The Facts on Omega-3 Fatty Acids

What Are Omega-3 Fatty Acids?

Omega-3s are nutrients you get from food (or supplements) that help build and maintain a healthy body. They’re key to the structure of every cell wall you have. They’re also an energy source and help keep your heart, lungs, blood vessels, and immune system working the way they should.

Two crucial ones -- EPA and DHA -- are primarily found in certain fish. ALA (alpha-linolenic acid), another omega-3 fatty acid, is found in plant sources such as nuts and seeds.

DHA levels are especially high in retina (eye), brain, and sperm cells.

Not only does your body need these fatty acids to function, they also deliver some big health benefits.

Health Benefits of Omega-3 Fatty Acids

Blood fat (triglycerides). Fish oil can lower elevated triglyceride levels. Having high levels of this blood fat puts you at risk for heart disease and stroke.

Rheumatoid arthritis. Fish oil supplements (EPA+DHA) may curb stiffness and joint pain. Omega-3 supplements also seem to boost the effectiveness of anti-inflammatory drugs.

Depression. Some researchers have found that cultures that eat foods with high levels of omega-3s have lower levels of depression. The effects of fish oil supplements on depression has been mixed. More research is needed to see if it can make a difference.

Baby development. DHA appears to be important for visual and neurological development in infants.

Asthma. A diet high in omega-3s lowers inflammation, a key component in asthma. But more studies are needed to show if fish oil supplements improve lung function or cut the amount of medication a person needs to control the condition.

ADHD. Some studies show that fish oil can reduce the symptoms of ADHD in some children and improve their mental skills, like thinking, remembering, and learning. But more research is needed in this area, and omega-3 supplements should not be used as a primary treatment.

Alzheimer's disease and dementia. Some research suggests that omega-3s may help protect against Alzheimer's disease and dementia, and have a positive effect on gradual memory loss linked to aging. But that's not certain yet.

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Where to Get Omega-3s

When possible, try to get omega-3 fatty acids from foods rather than supplements. Aim to eat nonfried, oily fish high in DHA and EPA omega-3 fatty acids at least two times a week.

These include:

  • Anchovies
  • Bluefish
  • Herring
  • Mackerel
  • Marlin
  • Orange roughy
  • Salmon
  • Sardines
  • Sturgeon
  • Lake trout
  • Tuna

While eating more fatty fish is a good idea, some are likely to have higher levels of mercury, polychlorinated biphenyls (PCBs), or other toxins. These include mackerel, wild swordfish, tilefish, and shark.

Fish like wild trout and wild salmon are safer.

Good food sources of ALA are:

  • Walnuts
  • Flaxseed and flaxseed oil
  • Canola oil
  • Soybean oil
  • Chia seeds

While foods containing omega-3 fatty acids have health benefits, some -- like oils and nuts -- can be high in calories. So eat them in moderation.

Should You Take Omega-3 Supplements?

Fish oil has both EPA and DHA. Algae oil has DHA and may be a good option for people who don't eat fish.

Talk to your doctor about taking a supplement first. They may have specific recommendations or warnings, depending on your health and the other medicines you take.

There are also omega-3 prescriptions available. Epanova, Lovaza, Omtryg, and Vascepa contain DHA/DPA and are recommended for adults with triglycerides 500 mg/dL or above. Unlike fish oil supplements, these medications are approved and monitored for quality and safety by the FDA for specific use.

Some people with heart disease may be advised to take 1 gram (1,000 milligrams) daily of a combination DHA/EPA from fish oil.

People with other health conditions may take doses of up to 4 grams a day.

But if you have cardiovascular (heart and blood vessel) disease and high levels of triglycerides, omega-3 supplements might raise your risk of atrial fibrillation. Atrial fibrillation is the most common type of faulty heart rhythm (cardiac arrhythmia). 

That’s why it’s so important to check with your doctor before you take omega-3 supplements, especially if you take other medications or you have health issues.

The most common side effects from fish oil are indigestion and gas. Getting a supplement with a coating might help.

Omega-3 supplements (DHA/EPA) can make bleeding more likely. If you have a bleeding condition -- or take medicines that could increase bleeding, like apixaban (Eliquis), betrixaban (Bevyxxa), clopidogrel (Plavix), prasugrel (Effient), rivaroxaban (Xarelto), ticagrelor (Brilinta), warfarin (Coumadin), and some NSAIDs -- talk to a doctor before using any omega-3 supplements.

WebMD Medical Reference Reviewed by Neha Pathak, MD on May 03, 2021

Sources

SOURCES:

FDA.

American Heart Association: "Fish, Levels of Mercury and Omega-3 fatty acids."

Ronald Glick, MD, medical director, Center for Integrative Medicine, University of Pittsburgh Medical Center.

Erminia M. Guarneri, MD, cardiologist; founder, Scripps Center for Integrative Medicine, Scripps Health, La Jolla, CA; president, American Board of Integrative Holistic Medicine;  founder, Guarneri Integrative Health at Pacific Pearl La Jolla; author, The Heart Speaks.

Harvard School of Public Health.

David C. Leopold, MD, director of integrative medical education, Scripps Center for Integrative Medicine, La Jolla, CA.

Natural Medicines Comprehensive Database Monograph: "Fish oil."

Natural Standard Patient Monograph: "Omega-3 fatty acids."

Gail Underbakke, RD, MS, nutrition coordinator, preventative cardiology program, University of Wisconsin Hospital and Clinics.

European Heart Journal: “Omega-3 fatty acids supplementation and risk of atrial fibrillation: an updated meta-analysis of randomized controlled trials.”

NIH Office of Dietary Supplements: “Omega-3 Fatty Acids.”

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