1) Recently reported associations between synovitis, cartilage damage andplasma levels of omega-3 and omega-6 fatty acids in patients with osteoarthritissuggest that fish oil supplements might be beneficial additions to the therapeuticregime in this disease. 2) Osteoarthritis (OA) is characterized by degeneration and loss of articularcartilage, and accompanying synovial inflammation (synovitis). 3) Synovitis can cause swelling, tenderness and restricted movement in OApatients. 4) In OA, inflammatory cytokines (IL-1B, TNF, IL-6)amplify the pathophysiologicalprocesses that result in joint damage. 5) In OA, low-grade inflammation influences the long-term outcomes in patients. 6) Treatments that safely reduce the inflammation underlying cartilagedegeneration in OA are important. 7) Plasma levels of long chain omega-6 (n-6) and omega-3 (n-3) fatty acidscorrelate with MRI evidence of synovitis in the knees of patients with OA. 8) The inflammatory effects of omega-6 eicosanoids derived from arachidonicacid are greater than the anti-inflammatory effects derived from the omega-3 fattyacids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 9) The availability of arachidonic acid for production of inflammatoryeicosanoids could be a predisposing factor for synovitis in early OA. 10) The n-6 (AA) and n-3 (EPA) fatty acid ratios could be more important thanthe absolute amounts of these fatty acids. 11) EPA and DHA reduced expression of degradative enzymes and inflammatorycytokines. 12) Long-term fish oil treatment at anti-inflammatory doses inhibits prostaglandinE2 synthesis. 13) Established benefits for omega-3-rich supplements in patients withrheumatoid arthritis include: * Reduced symptom severity * Increased remission * Improvement in markers of cardiovascular risk * Decreased use of NSAIDs 14) The reduced use of NSAIDs is important as these drugs whilst providing aprompt analgesic effect have not been shown to improve long-term outcomes inRA, and their use can distract clinicians from prescribing more effective long-term disease-suppressing agents. 15) Moreover, NSAIDs are associated with an increased risk of potentially life threateninggastrointestinal bleeding and serious thrombotic cardiovascular events,including myocardial infarction and stroke. 16) The NSAID-sparing effect and the direct collateral cardiovascular benefits areimportant potential advantages of fish oil use for long-term analgesia in a diseasesuch as osteoarthritis. 17) Treatment with omega-3 fatty acids has the potential to play a key part inthe management of patients with osteoarthritis. 18) The omega-3 fats in dietary fish oil, EPA and DHA, inhibit the omega-6 fattyacid arachidonic acid cascade into the inflammatory prostaglandins and leukotrienessuch as PGE2 and LTB4. 19) Competitive inhibition of arachidonic acid metabolism by EPA and DHA couldreduce inflammation, pain and synovitis. 20) EPA and DHA suppress chondrocyte metalloproteinases production, anddietary fish oil has a protective effect on cartilage and subchondral bone in OA.