Positive effects of omega-3 supplementation on various disease outcomes, including joint pain and stiffness, have been reported for patients with RA.
It should be noted that omega-3 supplements may take up to 3 months to exert a maximal effect
A systematic review evaluating the effect of marine fish oil on pain in arthritic disease concluded that patients with RA experienced a reduction in pain (standard mean difference [SMD] –0.21, 95% confidence interval [CI] –0.42 to –0.00) with low heterogeneity observed between studies (I2 = 32%).
Beneficial outcomes have also been reported in a meta-analysis of randomised controlled trials where supplementation with n-3 PUFAs for 3–4 months reduced patient reported joint pain intensity (SMD −0.26, 95% CI −0.49 to −0.03, p = 0.03), the amount of morning stiffness (measured in minutes) (SMD −0.43, 95% CI −0.72 to −0.15, p = 0.003) and the number of painful and/or tender joints (SMD −0.29, 95% CI −0.48 to −0.10, p = 0.003). Although significant, these differences are very small. Taking a fish oil supplement did not impact doctor-assessed pain (SMD −0.14, 95% CI −0.49 to 0.22, p = 0.45).