If we compare the joints of the human body to an automobile engine, the joint fluid in the body mimics the oil in the car engine. At regular intervals we replace the oil in our care engines because of the heat and friction breakdowns the viscosity of the oil. The oil becomes thinner and less able to protect the metal surfaces from excessive wear. Hyaluronic acid benefits our joints in the same way. As we age the viscosity of the joint fluid lessens. HA helps to maintain normal joint cushioning.