Cod liver oil has been used for centuries in many countries, including the United States, to treat a variety of illnesses and as a dietary supplement. It's also used topically to relieve skin irritations and joint pain. Cod liver oil has many healthy benefits, but there are side effects and warnings.
Centuries ago in Europe, Scotland, Iceland and other countries, cod liver oil was used as a fuel for lamps, to manufacture textiles and to soften leather. Its use in animal feed resulted in shiny, healthy coats, possibly prompting people to consume cod liver oil for the same benefit. Fishermen rubbed cod liver oil onto sunburn and sore joints. In the 1930s in the United States, it was discovered that cod liver oil added to the diet prevented the debilitating childhood disease rickets (a disease related to vitamin D deficiency). Today, cod liver oil is used as a dietary supplement and is being studied for other potential medicinal uses.
Cod liver oil pills are used by herbalists to treat Crohn's disease, rheumatoid arthritis, high triglycerides and high blood pressure. It's also used to a lesser degree to treat mental disorders, asthma, diabetes, cystic fibrosis, skin conditions, cardiac disease, high cholesterol, ulcerative colitis, atherosclerosis, lupus, multiple sclerosis, osteoporosis, macular degeneration and sickle cell anemia. Cod liver oil is recommended for those who have a deficiency in omega-3 fatty acids, vitamin A or vitamin D.
Cod liver oil is very high in vitamins A and D, as well as the omega-3 fatty acids EPA and DHA. One 400mg capsule contains 1,250 IU of vitamin A and 135 IU of vitamin D.
A 2008 study by the Vascular and Inflammatory Diseases Research Unit, University Division of Medicine and Therapeutics, Ninewells Hospital and Medical School, UK, indicates that "...cod liver oil supplements containing n-3 fatty acids can be used as NSAID-sparing agents in RA patients." (See Resources.) In other words, due to its anti-inflammatory properties, cod liver oil allowed patients with rheumatoid arthritis to rely less on non-steroidal anti-inflammatory drugs.
Side Effects & Warnings
Reported side effects of cod liver oil include nausea and loose stools. It may increase the effect of antiplatelet and anticoagulant drugs. Excessive use of cod liver oil may cause Vitamin A toxicity which can result in hair loss, liver damage, bone loss and confusion. The U.S. Food and Drug Administration has not approved the use of cod liver oil as a medication. Consult your physician before taking cod liver oil.