To follow up here is an excerpt on glucosamine and its method of action from the Glucosamine and Arthritis Information Center:
WHAT IS GLUCOSAMINE AND HOW DOES IT WORK?
Firstly healthy cartilage needs three things: water for lubrication and nourishment, proteoglycans to attract and hold the water, and collagen to keep the proteoglycans in place.
Proteoglycans are like a rope that threads itself through the collage and are essential as they hold many times their own weight of water, which both lubricates and nourishes the collagen. If the cartilage is damaged the thread of rope becomes weak and ‘leaks’ out and thus the collagen loses its nourishment as the proteoglycans lose their grip and float away. Thus the cartilage cannot withstand shocks, cracks and may wear out completely.
Glucosamine is a major building block of the water – loving proteoglycans. Besides being a building block for the synthesis of proteoglycans, its mere presence acts as a stimulus to the cells that produce proteoglycans – in fact glucosamine is a key factor in determining how many proteoglycans are produced by the cells.
Glucosamine has been shown to speed up production of both proteoglycans and collagen and it normalises cartilage metabolism which helps keep cartilage from breaking down.
Thus because of the affect of glucosamine on cartilage metabolism it can in fact help the body to repair damaged or eroded cartilage. In other words, glucosamine strengthens your body’s natural repair mechanisms.
Besides stimulating cartilage production, glucosamine also reduces joint pain and inflammation.