VITAMINS & SUPPLEMENTS · GUIDE
Canned, Smoked and Cooked Fish: What Happens to Omega-3 and Sodium
What studies found about frying, grilling and canning and the EPA and DHA left in fish, USDA sodium figures for canned and smoked fish, and pregnancy cautions for smoked fish.
Content last updated . This page has not been medically reviewed.
Back to Omega Fatty AcidsWhat the question is
Does cooking, canning or smoking destroy the omega-3 in fish? The studies we read disagree, partly because they tested different fish and methods. There is no one rule that fits all fish.What the studies found
Grilling, pan-frying or deep-frying (Pacific saury, Japan, 2016)
One fatty fish species, lab studyFish retained about 84% of DHA and 87% of EPA when grilled, 85% and 77% when pan-fried, and 58% and 51% when deep-fried. Most of the loss was physical: juices lost in cooking or fat that moved into frying oil, not oxidation. [5]
Boiling, microwaving, frying and canning (skipjack tuna, India, 2010)
One species; small studyEPA and DHA losses were least with cooking, then microwave heating; deep-fried tuna lost 70% of EPA and 85% of DHA; the authors reported canning "totally" destroyed these fatty acids. The tuna was low in EPA and DHA to begin with. [6]
Canned fish in brine (2026)
Composition survey of several speciesThe fatty acid composition of canned fish was very similar to fresh fish, and the authors saw no significant oxidative damage from preserving. [7]
Processed pollock (Germany, 2012)
Market surveyBreaded, pre-fried pollock fillet had extraordinarily high fat and omega-6 content compared with pure fillets. [8]
The two canning studies point in opposite directions. Differences in species, fat content, packing liquid and methods could explain this, but the sources do not settle it, so we say the evidence is mixed. USDA lists canned tuna and canned salmon as separate entries with their own EPA and DHA values; see the content tables. [9]
Sodium in canned and smoked fish (USDA)
USDA FoodData Central (SR Legacy, 2018) reports milligrams of sodium per 100 g. These are different samples, not before-and-after tests of one fish. [9]| USDA entry | Sodium, mg per 100 g |
|---|---|
| Salmon, chinook, raw | 47 |
| Salmon, chinook, smoked | 672 |
| Salmon, chinook, smoked (lox) | 2,000 |
| Herring, Atlantic, cooked | 115 |
| Herring, Atlantic, kippered | 918 |
| Tuna, light, canned in water, drained | 247 |
| Tuna, light, canned in water, without salt | 50 |
| Anchovy, European, raw | 104 |
| Anchovy, European, canned in oil, drained | 3,668 |
What this means for choosing
- Grilled, baked or poached fish appeared to keep more EPA and DHA than deep-fried fish in the saury and tuna studies. [5][6]
- Canned oily fish is a convenient source, and the NHS notes canned sardines, pilchards and tinned salmon can be eaten with their soft bones for calcium and phosphorus. [1]
- Salt content differs widely between products; check the label. A "no added salt" entry exists in USDA for canned tuna. [9]
- No study we read tested home freezing, air frying or slow cooking: Proper evidence not found for those methods in our searches (PubMed searches on cooking and canning effects on omega-3).
Where to go next
For species and serving sizes see fish and seafood omega-3 content tables. For mercury limits see official fish-eating advice, and for the farmed-versus-wild question see farmed vs wild fish. Medicine questions, such as blood thinners, go to a pharmacist: medication interactions.Frequently asked questions
Does frying fish destroy omega-3?
In a saury study deep-frying kept about half of EPA and DHA, versus about 85% for grilling and pan-frying DHA. [5] In a tuna study frying lost 70% of EPA and 85% of DHA. [6]
Does canning remove omega-3?
Mixed evidence: one tuna study said canning destroyed EPA and DHA, [6] while a 2026 brine-canned survey found composition similar to fresh fish. [7]
Is smoked salmon safe in pregnancy?
The NHS says smoked fish should be thoroughly cooked in pregnancy. [1]
Is canned fish too salty?
Some are. USDA lists 3,668 mg of sodium per 100 g for canned anchovy and 247 mg for canned light tuna in water. [9] The NHS suggests choosing fish in water over brine. [3]
Is fresh fish always better than canned?
The sources do not say so universally; the evidence is mixed. [7]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety points first
- Pregnancy: the NHS says pregnant women should eat smoked fish only if it is thoroughly cooked, and lists cold-smoked and cured fish, such as smoked salmon, as foods that must be cooked until steaming hot. [1][2]
- Salt: canned, smoked and cured fish can be high in sodium (table below). The NHS says adults should have no more than 6 g of salt a day and suggests fish tinned in water instead of brine, and eating cured fish less often. [3]
- Allergy: cooking fish or shellfish does not make a person with a fish or shellfish allergy less likely to have a bad reaction. [1]
- Kidney conditions: people on a kidney diet should ask their kidney team before relying on canned or smoked fish; a Latin American study of processed fish looked at protein, phosphorus and potassium for this reason. [4]
References
- NHS, Fish and shellfish. Read 2026-10-23.
- NHS, Foods to avoid in pregnancy. Read 2026-10-23.
- NHS, Salt: the facts. Read 2026-10-23.
- Risk-benefit of some mollusks and processed fishes in the renal patient's diet. Arch Latinoam Nutr 2010. Read 2026-10-23.
- Mechanisms of DHA and EPA loss from Pacific saury and retention after various cooking methods. J Food Sci 2016. Read 2026-10-23.
- Effect of different types of heat processing on chemical changes in tuna. J Food Sci Technol 2010. Read 2026-10-23.
- Canned Fish in Brine: Variability in Macronutrient and Fatty Acid Composition. Biology 2026. Read 2026-10-23.
- Survey of n-3 and n-6 polyunsaturated fatty acids in fish and fish products. Lipids Health Dis 2012. Read 2026-10-23.
- USDA FoodData Central, SR Legacy dataset (April 2018 release, CSV download). Read 2026-10-23.