Cod Liver Oil vs Fish Oil: Differences, Vitamin A Risks and Which to Choose
Fish oil is pressed from the flesh of oily fish and provides EPA and DHA. Cod liver oil comes from cod livers and also contains vitamins A and D. That extra vitamin A is the catch: one tablespoon of cod liver oil can exceed the adult upper limit for vitamin A. For omega-3s alone, fish oil is the safer, more flexible choice.
Cod liver oil vs fish oil is a common point of confusion, since both come from fish and both supply omega-3s. The difference is where the oil comes from, and what else comes with it.
Side-by-side
| Cod liver oil | Fish oil | |
|---|---|---|
| Source | Liver of cod | Flesh of oily fish |
| EPA + DHA | Moderate | Moderate to high (concentrates available) |
| Vitamin A | High: about 4,080 mcg RAE per tablespoon | Little or none |
| Vitamin D | High: about 1,360 IU per tablespoon | Little or none |
| Risk of exceeding limits | Real, especially vitamin A | Low |
| Best for | People who also need vitamins A and D | Omega-3s on their own |
The vitamin A problem
The upper limit for preformed vitamin A (retinol) is 3,000 mcg RAE a day for adults. A tablespoon of cod liver oil contains more than that. Too much preformed vitamin A over time can cause:
- Liver damage
- Bone thinning and higher fracture risk
- Headaches and dizziness
- Birth defects when taken in high amounts during pregnancy
Capsules contain less than a tablespoon, but the amounts add up quickly, especially alongside a multivitamin.
Vitamin D: a benefit or a risk
Cod liver oil's vitamin D can help people who get little sun. But if you already take vitamin D, check the total stays under 4,000 IU. Our guide to how much vitamin D is too much explains the limits.
When cod liver oil makes sense
- You don't take other vitamin A or D supplements
- You eat little liver, dairy or fortified foods
- You use a modest dose, such as one teaspoon or a few capsules, and count the vitamins
The verdict
For omega-3s, fish oil is the simpler, safer option: you can raise the dose without overdoing vitamins A and D. Cod liver oil can fit if you want all three nutrients, but measure carefully, and talk to your clinician first if you're pregnant. Comparing other omega-3 sources? See fish oil vs krill oil and algae oil vs fish oil.
Frequently asked questions
Can I take cod liver oil while pregnant?
Talk to your clinician first. High intakes of preformed vitamin A can cause birth defects, so pregnant people should avoid exceeding the vitamin A limit.
Can I take cod liver oil and a multivitamin?
Check the vitamin A and D in both. Together they can push you over the upper limits.
Sources
This page is for education and is not a substitute for advice from your doctor. Read our medical disclaimer.