What's in each
| Cod liver oil, 1 tablespoon | Typical fish oil, 1,000 mg softgel | |
|---|---|---|
| Where it comes from | Cod livers | Fish |
| EPA plus DHA | About 2.4 g (0.9 g EPA, 1.5 g DHA) | About 300 mg (180 mg EPA, 120 mg DHA) |
| Vitamin A (preformed) | About 4,080 mcg RAE (13,600 IU) | Usually little or none; check the label |
| Vitamin D | About 34 mcg (1,360 IU) | Usually little or none; check the label |
A teaspoon is a third of a tablespoon, so it carries about a third of those amounts.
Vitamin A: the main risk
Your body stores extra vitamin A, mainly in the liver, so it can build up. The adult upper limit for preformed vitamin A is 3,000 mcg RAE (10,000 IU) a day from food and supplements combined. Regular high intake can cause dry skin, painful muscles and joints, fatigue, depression and abnormal liver tests.
| Age | Upper limit for preformed vitamin A |
|---|---|
| 1 to 3 years | 600 mcg RAE |
| 4 to 8 years | 900 mcg RAE |
| 9 to 13 years | 1,700 mcg RAE |
| 14 to 18 years | 2,800 mcg RAE |
| 19 and older, including pregnancy | 3,000 mcg RAE |
Pregnancy: too much preformed vitamin A can cause birth defects of the eye, skull, lungs and heart. NIH's fact sheet notes that experts advise people who are or might be pregnant, and those breastfeeding, not to take more than 3,000 mcg RAE (10,000 IU) a day of vitamin A from supplements. Check every product you take, including prenatal vitamins and multivitamins, and ask your clinician before using cod liver oil.
Children have much lower limits, so give cod liver oil to a child only with a clinician's advice. Beta-carotene from plants is not linked to birth defects the way preformed vitamin A is. If you want to know your level, see the vitamin A lab guide.
Vitamin D in cod liver oil
Fish liver oils are one of the few natural food sources of vitamin D. The upper limit for adults is 100 mcg (4,000 IU) a day from all sources. If you already take a vitamin D supplement, add the cod liver oil amount to it. A vitamin D blood test shows where you stand.
How to choose
- You want omega-3s only: fish oil lets you get EPA and DHA without stacking vitamins A and D. Compare products by EPA plus DHA per serving, not total oil. See fish oil vs krill oil.
- You eat little fish and get little sun: cod liver oil can cover omega-3s and some vitamin D, as long as the vitamin A stays within limits.
- You're pregnant, could become pregnant, or breastfeeding: a fish oil without vitamin A is the simpler choice; ask your clinician.
- You take a blood thinner: omega-3s can lengthen clotting time, so ask your clinician first.
- Mercury: omega-3 supplements have not been found to contain mercury, because it is removed during processing.
Gabriel Plus members get member prices on supplements; for example, omega-3 fish oil, 60 softgels, is $47.30 (list price $86.99). Gabriel can check any supplement label against your other vitamins for free.
Common questions
Is cod liver oil the same as fish oil?
No. Both supply the omega-3s EPA and DHA, but cod liver oil comes from cod livers and also contains vitamin A and vitamin D. Fish oil mainly supplies omega-3s.
Is cod liver oil better than fish oil?
Not for omega-3s alone. It adds vitamins A and D, which can help if you're low, but the vitamin A can push you over the upper limit, especially with a multivitamin.
Can you take cod liver oil while pregnant?
Ask your clinician first. High preformed vitamin A can cause birth defects, and experts cited by NIH advise not taking more than 3,000 mcg RAE (10,000 IU) a day of supplemental vitamin A in pregnancy.
Can I take cod liver oil and fish oil together?
You can, but there's rarely a reason to. Add up EPA plus DHA, vitamin A and vitamin D across both, and keep vitamin A and D within the upper limits.
How much vitamin A is in cod liver oil?
In USDA data, about 4,080 mcg RAE (13,600 IU) per tablespoon, more than the adult upper limit. Products vary widely, so check the label.
Sources
- Vitamin A and Carotenoids: Fact Sheet for Health Professionals NIH Office of Dietary Supplements
- Omega-3 Fatty Acids: Fact Sheet for Health Professionals NIH Office of Dietary Supplements
- Vitamin D: Fact Sheet for Health Professionals NIH Office of Dietary Supplements
- Fish oil, cod liver (SR Legacy 173577) USDA FoodData Central
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.