo group. Participants >65 yr. reported a significant decline in moderate and hard activities (P<.05) in both groups from baseline to final. A statistically significant increase in interleukin 1-beta (IL-1β) was observed in both groups, males greater than females. A greater increase occurred in the placebo group (637.33%) vs. FDGP (194.64%). Levels of IL-1β and cartilage oligomeric protein (COMP) increased more in those 65 years and older across both genders. In regards to cartilage turnover, both groups had a statistically significant increase in COMP (154.2% FDGP vs. 172.27% placebo). We showed that age has a significant impact on physical activity levels, inflammation, and cartilage metabolism in people with knee OA. FDGP supplementation may decrease age-related inflammation, decline in physical activity and cartilage matrix breakdown in those with OA.