Cod Liver Oil

Once used mainly as a vitamin supplement for children, cod liver oil is more likely now to be promoted for older people suffering from severe osteoarthritis. Fish oil, rich in omega-3 fats, helps counter inflammation, so some people with another form of arthritis, rheumatoid arthritis (an inflammatory disease), take fish oil supplements to help reduce symptoms. There is also an inflammatory element in osteoarthritis, it is now known, and thus some people think that fish oil, specifically cod liver oil, might be useful.

Claims, purported benefits: Treats or cures arthritis. Prevent heart attacks and stokes. Fights cancer, prevents Alzheimer’s disease, depression.

Bottom line: No solid research has ever shown that cod liver oil prevents cancer, Alzheimer’s, or depression, but there is some evidence that fish oil, including cod liver oil, may ease the pain of arthritis and improve joint stiffness. Like all fish oil supplements, the oil may help reduce the risk of heart disease and stroke, especially in people who have already had a heart attack or are at high cardiovascular risk.

Potential problem: Cod liver oil, bottled or in capsule form, often contains very high levels of A, which can weaken bones and cause birth defects. Just one teaspoon may have 4,500 IU of A, and the standard dose is one to three teaspoons a day. Capsules of cod liver oil contain less oil, but the vitamin can still add up, especially on top of the amount you get from foods and from a multivitamin, if you take one. Studies have found that as little as 6,000 IU of vitamin A daily can interfere with bone growth and promote fractures. And women of childbearing age should not exceed 10,000 IU of vitamin A because of the risk of birth defects. So make sure the label says that the vitamin A content has been reduced. Fish oil supplements, and fish itself, do not have much vitamin A, which is concentrated in the liver (in beef and chicken liver as well).

Another potential problem: Since the oil is made from livers, which filter out toxins, there is greater concern about contaminants (such as PCBs), even though the oil is supposed to be purified.