Is cod liver oil good for you? There are possible benefits — but also risks, experts say

Cod liver oil is rich in essential vitamins, antioxidants and healthy fatty acids. You’ve probably heard of fish oil capsules, a mainstay in the drugstore supplement aisle. Similarly, cod liver oil is also full of nutrients that may have health benefits.

Cod liver oil provides a hefty dose of vitamins A and D, which, along with essential fatty acids, can help support a healthy heart, bones, eyes and more. The supplements are often marketed to promote overall wellbeing, fight inflammation, boost immunity and reduce joint pain. Cod liver oil is not new, but it has become increasingly popular.



It's also made headlines in recent months amid a , a highly contagious but . The outbreak — which started in January in Texas and has since spread to nearby states — has killed two people and sickened over 500 so far. As the outbreak spreads, so have claims about unproven remedies, including cod liver oil.

that some families in the area are forgoing conventional medicine in favor cod liver oil supplements, which are being given out for free by some doctors. However, health experts warn that there is no evidence to suggest cod liver oil is effective to treat or prevent measles, and it can be harmful in high doses. So, what exactly is cod liver oil, and does it ever have health benefits? Experts discuss what the research shows, risks and how to take cod liver oil.

Cod liver oil is derived from the liver of codfish, typically Atlantic or Pacific cod, Dr. Zachary Mulvihill, a physician with the Integrative Health and Wellbeing Program at NewYork-Presbyterian and Weill Cornell Medicine, tells TODAY.com.

The oil is extracted from the nutrient-dense liver of the cod and sold as a supplement in liquid or capsule form. Cod liver oil contains high amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential omega-3 fatty acids that the body doesn't make enough of, so we need to get them from food, says Mulvihill. The livers of cod are also rich in fat-soluble vitamins, namely vitamins A and .

In fact, most cod liver oil supplements contain or exceed the "upper tolerable limit" of vitamins A and D, or the maximum daily amount unlikely to cause negative health effects, Melissa Prest, registered dietitian and spokesperson for the Academy of Nutrition and Dietetics, tells TODAY.com. Consult your doctor before adding cod liver oil to your daily routine to find the right dosage for your needs.

Fish oil is a generic term for oil derived from the fatty tissues of various fish, such as salmon or mackerel, the experts note. Regular fish oil contains more DHA and EPA omega-3 fatty acids but much less vitamin A and D than cod liver oil. “The research is extremely robust for omega-3 fish oils.

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That’s one of the reasons why they are such a popular supplement, and they do have a lot of benefits, mainly anti-inflammatory and cardiovascular," says Mulvihill. However, “the research on cod liver oil is more limited,” Mulvihill adds. Cod liver is rich in important nutrients that have potential health benefits.

When taken appropriately, cod liver oil may help: Cod liver oil is rich in vitamin A, an antioxidant that helps with vision, immune function and skin health, Julia Zumpano, a registered dietitian at the Cleveland Clinic Center for Human Nutrition, tells TODAY.com. Vitamin D helps the body absorb calcium and phosphate, which are essential for healthy bones, teeth and muscles, Zumpano adds.

Traditionally, cod liver oil was used to treat and prevent vitamin A and D deficiencies, which were more common when malnutrition was a significant problem in the U.S. “Cod liver oil was a folk remedy for rickets, which is caused by a vitamin D deficiency,” says Mulvihill.

Rickets is the softening and weakening of bones in children, which can cause deformities. Vitamin A deficiency can lead to vision loss, skin problems and impaired immune function, the experts note. Today, vitamin A deficiencies are rare in the U.

S., Mulvihill says. Vitamin D insufficiency is more common, he adds, but it's easy to get more vitamin D from sunlight and fortified foods.

Additionally, most people take multivitamins, which contain vitamins A and D. Unless you have a deficiency, you won't benefit from getting an extra dose of vitamin A or D via cod liver oil, the experts say. The other potential benefits of cod liver oil come from its omega-3 fatty acids.

"There's definitely science that proves the benefits of taking omega-3s" says Zumpano. These include fighting inflammation, lowering cholesterol and triglycerides, reducing the risk of heart disease, and supporting cognitive function. While cod liver oil is an excellent source of important vitamins and omega-3s, the science linking these supplements to health benefits is often inconclusive, the experts say.

“I’m very skeptical about specific claims,” says Mulvihill. Cod liver oil is used for many health conditions, including heart disease, high blood pressure and arthritis, but there is no credible scientific evidence to support these uses, according to . “There’s just a lot of unclear information about it.

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It’s not a miracle supplement," Prest adds. In multiple interviews, U.S.

Health and Human Services Secretary to prevent and treat measles. in March about the government’s response to the measles outbreak, Kennedy said, “We’re delivering vitamin A” in West Texas. “Also cod liver oil, which has high, high concentrations of vitamin A.

” There is no evidence that cod liver oil or vitamin A prevents measles, Dr. Jeffrey Kahn, chief of infectious diseases at Children’s Health and professor at UT Southwestern Medical Center, tells TODAY.com.

with two doses of the MMR vaccine, which is 97% effective. In a March 7 health alert, the said vitamin A is “not a substitute for vaccination.” Cod liver oil won't cure measles either — in fact, no antiviral treatment for measles exists, .

However, vitamin A deficiency can increase the likelihood of developing severe measles if you're already infected, so vitamin A is sometimes given to people with measles in low-income countries where malnutrition and vitamin deficiencies are very common, says Kahn. "These settings, particularly in developing countries, are vastly different from what we have here in the States,” Kahn adds. Most people in the U.

S. get enough vitamin A from their diet, and deficiencies are rare. According to the , vitamin A may be given as part of supportive care to children with severe measles, such as those who are hospitalized, but only under the supervision of a health care professional.

Otherwise, taking a high doses of vitamin A or cod liver oil can do more harm than good, the experts warn. It's easy to overdose on vitamin A, which can cause organ damage. Since the measles outbreak started, Covenant Children’s Hospital in Lubbock, Texas, has treated multiple children for measles and vitamin A toxicity, some of whom reported taking vitamin A to treat and prevent measles, a spokesperson tells TODAY.

com in a statement. Cod liver oil, when taken appropriately as directed by a doctor, is generally safe, the experts note. However, side effects may occur, including: Vitamins A and D are fat-soluble, which are stored in the body's fatty tissues and liver, says Kahn.

Unlike water-soluble vitamins, which are excreted through urine, these can build up in the body. “If you are exceeding the normal dose for a period of time, that could lead to toxicity," says Prest. Vitamin A or D toxicity can lead to serious health problems if left untreated.

If you have concerns, talk to your doctor, who can perform a blood test to check your vitamin levels, Prest adds. “Generally, I think fish oil is a safer bet because you’re getting more EPA and DHA, and there’s more research on them specifically. .

.. Then you can supplement with vitamin A or D separately if you have a deficiency,” says Mulvihill.

Also, cod liver oil is a dietary supplement, which aren't approved by the U.S. Food and Drug Administration.

“There could be varying amounts of vitamins, so read the labels,” says Prest. Opt for supplements from reputable sources and oil from 100% wild cod if possible, says Mulvihill. Cod liver oil may contain low levels of mercury, which accumulates in fish from the environment, but the amount is typically safe for most people to consume, the experts say.

Some people should not take cod liver oil due to the health risks. These include, but are not limited to, people who: During pregnancy, excessive levels of vitamin A may harm the fetus or cause birth defects, the experts note. Always talk to your doctor before starting cod liver oil, especially if you have underlying conditions or take medications.

There is no established dosage or recommended daily intake for cod liver oil. Doses can range from 5-20 milliliters, says Prest. In adults, a typical dosage is 1 teaspoon of oil or one to two capsules per day.

Consult your doctor to find out what dose is appropriate for you, and always take supplements as directed. Cod liver oil can be taken daily, the experts note. Most of the research on cod liver oil has shown that doses between 10–20 milliliters are safe to take daily for up to four months, says Prest.

"That's how long it was usually studied for, but it may be appropriate when taken for longer," Prest adds. Cod liver oil shouldn't replace a healthy, balanced diet. If you're looking to increase your intake of vitamin A and D, the experts recommend first eating more nutrient-rich, whole foods.

Caroline Kee is a health reporter at TODAY based in New York City. She covers a range of medical news, consumer health, and wellness topics..