Risks and Benefits of Cod Liver Oil


There are health benefits of cod liver oil and there are drawbacks. Cod liver oil benefits may not outweigh the risks. The primary benefit of cod liver oil is related to its omega-3 content, but fish oils derived from the flesh of fish, rather than the liver, provide that benefit without the risks.

The health benefits of cod liver oil are related, primarily to omega-3 fatty acids. These are essential for the healthy function of the brain, the heart, the joints, the digestive system and many other systems of the body. Another benefit of cod liver oil is related to its vitamin E content, which helps the body process the fatty acids, is an essential antioxidant and promotes the health of the skin and the hair.

Omega-3 Fatty Acids/Benefits of Cod Liver Oil

Omega-3s are essential to human health, cannot be produced inside the body, and so, must be obtained from food or through supplementation. The best know source of omega-3 fatty acids is fish. Some fish contain more omega 3s than others.

There are two types of omega-3 fatty acids that have been identified as essential for human health. They are Docosahexaenoic Acid or DHA and Eicosapentaenoic Acid or EPA. These are found primarily in fish. The body can convert another omega-3 fatty acid, known as Alpha-linolenic acid or ALA, to DHA and EPA, but the process is relatively inefficient. It is believed that one would have to consume a great deal of ALA in order to get the health benefits provided by DHA and EPA.

The omega-3 found in flax seed oil is ALA. And some believe that flax seed oil can provide cod liver oil benefits, without the risks, but this is debatable. Although there are no risks associated with flax seed oil, it is unknown if ALA provides the same health benefits as DHA and EPA.

The Risks

Cod liver oil contains large amounts of vitamin A and vitamin D and may contain contaminants such as mercury and pesticides. The body needs adequate amounts of vitamin A, but large amounts can be toxic. Vitamin D is not commonly found in natural foods, but many processed foods are fortified with vitamin D to ensure good nutrition.

At one time the benefits of cod liver oil were believed to be associated with its vitamin A and D content. This was before omega-3 fatty acids had been identified and before food fortification was a common practice. It was also before taking daily multi-vitamins became a common practice and before industrial pollutants had contaminated our oceans.

Vitamin D

While no tolerable upper limit for vitamin D consumption has been established, adequate intake for adults, under the age of 50, and children is believed to be around 200 units per day. Adults over 50 should increase consumption to 400 units per day for men and 600 units per day for women. Vitamin D is necessary for the body to process calcium and is therefore a factor in preventing osteoporosis and maintaining bone health. However, one of the popular cod liver oil products contains 4000 to 5000 units of vitamin D per teaspoon, more than anyone needs on a daily basis.

Vitamin A

A tolerable upper limit for vitamin A has been established. The maximum amount of vitamin A that a 25 year old man should consumer per day is 10,000 IU. Women should consume less than half that amount. Women who are pregnant should avoid dietary supplements that contain vitamin A because of the risk of birth defects. While vitamin A is necessary for fetal development and overall good health, it is stored in the fat cells and there is a great risk of over supplementation. Excess consumption of vitamin A is also believed to contribute to osteoporosis.

One of the popular cod liver oil products contains 4000-5000 IU of vitamin A, per teaspoon. When added to the amount that may be present in other dietary supplements, as well as the food that a person consumes per day, it will put most people over the safe upper limit for vitamin A. While the benefit of cod liver oil for supplying essential omega 3s is known, it is unknown if excess consumption of vitamin A will counteract those effects.

A better choice for vitamin A supplementation is beta carotene and other carotenoids. Present in the better daily dietary supplements, carotenoids are converted by the body to vitamin A on an as-needed basis and are not associated with the negative effects of “pre-formed” vitamin A. The only known side effect of excess consumption of carotenoids is a yellowing of the skin, called carotenosis, which is not dangerous, but may be undesirable.


Fish oil derived from the flesh of fish does not contain the vitamins A and D. Those vitamins are usually present in adequate amounts in daily multi-vitamins and fortified foods. Though extra vitamin D supplementation is often recommended for persons over the age of 50, it is not a benefit of cod liver oil and there are better choices for vitamin D supplementation.

From an environmental standpoint, over harvesting of the cod fish has led to the depletion of many populations. Farms affect the health of wild fish. The equipment used for harvesting damages the habitat of other water dwelling life forms. Although there are cod liver oil benefits, these health benefits can be obtained from other sources that do not cause damage to our environment.

You can get the health benefits of cod liver oil by taking fish oil supplements derived from the flesh, rather than the liver of fish. To learn more, please visit the Fish Oil Guide.