Cod Liver Oil vs Fish Oil: Which One's for You?

Grandpa used to say there are two kinds of people: those who take cod liver oil and those who haven't been told about it yet. Charming, but not quite accurate. Cod liver oil and fish oil are cousins, not twins, and the right pick depends on what you want from your daily habit.

Let's settle the family argument.

Quick heads-up: Grandpa Finn's doesn't sell cod liver oil. This guide is general education about cod liver oil and its nutrients, not a claim about any Grandpa Finn's product. Our range is Omega-3 Fish Oil (EPA and DHA), a Daily Multivitamin and the Daily Stack with both.

The short answer

• Fish oil is an omega-3 supplement. It's usually made from the flesh of oily fish and supplies EPA and DHA.
• Cod liver oil is an omega-3 supplement plus a source of vitamin A and vitamin D, because it comes from the liver, where fish store fat-soluble vitamins.

Neither one is "better" across the board. They do slightly different jobs.

Where each oil comes from

Fish oil

Fish oil is typically extracted from the bodies of oily fish such as anchovies, sardines and mackerel. The NIH Office of Dietary Supplements lists fish oil as one of the main types of omega-3 supplement, available in a wide range of doses and forms.

Cod liver oil

Cod liver oil comes from cod livers. Alongside omega-3s, it naturally contains preformed vitamin A and vitamin D. The NIH names fish liver oils among the best natural sources of vitamin D, and Harvard's Nutrition Source puts cod liver oil at the top of its vitamin D food list.

Side-by-side comparison

Amounts vary a lot between brands, so the label is the only reliable guide. Look at the EPA + DHA line, not just the capsule size.

What the nutrients do

Omega-3s: in both

EPA and DHA are part of every cell membrane in your body. DHA is especially concentrated in the brain and retina (NIH ODS). As part of a healthy diet, omega-3s support normal heart health and normal brain and eye function.*

Vitamin A: cod liver oil only

Vitamin A is important for normal vision, the immune system, and growth and development (NIH ODS).*

Vitamin D: cod liver oil only

Vitamin D helps your body absorb calcium and supports normal bones, muscle function and immune system function (NIH ODS).*

Which should you choose?

Choose fish oil if…

• You mainly want omega-3s.
• You already take a multivitamin with vitamin A and D, or eat liver often, and don't want to double up.
• You're pregnant or planning to be, and your doctor has OK'd an omega-3 supplement but you want to avoid extra preformed vitamin A.

Choose cod liver oil if…

• You want omega-3s and vitamins A and D in one go.
• You get little sun, especially in winter (see vitamin D in winter).
• You don't take other products that already contain vitamin A.

Or pair fish oil with a multivitamin

Many people take a fish oil for omega-3s and a multivitamin for broader coverage. If you do, check that your total vitamin A and D stays under the upper limits. That's the idea behind Grandpa Finn's Daily Stack: our Omega-3 Fish Oil plus our Daily Multivitamin.

Safety checks before you choose

Vitamin A upper limit

The NIH sets the adult upper limit for preformed vitamin A at 3,000 mcg a day from all sources, including food and supplements. Too much preformed vitamin A during pregnancy can harm a developing baby, so pregnant people should not take cod liver oil without medical advice.

Vitamin D upper limit

For adults, the NIH upper limit for vitamin D is 100 mcg (4,000 IU) a day from all sources. More isn't better.

Omega-3 dose and blood thinners

The NIH notes that the US FDA advises no more than 5 g a day of EPA and DHA combined from supplements. High doses may cause bleeding problems with warfarin and other anticoagulants. Harvard adds that omega-3 supplements can act as a mild blood thinner, so tell your doctor if you start one.

Don't forget the fish on your plate

Harvard's researchers note that eating fatty fish has a stronger evidence base than supplements alone, and suggest seafood 1–2 times a week. A supplement is a top-up, not a replacement. Grandpa's rule: sardines on toast first, capsule second.

Frequently asked questions

Is cod liver oil better than fish oil?

Neither is better overall. Cod liver oil adds vitamins A and D; fish oil gives you omega-3s without them.

Can I take cod liver oil and fish oil together?

Most people don't need both. If you do, add up the omega-3s and the vitamin A and D, and ask your pharmacist.

Which has more omega-3?

It depends on the product. Compare the EPA + DHA per serve on each label.

Is fish oil safe in pregnancy?

Ask your doctor. Cod liver oil in particular isn't recommended in pregnancy without medical advice because of its vitamin A.

Does either oil treat any medical condition?

No. Dietary supplements aren't intended to diagnose, treat, cure or prevent any disease. They support normal function as part of a balanced diet.*

Grandpa's verdict

Want omega-3s? Fish oil does the job. Want the old-school all-rounder with vitamins A and D? Cod liver oil is the classic. Want to keep it simple? Pair a fish oil with a multivitamin and check the totals.

Want a top-up? Grandpa Finn's makes an Omega-3 Fish Oil and a Daily Multivitamin, or grab both together as the Daily Stack. Shop the range.

Sources

• NIH Office of Dietary Supplements, Omega-3 Fatty Acids – Consumer Fact Sheet
• NIH Office of Dietary Supplements, Vitamin A and Carotenoids – Consumer Fact Sheet
• NIH Office of Dietary Supplements, Vitamin D – Consumer Fact Sheet
• Harvard T.H. Chan School of Public Health, Omega-3 Fatty Acids
• Harvard T.H. Chan School of Public Health, Vitamin D

Grandpa's fine print: This article is general information only, not medical advice. Supplements don't replace a varied, balanced diet. Talk to your doctor or pharmacist before starting any supplement, especially if you're pregnant, planning a pregnancy or breastfeeding, taking blood thinners (anticoagulants such as warfarin) or other medicines, have a health condition, or are buying for a child. Always read the label and use only as directed.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.