Uses

Overview: Cod liver oil is available over the counter as a supplement. It may be used to increase the levels of omega-3 fatty acids, vitamin A, and vitamin D in your body. Common side effects include having a bad taste in your mouth or bad breath, heartburn, nausea, upset stomach, and diarrhea. Taking too much vitamin A or vitamin D from cod liver oil and other supplements can be harmful. Before taking cod liver oil, tell your health care provider about all of your health conditions, including any food allergies, and any medicines or supplements you may be using.

What is cod liver oil used for?

Cod liver oil is commonly used to raise the levels of omega-3 fatty acids, vitamin D, and vitamin A in your body. It is also used for other reasons, but its benefits are not well defined.

Note: The FDA has not reviewed cod liver oil for safety and effectiveness. Learn more about dietary supplements here.

How does cod liver oil work (mechanism of action)?

Cod liver oil is made from the liver of Atlantic cod, a large fish that lives in the very cold ocean waters near Norway and Iceland. Cod liver oil is rich in various nutrients, including omega-3 fatty acids, vitamin A, and vitamin D.

Cod liver oil can contain very large amounts of vitamin A and vitamin D. These vitamins are fat-soluble vitamins that have many important functions in your body. On average, one teaspoon of pure cod liver oil contains 10 mcg (400 IU) of vitamin D and 600 mcg of vitamin A. This is more than half of the entire daily recommended intake of these vitamins for most adults. But each cod liver oil product is different, and a specific product may contain much lower or higher levels of these vitamins. Much lower levels may not be helpful for increasing vitamin A and vitamin D levels in your body. Much higher levels may cause serious side effects.

Cod liver oil also contains docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), the omega-3 fatty acids found in fish oil. While cod liver oil is made only from the liver of the fish, fish oil is made from the whole fish. As a result, fish oil contains much larger amounts of DHA and EPA than cod liver oil. In the U.S., most people get enough omega-3 fatty acids from their diet, such as from fish and some fortified foods. For example, most people can get enough DHA and EPA by eating two to three servings of low-mercury fish each week.

Cod liver oil naturally contains many nutrients. But the amounts of each nutrient in a specific cod liver oil product may vary. Different amounts of these nutrients may change the effects of cod liver oil on the body. Some cod liver oil dietary supplements are made to contain a specific amount of only some of these nutrients.

How should I store cod liver oil?

You should store cod liver oil according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.