Cod liver oil, obtained from the liver of the codfish, was a common supplemental source of vitamin D for children until the 1960s. With the advent of much easier-to-swallow chewable vitamins, cod liver oil fell out of favor, but has experienced resurgence with the interest in omega-3 fatty acids found mainly in fish oil. Cod liver oil also contains vitamin A and vitamin E.
Vitamin A
As with other fat-soluble vitamins, the body stores vitamin A in the tissues until needed. You need 2,310 international units of vitamin A per day if you're a woman; men need 3,000 IU per day. Children ages 9 to 13 need 2,000 IU, while children 4 to 8 need 1,320 IU, and children 1 to 3 need 1,000 IU. Vitamin A deficiency is one of the world's leading causes of blindness in children. Too much vitamin A, however, can cause birth defects, low bone density, liver abnormalities and problems with your nervous system. The amount of vitamin A in a dose of cod liver oil varies among manufacturers. One commercial brand recommends 1 tsp. or 5 ml as a dose, while another recommends 1 tbsp. or 15 ml -- three times as much. The 1 tbsp. dose contains 4,303 IU of vitamin A, and the manufacturer recommends 1 to 2 tbsp. per day. Read labels carefully to avoid overdosing on vitamin A and ask your doctor about a recommended dose.
Vitamin D
Interest in vitamin D has also experienced resurgence. The recommended daily dose of vitamin D increased to 600 IU for males and females ages 1 to 70, and 800 IU for those over age 71 in 2010. While vitamin D has a well-established role in absorbing calcium through the intestine, the vitamin may also play a part in insulin secretion and immune system function. Several commercial brands of cod liver oil contain approximately 400 IU of vitamin D.
Vitamin E
Vitamin E, another fat-soluble vitamin, also is in cod liver oil supplements. One commercial brand contains 10 IU of vitamin E. The recommended daily allowance of vitamin E is 22.4 IU, but around 11 percent of all American adults took vitamin E supplements containing 400 IU or more, according to findings of the 1999-2000 National Health and Nutrition Examination Survey. Vitamin E also may help prevent heart disease.
Omega-3 Fatty Acids
Although not vitamins, many people take fish oil and cod liver oil for its omega-3 fatty acid content. Omega-3 fatty acids help lower cholesterol levels and blood pressure and decrease the blood's ability to form clots, all of which can lower your risk of heart disease. Ask your doctor before taking omega-3 supplements if you take blood thinners, as they may increase your bleeding tendency.
References
- Office of Dietary Supplements: Vitamin A
- Carlson Labs: Cod Liver Oil Regular Flavor
- Linus Pauling Institute; Vitamin D; Jane Higdon, Ph.D.; March 2004
- Office of Dietary Supplements: Vitamin E
- National Library of Medicine: Twinlab Emulsified Norwegian Cod Liver Oil Mint Flavor
- Mayo Clinic; Omega-3 Fatty Acids; December 2010
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