Omega-3 fatty acids are essential fats that you must get from your diet.

These incredibly healthy fats have important benefits for your body and brain (1, 2).

However, most people who eat a standard Western diet are not eating nearly enough omega-3 fats (3, 4).

This is the ultimate beginner’s guide to omega-3 fatty acids.

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Omega-3, or n-3, fatty acids, are a family of polyunsaturated fats that you must get from your diet.

They’re termed essential fatty acids, as they’re needed for health, but your body cannot produce them as it can other fats.

As polyunsaturated fatty acids, their chemical structure has several double bonds. Omega-6 fatty acids are another type of polyunsaturated fat.

The "omega" naming convention has to do with the placement of the double bond in the fatty acid molecule. Omega-3s have the first double bond placed three carbon atoms away from the omega end.

SUMMARY Omega-3 fatty acids are polyunsaturated fats that your body needs but cannot produce. For this reason, they’re classified as essential fatty acids.

There are many fatty acids that belong to the omega-3 family. The most important ones are EPA, DHA, and ALA.

EPA (eicosapentaenoic acid)

EPA is a 20-carbon-long omega-3 fatty acid. It’s primarily found in fatty fish, seafood, and fish oil.

This fatty acid has many essential functions. Most importantly, it’s used to form signaling molecules called eicosanoids. These can reduce inflammation (5).

EPA has been shown to be particularly effective against certain mental conditions, especially depression (6).

DHA (docosahexaenoic acid)

DHA is a 22-carbon-long omega-3 fatty acid. It is primarily found in fatty fish, seafood, fish oils, and algae.

The main role of DHA is to serve as a structural component in cell membranes, particularly in nerve cells in your brain and eyes. It makes up about 40% of polyunsaturated fats in your brain (7).

DHA is very important during pregnancy and breastfeeding. It’s absolutely crucial for the development of the nervous system. Breast milk may contain significant amounts of DHA, depending on the mother’s intake (8, 9, 10, 11).

ALA (alpha-linolenic acid)

ALA is an 18-carbon-long omega-3 fatty acid. It’s the most common dietary omega-3 fatty acid, found in certain high-fat plant foods, especially flax seeds, chia seeds, and walnuts.

Aside from being used for energy, ALA doesn’t have many biological functions.

Nevertheless, it’s categorized as an essential fatty acid. This is because your body can convert it into EPA and DHA, omega-3 fatty acids with various essential, biological functions (12).

However, this process is highly inefficient in humans. According to one estimate, only about 5% of ALA gets converted into EPA, and as little as 0.5% into DHA (13).

For this reason, ALA should never be relied on as your sole omega-3 source. Most of the ALA you eat will simply be used for energy.

SUMMARY There are three main types of dietary omega-3 fats. EPA and DHA are found in seafood and fish, while ALA is mostly abundant in high-fat plant foods.

Omega-3 fatty acids are among the world’s most comprehensively studied nutrients.

They have been shown to have powerful health benefits on the following conditions:

  • Blood triglycerides. Omega-3 supplements can significantly lower blood triglycerides (14, 15, 16).
  • Cancer. Eating foods high in omega-3 has been linked to a reduced risk of colon, prostate, and breast cancers. Still, not all studies agree (17, 18, 19, 20, 21, 22).
  • Fatty liver. Taking omega-3 fatty acid supplements can help get rid of excess fat from your liver (23, 24).
  • Depression and anxiety. Taking omega-3 supplements, such as fish oil, can help reduce symptoms of depression and anxiety (25, 26, 27, 28).
  • Inflammation and pain. Omega-3s can reduce inflammation and symptoms of various autoimmune diseases, such as rheumatoid arthritis. They’re also effective at reducing menstrual pain (29, 30, 31).
  • ADHD. In children with ADHD, omega-3 supplements can significantly improve various symptoms (32, 33).
  • Asthma. Omega-3s may help prevent asthma in children and young adults (34, 35).
  • Baby development. DHA taken during pregnancy and breastfeeding can improve your baby's intelligence and eye health (36, 37, 38).
  • Dementia. Some studies link a higher omega-3 intake to a reduced risk of Alzheimer's disease and dementia (39, 40, 41).

Despite improving several risk factors for heart disease, omega-3 fatty acids have not been shown to prevent heart attacks or strokes. The largest review studies found no benefit (42, 43).

SUMMARY Omega-3 fatty acids have been studied thoroughly. They have been shown to fight depression, reduce the amount of fat in your liver, lower blood triglycerides, and help prevent asthma.

Mainstream health organizations like the World Health Organization (WHO) and European Food Safety Authority (EFSA) recommend a minimum of 250–500 mg combined EPA and DHA each day for healthy adults (44, 45, 46).

The American Heart Association recommends eating fatty fish at least twice per week to ensure optimal omega-3 intake for heart disease prevention (47).

For pregnant and breastfeeding women, it’s recommended to add an additional 200 mg of DHA on top of the recommended intake (48).

The National Academies of Sciences, Engineering, and Medicine have also developed intake recommendations for ALA. For adults, the recommended intake is 1.6 and 1.1 grams per day for men and women, respectively (49).

If you’re trying to improve a specific health condition, ask your healthcare provider for dosage recommendations.

Keep in mind that your omega-6 intake may partly determine how much omega-3 you need. Cutting back on omega-6 may reduce your requirement for omega-3 (50, 51).

SUMMARY It’s generally recommended to eat fatty fish at least twice per week or to take at least 250–500 mg of combined EPA and DHA per day from a supplement.

The best way to ensure optimal omega-3 intake is to eat fatty fish at least twice per week.

However, if you don't eat a lot of fatty fish or seafood, you may want to consider taking a supplement.

In fact, most of the studies on the benefits of omega-3 use supplements.

Good EPA and DHA supplements include fish, krill, and algal oils. For vegetarians and vegans, taking a DHA supplement made from algae is recommended.

When it comes to omega-3 supplements, there are many choices and not all of them are good. Some may even contain harmful compounds due to pollution. Be sure to educate yourself before buying a supplement.

SUMMARY People who don’t frequently eat fatty fish or seafood should consider taking an omega-3 supplement. Fish, krill, and algal oils are good choices.

When it comes to nutrition, more is not always better.

As with most nutrients, there is an upper limit for how much you should take.

According to the Food and Drug Administration (FDA), taking up to 2,000 mg of combined EPA and DHA per day from supplements is safe.

In high doses, omega-3s have blood-thinning effects. Speak to your doctor if you have a bleeding disorder or are taking blood thinning medications.

Cod liver oil is also very high in vitamin A, which can be harmful in large doses (52).

Make sure to read and follow the dosage instructions.

SUMMARY Taking up to 2,000 mg of omega-3 per day from supplements is safe according to the FDA. Speak to a healthcare professional if you take blood-thinning medications or have a bleeding disorder.

Getting omega-3 fats from whole foods is not that hard — at least if you eat fish.

Here are a few foods that are very high in omega-3:

  • Salmon: 4,023 mg per serving (EPA and DHA)
  • Cod liver oil: 2,664 mg per serving (EPA and DHA)
  • Sardines: 2,205 mg per serving (EPA and DHA)
  • Anchovies: 951 mg per serving (EPA and DHA)
  • Flax seeds: 2,338 mg per serving (ALA)
  • Chia seeds: 4,915 mg per serving (ALA)
  • Walnuts: 2,542 mg per serving (ALA)

Other foods that are high in EPA and DHA include most types of fatty fish. Meat, eggs, and dairy products from grass-fed or pasture-raised animals contain decent amounts as well.

Several common plant foods are also high in the omega-3 fatty acid ALA, including soybeans, hemp seeds, and walnuts. Other vegetables, including spinach and Brussels sprouts, contain small amounts.

SUMMARY Foods that are very high in EPA and DHA include salmon, cod liver oil, sardines, and anchovies, while those packed with ALA include flax seeds, chia seeds, and walnuts.

Here are quick answers to some common questions about omega-3 fatty acids and fish oils.

1. What is the best form of fish oil?

Omega-3 fatty acids in most fish oils are in the ethyl ester form.

However, omega-3 in the triglyceride and free fatty acid forms seem to be absorbed better (53, 54).

2. What happens with excess omega-3s in the body?

They will simply be used as a source of calories, like other fats.

3. Can you cook with omega-3 oils?

It’s not recommended to cook with omega-3 oils, as they’re high in polyunsaturated fats, which can easily be damaged in high heat.

For this reason, you should store them in a dark, cool place and not buy them in bulk, as they can spoil.

Omega-3 fatty acids are vital to health.

If you don't frequently eat fatty fish or seafood, you should consider taking an omega-3 supplement.

It’s a simple but effective way to improve both your physical and mental health. Plus, it may reduce your risk of disease.

You can find omega-3 supplements, including vegan varieties, locally or online.