The effect of freeze-dried whole raspberry powder on gait performance, mobility, and serum biomarkers of cartilage metabolism in symptomatic knee osteoarthritis

Objective: The purpose of the study was to investigate the effects of freeze-dried raspberry consumption on gait performance, mobility assessed by physical activity, and serum biomarkers of cartilage metabolism (YKL-40, insulin growth factor-1, insulin growth factor binding protein- 3, and hyaluronic acid) in individuals with current symptomatic knee osteoarthritis. Methods: A double-blinded, randomized placebo-controlled study design was used with evaluations at baseline (before treatment intervention), midpoint (8 weeks), and after intervention (16 weeks). Sixty-three participants (both men and women) with self-reported mild to moderate degree of pain in the knee due to symptomatic OA were recruited. Participants were randomized into two groups, either placebo (n=29) or treatment group (n=34). The treatment group consumed 35 grams of freeze-dried raspberry powder mixed with 10-12 ounces of water, consumed daily. The placebo group consumed 35 grams of a control powder similar in color, fiber, carbohydrates, and calories. Anthropometric measurement of height, weight, blood pressure, and leg length were obtained at baseline, midpoint, and final visit. Additionally, participants filled out the International Physical Activity Questionnaire (IPAQ) at each visit. Finally, gait analysis was performed using the GAITRite® system at each visit. Overnight fasting venous blood was collected at each visit to assess markers of cartilage metabolism (YKL-40, IGF-1, IGFBP-3, and hyaluronic acid). Treatment effects were analyzed using repeated measures ANOVA. Results: A total of 44 participants completed the study with an attrition rate of 30%. Average sitting time, measured by minutes per day, showed a progressive decrease from baseline to end of the study in the raspberry group, where the placebo group showed a consistent level for the duration of the study. The raspberry group showed an increase in house-related physical activity, measured by metabolic equivalents (METs), whereas no significant changes were observed in the placebo group. For cartilage metabolism markers: hyaluronic acid, IGF-1, IGFBP-3, and YKL-40, the raspberry group showed consistent biomarkers throughout the study without significant changes. The placebo group showed a progressive increase in IGFBP-3 and YKL-40 throughout the duration of the study, markers which are associated with advancing degradation of cartilage. IGF-1 and hyaluronic acid showed no significant changes over time in the placebo group. At a normal walking cadence, the placebo group showed a significant increase in cadence, velocity, right and left leg single support percentage, and right and left leg step length; additionally, with a decrease in right and left leg single support percentage and right and left leg cycle time, suggesting an improvement based on the placebo effect. The raspberry group showed improvement with an increase in cadence and a decrease in right leg cycle time at a normal walking cadence. However, at a fast walking cadence, only the raspberry group showed significant improvements, whereas the placebo showed no significant improvements. The raspberry group increased in cadence, velocity, and left leg single support, while decreasing in left and right leg double support percentage and left and right cycle time. Conclusions: The findings of this study suggest that incorporation of whole raspberries may increase physical activity, improve gait performance, and prevent further cartilage degradation; therefore improving quality of life in individuals with symptomatic knee OA.