The Difference Between Cod Liver Oil & Omega-3 Supplements

Cod liver oil is one source of essential omega-3 fats, but not necessarily the best source. Although other types of fish oil are richer in omega-3 fats, some people choose cod liver oil because it also provides significant amounts of some vitamins. Check with your doctor before taking any type of omega-3 supplement to make sure it is safe for you to do so.

Fish oil, including cod liver oil, provides omega-3 fats. (Image: KirS-UA/iStock/Getty Images)

Consider Omega-3 Content

Cod itself isn't a very good source of omega-3 fats, with a 3-ounce serving providing 134 milligrams of the recommended 500 milligrams per day. Cod liver oil does provide these healthy fats, however, with each teaspoon containing 1,034 milligrams. Other types of fish oil are better sources of omega-3s. For example, a teaspoon of salmon oil has 1,905 milligrams and a teaspoon of menhaden oil has 1,544 milligrams. Commercial fish oil or omega-3 supplements often contain a mix of fish oils.

Compare Vitamin Content

Cod liver oil is sometimes recommended over other types of fish oil because of its higher vitamin D and vitamin A content. While a teaspoon of salmon or menhaden oil doesn't provide a significant amount of any vitamins, the same amount of cod liver oil provides 2 percent of the daily value for vitamin D and 100 percent of the DV for vitamin A. You need vitamin D for bone health and proper immune, muscle and nerve function. Vitamin A is essential for good vision and immune function.

Potential Side Effects

Fish oil of any type can cause side effects, including uneven heartbeat, flu symptoms, chest or back pain, skin rash, upset stomach or an unpleasant taste in your mouth. Choosing a time-release version of fish oil pills may help limit these side effects. Fish oil may increase blood sugar levels, so diabetics may want to avoid fish oil supplements.

Note Interactions and Other Considerations

Fish oil can interact with diuretics, beta-blockers, blood thinners and birth control pills. Choose fish oil supplements that have been certified free of lead, mercury and cadmium. Because of the high amounts of vitamin A in cod liver oil, it can increase your risk for vitamin A toxicity. The tolerable upper intake level for vitamin A for adults is 10,000 international units, which is found in just 2 teaspoons of cod liver oil. Just 1 teaspoon per day of cod liver oil surpasses the UL for children under the age of 9.