Home / Vitamins and minerals

Cod liver oil supplements: how to choose and how much is too much

By the Life in Good Form editors. Updated 2026-10-15.

We research products from makers' specs and health sources; we do not run hands-on tests. Links to Amazon may earn us a commission at no cost to you. How this works.

What cod liver oil gives you that fish oil does not

The NIH Office of Dietary Supplements (ODS) lists cod liver oil alongside fish oil, krill oil and algal oil as sources of the long-chain omega-3s EPA and DHA. The difference, ODS notes, is that cod liver oil supplements also provide vitamin A and vitamin D.

That makes cod liver oil a combination product. It can be useful if you want some vitamin D along with omega-3s, but it also means you cannot take large amounts the way some people take fish oil, because the vitamin A adds up.

How much is in a softgel or a spoonful

Labels vary, so read the Supplement Facts panel, not the front of the bottle. Two examples from makers' own pages:

• NOW Foods Cod Liver Oil 1,000 mg softgel: 300 mcg vitamin A (33% DV), 10 mcg (400 IU) vitamin D (50% DV), 70 mg EPA and 100 mg DHA per softgel.
• Carlson Cod Liver Oil liquid: 370 mg EPA plus 500 mg DHA per serving, with a suggested adult use of 1 teaspoon (5 mL) daily at mealtime.

For comparison, ODS says a typical 1,000 mg fish oil capsule provides about 180 mg EPA and 120 mg DHA. So a single cod liver oil softgel gives fewer omega-3s than a typical fish oil capsule, while the liquid gives more per serving.

ODS food data puts 1 tablespoon of cod liver oil at 34 mcg (1,360 IU) of vitamin D, or 170% of the Daily Value. Liquid labels use smaller teaspoon servings, so measure carefully.

Vitamin A: the limit that matters most

Cod liver oil supplements contain preformed vitamin A, often listed as retinyl palmitate plus vitamin A from the oil itself. Preformed vitamin A counts toward the Tolerable Upper Intake Level (UL).

• The adult UL for preformed vitamin A is 3,000 mcg a day.
• The RDA is 900 mcg RAE for men and 700 mcg RAE for women.
• ODS says experts advise people who are or might be pregnant, and those breastfeeding, not to take more than 3,000 mcg RAE a day of vitamin A supplements, because high doses of preformed vitamin A can cause birth defects.

One 300 mcg softgel is well under the limit. The risk comes from stacking: several softgels a day, plus a multivitamin, plus a separate vitamin A product. Before adding cod liver oil, total the vitamin A from every supplement you take.

Vitamin D: useful, but also capped

The RDA for vitamin D is 15 mcg (600 IU) a day for most adults. The UL for adults and teens is 100 mcg (4,000 IU) a day, and it is lower for young children: 63 mcg (2,500 IU) at age 1 to 3 and 75 mcg (3,000 IU) at age 4 to 8.

A 400 IU softgel covers part of the RDA. If you already take a vitamin D3 supplement, check whether adding cod liver oil pushes your daily total past the UL.

Omega-3 safety and medicines

ODS reports that omega-3 supplements have not been found to contain methyl mercury, because it is removed during processing and purification.

No UL is set for omega-3s. FDA has concluded that supplements providing no more than 5 g a day of EPA and DHA are safe when used as recommended, and the European Food Safety Authority found long-term intake up to about 5 g a day appears safe. Cod liver oil servings are far below that, so the vitamins usually limit the dose before the omega-3s do.

If you take warfarin, ODS notes that fish oil might prolong clotting times when taken with it, although most research at 3 to 6 g a day found no significant effect. Tell your doctor before starting.

Softgel or liquid: how to choose

• Softgels give a fixed, modest dose and no taste. They suit people who want a little vitamin D and omega-3 and already eat or take other sources of vitamin A.
• Liquid gives more omega-3 per serving, and many come in lemon or unflavored versions. Measure with a real teaspoon, since the label serving is small.
• Gummies often add other vitamins. Check the vitamin A and D amounts against what you already take.

Whichever form you choose, check the label for vitamin A in mcg, vitamin D in mcg and IU, and EPA and DHA in mg. NOW Foods labels its softgel for adults only and advises talking to a physician if pregnant, nursing or taking medication.

What to look for when you buy

Questions people ask

Is cod liver oil the same as fish oil?

Both supply EPA and DHA, but NIH notes cod liver oil also provides vitamin A and vitamin D. That extra vitamin A is why you cannot take as much cod liver oil as fish oil.

How much cod liver oil per day is safe?

Follow the label serving and keep total preformed vitamin A from all supplements under 3,000 mcg a day for adults, and vitamin D under 4,000 IU. One typical softgel or one teaspoon serving is usually well inside both.

Can I take cod liver oil while pregnant?

Ask your prenatal clinician first. NIH says pregnant people should not take more than 3,000 mcg RAE a day of vitamin A supplements, and your prenatal vitamin may already contain vitamin A.

Can kids take cod liver oil?

Only with a pediatrician's advice and a product labeled for children. Vitamin D upper limits are lower for kids, 2,500 IU at ages 1 to 3, and some adult products are labeled for adults only.

Does cod liver oil contain mercury?

NIH reports omega-3 supplements have not been found to contain methyl mercury, because it is removed during processing and purification.

Sources

• Omega-3 Fatty Acids: Fact Sheet for Health Professionals (ods.od.nih.gov), NIH Office of Dietary Supplements
• Vitamin A and Carotenoids: Fact Sheet for Health Professionals (ods.od.nih.gov), NIH Office of Dietary Supplements
• Vitamin D: Fact Sheet for Health Professionals (ods.od.nih.gov), NIH Office of Dietary Supplements
• Cod Liver Oil, Extra Strength 1,000 mg Softgels (www.nowfoods.com/products/supplements/cod-liver-oil-extra-strength-1000-mg-softgels), NOW Foods
• Cod Liver Oil (carlsonlabs.com), Carlson Labs

Sources checked 2026-10-15.