What Are Omega-3 Fatty Acids?

Medically Reviewed by Zilpah Sheikh, MD on November 05, 2023
4 min read

Omega-3 fatty acids are polyunsaturated fats (or "healthy fats") you have to get from foods or supplements because your body doesn't make them. They're part of the support structure of every cell in your body; they give you energy; and they help keep your heart, lungs, blood vessels, and immune system working the way they should.

There are three main types of omega-3s:

  1. Eicosapentaenoic acid (EPA): found in fish
  2. Docosahexaenoic acid (DHA): also in fish
  3. Alpha-linolenic acid (ALA): in plant foods

Not only does your body need omega-3 fatty acids to function, it also gets tons of health benefits from them, including those that support your brain and heart.

Heart health

Some research shows that eating fish high in omega-3s may reduce your odds of cardiovascular disease by lowering your cholesterol and triglycerides (fats in your blood). But taking fish oil supplements doesn't seem to have the same benefits. In fact, one large study ended early because fish oil supplements actually raised participants' chances of having atrial fibrillation, an irregular heartbeat that can cause a stroke.

Autoimmune diseases

Omega-3s in fish and fish oil supplements may help with symptoms of several autoimmune disease like rheumatoid arthritis, lupus, and Crohn's disease. But we need more research to understand how they work and if omegas-3s from fish are better than those in supplements.


Several clinical trials have studied how well omega-3s work in helping people who aren't getting relief from antidepressants. A meta-a-

+ nalysis of different studies found that omega-3s can help relieve some symptoms of depression. But more research is needed because some of the studies had mixed results.

Brain development in infancy

You need to get plenty of omega-3s while you're pregnant for your growing baby. It's important for their brain development and future thinking and reasoning skills.

Asthma in children

A diet high in omega-3s lowers a child's chances of having symptoms of asthma from indoor pollutants. Researchers suggest kids are better protected when they eat more foods with omega-3s and less of those with omega-6 fatty acids, like soybean and corn oils.

Symptoms of attention-deficit/hyperactivity disorder (ADHD)

Research has found that children diagnosed with ADHD have low levels of omega-3 fatty acids in their blood, particularly DHA. Other research also shows that fish oil might improve the symptoms of ADHD in some children, but more research is needed and omega-3 supplements should not be used as a primary treatment.

Cognitive decline

Some research suggests that omega-3s may help protect against cognitive decline, Alzheimer's disease, and dementia and have a positive effect on gradual memory loss linked to aging. But studies suggest you get the most benefit when your diet is full of omega-3s before symptoms set in.

When possible, try to get your omega-3 fatty acids from foods rather than supplements.

Fish high in omega-3s

Aim to eat nonfried, oily fish high in DHA and EPA at least two times a week. Here are several:

  • Anchovies
  • Bluefish
  • Flounder
  • Freshwater trout
  • Herring
  • Salmon
  • Sardines
  • Sturgeon
  • Tuna

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

Vegan sources of omega-3s

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

Bear in mind that oils and nuts can be high in calories, so eat them in moderation.

The National Institutes of Health suggests you eat about 1-1.5 grams of omega-3 fatty acids every day as part of a healthy diet. It's best if it comes from food rather than supplements. You can get more than enough from a 3-ounce filet of fresh salmon.

There isn't much research on the symptoms of omega-3 deficiency. Most focus, instead, on how omega-3s benefit your health.

But if you don't get enough omega-3s in your diet, you could have rough, scaly skin or a red, itchy rash.

Omega-3 deficiency isn't very common in the U.S.

Talk to your doctor first before you take any supplements. They may have specific recommendations or warnings, depending on your health and other medicines you take.

The FDA doesn't regulate supplements for effectiveness, and research shows fish oil supplements don't help lower your chances or heart disease. But that doesn't mean they might not not help relieve symptoms of other conditions.

The most common side effects from fish oil are indigestion and gas.

Other side effects include:

  • Bad breath
  • Bad-smelling sweat
  • Headache
  • Heartburn, nausea, and diarrhea
  • Unpleasant taste in your mouth