Choose the Right Omega-3 Supplement for Heart Health
Certain brands may be useless at best, dangerous at worst. Here’s what you need to know before you buy an omega-3 supplement.
The fact that fish is good for the heart is hard to debate. Unlike animal protein, fish is low in saturated fat as well as calories. But its primary cardiovascular benefit comes from eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two forms of omega-3 fatty acid found in abundance in certain forms of fatty fish. Studies of populations that consume a diet rich in fish have verified the association between high dietary intake of omega-3 ("fish oil") and low rates of cardiovascular disease.
The American Heart Association (AHA) recommends that people with heart disease consume one gram (g) of EPA/DHA combined every day. But even if you like fish, consuming this amount would require you to eat an omega-rich fish such as salmon or mackerel at every meal—and you still might not reach your omega-3 goal. Can you get the benefits of EPA and DHA from taking omega-3 supplements? The answer is yes, providing you choose the right supplement.
Benefits of Omega-3
It is important to know what omega-3 supplements can offer.
Studies have shown that EPA/DHA appears to stabilize arterial plaque, lower blood pressure modestly and possibly reduce platelet aggregation—all desirable for patients at risk for a cardiovascular event. But the primary benefit of fish oil stems from its ability to lower triglycerides. The National Cholesterol Education Program defines normal triglyceride levels as less than 150 mg/dL.
In a meta-analysis of 25 studies, increasing omega-3 consumption by one g per day lowered triglyceride levels an average of 8 mg/dL. The higher the participants’ triglyceride levels, the greater the effect. In patients with higher-than-normal triglycerides, levels dropped by 27 mg/dL. In a different study of patients with hypertriglyceridemia (levels above 500 mg/dL), a dose of 4 g per day caused levels to drop by 39 percent.
If you have hypertriglyceridemia, you may benefit from prescription omega-3. Each capsule of this pure, high-dose formula contains 375 mg of DHA and 465 mg of EPA, so taking two to four capsules a day provides enough omega-3 to do the job.
Omega-3s may also prevent arrhythmias after a heart attack. In the largest trial ever conducted on fish-oil therapy in heart patients—the 11,323-patient GISSI-Prevention trial—EPA/DHA substantially reduced the number of fatal heart attacks. Other trials have not reached the same conclusion, however.
It is important to know that while omega-3s lower triglycerides, they can also raise "bad" LDL cholesterol levels about 10 mg/dL. For this reason, taking an LDL-lowering statin may be a good idea if you take fish-oil supplements.
The latest finding in favor of fish oil came in January 2011, when a study reported in the online edition of the Journal of the American College of Cardiology found that adding omega-3 supplements to a standard medication regimen for heart failure increased patients’ heart function and blood oxygen levels, allowing them to exercise longer. Moreover, during the one-year study, hospitalization rates were one-fifth of those for patients not taking omega-3.
How to Choose an EPA/DHA Supplement
Not all EPA/DHA supplements are created equal. Regardless of the strength printed on the label, you need to verify how much of each fatty acid is in each capsule. If the amount doesn’t add up, you can be sure the remainder is a filler you don’t want to ingest.
"If a 1,000-mg capsule contains only 180 mg of EPA and 120 mg of DHA, the rest of the capsule is filled with fish blubber, which is pure fat," says Leslie Cho, MD, Director of the Women’s Cardiovascular Center. "Because omega-3 supplements are not regulated by the Food and Drug Administration, you will never see ‘fish blubber’ or anything like it listed on the label," she says.
"Besides, you would have to swallow 13 capsules a day to meet AHA requirements," she adds.
In early 2010, the San Jose Mercury News revealed that some over-the-counter omega-3 supplements contain PCBs, a toxic substance banned in 1979. An environmental group tested 10 national brands and found all contained some PCBs, and one-third had levels up to 10 times higher than California considers "no significant risk" (see www.MercuryNews.com_ci14501591 for details).
Omega-3 manufacturers say they are being unfairly attacked, because the PCBs come from the fresh fish from which the capsules are made. The amount of PCBs in the fish varies, depending on the type of fish and where it is caught. The AHA recommends pregnant women and children should avoid eating the fish most likely to contain contaminants, and that everyone should eat a variety of fish to minimize potential risk (see www.heart.org/gettinghealthy).
What You Should Do
For patients with heart disease, Cleveland Clinic supports the AHA’s recommendations to eat at least two 3.5-ounce servings of fatty fish a week. Of course, the fish should be broiled or baked, not fried.
If you don’t like fish, cannot eat fish twice a week or will not eat the kind that is high in omega-3, you can substitute fish-oil supplements. You need one gram per day, so make sure the product you choose contains enough EPA and DHA that you will ingest 1,000 mg in a capsule or two.
As for PCBs, the newspaper article resulted in a lawsuit brought against the manufacturers of the products tested. The lawsuit has yet to be settled, but it may have basis in a California law passed in 1986 that requires manufacturers to list detectible levels of PCBs and other banned chemicals, such as mercury, on the label. Until this is done, it is impossible for consumers to know if an over-the-counter omega-3 supplement contains PCBs, and if so, how much.
"We do know EPA and DHA are beneficial for the heart. Whether low levels of PCBs—whether found in fish or fish-oil capsules—negate this benefit is still controversial," says Dr. Cho.