Fish Oil Supplements: (EPA, DHA, and Omega-3)
- The recommended omega-3 intake is double (1000 mg/d) for people with heart disease compared to those without (250-400mg/d of EPA plus DHA). Therefore most people with heart disease will require fish oil supplements to achieve a reasonable target whereas those without heart disease may not require such supplements. 1, 2
- Optimal levels of n-3 PUFAs (polyunsaturated fatty acids) can be achieved by consuming 1-2 servings/wk (6-12 oz) of wild salmon or similar oily fish, or more frequent intake of smaller or less n-3 PUFA–rich servings because they persist for weeks in tissue membranes.
- People with CAD may require 2-3 servings/wk (12-18oz) of fish richest in n-3 PUFAs (e.g., farmed salmon, anchovies, and herring), more frequent consumption of other fish. Since the average consumption of fish in the US is <5oz/wk, these individuals will often require the use of supplements.
- Two long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have now been identified as the beneficial constituents in fish. DHA promotes prostaglandin-3 series and its health benefits include inhibiting blood clotting, lowering blood pressure, and alleviating inflammation.1
- In people with high triglycerides, large doses of EPA and DHA (3-4g/d) can also lower triglycerides by 30-40%.3
- Fish oil capsules contain 20% to 80% of EPA and DHA by weight (200-800 mg/g), little to no mercury and minimal amounts of PCBs and dioxins. Given the small amounts of fish oil consumed (1-3 g/d), exposure to PCBs and dioxins from fish oil intake is low.
- “Functional foods” supplemented with EPA and DHA (e.g., dairy products, salad dressings, cereals) can also provide reasonable intake to individuals not consuming seafood.
Omega-3 PUFA for Vegetarians
- The average intake of fish in the American diet is about 130 g/wk. The average intake in India is likely to be far lower or negligible, since more than 50% of the populations who are vegetarian do not consume any fish at all. Those who do often consume small quantities of lean fish, which is low in omega-3 fatty acids. Furthermore, the most common method of preparing fish is frying which destroys all the beneficial omega-3.
- For those who do not consume fish, alpha-linolenic acid (ALA) can be alternative source of omega-3. ALA is converted in the body to EPA and DHA but the conversion occurs to a low extent (10% to 15% efficiency). In humans, ALA is converted to EPA in small quantities (in women more than men); further conversion to DHA is very limited. Unlike DHA and EPA, ALA does not lower triglycerides.
- ALA is present in green leafy vegetables, flaxseed, canola, soybeans, walnuts, and their oils.. Consumption of ALA (e.g., 2-3 g/d) may reduce cardiovascular risk or affect neurodevelopment, but benefits are less established compared with those for EPA and DHA.
- Flaxseed is the richest plant source of omega-3 fatty acid (alpha-linolenic acid) and the phytohormone lignans. Flaxseed is emerging as an important functional food ingredient because of its rich (50%) contents of ALA, fiber, high-quality protein, lignans, and phenolic compounds.
- Intakes of 3-4 g of omega -3 per day is associated with moderate increase in bleeding time, which is generally lower than that seen with aspirin therapy.
- Recent ( 2010) studies on survivors of heart attack with modest consumption of omega 3 (226 mg of EPA combined with 150 mg of DHA or 1.9 g of ALA, or both) did not reduce recurrent heart attacks. This suggest that, omega 3 supplements are much weaker than previously suspected, among those who were receiving state-of-the-art antihypertensive, antithrombotic, and lipid-modifying therapy.4
Sources
1. Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. Jama. Oct 18 2006;296(15):1885-1899.
2. Defilippis AP, Blaha MJ, Jacobson TA. Omega-3 Fatty acids for cardiovascular disease prevention. Curr Treat Options Cardiovasc Med. Aug 2010;12(4):365-380.
3. Goldberg I.J, Eckel RH, McPherson R. Triglycerides and heart disease: still a hypothesis? Arterioscler Thromb Vasc Biol. Aug 2011;31(8):1716-1725.
4. Kromhout D, Giltay EJ, Geleijnse JM. n-3 fatty acids and cardiovascular events after myocardial infarction. N Engl J Med. Nov 18 2010;363(21):2015-2026.