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Fish oil trials for rheumatoid arthritis

Fish body oil

Data from 10 trials from 1985 onwards have been combined in a report to assess the potential therapeutic effect of fish body oil in rheumatoid arthritis. A more recent review article gave an overview of results from 17 RCTs into the same subject.


The quality of the trials included in this report ranged between low and moderate, and results were combined because of the small number of participants.

  • Fish body oil significantly decreased the number of tender joints and shortened the duration of morning stiffness compared to the placebo treatments.
  • It failed to make a significant change in a number of other disease measures (for example grip strength, blood tests for disease activity and the overall disease severity).

Review article

Trials included in this article used daily doses of between 1.6–7.1 g (average 3.5 g) omega-3 fatty acids

The evidence suggests that fish oil supplements were generally well tolerated and significantly reduced the following:

  • joint pain
  • the duration of morning stiffness
  • fatigue time
  • the number of tender or swollen joints
  • the use of painkillers.

Fish liver oil

In this 9-month trial, 97 people with rheumatoid arthritis were randomly selected to receive either 10 capsules of SSMO1, which contain both fish liver oil (1 g per capsule) and fish body oil, or 10 placebo capsules once a day.

  • There was no difference in outcome after 12 weeks of the trial, but participants given SSMO1 had a modest improvement in pain after 24 and 36 weeks compared to the placebo group.
  • 39% of the active treatment group reported a significant reduction in their daily NSAID need compared to just 10% in the placebo group (this was a significant difference).
  • Approximately 65% of participants in the fish liver oil group completed the trial, compared to 54% of the placebo group. Withdrawal from the trial wasn’t put down to side-effects, but it might have been related to the large number of capsules participants were asked to take every day.
  • In those who completed the trial, there was no significant difference in the number or type of side-effects reported, most of which were mild and gastrointestinal in nature.
  • Because we can’t tell whether the results were caused by the fish liver oil, the fish body oil or the combination of the two, we haven’t been able to make a conclusion about the use of fish liver oil to treat rheumatoid arthritis based on this RCT alone.


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