Evaluation of the efficacy of extract supplement in individuals with knee discomfort associated with physical activity: A randomized, double-blind, placebo-controlled study.

The aim of the present study was to assess the efficacy and safety of the oral administration of extract (ADE) supplement to individuals with knee discomfort associated with physical activity. A randomized, double-blind, placebo-controlled study was conducted using 48 subjects. The subjects were randomly allocated to an ADE diet group (oral administration of ADE-containing diet, n=24) or a placebo group (n=24), and the intervention was conducted for 12 weeks. A total of 22 subjects in the placebo group and 22 subjects in the ADE diet group were assessed to be eligible for assessment of the efficacy of supplement. Knee function was assessed by changes in the scores of the Japanese Knee Osteoarthritis Measure (JKOM) questionnaire and the scores of the Japan Orthopedic Association (JOA) criteria, as well as by analyzing the levels of type II collagen synthesis and degradation biomarkers (procollagen II C-terminal propeptide, cross-linked C-telopeptide of type II collagen, collagen type II cleavage and matrix metalloproteinase-13). Outcomes were measured at the baseline and at 4, 8 and 12 weeks from the start of administration. Subscale II (joint flexion/stiffness) of the JOA criteria was markedly improved in the ADE diet group compared with the placebo group at 8 and 12 weeks during the intervention. Furthermore, in the subgroup analyses using subjects with mild knee discomfort, subscale II (pain/stiffness) and IV (general activities) scores of JKOM were significantly improved (P<0.05) and total JKOM score was markedly improved in the ADE diet group compared with the placebo group at week 8 of the intervention. No adverse effects were identified for the administration of ADE. In conclusion, these observations suggest that the administration of an ADE-containing diet is safe and improves joint function (flexion and stiffness) and general activity in subjects with mild knee discomfort. Therefore, ADE could be a promising candidate as a functional food that is beneficial to joint health.