How does the human body reduce friction?

The human body creates synovial fluid, which is found in our joints. This is a lubricating fluid, which reduces friction. When a joint loses its synovial fluid, bones can touch each other, which causes joint pain. This can be alleviated medically by having a series of joint injections with an artificial synovial fluid called hyaluronic acid. There are two common supplements, which are also used to reduce joint friction, glucosamine and chondroitin.