In this article:
- Fish oil supplementation can be considered for arthritis, along with first-line drugs such as analgesics (ibuprofen, diclofenac), due to its anti-inflammatory effects. Studies have demonstrated this effect in patients with mild joint disease, but there is a lack of concrete evidence supporting its use in moderate to severe rheumatoid arthritis.
- The anti-inflammatory properties of fish oil are obvious at doses of >2.7 g/day EPA plus DHA, which is equivalent to 6-9 capsules of fish oil per day.
- The side effects of fish oil supplementation are mild and include gastrointestinal disturbances, bad taste and smell, and headache. Higher doses of >2.7 g/day may lead to bleeding tendencies in older adults.
- Fish oil from the fleshy part of cold-water fish is better than fish liver oil as the latter may cause vitamin A and D toxicity.
The importance of omega-3 fatty acids (omega-3 polyunsaturated fatty acids) in fish oil has been a topic of research due to the building evidence of their protective effects on the brain, heart, eyes, and musculoskeletal system.
There are three major omega-3 fatty acids:
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
- Alpha-linolenic acid (ALA)
EPA and DHA are macronutrients not synthesized in the body but are concentrated in large amounts in the flesh of marine animals.
Cold-water fatty fish, such as salmon, mackerel, tuna, herring, and sardines, have a higher amount of long-chain polyunsaturated fatty acids (PUFA) than less fatty fish, such as tilapia, cod, bass, and shellfish.
Plants are the major source of ALA, which can be converted to EPA and DHA in the liver but in limited quantities. Thus, it is more efficient to increase the intake of EPA and DHA through diet or supplements.
The American Heart Association recommends eating 2 servings (1 serving = 4 oz cooked fish) of fatty fish per week. (1) Approximately 8 oz of fatty fish provides 1-4 g of EPA+ DHA.
Results from a cross-sectional study of patients with rheumatoid arthritis found that subjects who consumed fatty fish >2 times a week had lesser values of inflammatory marker (C-reactive protein) than the subjects who consumed fatty fish <1 time a month. (2)
Plant sources of omega-3 fatty acids:
- Chia seeds
- Canola oil
Omega-3 supplements include:
- Fish oil
- Fish liver oil like cod liver oil, which also contains vitamins A and D
- Krill oil
- Algal oil
- Flaxseed oil, a source of ALA
How Does Fish Oil Improve Arthritis?
Rheumatoid arthritis is a chronic autoimmune disease characterized by pain, swelling, and joint destruction.
The benefits of fish oil are thought to be due to its high concentration of EPA and DHA. Both EPA and DHA are needed in the formation of various lipid-containing molecules that play a major part in altering inflammatory response in the body. Thus, EPA and DHA help resolve inflammation.
By reducing the inflammatory mediators (prostaglandin E2, leukotriene B4 cytokines, and reactive oxygen species) in the joint space, EPA and DHA alleviate the pain associated with rheumatoid arthritis and allow a reduction in the use of analgesics (NSAIDs) and disease-modifying drugs (steroids, immunosuppressants).
Large patient studies have shown that fish oil supplementation along with conventional medication, can reduce the pain, joint stiffness, and a number of joints affected with rheumatoid arthritis. The beneficial effect though is not immediate and takes at least 3-4 months to set in. (8)
However, note that cod liver oil, in addition to being a good source of EPA and DHA, contains high amounts of fat-soluble vitamins A and D, which, when consumed at anti-inflammatory doses, may produce vitamin toxicities. (6)
Side Effects of Fish Oil
Taking fish oil supplements may cause:
Because fish oil is highly unstable, it is subject to oxidation and rancidity, which may cause the common gastrointestinal side effects. (7)
To avoid these side effects:
- Avoid aerated drinks before consuming fish oil supplements.
- Take supplements before meals.
- Avoid consuming liquids immediately after taking fish oil.
- Refrigerate liquid fish oil.
- Consult your healthcare provider if you are taking medication that affects blood clotting or if you are allergic to fish.
Various studies suggest a dose-response relationship between fish oil supplementation and its anti-inflammatory effects, with a threshold dose of 2.7 g/day of EPA. This daily intake of EPA plus DHA is roughly provided by 9 standard fish oil capsules. (9)
Standard fish oil is available both in capsules and liquid formulations. Capsules are largely preferred over fish oil liquid as they mask the unpleasant taste and odor.
If a liquid fish oil preparation is your choice, then it is advised to layer the amount over 30 ml of juice (without stirring) and take it in a single gulp. This should be followed by slowly sipping 30 ml of juice to remove any unpleasant taste from the lips.
Drug and Fish Oil Interactions
Fish oil and conventional medication have several beneficial interactions to treat rheumatoid arthritis:
- Fish oil and NSAIDs: Fish oil and NSAIDs work by inhibiting cyclooxygenase, which is the main enzyme involved in generating inflammatory mediators. One study found that fish oil supplementation reduced conventional analgesic use and gastric irritancy in patients with rheumatoid arthritis. (10)
- Fish oil and cyclosporine: Cyclosporine is an immunosuppressant commonly used in moderate to severe forms of rheumatoid arthritis. Its side effects include hypertension and kidney toxicity. Fish oil, through its effect on reducing proinflammatory mediators, decreases these side effects of cyclosporine. (11)