My diet:

Fish oil

No E-numberFats & oilsOrigin: Animal
Get a personal answer

Pick your family’s diets in the bar above.

Every diet

VeganNo

It comes from fish.

Gluten-freeYes
HalalDepends

The fish has to be a permitted species and halal handled, and most oil is not certified.

KosherYes

Fish is kosher, and kosher certification confirms it.

KetoYes

It is almost pure fat.

Low-FODMAPYes
The short answer
Fish oil is the omega-3 concentrate from oily fish, and it is safe but not vegan. The label that matters is the EPA and DHA per serving, and the fish itself is the better and cheaper source of both.
Use in moderation

Safe in small amounts; may bother some people or raise blood sugar.

E-numberNone
Comes fromAnimal
What it doesFats & oils
Glycemic index—
Daily limitNot set
Also calledFish oil, Cod liver oil

Rules by country

🇺🇸 US FDANot evaluated as an additive
🇪🇺 European UnionNot evaluated as an additive
🇨🇦 Health CanadaNot evaluated as an additive
CaliforniaNo extra rules

Fish oil sold as a food is outside the additive system and carries no E-number, so none of the three regulators has evaluated it as an additive. As a supplement it is a dietary supplement in the United States and a food in Canada, and the label has to state the EPA and DHA content per serving rather than the weight of the oil alone.

Daily limit: Experts haven’t set a number because normal food amounts are far below any level of concern.

What is it?

A typical softgel holds about 1 gram of fish oil and that gram is roughly 180 mg of EPA and 120 mg of DHA; a stronger product may carry twice that. The rest is fat that does very little. Cod liver oil is different again, because the liver is where the fish stores its vitamin A and vitamin D, so it comes with those too.

Where it comes from: Pressed or extracted from the flesh of oily fish, usually sardines, anchovies, herring or mackerel. Cod liver oil comes from the liver, and most commercial fish oil is purified to remove the fishy smell and the heavy metals that small fish can carry.

Why it’s in food

  • Omega-3 supplement capsules
  • Infant formula fortification
  • Enriching foods and drinks
  • Cod liver oil supplements

Often found in

Fish oil capsulesInfant formulaOmega-3 fortified milkNutrition barsCod liver oil supplements

Also listed as: Fish oil, Cod liver oil, Marine oil, Fish oil (omega-3), Omega-3 fish oil

Health & gut impact

Omega-3 contentBenefit

A standard 1 gram softgel holds about 300 mg of EPA and DHA combined. EFSA sets an adequate intake of 250 mg a day for adults, so one capsule covers it and a diet that already eats oily fish may need no supplement at all.

EFSA, dietary reference values for omega-3 fatty acids

Mercury and heavy metalsUnder study

Commercial fish oil is purified, and the amounts of mercury in purified oil are low, but a label should still carry a purity statement or a testing mark. Small oily fish such as sardines and anchovies carry less mercury than the large predatory fish sold as fillets.

FDA, Generally Recognized as Safe (GRAS) determination for fish oil

Freshness and oxidationUnder study

Omega-3 fatty acids oxidize when the oil sits warm, open or in the light, and oxidized oil is worth far less than the label claims. Look for a product that prints a peroxide or TOTOX value, and keep the bottle in the fridge rather than on the shelf.

EFSA Journal, scientific opinion on dietary reference values for omega-3 fatty acids

What can I use instead?

Algal oil

Ratio: One for one in a supplement

Best for: A plant source of DHA and EPA

Flaxseed oil

Ratio: A spoonful in food rather than a capsule

Best for: Adding plant omega-3 to a diet

Sardines and mackerel

Ratio: Two small portions a week

Best for: Omega-3 and protein without a capsule

Related

More fats & oils:

Algal oilAlgal oil is omega-3 from microalgae grown in a tank, and it is the plant-based stand-in for fish oil. It is safe, vegan and gluten-free, and it supplies the DHA that most plant omega-3 sources do not.Generally safeAvocado oilAvocado oil is usually pressed from the avocado pit, so it tastes neutral rather than like avocado. It is safe, high in monounsaturated fat, and its high smoke point makes it one of the better oils for hot cooking.Generally safeBeef tallowBeef tallow is cattle fat. It is not vegan. It is gluten-free and used for high-heat frying. Halal and kosher versions exist only when the animal and the plant are certified.Use in moderationButterButter is a dairy fat. It is not vegan. It is gluten-free, and a normal pat is low enough in lactose that many low-FODMAP plans allow it. Peanut butter and cocoa butter are not this food.Use in moderation

Common questions

Is fish oil better than eating fish?

For most people, eating the fish is better. You get the same omega-3s plus the protein and the vitamin D, and the fish carries none of the oxidation risk of a bottle that has sat on a shelf.

How much fish oil should I take?

Read the back of the softgel rather than the front. One standard 1 gram capsule gives roughly 300 mg of EPA and DHA, and EFSA sets the daily adequate intake for adults at 250 mg, so one capsule covers a day's supply.

Does fish oil cause fishy burping?

It can, especially with a softgel taken on an empty stomach. Taking it with a meal and keeping the bottle in the fridge reduces both the aftertaste and the reflux.

Is cod liver oil the same as fish oil?

No. Cod liver oil comes from the liver, so it carries vitamin A and vitamin D as well as omega-3s. Regular fish oil is made from the flesh and is much higher in EPA and DHA per gram.

Is Fish oil safe?

Use in moderation (78/100). Fish oil sold as a food is outside the additive system and carries no E-number, so none of the three regulators has evaluated it as an additive. As a supplement it is a dietary supplement in the United States and a food in Canada, and the label has to state the EPA and DHA content per serving rather than the weight of the oil alone.

Is Fish oil vegan?

No. It comes from fish.

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Scientific sources & regulatory citations
  • EFSA, dietary reference values for omega-3 fatty acids
  • FDA, Generally Recognized as Safe (GRAS) determination for fish oil
  • EFSA Journal, scientific opinion on dietary reference values for omega-3 fatty acids