The effect of freeze dried whole blueberries on pain, gait performance and inflammation in individuals with symptomatic knee osteoarthritis

Objective: The purpose of this study was to examine the effect of freeze dried whole blueberries on pain, gait performance and inflammation in individuals with symptomatic knee osteoarthritis (OA).

Methods: A total of 63 men and women with symptomatic knee OA were recruited and randomized into either a treatment group (blueberry group) or placebo group, for a period of 4 months (120 days). The treatment group (n = 33) consumed 40 grams of freeze dried whole blueberry powder divided into two parts per day (each 20-gram packet was reconstituted with 6-10 oz water). The placebo group (n=30) consumed 40 grams of control powder also divided into two parts per day, which was composed of a mixture of maltodextrins and fibers to mimic the carbohydrate composition of whole blueberries, but without whole blueberry content. The appearance of the placebo powder, along with energy content, are similar to the blueberry powder. Demographic information including weight, height, blood pressure (systolic and diastolic) were collected at baseline, midpoint (60 days), and final point (120 days) visits. Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaires were conducted at the baseline, midpoint (60 days), and final point visit (120 days). Gait analysis was also performed at these time points. Additionally, overnight fasting venous blood samples were collected at baseline, midpoint, and final visits to assess biomarkers of inflammation. Treatment effects were examined with repeated measures analysis of variance (ANOVA).

Results: A total of 49 participants completed the study with an attrition rate of 22%. WOMAC total score and sub-groups, including pain, stiffness, and difficulty to perform daily activities, decreased significantly at midpoint and final point over baseline in the blueberry group. In the placebo group, there was no change in the WOMAC total score. Increased normal pace walking cadence and velocity were observed at final point over baseline in both groups. Normal paced step and stride length for both limbs increased at midpoint over baseline and continued to increase at final point in the blueberry group. Normal waking pace single support percentage for both limbs increased at final point over baseline, while double support percentage for both limbs decreased in the blueberry group. For the inflammation changes, no significant changes were observed in plasma concentrations of tumor necrosis factor (TNF)-α, interleukin(IL)-1β, IL-6, IL-10, IL-13, matrix metalloproteinases (MMP)-3, and MMP-13, in the blueberry group. However, significant increases in TNF-α and IL-1β were noted at midpoint over baseline in the placebo group. Weight and BMI were significantly increased in the placebo group, while individuals in the blueberry group maintained their weight and BMI during the study period. Systolic and diastolic blood pressure decreased significantly in the blueberry group at midpoint over baseline and at final point over baseline, while there were no changes observed in the placebo group. However, there were no significant differences between the blueberry and the placebo group in regard to the WOMAC total and sub-group scores, gait parameters, and inflammatory and anti-inflammatory biomarkers, weight, BMI, and blood pressure at any time point.

Conclusions: The findings of this study suggest that daily incorporation of whole blueberries may reduce pain, stiffness, and difficulty to perform daily activities, while improving gait performance, and would therefore improve quality of life in individuals with symptomatic knee OA.