Dietary Supplements and Cardiovascular Health

Omega-3 Fatty Acids

“Fish and Omega-3 Fatty Acids,” reprinted with permission.© 2009 American Heart Association, Inc. (www.americanheart.org).

American Heart Association (AHA) Recommendation

Omega-3 fatty acids benefit the heart of healthy people, and those at high risk of—or who have—cardiovascular disease. We recommend eating fish (particularly fatty fish) at least two times a week. Fish is a good source of protein and doesn’t have the high saturated fat that fatty meat products do. Fatty fish like mackerel, lake trout, herring, sardines, albacore tuna, and salmon are high in two kinds of omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). To learn about omega-3 levels for different types of fish—as well as mercury levels, which can be a concern—see our Encyclopedia en- try on Fish, Levels of MercuryandOmega3FattyAcids[http://www.americanheart.org/presenter.jhtml?identifier=3013797]. We also recommend eating tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils. These contain alpha-linolenic acid (LNA), which can become omega-3 fatty acid in the body. The extent of this modification is modest and controversial, however. More studies are needed to show a cause-and-effect relationship between alpha linolenic acid and heart disease.  Table 70.1 is a good guide to use for consuming omega-3 fatty acids. Patients taking more than 3 g of omega-3 fatty acids from capsules should do so only under a physician’s care. High intakes could cause excessive bleeding in some people.

Background

In 2002, the American Heart Association released a scientific statement, “Fish Consumption, Fish Oil, Omega-3 Fatty Acids and Cardio-vascular Disease,” on the effects of omega-3 fatty acids on heart function (including antiarrhythmic effects), hemodynamics (cardiac mechanics),

Dietary Supplements and Cardiovascular Health

and arterial endothelial function. The link between omega-3 fatty ac ids and CVD risk reduction are still being studied, but research has shown that omega-3 fatty acids:

• decrease risk of arrhythmias, which can lead to sudden cardiac death;

• decrease triglyceride levels;

• decrease growth rate of atherosclerotic plaque;

• lower blood pressure (slightly).

What do epidemiological and observational studies show? Epidemiologic and clinical trials have shown that omega-3 fatty acids re-duce CVD incidence. Large-scale epidemiologic studies suggest that people at risk for coronary heart disease benefit from consuming omega-3 fatty acids from plants and marine sources. The ideal amount to take isn’t clear. Evidence from prospective secondary prevention studies suggests that taking EPA+DHA ranging from 0.5 to 1.8 g per day (either as fatty fish or supplements) significantly reduces deaths from heart disease and all causes. For alpha-linolenic acid, a total intake of 1.5–3 g per day seems beneficial. Randomized clinical trials have shown that omega-3 fatty acid supplements can reduce cardiovascular events (death, nonfatal heart attacks, nonfatal strokes). They can also slow the progression of atherosclerosis in coronary patients. However, more studies are needed to confirm and further define the health benefits of omega-3 fatty acid supplements for preventing a first or subsequent cardiovascular event.

Table 70.1. Summary of Recommendations for Omega-3 Fatty Acid Intake

Population Recommendation

Patients without documented Eat a variety of (preferably fatty) fish at

coronary heart disease (CHD) least twice a week. Include oils and foods rich

                                                                                  in alpha-linolenic acid (flaxseed, canola and

                                                                                  soybean oils, flaxseed, and walnuts).

Patients with documented CHD Consume about 1 g of EPA+DHA per day,

                                                                                  preferably from fatty fish. EPA+DHA in capsule

                                                                                  form could be considered in consultation with

                                                                                  the physician.

Patients who need to lower 2 to 4 g of EPA+DHA per day provided as

triglycerides capsules under a physician’s care.

 

Cardiovascular Disorders Sourcebook, Fourth Edition

For example, placebo-controlled, double-blind, randomized clinical trials are needed to document the safety and efficacy of omega-3 fatty acid supplements in high-risk patients (those with type 2 diabetes, dyslipidemia, hypertension, and smokers) and coronary patients on drug therapy. Mechanistic studies on their apparent effects on sudden death also are needed. Increasing omega-3 fatty acid intake through foods is preferable. However, coronary artery disease patients may not be able to get enough omega-3 by diet alone. These people may want to talk to their doctor about taking a supplement. Supplements also could help people with high triglycerides, who need even larger doses. The availability of high quality omega-3 fatty acid supplements, free of contaminants, is an important prerequisite to their use.