A recent Nutrients journal study reviewed the efficacy of omega-3 polyunsaturated fatty acids (PUFAs) in modulating the progression of osteoarthritis (OA).

Study: Omega-3 Supplementation and Its Effects on Osteoarthritis. Image Credit: fongbeerrredhot / Shutterstock.com

How is OA treated?

OA is a degenerative joint disease in which the destruction of the articular cartilage leads to a pro-inflammatory response. In OA, disease progression can be influenced by several factors, such as the extent of inflammation, trauma, biomechanics, and metabolism.

At joint surfaces, articular cartilage facilitates a low friction area and greater load transmission with joint articulations. In addition to articular cartilage, OA can also adversely impact the ligaments, adjacent synovium, and subchondral bone, all of which contribute to joint pain.

Typically, symptomatic OA is treated with land-based exercise programs, education, and weight-management programs. Pharmacological treatment is also available for OA; however, the presence of comorbidities makes medication-based care provision complex. Thus, there remains an urgent need for alternative treatment methods to address OA progression.

Previous research has shown that nutritional supplements and diet modifications could benefit OA patients. The anti-inflammatory properties of omega-3 PUFAs play a key part in the catabolic and inflammatory processes, which contribute to OA disease progression.

Omega-3 supplementation and reduced inflammation in OA

Omega-3 PUFAs are associated with anti-inflammatory effects that have been shown to reduce carcinogen and vascular biomarkers, including those associated with chronic inflammation, metabolic diseases, and conditions that reduce the strength of the musculoskeletal system.

Specialized pro-resolving lipid modulators (SPMs) counter-regulate pro-inflammatory mediators and encourage the production of anti-inflammatory mediators at the cellular level through apoptotic cells, cellular debris, and macrophage phagocytosis of pathogens. In fact, one study reported that SPM administration for eight to 12 weeks led to improvements in knee OA symptoms.

The ratio of n-6 to n-3 PUFAs is crucial to determine whether a pro- or anti-inflammatory response dominates. Previous research has revealed that a higher n-6/n-3 ratio was associated with greater knee OA pain and functional limitations.

Individuals with greater intakes of saturated fatty acids have also been shown to exhibit reduced joint space width. However, this effect was not observed among those consuming more PUFAs.

Upon examining the association between PUFAs and synovial fluid taken from the knee and shoulder joints, a positive correlation was observed between n-6 PUFA and synovitis. However, an inverse relationship was noted between n-3 PUFAs and patellofemoral cartilage loss.

A high n-3 diet has been associated with reduced OA disease progression. In a mouse model, 12 weeks of supplementation with soybean and linseed oil led to greater cartilage thickness and reduced tumor necrosis factor α (TNF-α) levels in both chondrocytes and serum. In human studies, treatment with docosahexaenoic acid (DHA) has led to reduced apoptosis and higher chondrocyte proliferation, which reflects increased autophagy and thicker cartilage.

Omega-3 PUFAs, OA, and comorbidities

Cardiovascular morbidity is inversely related to aerobic exercise, which is often negatively affected due to OA. Previous studies have shown that individuals supplementing with eicosapentaenoic acid (EPA) and DHA exhibit significant reductions in triglyceride levels, neutrophil counts, and white blood cell (WBC) counts, thus implying that omega-3 supplementation has the potential to mitigate adverse musculoskeletal events and preserved physical function.

Maintaining muscle mass is crucial to maintaining physical activity levels and reducing the risk of comorbidities. To this end, omega-3 supplementation has been shown to elicit indirect benefits through muscle recovery post-workout. In a previous study involving older adults between 60 and 85 years of age, omega-3 supplementation derived from fish oil led to increased hand grip strength and greater quadriceps muscle volume.

Delayed onset muscle soreness (DOMS) involves reduced joint range of motion, muscle power, and muscle swelling. One study has shown that supplementation with EPA and DHA led to significant improvements in joint range of motion, reduced muscle soreness, and higher maximal voluntary contraction.

Conclusions

Research has consistently demonstrated that omega-3 PUFAs reduce cartilage degradation and inflammatory biomarker levels, thereby mitigating the progression of OA. Omega-3 PUFAs also provide indirect benefits by improving muscle tissue recovery following exercise. In the future, more clinical trials are needed to provide a better understanding of standardized omega-3 supplementation for the modulation of OA.

Importantly, there is inconclusive evidence on the optimal dosage of omega-3 PUFA supplements, as well as the ratio of DHA to EPA and n-6/n-3. Furthermore, most research has been conducted using animal models and not humans. The source of omega-3 PUFAs can also influence potential outcomes by affecting their bioavailability.