Seafood Long-Chain n-3 PUFAs and CVD

Rimm EB, Appel LJ, Chiuve SE, et al.
Seafood Long-Chain n-3 Polyunsaturated Fatty Acids and Cardiovascular Disease: A Science Advisory From the American Heart Association. Circulation 2018;May 15:[Epub ahead of print].

The following are key points to remember from this American Heart Association (AHA) Science Advisory on seafood long-chain (LC) n-3 polyunsaturated fatty acids (PUFAs) and cardiovascular disease (CVD):

  1. This AHA Science Advisory reviews recent evidence of the effect of n-3 PUFA supplementation on clinical cardiovascular events, and makes a suggestion in the context of the 2015–2020 Dietary Guidelines for Americans and in consideration of other constituents of seafood and the impact on sustainability. The conclusion was that 1-2 seafood meals per week be included to reduce the risk of congestive heart failure (CHF), coronary heart disease (CHD), ischemic stroke, and sudden cardiac death.
  2. Several potential mechanisms have been investigated, including antiarrhythmic, anti-inflammatory, decreased platelet-monocyte aggregation and platelet activation, and endothelial function, although for most, longer-term dietary trials of seafood are warranted to substantiate the benefit of seafood as a replacement for other important sources of macronutrients.
  3. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are the long chain (LC) n-3 PUFAs most closely associated with lower CVD risk. The content of LC n-3 PUFAs is variable in seafood. Cold-water oily fish such as salmon, anchovies, herring, mackerel (Atlantic and Pacific), tuna (bluefin and albacore), and sardines have the highest levels (range 1100-2400 mg per 4 oz). In contrast, shrimp, lobster, scallops, tilapia, and cod have lower levels (about 100-200 mg per 4 oz). Dietary guidelines recommend at least 2 servings per week of seafood to provide an average of 250 mg EPA+DHA per day in place of other animal sources of protein.
  4. Greater consumption of seafood has also been associated with several electrophysiological indexes including lower heart rate, slower atrioventricular conduction, lower likelihood of abnormal repolarization (prolonged QT), and optimal values of several heart rate variability components. These effects are associated with a lower risk of developing ventricular arrhythmias and sudden cardiac death. Consuming approximately 1-2 fatty fish meals per week is associated with a 50% lower risk of sudden cardiac death compared with little or no seafood intake after adjustment for potentially confounding factors. In the Physicians’ Health Study, there was no significant relationship between dietary n-3 intake or blood n-3 PUFA levels and nonfatal myocardial infarction, despite the strong inverse association with sudden cardiac death. The effect on prevalence of CHF is inconclusive.
  5. In two large US cohorts, substitution of 3% of total protein calories in processed meat with 3% of total protein calories from seafood was associated with 31% lower risk of cardiovascular mortality. The benefit is likely greatest when an individual increases intake from 0 seafood meals per week to 1-2 seafood meals a week, and could be greater if seafood replaces the intake of unhealthy foods, but not for healthy vegetarian diets.
  6. Regarding strokes, results from the Nurses’ Health Study and Health Professionals Follow-up Study indicate that intake of seafood was associated with a lower risk of ischemic stroke, but has no impact on risk of hemorrhagic stroke. In the Cardiovascular Health Study, consumption of tuna or other broiled and baked fish was associated with a 40% lower risk of ischemic stroke among older adults; however, intake of fried fish or fish sandwiches was associated with a higher risk of ischemic stroke.
  7. A number of prospective observational studies have evaluated how seafood LC n-3 PUFAs, assessed largely with circulating biomarker levels, impacts recurrent events among patients with CHD. Although trends are positive, recent trials do not convincingly support fish or fish oil supplements to prevent recurrent coronary events in stable CHD.
  8. Despite concerns, there is no evidence of a negative interaction or attenuation of the benefits of seafood derived LC n-3 PUFAs by increased intake of n-6 PUFAs (e.g., vegetables oils). In the Nurses’ Health Study, women in the highest tertile of both dietary PUFAs had a 54% lower risk of sudden cardiac death compared to women in the lowest tertile of both.
  9. The evidence does not support avoiding cold-water fish 1-2 times per week because of the increased level of mercury in cold-water fatty fish. At this time, there is no evidence that farm-raised salmon and trout have any less benefit than wild caught fish.
  10. The 2015–2020 Dietary Guidelines for Americans include seafood as a component of the healthy US diet, the DASH diet, and the Mediterranean diet. Others such as the Nordic diet, the Prudent diet, and the Alternative Healthy Eating Index also have seafood recommendations (or LC n-3 PUFAs), and all have been consistently linked to lower risk of CHD.

Clinical Topics: Arrhythmias and Clinical EP, Diabetes and Cardiometabolic Disease, Dyslipidemia, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Lipid Metabolism, Nonstatins, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Diet

Keywords: Arrhythmias, Cardiac, Biological Markers, Blood Platelets, Brain Ischemia, Coronary Disease, Death, Sudden, Cardiac, Diet, Mediterranean, Diet, Vegetarian, Docosahexaenoic Acids, Eicosapentaenoic Acid, Fatty Acids, Omega-3, Fish Oils, Fish Oils, Heart Failure, Mercury, Monocytes, Myocardial Infarction, Platelet Activation, Primary Prevention, Salmon, Seafood, Stroke, Tilapia, Trout, Tuna, Vegetables

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