New research is suggesting that regular grape consumption may help alleviate pain associated with symptomatic osteoarthritis (OA) of the knee, and improve joint flexibility and overall mobility. Researchers, led by Shanil Juma, Ph.D. of Texas Woman’s University, attribute these potential benefits to the polyphenols found in grapes.
The researchers found that both men and women consuming a grape-enriched diet had a significant decrease in self-reported pain related to activity and an overall decrease in total knee symptoms. This beneficial effect was more pronounced in females. Additionally, age-related differences were observed: there was a 70% increase in very hard activity for those under 64 years of age consuming the grape powder, while those receiving the placebo reported a significant decrease in very hard activity. Participants over 65 years, whether consuming grapes or the placebo, reported a decline in moderate to hard activities.
Evidence of increased cartilage metabolism was observed in men consuming the grape-enriched diet; they had higher levels of an important cartilage growth factor (IGF-1) than those on placebo. This protective effect was not observed in the females.
Asked about the background of this study, Dr. Juma told OTW, “Nutrition and lifestyle factors are associated with reduced risk for chronic and age-related disease conditions. Studies which are population based have shown that diets rich in fruits and vegetables have positive impact on health. Fruits and vegetables have bioactive constituents that are known to have anti-oxidative and anti-inflammatory properties. Grapes are a rich source of these bioactive constituents known as polyphenols. Resveratrol, a polyphenolic compound associated with grapes, has been shown to have potent anti-inflammatory action in both cell and animal models of various chronic disease conditions. In vitro studies have also demonstrated that resveratrol protects cartilage cells in presence of inflammatory compounds and promotes cartilage health.”
“Therefore, the goal of our study was to investigate the benefits of whole grape with all of its bioactive constituents on cartilage health. Hence, we planned a short term clinical study to demonstrate whether incorporation of whole grape powder (47 grams daily) into the diet for a period of four months improves joint function (flexibility and mobility), decrease pain symptoms, and reduces inflammation (serum biomarkers) in individuals who have self-reported symptomatic knee osteoarthritis.”
He added, “Based on these promising preliminary findings, our research goals are two-fold. First, we plan to conduct in vitro studies with human cartilage cells to understand the mechanisms by which polyphenols in whole grapes protect cartilage cells from destruction due to aging and inflammation. Second, we hope to conduct a larger study with a longer duration of treatment with whole grapes. The primary outcomes would focus on improvement in functional capacity involving gait, balance, and motion analysis. Additionally, a radiographic assessment of the afflicted knee joint before and after the treatment with whole grapes would support if grapes with its bioactive constituents have structural modifying ability in regards to cartilage health.”
