Advise Me

Should I Take Cod Liver Oil or Consider Other Fish in the Sea?

Back in the day – like centuries ago – cod liver oil was touted as a cure-all. Want to prevent a cold?  Take a spoonful of cod liver oil. Got rickets? One more spoonful.

I mean, we’ve all heard the saying, “A spoonful of cod liver oil makes the medicine go down,” right? Or, was that sugar?

Either way, cod liver oil is making a comeback these days. It’s being touted for numerous health benefits, even despite the fact there isn’t enough evidence to prove the claims.

So, is cod liver oil all it’s cracked up to be, or are there better fish in the sea?

Potential benefits of cod liver oil … and other fish oils

Cod liver oil can be consumed by eating the liver of a cod fish. But unless you live by the sea, you’ve probably only seen cod liver oil in capsule or liquid form.

As with most fish oils (from other sources), cod liver contains omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which is a type of healthy fat that has been linked with cardiovascular health, immunity and brain development. Unlike other fish oils, however, cod liver does contain a relatively higher amount of fat-soluble vitamin A and vitamin D.

“Because the Western diet is higher in processed food, it's difficult for many adults to get enough omega-3 fats from dietary sources,” said Jennifer Oikarinen, a registered dietitian at Banner - University Medical Center Phoenix. “So many people look to other alternatives, such as fish oils and other plant-based means of getting omega-3s. But I don’t recommend supplementation with cod liver.”

What’s the catch?

While cod liver oil and fish oils may provide some potential benefits, here are some reasons why you might want to reconsider cod liver.

Liver toxins

Fish oil is taken from the flesh of various small, cold-water fish, such as mackerel, sardines and herring and even krill or algae oils. Whereas, cod liver oil is extracted from—you guessed it—the livers of cod fish. Why is this important? Because the liver is biologically designed to process toxins.

“Cod fish are long-living fish, which means they accumulate a lot more toxins than smaller-species, such as mackerel or herring,” Oikarinen said. “Those toxins accumulate over time and are also processed by the liver—the same organ that is used to extract oil.”

According to 2018 study, researchers found that an accumulation of heavy metals in freshwater fish were the greatest in the liver and gills.

The ol’ bait and switch

Also, when you take cod liver oil, you might not actually be getting cod livers in your oil. Since the dietary supplement industry isn’t regulated in the U.S., you might not be getting what is advertised. Many brands may use less expensive sources for oil and even supplement with synthetic or natural vitamin A. So, buyer beware.


If you are ecologically conscious, you may want to consider another source, since some species of cod are endangered. In fact, the Atlantic cod is currently considered vulnerable to extinction.

Risk of dangerous bleeding

Cod liver oil can act as a blood thinner, affecting blood clotting, so if you are on blood thinners, pregnant or pre-surgery, you’ll want to check with your doctor first.

Tips for buying fish oils

If these reasons have steered you away of cod liver but you’re still in the market for a good fish oil supplement, here are some things to consider before taking the plunge:

  • Check with your doctor first if you are taking blood thinners, pregnant or are pre-surgery.
  • Choose small-fish formulations such as mackerel, herring, krill or algae.
  • Aim for 3 to 9 grams of total fish oil – that’s about 1 to 3 grams of EPA and DHA – a day.
  • Look for cod liver oil supplements with third-party certifications, such as the Good Manufacturing Practice (GMP) or NSF International, to verify ingredients and doses are accurately represented on the label.
  • Check for smell. If your fish oil capsules smell terribly bad – like more than a little fishy – don’t take them. This could be a sign of a poor product.
  • Some fish oils can give you some unpleasant fish burps. If this is the case, consider other fish-free ways to get your omega-3s in your diet, from foods like flaxseeds, chia seeds and mixed greens, or from supplements derived from algae.

Looking for other ways to up your vitamins A, D and Omega-3s? Talk to your doctor or speak with a registered dietitian. To find a Banner Health specialist near you, visit

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