Omega-3 Foods: The Best Sources of ALA, EPA, and DHA

Omega-3 foods can feel confusing because the word “omega-3” gets used as if it means one single thing. In reality, omega-3 is a family of fats, and the type of omega-3 matters.

The three names worth knowing are ALA, EPA, and DHA. ALA is found mostly in plant foods such as chia seeds, flaxseed, walnuts, and rapeseed oil. EPA and DHA are found mainly in oily fish, seafood, and algae.

EPA and DHA are produced by microalgae at the base of the marine food chain and then accumulate in fish tissues as they move through the food chain. For a deeper explanation of brain health, heart health, and omega-3 status, my full omega-3 fatty acids guide covers the science in more detail.

This is why omega-3 foods need a little more explanation than “eat more fish.” Helpful, yes. Specific, no.

The Three Omega-3 Forms Found in Food

ALA, or alpha-linolenic acid, is a plant-based omega-3. It is an essential fat, so it needs to come from the diet. Chia seeds, ground flaxseed, walnuts, soya, and rapeseed oil are useful sources.

EPA and DHA are longer-chain omega-3 fats. They are found mainly in oily fish, seafood, and algae-based oils. DHA is especially important in brain and retina tissue, while EPA is involved in inflammatory signaling and cardiovascular health research. The BDA notes that EPA and DHA are important for the heart, blood vessels, lungs, immune and hormone systems, while DHA is important for brain and retina development in infants.

ALA can be converted into EPA and DHA, but the process is limited. This process depends on genetics, and only small amounts are formed, at roughly 5-8% for EPA and 1-4% for DHA.

Best Foods for EPA and DHA

Oily fish is the primary dietary source of omega-3, in particular EPA and DHA.
Good options include salmon, sardines, mackerel, trout, herring, and anchovies. Fresh, frozen, and tinned fish can all be useful. Smoked or brined fish may be higher in salt, so read the label for sodium content.

The NHS recommends at least two portions of fish per week, including one portion of oily fish. One portion is around 140g cooked weight. BHF also describes oily fish as the best food source of EPA and DHA omega-3 fats.

A simple weekly pattern could be salmon one evening, sardines or mackerel another day, and plant omega-3 foods used throughout the week. It does not need to be fancy. Half the time, the most useful nutrition advice is what survives a busy Thursday.

Plant Omega-3 Foods

The most practical options are chia seeds, ground flaxseed, walnuts, hemp seeds, soya, and rapeseed oil. These foods provide omega-3 fatty acids in their precursor form, meaning the body must convert ALA into EPA and DHA via enzymatic pathways.

For chia seeds and flaxseed, the everyday kitchen detail matters. I would recommend grinding flaxseeds to break the food matrix and release more nutrients. Otherwise, the flaxseed can pass through the digestive tract intact, and you may miss some of the omega-3 locked inside the seed.

Chia seeds can be used whole because they swell and gel when hydrated, which makes them easy to add to puddings, porridge, yogurt, or breakfast jars.

Walnuts are probably the least dramatic option, which is exactly why I like them. Add them to breakfast, salads, homemade snacks, or baking, and they do their job.

What About Algae?

Algae deserves a mention because it sits at the beginning of the marine omega-3 chain. Microalgae produce EPA and DHA, then fish accumulate these fats through the food chain. This is why oily fish is such a rich source of long-chain omega-3.

For people whose diet does not include fish, algae-derived omega-3 becomes relevant because it provides a direct source of DHA, and in some products EPA too. I explain this more fully in my omega-3 supplements guide, because most algae-derived omega-3 is taken as algal oil rather than eaten as a regular food.

This makes algal oil especially useful for vegans, vegetarians, people who dislike fish, or anyone who wants a direct source of DHA without seafood.

Omega-3 Foods at a Glance

If you’re wondering how to boost your intake, here’s a list of foods rich in Omega-3 fatty acids:

Food	Main omega-3 type	Best use
Salmon	EPA + DHA	Main meals
Sardines	EPA + DHA	Budget-friendly oily fish
Mackerel	EPA + DHA	Salads, toast, main meals
Trout	EPA + DHA	Alternative to salmon
Chia seeds	ALA	Puddings, porridge, yogurt
Ground flaxseed	ALA	Breakfast bowls, baking
Walnuts	ALA	Snacks, salads, breakfast
Rapeseed oil	ALA	Everyday cooking
Algal oil	DHA + EPA	Direct fish-free source

Omega-3 Food Sources

1. Fatty Fish

2. Chia Seeds

3. Walnuts

4. Flaxseeds

5. Algal Oil

6. Cod Liver and Cod Liver Oil

Cod liver and cod liver oil have a long history of use in Northern European diets and remain a notable source of omega-3 fatty acids, particularly DHA and EPA. Unlike standard fish oil, cod liver oil is explicitly derived from the liver of the cod fish and naturally contains vitamins A and D alongside omega-3s. This combination can be beneficial in small, appropriate amounts, especially in populations with limited sun exposure.

However, because vitamins A and D are fat-soluble and can accumulate in the body, cod liver oil should be used with care and not treated as interchangeable with regular fish oil supplements. From a dietary perspective, cod liver itself is nutrient-dense but not commonly consumed. In contrast, cod liver oil is best viewed as a targeted supplement rather than a daily necessity, especially when omega-3 intake is already adequate from oily fish or other sources.

NOTE! Cod Liver is recomended for occasional use.

Cod liver is a concentrated source of omega-3 fatty acids, particularly DHA and EPA, and naturally contains vitamins A and D. While it can contribute meaningfully to omega-3 intake, its high vitamin A content means it is best consumed occasionally rather than regularly, and it is not suitable for everyone. Cod liver should be viewed as a traditional, nutrient-dense food rather than a staple omega-3 source.

In summary, the best choice depends on how someone actually eats. A person who enjoys fish may get EPA and DHA through oily fish. A vegan reader may need algal oil for direct DHA. Someone in between may occasionally eat both plant foods and fish.