"If you're among the estimated 27 million Americans who suffer from osteoarthritis of the knee or hip, then perhaps you've tried the nutritional supplements glucosamine and chondroitin. They've been marketed for joint health for about 20 years, and sales are still brisk. But do they help?"

"Some horses might say yes. The supplements were first tried in horses, and there's some evidence that the supplements might improve joint function for them."

"Glucosamine and chondroitin are also marketed to dog owners. But what about us humans? Unfortunately, researchers say that for us the results just don't match the glowing testimonials."

"It would seem to make sense that glucosamine and chondroitin could help. They're both natural substances found in cartilage, that hard connective tissue that pads joints."