Flaxseed oil is sometimes promoted for rheumatoid arthritis (RA) due to its high content of alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid. Omega-3s are known for their anti-inflammatory properties, and some clinical evidence supports the use of marine-derived omega-3s (like EPA and DHA from fish oil) for reducing RA symptoms. However, the conversion of ALA to EPA and DHA in humans is inefficient, and studies specifically evaluating flaxseed oil for RA have shown inconsistent or limited benefit.

A few small clinical trials have explored flaxseed oil supplementation in RA patients. Some reported modest improvements in morning stiffness and joint pain, but most found no significant effects compared to placebo or fish oil. Systematic reviews and guidelines generally conclude that while marine omega-3s can provide symptom relief in RA, evidence for plant-based ALA (as found in flaxseed oil) is insufficient or weak. Traditional use specifically for RA is not well documented, though flaxseed has been used historically for general inflammation.

In summary, while there is a scientific rationale for considering flaxseed oil as a supplementary anti-inflammatory agent, robust clinical evidence supporting its use for RA is limited. The current scientific consensus rates the evidence as low, and flaxseed oil is not recommended as a primary therapy for rheumatoid arthritis.