HIGHLIGHTS
• Avocado and soya unsaponifiables (ASUs) increased the levels of TGF-β1 and TGF-β2 in canine synovial fluid.
• TGF-βs control proliferation of numerous types of cells and are present in cartilage matrix.
• ASUs are disease-modifying agents that can be used in the management of arthritis.

Avocado and soybean unsaponifiables (ASUs) are used as a supplement to ameliorate signs of arthritis. Their efficacy seems to result from synergism between the active components of the avocado and soya, which have yet to be identified. In vitro studies with cultured articular chondrocytes have shown that ASUs stimulate the synthesis of matrix components by chondrocytes and decrease matrix metalloproteinase production. This is believed to occur through increased production of transforming growth factor-β (TGF-β). This study investigated the effect of ASU administration on the levels of 2 isoforms of TGF-β, TGF-β1 and TGF-β2, in canine synovial fluid. The control group was fed a normal diet. The low-dose treatment group was administered 300 mg ASU every 3 days and the high-dose group was given 300 mg daily. Synovial fluid samples before treatment and at the end of first, second, and third months were obtained under anesthesia. Significant increases of TGF-β1 levels as well as TGF-β2 levels were noted between the treatment groups and the control group throughout the study period. No differences between the high- and low-dose groups were detected. The results of this study demonstrate that both high- and low-dose ASU treatments will increase the levels of TGF-β1 and TGF-β2 in synovial fluid. Previous in vitro studies have shown that TGF-β has the ability to stimulate extracellular matrix production, like collagen type II and proteoglycan, in chondrocytes. However, what effects the increase of TGF-β‚ in the synovial fluid may have on articular cartilage in vivo are unknown. 

Treatment with unsaponifiable extracts of avocado and soybean increases TGF-β1 and TGF-β2 levels in canine joint fluid. Altinel L, Saritas ZK, Kose KC, et al. J Exp Med 211:181-186, 2007.