The richest omega-3 foods are oily fish (salmon, mackerel, sardines, trout, herring and anchovies), which provide the long-chain omega-3s EPA and DHA. Plant foods such as ground flaxseed, chia seeds, walnuts, hemp seeds and rapeseed oil provide a different omega-3, ALA. To cook them well, keep the heat gentle and the timing short for fish, and treat seeds and nuts as delicate ingredients: grind flax, keep nuts cool, and save seed oils for dressings. Here's what to buy, how to cook each one, and the mistakes worth avoiding.
The three omega-3s, briefly
Omega-3s are a family of fats the body can't make in useful amounts on its own, so they come from food. There are three main ones:
- ALA (alpha-linolenic acid) comes from plants: flax, chia, walnuts, hemp and rapeseed.
- EPA and DHA come mainly from oily fish and seafood.
The body can convert some ALA into EPA and DHA, but only in small amounts, which is why oily fish is so often singled out. Diets that include oily fish regularly are associated with better heart health, and many national health bodies recommend it as part of a balanced diet. UK guidance, for example, suggests at least two portions of fish a week, one of them oily. If you're pregnant, planning a pregnancy or cooking for young children, there are limits on oily fish and certain larger species, so check the guidance where you live.
The best omega-3 foods to buy
| Food | Omega-3 type | Buy it as | Best way to cook or use |
|---|---|---|---|
| Salmon | EPA, DHA | Fillets, fresh or frozen; tinned | Bake, roast, pan-fry skin-side down, poach |
| Mackerel | EPA, DHA | Fillets; hot-smoked; tinned | Grill hot and fast; flake smoked into salads |
| Sardines | EPA, DHA | Whole fresh; tinned | Grill or barbecue whole; tinned on toast |
| Trout | EPA, DHA | Whole or fillets | Bake whole with herbs; pan-fry fillets |
| Herring, kippers, anchovies | EPA, DHA | Fresh, smoked, cured or tinned | Grill, or use anchovies melted into sauces |
| Flaxseed | ALA | Ground (or whole, to grind) | Stir into porridge, yogurt, smoothies, baking |
| Chia seeds | ALA | Whole | Soak into puddings; sprinkle on bowls |
| Walnuts | ALA | Halves, shelled | Toast lightly; add to salads, grains, breakfasts |
| Hemp seeds, rapeseed oil | ALA | Hulled seeds; cold-pressed oil | Sprinkle seeds; use the oil in dressings |
Tinned salmon, sardines and mackerel are some of the best-value sources there are, and soft edible bones in tinned salmon and sardines bring calcium too. One note: in UK guidance, tinned tuna doesn't count as an oily fish, because much of its oil is lost in processing. Fresh tuna does.
How to cook oily fish well
Oily fish is forgiving in one way (the fat keeps it moist) and unforgiving in another: overcook it and it turns dry, chalky and strong-tasting. Gentle, short cooking gives the best texture and keeps more of the fish's own oil in the fish rather than in the pan.
Salmon
To bake: heat the oven to 200°C (180°C fan). Season a fillet about 2.5cm thick, drizzle with olive oil, top with lemon slices and bake for 12–15 minutes, until it flakes easily but is still slightly translucent in the very centre. It will finish cooking as it rests. To pan-fry: pat the skin completely dry, lay it skin-side down in a medium-hot oiled pan and leave it alone for 4–5 minutes, until the skin is crisp and the flesh has turned pale two-thirds of the way up. Flip for 30–60 seconds. The book's Baked Salmon with Lemon & Dill is the easiest way in.
Mackerel
Mackerel loves high heat and sharp flavours. Slash the skin a few times, brush with oil, season and grill skin-side up for 4–5 minutes, until blistered. Serve with something acidic to cut the richness: tomatoes, citrus, capers, horseradish or pickled onions. Grilled Mackerel with Tomato Salsa does exactly that.
Sardines
Fresh sardines are at their best grilled or barbecued whole: rub with olive oil and salt and cook for 2–3 minutes each side until the skin chars and the flesh lifts from the bone. Finish with lemon, parsley and a pinch of chilli, as in the book's Grilled Sardines with Lemon & Herbs. Tinned sardines need no cooking at all: mash onto toast with lemon, or fold through hot pasta with tomatoes and garlic.
Trout
A whole trout, stuffed with lemon slices and dill, roasts in about 20 minutes at 200°C (180°C fan). Fillets pan-fry in 3–4 minutes, skin-side down for most of that time. Toasted almonds and a squeeze of lemon are the classic finish.
Tip: less fishy kitchen. Cook fish en papillote. Put the fillet on a sheet of baking paper with lemon, herbs and a splash of olive oil, fold into a sealed parcel and bake at 200°C (180°C fan) for 12–15 minutes. The fish steams gently in its own juices, and most of the smell stays in the parcel.
How to use plant omega-3s
ALA-rich seeds, nuts and oils are delicate: their fats go stale (rancid) when exposed to heat, light and air. A few habits keep them tasting fresh.
- Grind flaxseed. Whole flaxseeds often pass through undigested. Buy ground flaxseed in small packs, or grind your own a week's worth at a time, and keep it in the fridge. Stir 1 tbsp into porridge, yogurt or smoothies.
- Soak chia. Chia swells into a gel when soaked, which makes it perfect for puddings and for thickening overnight oats. About 3 tbsp sets 200ml of milk.
- Toast walnuts lightly. 5–6 minutes at 180°C (160°C fan) is enough to deepen the flavour without scorching. Store shelled walnuts in the fridge or freezer; they taste bitter and papery once rancid. The Walnut-Cacao Omega Smoothie in the book blends them into breakfast.
- Don't fry with flaxseed oil. Keep flax and walnut oils for dressings and drizzling. For cooking, use olive or rapeseed oil.
For more breakfast ideas using these seeds and nuts, see anti-inflammatory breakfasts you can make in ten minutes.
Common mistakes
- Overcooking fish. Take it off the heat while the centre is still just translucent. Residual heat does the rest.
- Ignoring tins. Tinned sardines, mackerel and salmon are cheap, long-lasting and ready to eat. Keep a few in the cupboard; our healthy pantry checklist has more store-cupboard staples.
- Leaving seeds and nuts in a warm cupboard. Heat speeds up rancidity. The fridge is better, the freezer better still for nuts.
- Drowning fish in heavy sauces. Oily fish already has richness. Lemon, herbs, tomatoes and a little olive oil suit it far better than cream.
- Deep-frying as the default. Battered and deep-fried fish adds a lot of other fat. Grilling, baking, poaching and steaming suit oily fish best.
For complete recipes, The Anti-Inflammatory Kitchen has a whole chapter of fish and seafood mains, from traybakes to curries. You can search salmon in the recipe finder to see them together, and for how oily fish fits into a wider week of cooking, read our guide to anti-inflammatory eating.
This is general information about food and cooking, not medical advice. If you have a medical condition, are pregnant, or have questions about your diet, talk to your doctor or a registered dietitian.
Questions people ask
Does tinned fish count as oily fish?
Tinned salmon, sardines, mackerel and pilchards do. In UK guidance, tinned tuna doesn't, because much of its oil is removed during processing.
How often should I eat oily fish?
Guidance varies by country. UK advice is at least two portions of fish a week, one of them oily, with lower limits for some groups, including people who are pregnant. Check your national guidance.
Can vegetarians and vegans get omega-3 from food?
Plant foods such as flaxseed, chia, walnuts and hemp provide ALA, and the body converts a small amount into EPA and DHA. A registered dietitian can advise on meeting your needs on a plant-based diet.
Does cooking destroy omega-3s?
Gentle cooking such as baking, poaching, steaming or grilling suits oily fish well. Very long, very hot cooking and deep-frying are the methods to use sparingly.