Mining for Oil: Taking Fish-Oil Supplements

Who Should Take Fish-Oil Pills?
Nearly every month there’s another study showing the health benefits of fish, and some of these studies have used fish-oil supplements. These supplements contain heart-healthy omega-3 fatty acids, but not the other good things in fish, and they are not without risk. But medical opinion about these supplements has changed somewhat because of ongoing research and advice from the American Heart Association (AHA).

Here’s who should consider taking fish-oil supplements:

People who already have coronary artery disease, notably those who have had a heart attack. There is solid evidence that omega-3s can help protect them. Thus, a few years ago the AHA started recommending 1 gram a day of omega-3s, preferably from fish, for these people, with their doctors’ approval. That’s the amount in a serving of fatty fish, such as 3 ounces of salmon. But most people don’t eat fish every day, and many choose less-fatty fish (it takes 12 ounces of canned tuna or 7 ounces of flounder to supply 1 gram of omega-3s). Moreover, since fish may contain mercury, many experts advise limiting fish intake to 12 ounces a week, on average. So to get enough omega-3s without going overboard on fish, people with heart disease should consider taking fish-oil supplements on days when they don’t eat fish.

Those with high triglycerides. These fats in the blood increase the risk of heart disease. It’s well known that omega-3s help lower triglycerides. The AHA recommends 2 to 4 grams a day from supplements for people with high triglycerides, but only under the care of a physician.

Those with rheumatoid arthritis, psoriasis, or other auto-immune disorders. Omega-3s may help relieve the inflammatory symptoms of such auto-immune diseases by suppressing the immune response. Thus, they can help reduce the joint pain and swelling of rheumatoid arthritis. The Arthritis Foundation says the supplements are worth trying. Clinical studies suggest about 3 grams of omega-3s a day.

What about people with coronary risk factors, such as diabetes or high blood pressure, but no apparent heart disease? We suggest that they get their omega-3s from two or three weekly servings of fatty fish. There have been no clinical studies to see if fish-oil supplements will help them.

Not for everyone
If fish oil is so great, why shouldn’t everyone take supplements?

  • The decreased ability of the blood to clot, which helps prevent heart attacks, has a negative side, notably an increased risk of hemorrhagic stroke. People with bleeding disorders, those taking anticoagulants, and those with uncontrolled hypertension should not take fish oil supplements.
  • Large doses of fish oil may suppress the immune system. Thus, supplements may be risky for those with weakened immune systems. What’s a “large dose”? One definition is 3 grams or more a day, but no one really knows what the cutoff point is.
  • Large doses can increase glucose levels in people with diabetes.
  • Large doses can cause nausea, diarrhea, belching, and a bad taste in the mouth.
  • The supplements may contain contaminants and may not contain the labeled dose. Testing by Consumer Reports of top-selling supplements was reassuring on both counts, even for the least expensive brands, but that doesn’t mean that the next batches will be okay–or that other brands on the market are. Similarly, tests by have found no detectable levels of mercury in fish-oil supplements, but did find that some brands didn’t contain the labeled amounts of omega-3s.

Fathom this: It is rare for a major health group like the AHA to recommend any dietary supplement. But remember, its advice concerns the treatment of specific diseases. For everyone else, two or three small servings of fish a week is still the way to go. Fish may be more beneficial than the supplements because it contains other important nutrients, some potentially cardio-protective. And fish can take the place of meat, which is usually high in saturated fat and thus bad for the heart.