A number of well-designed clinical trials show that SAMe may support pain and inflammation alleviation in the joints, and researchers think it may also assist in cartilage repair, although they are not clear about how or why this works. In several short term studies (ranging 4 – 12 weeks), SAMe supplements were therapeutically effective in adults with knee, hip, or spine osteoarthritis. SAMe was as effectives in diminishing morning stiffness, decreasing pain, reducing swelling, improving range of motion, and increasing walking pace. Several studies also suggest that SAMe has fewer side effects.
The potential therapeutic benefit of SAMe for osteoarthritis was discovered when patients enrolled in clinical trials of SAMe for depression. Participants reported marked improvement in their osteoarthritis symptoms (76). Nine clinical trials in Europe (77) and one in the United States (7) with a total of > 22 000 participants have confirmed the therapeutic activity of SAMe against osteoarthritis.
Experimental studies indicate that SAMe increases chondrocyte proteoglycan synthesis (78) and proliferation rate (79). SAMe induces the synthesis of polyamines which might stabilize the polyanionic macromolecules of proteoglycans and assists attack by proteolytic and glycotic enzymes (80). Furthermore, in vitro studies show that SAMe can antagonize the tumor necrosis factor α–induced decreases in synovial cell proliferation and fibronectin mRNA expression (81). These findings indicate that in cultured synovial cells, SAMe restores basal conditions after cytokine-induced cell damage. In addition, oral administration of SAMe (400 mg for 7 d) to four subjects significantly increased SAMe concentrations in synovial fluid by 3–4-fold compared with pre-dosing values (32).