Omega-3 Fatty Acids and Heart Health

Lifestyle intervention such as consistent aerobic exercise and a diet high in fruits and vegetables promotes cardiovascular health. A heart-healthy lifestyle decreases the risk of coronary heart disease and heart attack. Although it may seem intuitive that dietary fat is bad for the heart and that it must be avoided, certain unsaturated fats are heart healthy, and other saturated fats are not good for the heart. These heart-healthy unsaturated fats are known as omega-3 fatty acids. The 3 main omega-3 fatty acids that are beneficial for cardiovascular health are α-linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is primarily found in plant-based foods such as olive, soybean, canola, walnut, and flaxseed oils, and in walnuts and flaxseeds, as well. EPA and DHA are primarily found in marine-based foods that include the variety of fatty fish, such as tuna, salmon, mackerel, herring, trout, halibut, and cod. This Cardiology Patient Page will present the beneficial effects of omega-3 fatty acids on cardiovascular health, explain the possible mechanisms for these effects, and offer recommendations that can be implemented into a healthy lifestyle to further promote good cardiovascular health.

Several studies have shown that individuals who consumed fatty fish a few times per week had almost one-half the risk of death from coronary heart disease and almost one-third the risk of death from a heart attack in comparison with those who consumed no fish.¹ In 1 study, the risk of death from coronary heart disease was 21%, 29%, 31%, and 34% lower in those who consumed fish 1 to 3 times per month, once per week, 2 to 4 times per week, and >5 times per week, respectively, in comparison with those who consumed no fish.² Similarly, ALA consumption has also been shown to reduce the risk of death from coronary heart disease and from heart attack. Regarding omega-3 fatty acid supplement capsules, in the largest randomized controlled trial to date, consisting of 11 324 patients with coronary heart disease, those who took fish oil and ALA capsules daily had a 15% reduction in death, heart attack, and stroke incidence, a 20% reduction in death from any health-related cause, and a 45% reduction in sudden death from a heart attack in comparison with placebo over 3.5 years of follow-up. In addition, triglyceride levels decreased by 4%.³ This suggests that consuming omega-3 fatty acids may reduce the risk of death from heart disease for both men and women. Omega-3 fatty acid consumption has also been shown to reduce resting blood pressure modestly and to decrease body fat levels, both of which can improve heart health.

There are several potential mechanisms for the favorable effects of omega-3 fatty acids on overall cardiovascular health (Table 1). Omega-3 fatty acids lower triglyceride levels and increase high-density lipoprotein (ie, good cholesterol) levels. They may also decrease platelet aggregation, which can prevent the coronary arteries from occluding (occlusion would prevent or decrease blood flow to the heart). Aspirin also prevents platelet aggregation. Omega-3 fatty acids may decrease the chance of the heart having an abnormal rhythm. Omega 3- fatty acids may also increase compliance of arteries, decrease atherosclerosis through their effects on metabolism, and reduce inflammatory markers in the body.⁴

Many studies have shown that omega-3 fatty acids reduce cardiovascular disease and improve outcomes. Although it is unclear whether plant-derived omega-3 fatty acids (ie, ALA) or fish-derived omega-3 fatty acids (ie, DHA, EPA) are more important for the heart, both should be a part of a healthy diet. Evidence suggests that 0.5 to 1.8 g/d of combined EPA and DHA, either as fatty fish or through supplement capsules, is recommended; 1.5 to 3 g/d of ALA is also beneficial, either through plant-based foods or supplement capsules.⁴ Table 2 lists various food sources of omega-3 fatty acids and their omega-3 fatty acid content. The American Heart Association dietary guidelines recommend including at least 2 servings of fatty fish per week in a healthy diet. Including vegetable oils, such as soybean, canola, walnut, flaxseed, and foods such as walnuts and flaxseeds, all of which are good sources of ALA, is also recommended.⁴ When possible, omega-3 fatty acids should be consumed through food sources. However, when this is not feasible, for vegetarians, and for convenience, consumption of high-quality omega-3 fatty acid capsules may also be beneficial. Patients should consult with their physicians before taking these supplements. It is important to know that any potential long-term adverse effects of these capsules are not yet known.