Glucosamine is a natural substance found in the human body. It plays an important role in the health and resiliency of your cartilage. Cartilage is the soft tissue that forms the cushions that keep your bones from grinding against each other in your joints. Without cartilage, your knees and elbows would quickly wear out.
Chondroitin is made from two sugar like molecules that are attached to each other. Long chains of chondroitins form part of the ground substance of cartilage tissue and help to make cartilage resilient to the pressures it experiences from bearing weight.