Cod liver oil is rich in important nutrients, but the supplements have potential risks. Experts discuss the benefits, side effects, and dosage.
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 U.S outbreak of measles, a highly contagious but vaccine-preventable disease
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.
NBC News previously reported 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.
What is 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 vitamin D. 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.
Cod liver oil vs. fish oil
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…. 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 oil benefits
Cod liver is rich in important nutrients that have potential health benefits. When taken appropriately, cod liver oil may help:
- Treat vitamin A or D deficiency
- Fight inflammation
- Support heart health
- Promote bone health
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.
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