The AHA's new fish oil guidelines say patients with documented CHD ideally should get their daily fish oil fix from an approximately 3-ounce serving of a fatty fish such as salmon, herring, trout, or sardines. Somewhat leaner fish, such as canned tuna, halibut, and flounder also are fine but must be consumed in larger portions, according to the guidelines that were released in November (Circulation 106[21]:2747-57, 2002).
In a major departure, the AHA also said—for the first time—that a recommended nutrient could alternatively be consumed as a supplement. In this case, that would typically mean 1-g fish oil capsules that are widely marketed and contain 180 mg of eicosapentaenoic acid and 120 mg of docosahexaenoic acid. Patients should take three of these capsules per day.
“This is the first pill supplement ever recommended by the AHA,” William S. Harris, Ph.D., said in an interview at the AHA's annual scientific sessions.
The AHA's nutrition committee found compelling evidence from controlled studies reported since 1999 that daily intake of about a gram of omega-3 fatty acids can reduce the incidence of new CHD events in patients with established disease. The committee realized that many Americans would find it difficult to eat sufficient amounts of fish. Accumulated evidence also has shown that fish oil capsules provide a similar benefit, and that they appear to be safe, said Dr. Harris, coauthor of the recommendations and co-director of the Lipid and Diabetes Research Center at the Mid-American Heart Institute, Kansas City, Mo.
The major downside to heavy fish intake is that some species may contain mercury or other environmental pollutants. Mercury intoxication is mainly an issue for children and women who are pregnant or breast-feeding, the guidelines note. “For middle-aged and older men and for postmenopausal women, the benefits of fish consumption far outweigh the risks within the guidelines established by the FDA and the Environmental Protection Agency.”
Fish oil capsules should be “high quality” and free of contaminants, the guidelines state. But the public has no way to confirm these characteristics, Dr. Harris said. The U.S. Pharmacopeia is developing a program to certify nutritional supplements for purity and potency, but it's not yet fully in place. Another possibility is that the AHA may start certifying fish oil supplements.
Until then, patients should look for 1-g fish oil capsules that each contain 180 mg of eicosapentaenoic acid and 120 mg of docosahexaenoic acid. This content provides some reassurance that the oil has been thoroughly processed and that contaminants have been removed, Dr. Harris said. A Norwegian firm produces an ultrapurified 1-g capsule that contains 850 mg of omega-3 fatty acids, and it is seeking a partner for U.S. marketing, he said. But these capsules will probably be more expensive than others that retail for as little as 5 cents a capsule.
The new guidelines also advise people without cardiovascular disease to eat at least two servings of fish a week and eat foods rich in
–linoleic
acid, such as flaxseed, canola, and soybean oils; walnuts; and flaxseed. Fish
oil supplements are generally benign, so there is no known downside if people
use the capsules for primary prevention, he said.The guidelines also say that people who need to lower their triglyceride level—usually when it exceeds 200 mg/dL—can do so by taking 2-4 g of omega-3 fatty acids a day.
Physicians shouldn't misconstrue this recommendation as a knock against drugs such as fibrate or niacin, which are the established agents for lowering triglyceride levels. But omega-3 fatty acids have some efficacy for lowering triglycerides and are an option for patients, Dr. Harris said.