Fish Oil for Rheumatoid Arthritis

Medically Reviewed by David Zelman, MD on June 02, 2024
5 min read

Rheumatoid arthritis (RA) is often painful, but there are many ways to ease its symptoms. You may have heard that fish oil, which contains omega-3 fatty acids, can help decrease the swelling and irritation that comes with RA. But does it work? And is it safe?

Omega-3 fatty acids are a complex mix of fats and oils that are a crucial ingredient to our health. They’re an important part of the membranes around our cells, and help many tissues function properly, particularly our brains. But your body can’t make them efficiently. Instead, you have to get them through what you eat.

Good sources of omega-3s include fish (such as salmon or herring), plant oils (such as canola oil), as well as nuts and seeds (such as chia seeds and walnuts). You can also take supplements, either as capsules or liquid, that contain various doses of omega-3 fatty acids.

Much of the harm that RA causes results from inflammation that happens when your body’s immune system attacks its own healthy cells. Your body’s immune response is complicated, with many substances playing key roles. Omega-3s are an important part of that complex web.

They help decrease inflammatory cytokines. Those are molecules that send signals to ramp up your immune system. Omega-3s also help maintain the right balance of T cells, white blood cells that kill viruses, cancer cells, and other invaders.

Omega-3 fatty acid supplements for RA have been widely studied. Fish oil, in particular, has been shown to reduce joint pain, as well as the stiffness you might feel when you wake up after a night’s sleep. Other studies have suggested these supplements may help people with RA get by with lower doses of nonsteroidal anti-inflammatory drugs (NSAIDs). That’s important, since NSAIDs can cause many side effects if you take them too long. But fish oil doesn’t seem to slow progression of the RA itself. It just helps to relieve symptoms.

Of course, supplements aren’t the only source of omega-3s. Diets rich in these fatty acids may also prove useful. More research is needed about that, though.

Experts don’t usually recommend routine use of supplements unless you’re trying to fix a nutrient deficiency. In general, the best way to get more omega-3 fatty acids is through what you eat.

There are several types of omega-3s. Two of the main ones are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Both come only from marine sources like fatty fish and algae. A third type, alpha-linolenic acid (ALA), comes from plants like seeds and nuts, as well as vegetable oils. ALA, though, can’t be used in its original form. Your body has to convert ALA to EPA and DHA, but humans can’t do this well.

You may have heard that the Mediterranean diet is a healthful approach. This eating plan focuses on vegetables, fruits, whole grains, and seafood. And that’s a great way to work omega-3s into your meals. Fish with lots of omega-3s include sardines, halibut, salmon, and Atlantic mackerel.

To avoid taking in too much toxic mercury, polychlorinated biphenyls (PCBs), or other environmental contaminants, don’t eat large, predatory fish like king mackerel and swordfish too often. When you do, remove the skin, fat, and internal organs of the fish before cooking. This will decrease your exposure.

For vegetarians, a good option is algae, as well as nuts and seeds.

If you’re considering a supplement, check with your doctor first. They can help you find the right dose and make sure the omega-3s won’t interact with any other medications you take.

With RA, the main goal of treatment is to reach remission (low disease activity). One study suggested that, for people diagnosed with RA early in the course of their disease, higher blood levels of EPA were linked to higher odds of remission.

In general, the best way to treat rheumatoid arthritis is by taking your prescribed medications. Never stop them without talking with your doctor. At any stage of RA, though, there’s a possibility that omega-3 fatty acids might provide additional support for reducing joint pain and other symptoms.

Fish oil supplements are usually packaged as capsules, which should be refrigerated. Choose one made by a well-known company that certifies its product is free of heavy metals, including mercury. Keep in mind that the dose listed on the label takes into account the amount of EPA and DHA in the oil, rather than volume of the oil itself.

There’s no set dosage for children under 18. Adults should not go beyond 3 grams of omega-3s per day without a doctor’s OK. A typical capsule contains 0.18 grams of EPA and 0.12 grams of DHA.

For people with RA, research suggests the right amount is 2.7 grams per day of EPA plus DHA. This is a high dose, so talk with your doctor first. Some of this amount can come from the food you eat. For example, a 3-ounce serving of farmed salmon has more than 1.2 grams of EPA and over 0.5 grams of DHA.

It may take up to 3 months for fish oil to reach maximum effectiveness against joint pain and stiffness.

Talk to your doctor before you take fish oil capsules or any other dietary supplement. Omega-3 fatty acids can cause problems for people who have a bleeding disorder or bruise easily. Take special care if you’re on anticoagulants (blood-thinning medications) such as warfarin, clopidogrel, aspirin, or direct oral anticoagulants (DOACs). Omega-3s can increase the risk of bleeding for people on these drugs.

Be cautious if you have diabetes or schizophrenia, because these diseases affect how your body processes omega-3s.

Omega-3 fatty acid supplements can also interact with diabetes medications, since they may increase your fasting blood sugar levels. If you’re on a drug meant to lower your blood sugar, such as insulin, metformin, glyburide, or glipizide, your doctor might need to increase your dose if you take fish oil.

Other medications that can interact with fish oil include drugs and supplements to treat blood pressure, and the weight loss pill orlistat. Fish oil can also reduce your levels of vitamin E.

If you have a serious seafood allergy, avoid fish oil supplements. It’s unclear whether they’re safe for people who are allergic to seafood.

Overall, omega-3 fatty acids are considered safe. But it’s important to take the right amount. Even if you’re not prone to bleeding due to another medication or disease, higher doses of omega-3s put you at a higher risk of having a bleed.

Other possible side effects are digestive symptoms like gas, bloating, and diarrhea, though time-release capsules can help prevent these issues. You might notice a “fishy” aftertaste or bad breath when taking fish oil. Some people also develop a rash.