While the use of nutritional supplements for osteoarthritis (OA) has focused largely on the duo of glucosamine and chondroitin, research suggests that a popular supplement for heart disease and rheumatoid arthritis may also help OA – fish oil. Fish oil is the best source of omega-3 fatty acids, essential fatty acids our body needs to function properly.
Most studies of the effectiveness of fish oil for osteoarthritis have been done on animals, but a few studies have also been done in humans.
Animal Studies Offer the Most Evidence
Early evidence of potential effectiveness of fish oil for OA came in a 2011 study published in the journal Osteoarthritis and Cartilage. Researchers at the University of Bristol in the United Kingdom found that in guinea pigs – which spontaneously develop osteoarthritis – a diet rich in omega-3 fatty acids reduced the occurrence of OA in half compared to a standard guinea pig diet.
The scientists found that in guinea pigs fed the diet high in omega-3s, early signs of OA – such as the breakdown of cartilage and the loss of molecules that give cartilage its shock-absorbing properties – were reduced.
Another study published in the Annals of the Rheumatic Diseases in 2014 found that mice with knee OA that ate diets high in saturated fats or omega-6 fatty acids had significant worsening of their OA, while mice given omega-3 supplements had healthier joints.
What Human Studies Show
While these and other studies have established a connection between omega-3 and joint health in several animal species, their authors say more research is needed to determine if the supplements will prevent OA or decrease its severity in people. So far there have been no human studies that have consistently shown benefits of fish oil on cartilage, according to a 2015 literature review published the American Journal of Orthopaedics.
At least one study published since that review suggests that fish oil may help relieve OA symptoms. But that study, too, raises questions.
The multicenter study, published in Annals of the Rheumatic Diseases in January 2016, compared the effects of high-dose fish oil (4.5 g omega-3 fatty acids daily) to a mixture of one-tenth that dose combined with nine parts unrefined sunflower oil in 202 people with knee OA and knee pain. They evaluated patients on pain scores and several other measures – including function, quality of life, use of analgesics and anti-inflammatory drugs – at 3, 6, 12 and 24 months. The researchers then measured the patients’ change in cartilage volume at 24 months.
Although both groups showed symptom improvement, the low-dose fish oil group had greater improvement in pain and function scores compared with the high-dose group. There was no difference between the two groups in cartilage volume loss at two years, suggesting there was no additional benefit of high-dose fish oil compared to low-dose fish oil. The authors say the apparent benefit of the fish-sunflower oil blend over high-dose fish oil for pain and function requires further investigation.
Should You Take Fish Oil?
Despite the popularity of fish oil supplements for arthritis, researchers say there is insufficient evidence at this point to promote their use solely for the purpose of osteoarthritis treatment. “Possible efficacy in laboratory and animal studies has yet to be sufficiently observed and verified in clinical [human] trials,” write the authors of the 2015 review in the American Journal of Orthopaedics. At the same time, the authors say it is impossible to refute the benefits of fish oil as an adjunct to anti-inflammatory therapy.
In short, while the evidence is not great enough to promote fish oil as an OA therapy just yet, if you are taking fish oil to reduce inflammation – for rheumatoid arthritis or cardiovascular health, for example – the supplements could potentially provide the added benefit of protecting your joints from cartilage breakdown or reducing its severity.
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