Cosequin ASU Plus contains the same ingredients (Glucosamine, Chondroitin Sulfate, MSM, and ASU) as Cosequin ASU with the addition of HA and Green Tea Extract. HA is found naturally in the body and is the major component of synovial fluid, the substance that lubricates joints and keeps them moving fluidly. HA has been shown to be safe and it has been suggested that it may help provide joint comfort. Green Tea Extract is believed to work as an antioxidant and free radical scavenger by helping protect joint tissues from these compounds. The combination of ASU/Glucosamine/Chondroitin Sulfate with HA was shown to be more effective in reducing the expression of several factors involved in the breakdown of cartilage than ASU/Glucosamine/Chondroitin Sulfate or HA alone. ASU with Green Tea Extract was shown to be more effective than either ingredient alone in decreasing factor expression.