Osteoarthritis and diet: Joined at the hip - Veterinary Medicine
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Osteoarthritis and diet: Joined at the hip

Clinical Edge

Another means of reducing PGE2 and inflammatory mediator production is through the use of dietary long-chain omega-3 (n-3) polyunsaturated fatty acids, especially eicosapentaenoic acid. The primary omega-6 fatty acid in cell membranes is arachidonic acid, which serves as the precursor for the production of the potent inflammatory mediators in osteoarthritis: PGE2, thromboxane (TX) A2, and LTB4. If the diet is enriched with long-chain n-3 polyunsaturated fatty acids—specifically eicosapentaenoic acid and docosahexaenoic acid—part of the arachidonic acid in cell membranes will be replaced by these n-3 fatty acids.40-42 Eicosapentaenoic acid may then be used instead of arachidonic acid for the production of eicosanoids, resulting in a different and less inflammatory set of compounds (e.g., PGE3, TXA3, and LTB5 instead of PGE2, TXA2, and LTB4).40,41 Dietary n-3 polyunsaturated fatty acids also suppress the proinflammatory mediators IL-1, IL-2, and TNF in cartilage tissue.43,44 Thus, substituting omega-3 for part of the omega-6 fatty acids should reduce inflammation and improve inflammatory conditions including osteoarthritis.

A review of studies in arthritic people indicated that most showed positive results from long-chain n-3 polyunsaturated fatty acid supplementation.45 Recent research in dogs supports many of these earlier findings in people confirming the clinical benefits of dietary n-3 fatty acids in osteoarthritis. Twenty-two dogs with osteoarthritis of the hip were given a fatty acid supplement marketed for dogs with inflammatory skin conditions (DermCaps—DVM Pharmaceuticals).46 When treated according to the manufacturer's recommended dosage, 13 of 22 dogs had noticeable improvement in their arthritic signs within two weeks.46 Another uncontrolled study evaluated dogs with naturally occurring osteoarthritis of the elbow and used force-plate analysis before and after dogs were fed a diet enriched with n-3 polyunsaturated fatty acids. Improvements in vertical peak force were observed within seven to 10 days on the diet (S.C. Budsberg: Unpublished data, 2004). In yet another study, dogs fed a diet enriched with n-3 polyunsaturated fatty acids following corrective surgery for ruptured cruciate ligaments showed a significant decrease in synovial fluid PGE2.47 Synovial fluid MMP-2 and MMP-9—enzymes which degrade structural proteins in cartilage—were also decreased in these dogs compared with dogs fed the control diet. (See the article by Dr. Mark Waldron for details on the role of n-3 fatty acids in osteoarthritis.)

Glucosamine in osteoarthritis

Glucosamine, an endogenously produced amino-sugar, is the principal component of the O-linked and N-linked glucosaminoglycans in connective tissues.48 A decrease in glucosamine synthesis by chondrocytes has been implicated in osteoarthritis, whereas supplemental glucosamine has a stimulatory effect on chondrocytes.49 Glucosamine is considered a chondroprotective agent and may minimize the progression of osteoarthritis.48,49

Several short- and long-term, double-blinded, randomized trials evaluating glucosamine supplementation in people with osteoarthritis of the knee were recently reviewed by meta-analysis.50 These studies documented significant improvement in clinical signs of osteoarthritis in patients consuming 1,500 mg of glucosamine per day (approximately 21 mg/kg ideal body weight). Two of these studies followed patients for three years and demonstrated that oral glucosamine inhibited the long-term progression of osteoarthritis.50 In addition to its effect on cartilage metabolism, glucosamine demonstrates anti-inflammatory effects on osteoarthritis.48 Clinical studies involving glucosamine alone in dogs are lacking. However, several in vitro and in vivo canine studies showed a benefit with glucosamine and chondroitin sulfate combinations.49,51 In studies involving arthritic people, glucosamine and chondroitin sulfate were equally beneficial and indistinguishable from one another in their effects.50


Source: Clinical Edge,
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