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People traditionally take cod liver oil to improve their bone health, and some use it for osteoarthritis. But does it help?

Arthritis is a very prevalent condition and a leading cause of disability.

There are two common types. Both can cause joint pain, inflammation, stiffness, and other issues that limit mobility.

  • Rheumatoid arthritis (RA) is an inflammatory joint disease caused by a problem with the immune system.
  • Osteoarthritis (OA) is a degenerative condition that causes joint cartilage to wear away, leading to bone damage.

This article explores whether fish oil could help treat arthritis and professional guidance for using it.

It is worth noting from the outset that the American College of Rheumatology and the Arthritis Foundation do not recommend using fish oil for OA because there is not enough evidence that it is beneficial.

a person holding a fish oil tablet that may help treat arthritisShare on Pinterest
Fish oil may help reduce inflammation in joints.

Cod liver oil and fish oil contain high levels of two omega-3 fatty acids:

  • docosahexaenoic acid (DHA)
  • eicosapentaenoic acid (EPA)

Research — such as the studies that we cite below — indicates that EPA and DHA can both reduce inflammation. The role of fatty acids in curbing inflammation suggests that they may help treat RA and OA.

Fish oil and RA

A 2012 review looked at earlier research into the benefits of fish oil for treating RA. In particular, it explored the role of EPA and DHA in reducing joint swelling and pain.

The review found evidence that EPA and DHA from marine sources provided consistent but modest help in improving the following aspects of RA:

  • joint swelling and pain
  • morning stiffness in the joints
  • disease activity
  • the use of pain medication

According to a 2016 study, people with active RA who took daily omega-3 supplements were able to reduce their use of pain relief medication. The authors note, however, that this finding may only be true for people in hot climates.

Fish oil and OA

According to a 2015 review of the evidence, a number of studies in animals suggest that fish oil shows promise as a treatment for OA.

However, the authors acknowledge that confirming this in humans will require further research.

In one study, scientists found an improvement in pain and function after 2 years of use, and low dosages appeared to be at least as effective as high dosages. There were no significant improvements after 1 year.

Current guidelines do not recommend using fish oil for OA, due to a lack of evidence that it is effective in humans.

The omega-3s in fish oil may help combat a range of conditions with inflammatory features. Some of these conditions, beyond RA, include:

The most effective way to get essential omega-3s is by eating cold-water oily fish. Supplements are available, but the Food and Drug Administration (FDA) do not monitor them for quality or purity.

Fish oil is a dietary supplement from oily fish, such as:

  • mackerel
  • tuna
  • herring
  • salmon
  • cod, but specifically the liver

It also contains small amounts of vitamins and minerals, including:

Fish oil supplements are available as:

  • capsules
  • pastilles
  • chewable tablets
  • liquid

For people with RA, the Arthritis Foundation recommend taking up to 2.6 grams twice daily.

The supplement should contain at least 30% of the active ingredients EPA and DHA to provide the most benefit.

Cod liver oil or fish oil?

Fish oil is different from cod liver oil.

Cod liver oil contains oil from pressed cod livers only. It contains higher quantities of vitamins A and D than fish oil. The body needs these vitamins, but they can be harmful if people consume them in large quantities.

People who take fish oil or cod liver oil for arthritis will need to consume large amounts in order to obtain the benefits.

For this reason, fish oil is a more healthful source of omega-3s than cod liver oil, as people can consume large quantities without taking in too much vitamin A and D.

Rather than taking fish oil supplements, a person may prefer to include plenty of fish in their diet.

Good sources of omega-3s include:

  • salmon
  • tuna
  • sardines
  • mackerel

According to the Arthritis Foundation, eating 3–6 ounces of a variety of fish above between two and four times a week helps reduce inflammation and protect the heart.

When buying fish, consider the following points:

  • Is the fish likely to contain a high level of mercury? Check here.
  • Is it from a sustainable source? Check here.

Arthritis can be painful and limit a person’s mobility. A doctor can develop, monitor, and adjust a treatment plan to manage pain and reduce the risk of complications.

Fish oil may help treat RA by reducing inflammation in the joints. Further research is needed to confirm whether the oil improves symptoms of OA.

Fish oil may interact with some anti-inflammatory drugs, so it is important to talk to a doctor first before using it.

Fish oil supplements are available for purchase online.