The effect of freeze-dried whole blueberry powder on joint flexibility, mobility, and serum biomarkers of cartilage metabolism in symptomatic knee osteoarthritis

Objective: The purpose of this study was to examine the effect of freeze dried whole blueberry powder on joint flexibility, mobility, and serum biomarkers of cartilage metabolism in men and women ages 45-79 years old with symptomatic knee osteoarthritis. Methods: A total of 63 participants were recruited and randomized into two groups. The freeze dried blueberry powder (FDBP) group (treatment; n=33) consumed a total of 40 grams of freeze dried whole blueberry powder daily (packaged in 20 gram pouches to be consumed twice a day, to be equivalent to two servings of fresh blueberries) for 16 weeks. A control group (n=30) consumed 40 grams of a powder daily for 16 weeks which closely matched the freeze-dried blueberry powder in appearance and energy content but devoid of blueberries. All of the following outcomes were assessed at baseline, midpoint (8 weeks), and final visits. Flexibility of the afflicted joint(s) using range of motion (ROM) measurements were assessed using a 360 degree goniometer based on neutral zero method. The ROM parameters, extension (active and hyper) and flexion were performed by the same trained individual at each visit in triplicates. v Mobility was measured by the International Physical Activity Questionnaire Long Form (IPAQ) and blood specimens assessed changes in biomarkers of cartilage metabolism. Results: A total of 49 participants completed the study with an attrition rate of 22%. Range of motion increased slightly for both knees in FDBP group, while the placebo group had steady declines from baseline to final measurements. Physical activity measured in METs decreased for both groups, however activity levels decreased more in the placebo than the FDBP group. Slight improvements in hyaluronic acid from baseline to midpoint were noticed but from midpoint to final the concentrations slowly regressed. The FDBP group had an increasing trend in concentrations of IGF-1 with consistently stable concentrations of IGFBP-3, while the placebo group had declining concentrations of IGF-1 and increases in IGFBP-3 over the course of the study. The FDBP group had an overall decrease in concentrations of YKL-40 from baseline to the final evaluation, while the placebo group had a steady increase in concentration throughout the study period. Systolic and diastolic blood pressure decreased significantly in the FDBG from mid-point and final as compared to baseline measurements, while there were no changes observed in the placebo group. BMI increased significantly at final over baseline and midpoint in the placebo group, whereas the blueberry group maintained their body weight throughout the study. Conclusions: The findings of the study suggest that blueberries may have a positive effect on joint health by preventing further breakdown of cartilage and vi promoting repair. This was further supported by improvements in range of motion and maintenance of physical activity levels in the blueberry treatment group.