Effects of N-acetyl glucosamine and chondroitin sulfate supplementation on knee pain and self-reported knee function in middle-aged and older Japanese adults: a randomized, double-blind, placebo-controlled trial

There was no evidence of satisfying the standard to decide the efficacies of glucosamine and chondroitin in middle-aged and older Japanese adults with knee pain and/or stiffness. To investigate the effects of 24 week oral N-acetyl glucosamine and chondroitin sulfate supplementation on knee pain, self-reported knee function, physical activity, and physical performance. We randomly assigned 11 men and 39 women (aged 52–87 years) to receive 100 mg of N-acetyl glucosamine and 180 mg of chondroitin sulfate daily (Glu/Cho group) or a placebo (control, C group) for 24 weeks. The primary outcomes were a 100 mm visual analog pain scale (VAS) and the Japanese Knee Osteoarthritis Measure (JKOM) score. The secondary outcomes were physical activity and physical performance. We observed a significant group × time interaction on the JKOM score. According to the post hoc test, it significantly decreased (i.e., improved knee function) from the 4- to 12-week follow-up in the Glu/Cho group and the Glu/Cho group score was significantly lower than the C group at the 12-week follow-up. We found a significant interaction on household physical activity. There was no significant interaction on VAS or physical performance tests. The results of the present study were consistent with previous studies mainly conducted in European and American countries. These results suggest that consumption of N-acetyl glucosamine and chondroitin sulfate for 12 weeks or longer has a positive effect on self-reported knee function and household physical activity in middle-aged and older Japanese adults with knee pain and/or stiffness.