Vitamin D deficiency can cause bone and muscle problems, including the disorders rickets and osteomalacia. People who are low in vitamin D often take cod liver oil, which is high in this nutrient. There are some concerns with the use of cod liver oil as a treatment for vitamin D deficiency, and some doctors recommend using other ways of getting more vitamin D.
History
In Germany in the late 19th century, doctors noticed that consumption of 1 to 3 tbsp. of cod liver oil taken every day could reverse the signs of rickets in children. In the 1930s, scientists isolated vitamin D as the component of cod liver oil that helped treat the disorder.
Options
Traditionally, cod liver oil was only available in liquid form, which is unpalatable. Supplement manufacturers now offer capsules of cod liver oil, which dissolve in the digestive tract to release the oil there. Another option is flavored liquid cod liver oil, which helps mask the strong taste.
Considerations
Cod liver oil is one of the best natural sources of vitamin D, with 1,360 IU in 1 tbsp., about 340 percent of the recommended daily intake. Cod liver oil also contains the omega-3 fatty acids DHA and EPA. Most people in the U.S. do not get enough omega-3 fats in the diet, so taking cod liver oil regularly could also supply these compounds in addition to vitamin D.
Concerns
The biggest concern about using cod liver oil for the treatment of vitamin D deficiency is that this oil also contains high levels of vitamin A. Vitamin A can be toxic, especially when consumed in amounts over 10,000 IU at a time. Some brands of cod liver oil have up to 13,500 IU of vitamin A. The Weston A Price Foundation maintains that vitamin A found in food sources, such as cod liver oil, does not have the toxicity that synthesized vitamin A does, so this need not be a concern if using cod liver oil to increase the intake of vitamin D. Contamination with mercury is another concern, because many fish have high levels of this compound. However, many brands of cod liver oil have been purified to remove mercury contamination.
Alternatives
Mild deficiencies may be treated using food sources of vitamin D or through sunlight exposure, which causes the body to produce its own vitamin D. Foods high in vitamin D include fortified dairy products and breakfast cereals, fatty fish and egg yolk. Supplements in doses up to about 2,000 IU per capsule are available over-the-counter. Injectable vitamin D can be given by a doctor in the case of severe deficiency.
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