Omega-3 Fatty Acid Print Page

Common Names: Omega-3 fatty acid (fish oil, herring oil, cod liver oil, marine fish oil, DHA, EPA)

Scientific NamesOmega-3 unsaturated fatty acids

Bottom Line Effectiveness: Conflicting evidence exist for omega-3 fatty acids (DHA and EPA) and benefit in patients with RA; more studies are needed. Omega-6 and omega-9 fatty acids are not recommended.

Safety: DHA and EPA are likely safe in combined dose of <3 g/day; higher doses should be taken only while under medical supervision due to potential risk of bleeding.

What are Omega-3 fatty acids?

  • Omega-3 fatty acids are considered ‘essential’ fatty acids that the human body cannot produce. It is needed for human growth and development.
  • Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the key components found in marine fish or krill. 
  • Alpha-linolenic acid (ALA) is an omega-3 fatty acid found in plant sources (such as flaxseed)
  • Other unsaturated fatty acids (Omega-6 and Omega-9) are commonly promoted as natural supplements. However, Omega-6 and Omega-9 are readily obtained through diet alone.
    • The typical North American diet may be deficient in omega-3 fatty acids and can contain more than 15 – 20 times more Omega-6 than Omega-3.
    • Omega-9 fatty acid is produced in the body and available through food sources including animal fat and olive oil.  
  • It is important to maintain a proper ratio of Omega-3 to Omega-6 fatty acids:
    • Omega-3 fatty acids help to reduce inflammation, while some omega-6 fatty acids can boost inflammation.
    • Diets such as the Mediterranean diet may provide a better balance.

What are some sources of Omega-3?

  • Recommendations for daily Omega-3 intake (diet and supplement combined) for healthy adults range between 200-500mg of DHA and EPA.
    • Eating 2 servings of fatty fish per week will provide enough omega-3 fatty acids.
  • The best source of omega-3 fatty acids is fatty fish. Other sources are kelp, seaweed, fortified eggs, milk, yogurt, margarine and juice, and nuts, oils and soy products.
    • Studies have found in most cases ALA has about a 8-20% conversion rate to EPA (with an insignificant amount converted to DHA). (10)
      • 1 walnut contains around 360mg ALA (25mg EPA)
      • 1 tsp (2 grams) of ground flaxseed contains 570mg ALA (38 mg EPA)
      • 1 tsp (4.5 grams) of flaxseed oil contains 2400mg ALA (160mg EPA) (9)
  • Over the counter supplements of fish oil: 
    • Triple Concentration 600mg EPA + 300mg DHA = 900mg Omega 3
    • Alaskan Salmon Oil 90mg EPA + 110mg DHA = 200mg Omega 3
    • Super Concentration 420mg EPA+ 280mg DHA = 700mg of Omega 3

What are Omega-3 fatty acids used for in people with rheumatic conditions?

  • Omega-3 has been used for the management of rheumatoid arthritis (RA) and osteoarthritis (OA).

How is it thought to work?

  • Omega-3 fish oils (specifically, DHA and EPA) have anti-inflammatory properties
    • Other benefits of EPA and DHA may include cholesterol reduction, blood clot prevention, and potentially heart and blood vessel (cardiovascular) protection.
  • Plant source Omega-3 (ALA) does not seem to have as much benefit as EPA and DHA.

Omega-3 fatty acids (up to 3g of DHA + EPA) Studies up to 12 months have shown that patients with RA taking fish oil experienced reduced joint pain, joint swelling, duration of morning stiffness, and dose of non-steroidal anti-inflammatory drugs required for pain relief after a few months of use.
  • Likely beneficial in RA but studies used various doses of EPA and DHA. 
  • Supplementation may be beneficial especially if diet is deficient in omega-3 fatty acids. 
Omega-3 (up to 5.5g of EPA + DHA)
  • In one study, omega-3 fatty acids (DHA & EPA) increased the likelihood of disease remission and reduced the rate of medical therapy failure in patients newly diagnosed with RA treated with DMARDs. The target dose was 5.5g of DHA + EPA, however adherence was low and the average daily dose was 3.7g due to adverse effects.
  • In a study comparing the effect of EPA + DHA 4.5g with 0.45g in patients with knee OA, there were no change in cartilage volume observed on MRI after 2 years. The low dose fish oil resulted in more WOMAC pain reduction than high dose fish oil from baseline (-6 vs -3); adverse effects were similar between groups.
  • A systematic review of 18 RCTs examined patients with active RA taking various dose of omega-3. 4 studies found a statistically significant benefit in pain reduction of fish oil group (0.15-3.36g DHA + EPA/day) taken for 12 to 36 weeks compared to placebo. 2 studies measured pain score (VAS) decrease from baseline of 18% and 40% (from 3.8 and 4. One study did not show a decrease in pain but demonstrated a significant decrease in NSAID use in the fish oil group to 40.6% of original dose (vs. 84%).
  • Small well-conducted trial showed benefit of omega-3 in new onset rheumatoid arthritis, but high doses used were not well tolerated.
  • Small well-conducted trial did not show benefit in knee OA
  • Somewhat well conducted systematic review showing benefits of omega 3 in pain reduction in RA
  • Conflicting evidence on efficacy of omega 3 for RA, potentially due to difference in doses
Omega-6 and -9 fatty acids
  • No evidence that omega-6 fatty acids benefit patients with rheumatic conditions. 
  • In one small preliminary study, the combination of fish oil 3g/day and olive oil (omega-9) 9.6mL/day was shown to modestly reduce pain and improve function in patients with RA after 12 weeks of treatment.
  • Supplement with omega-6 fatty acids is not recommended.
  • Currently lack reliable evidence to recommend omega-9 fatty acids.

What are possible side effects and what can I do about them?

  • Fish oil is generally well tolerated when taken within the recommended dose range. 
  • Some common side-effects may include: fishy aftertaste, heartburn, and nausea. Rash and mild diarrhea have also been reported.
    • In amounts higher than recommended, fish oil may increase risk of bleeding by reducing the way platelets clump together (platelet aggregation). 
    • For fishy aftertaste, try: freezing the supplement, using an “enteric coated” capsule, and/or taking the supplement with a meal. 


With drugs:

  • Fish oil (DHA & EPA): has blood pressure lowering and blood thinning effects, which could increase the risk of low blood pressure and bleeding.  This risk would be higher in patients taking blood pressure lowering (antihypertensive) and blood thinning (anticoagulant/antiplatelet) drugs. 
    • Common antiplatelet and anticoagulant drugs may include: ASA (Aspirin), and clopidogrel (Plavix), ticagrelor (Brilinta), prasugrel (Effient), enoxaparin (Lovenox), dalteparin (Fragmin), warfarin (Coumadin), dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis) and others.

With other natural health products:

  • Fish oil (DHA & EPA): can interact with other natural products that have blood pressure lowering (antihypertensive) and blood thinning (anticoagulant/antiplatelet) effects. This would increase the risk of low blood pressure and bleeding.
    • Anticoagulant/antiplatelet: clove, garlic, ginger, ginkgo, Panax ginseng, turmeric, others.
    • Blood pressure lowering: Cat’s claw, co-enzyme Q-10, fish oil, stinging nettle, other

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For more information about omega 3-fatty acids, consult your physician and pharmacist.

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