A common degenerative joint disorder, knee osteoarthritis is a major cause of pain and disability. Ronald Watson, from The University of Arizona (Arizona, USA), and colleagues enrolled 33 people with osteoarthritis in the knee in a two-month long study during which each subject received either a supplement of passion fruit peel extract (150 mg per day) or placebo.  At the conclusion of the study period, the clinical symptoms of osteoarthritis, as measured by a standardized Osteoarthritis Index, improved significantly in the passion fruit group, with pain and stiffness of the knees reduced by about 18%, as compared with the placebo group.  In addition to the improvements in the pain and stiffness scores, the team reports that overall physical function improved by 19.6%.  Commenting that: “This beneficial effect of [passion fruit peel extract ] may be due to its antioxidant and antiinflammatory properties,” the researchers conclude that: “The results of this study show that [passion fruit peel extract] substantially alleviated osteoarthritis symptoms.”