Ever since scientists observed 30 years ago that Greenland's Eskimos, who subsist largely on fish, have appreciably lower rates of cardiovascular disease than non-fish eaters, the bulk of evidence has demonstrated that the omega-3 fatty acids found in fish may significantly lower the risk of developing heart problems.

Landmark study: In an Italian study involving 11,324 heart attack survivors, patients who took about 1 g of fish oil daily for three and a half years had a 30% lower risk of dying from cardiovascular disease and a 45% lower risk of having a sudden fatal heart attack. In 2000, the American Heart Association (AHA) began recommending omega-3 fatty acids to prevent heart attack and stroke.


Omega-3 fatty acids are a kind of polyunsaturated fat found chiefly in cold-water fish, such as salmon, mackerel, lake trout, herring and sardines. The two main omega-3 types are called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Another type of omega- 3, called alpha-linolenic acid (ALA), is found in walnuts, flaxseed, soybeans and canola oil.

Studies suggest that omega-3s may protect the heart by reducing systemic inflammation, which can damage arteries and leave them susceptible to plaque buildup. Omega-3s also are believed to decrease the "stickiness" of blood platelets, lowering the risk for clots that can cause heart attack and/or stroke.

Other research indicates that omega-3s may fight mild to severe depression, as well as autoimmune disorders such as rheumatoid arthritis, psoriasis and Crohn's disease. Unfortunately, most of us just don't eat enough omega-3—rich fish to reap the benefits.

How much is enough? The AHA recommends that healthy adults consume at least two fish meals weekly to help reduce the risk for cardiovascular disease—and it urges those with existing heart disease to get 1 g of fish oil daily to prevent future attacks, preferably from fatty fish.

I suggest that patients at increased risk for cardiovascular disease—including those with diabetes or peripheral arterial disease (a condition in which blockages restrict blood circulation, mainly in arteries to the kidneys, stomach, arms, legs and feet)—also consume 1 g of fish oil daily. You can do this by eating three to six ounces of fish every day, but it's more practical for most people to take a fish oil supplement.

The advantages of taking a fish oil supplement include…

  • Consistency. With a supplement, you generally know the amount of omega-Js you're getting. Independent testing by both Consumer Reports and ConsumerLab.com has shown that fish oil supplements by and large contain the levels of EPA and DHA cited on their labels. Of the dozens of products tested by these two watchdog groups, only one failed to provide the promised amount of omega-3s. (For a partial list of brands approved by ConsumerLab.com, see www.consumerlab.com/results/omega3.asp.) Fish, on the other hand, vary greatly in their omega-3 content. While 3.5 ounces of salmon, mackerel or bluefin tuna supply more than 1 g of EPA and DHA in total, the same amount of catfish, cod or canned light tuna provides almost none.
  • Safety. Virtually all fish contain mercury PCBs and dioxins. And, unfortunately, some of the best sources of omega-3s—including bluefin tuna and swordfish—also are among the fish with the most potential toxins. Fortunately, fish oil supplements appear to be generally contaminant- free. Of the 16 brands recently tested by Consumer Reports and the 41 tested by Consumer Lab. com, not a single product contained more than negligible levels of mercury, PCBs or harmful dioxins.


You don't have to buy the most expensive fish oil supplement to get a quality product. Low-price store or discount brands, such as CVS and Puritan's Pride, are comparable in both quality and content to higher-priced name brands. A month's supply can cost as little as $10.

So what should you look for? When choosing a product, consider the following guidelines (as indicated on the label and/or package insert)...

  • It contains both EPA and DHA (most provide both at a 1..5-to-7 ratio favoring EPA.
  • It is "molecularly distilled," a process used to separate the oils from any metals or other pollutants.
  • It is encapsulated under nitrogen rather than oxygen-oxygen can turn the oils rancid, giving them a "fishy" taste and smell.
  • It is highly concentrated to minimize the number of pills you'll need daily. Over-the- counter omega-J supplements may contain from 30% to 90% fish oil.
  • It is approved by the US Pharmacopeia (USP), the independent authority that sets quality standards for all US-manufactured pharmaceuticals and dietary supplements.


The FDA considers up to 3 g of fish oil daily to be generally safe. At or below this level, fish oil supplements are typically well-tolerated, though some people do experience gastrointestinal (GI) upset or an unpleasant "fishy" aftertaste, particularly when they first start taking them.

To minimize GI distress and the fishy aftertaste, divide the dose and take it with food twice a day. Freezing or refrigerating your fish oil supplements may minimize any stomach or intestinal symptoms, as well as any fishy aftertaste, and reduce or slow decomposition of the supplements. Fish oils, like all fats, will eventually deteriorate and turn rancid at room temperature.

Always check with your physician before beginning a supplement, particularly if you're taking any medication. If you're allergic to seafood or iodine (found in some fish and shellfish), do not take fish oil supplements. Get your omega-3s through ALA-rich foods or supplements. In addition, fish oil may not be advisable for people who...

  • Take a daily aspirin or another antiplatelet or anticoagulant drug. Because fish oil has a blood-thinning effect, it theoretically could increase your chances of bleeding, though in nearly 150 studies so far this has not emerged as a side effect.
  • Have type 2 diabetes. Some studies suggest that high-dose omega-Js may trigger short-term increases in blood sugar in people with type 2 diabetes. However, I routinely advise my patients with diabetes ro take up to 1 g of fish oil daily to stave off cardiovascular disease, and most do well on this modest dose. A person with diabetes should take omega-3 fish oil only under a doctor's supervision.
  • Have elevated LDL ("bad') cholesterol (above 130 mg/dL). There's evidence that taking omega-ls may actually increase LDl—possibly because they decrease triglycerides. Studies have shown that lowering triglycerides may increase LDL in some patients.

If on the other hand, you have low LDL levels (below 100 mgldt) and very high triglycerides (above 500 mg/dL), your doctor may suggest Omacor, a new prescription drug that is a highly concentrated form of omega-3. It was just approved by the FDA to treat high triglyceride levels.

Studies show that 4 g of Omacor daily may lower triglycerides by as much as 45%. Just be sure that your doctor routinely monitors your cholesterol and triglyceride levels while you're taking this or any omega-3 fish oil at doses exceeding 3 g daily.

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