Can Dietary Fatty Acids Be Beneficial For Osteoarthritis?
Osteoarthritis is the most common form of arthritis. Lawrence and colleagues estimated that 27 million adults in the United States had clinical osteoarthritis in 2008.1 These numbers have continued to increase with aging of the population and increasing obesity.2 Currently, there is low success with the non-surgical treatment of osteoarthritis. Researchers have found that pharmacological modalities, namely non-steroidal anti-inflammatory drugs (NSAIDs) and intra-articular corticosteroids, are only moderately effective, and found that only glucosamine sulfate delayed the progression of this disorder.3
Osteoarthritis is increasingly recognized as an inflammatory condition and researchers believe synovitis of the affected joints is the major cause of joint pain and contributes to the disease progression.4-8 Many of the current treatment modalities for osteoarthritis decrease synovitis but further research is needed to determine if modalities that decrease synovitis can alter disease progression.
Based on the assumption that modalities that decrease joint inflammation may reduce pain and halt disease progression, Hill and coworkers examined the effect of omega-3 fatty acids on knee osteoarthritis.9 This double-blind, multicenter, randomized control study examined the use of high-dose and low-dose fish oil for the treatment of knee osteoarthritis in 202 patients. This study was based upon previous research showing that high-dose fish oil has anti-inflammatory effects and is beneficial in the treatment of rheumatoid arthritis.10,11
The authors were unable to make conclusions regarding cartilage structure modification from their results. However, they did find improvement in pain and function scores with low-dose fish oil, resulting in better pain and function scores at 18 and 24 months in comparison to the scores with high-dose fish oil.9 It remains unclear why the low-dose fish oil outperformed the higher dose fish oil but the thinking is that the oleic acid, a monounsaturated omega-9 fatty acid, in the low-dose preparation may have had additional anti-inflammatory effects.
Regardless of the comparison of high-dose to low-dose fish oil, this well-done study provides important insight on the potential use of fish oil for the treatment of osteoarthritis. Further research is needed to compare fish oil treatment to placebo and examine the effect of fish oil on cartilage structure and disease progression.
References
1. Lawrence RC, Felson DT, Helmick CG, et al. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum. 2008;58(1):26-35.
2. Nguyen US, Zhang Y, Zhu Y, Niu J, Zhang B, Felson DT. Increasing prevalence of knee pain and symptomatic knee osteoarthritis: survey and cohort data. Ann Intern Med. 2011;155(11):725-732.
3. Reginster JY, Bruyere O, Neuprez A. Current role of glucosamine in the treatment of osteoarthritis. Rheumatology (Oxford). 2007;46(5):731-735.
4. Berenbaum F. Osteoarthritis as an inflammatory disease (osteoarthritis is not osteoarthrosis!). Osteoarthritis Cartilage. 2013;21(1):16-21.
5. Wenham CY, Conaghan PG. The role of synovitis in osteoarthritis. Ther Adv Musculoskelet Dis. 2010;2(6):349-359.
6. Ayral X, Pickering EH, Woodworth TG, Mackillop N, Dougados M. Synovitis: a potential predictive factor of structural progression of medial tibiofemoral knee osteoarthritis -- results of a 1 year longitudinal arthroscopic study in 422 patients. Osteoarthritis Cartilage. 2005;13(5):361-367.
7. Conaghan PG, D'Agostino MA, Le Bars M, et al. Clinical and ultrasonographic predictors of joint replacement for knee osteoarthritis: results from a large, 3-year, prospective EULAR study. Ann Rheum Dis. 2010;69(4):644-647.
8. Roemer FW, Zhang Y, Niu J, et al. Tibiofemoral joint osteoarthritis: risk factors for MR-depicted fast cartilage loss over a 30-month period in the multicenter osteoarthritis study. Radiology. 2009;252(3):772-780.
9. Hill CL, March LM, Aitken D, et al. Fish oil in knee osteoarthritis: a randomised clinical trial of low dose versus high dose. Ann Rheum Dis. 2016;75(1):23-29.
10. Proudman SM, James MJ, Spargo LD, et al. Fish oil in recent onset rheumatoid arthritis: a randomised, double-blind controlled trial within algorithm-based drug use. Ann Rheum Dis. 2015;74(1):89-95.
11. Fortin PR, Lew RA, Liang MH, et al. Validation of a meta-analysis: the effects of fish oil in rheumatoid arthritis. J Clin Epidemiol. 1995;48(11):1379-1390.
