New Review Endorses CV Benefits of Fish Oil

August 7, 2009 — A new review concludes that there is extensive evidence from three decades of research that fish oils, or more specifically the omega-3 polyunsaturated fatty acids (PUFAs) contained in them, are beneficial for everyone.
This includes healthy people as well as those with heart disease — including postmyocardial infarction (MI) patients and those with heart failure, atherosclerosis, or atrial fibrillation — say Dr Carl J Lavie (Ochsner Medical Center, New Orleans, LA) and colleagues in their paper published online August 3, 2009, in the Journal of the American College of Cardiology.
"We reviewed everything that was published on omega-3 that was clinically important, and the major finding is that there are a tremendous amount of data to support the benefits of omega-3, not just as a nutritional supplement — people have known that for years — but evidence that it prevents and treats many aspects of cardiovascular disease," Lavie told heartwire .
Omega-3 PUFA, says Lavie, "is a therapy that clinicians should be considering prescribing to their patients. Not just as something healthy but as something that may actually prevent the next event. In HF [heart failure], it may prevent death or hospitalization and the same thing post-MI." He and his colleagues reiterate the advice of the American Heart Association (AHA): that those with known coronary heart disease (CHD) or HF eat four or five oily-fish meals per week or take the equivalent in omega-3 supplements; healthy people should consume around two fatty-fish meals per week or the same in supplements.

Recommendations for Omega-3 Consumption

Mirroring recommendations from the AHA, European Society of Cardiology, and the World Health Organization (WHO), Lavie and colleagues recommend that healthy people consume at least 500 mg per day of EPA/DHA — equal to around two fatty-fish meals per week — and that those with known CHD or HF get 800 to 1000 mg per day EPA/DHA.

Other good reasons to take supplements include the fact that they have usually had impurities, such as mercury, removed, he notes.

Study Highlights

-3 large randomized clinical trials have confirmed a reduction in all-cause mortality rates from cardiovascular disease by levels ranging from 15% to 30% for total and cardiovascular mortality using combined doses such as EPA/DHA of 850 mg/day.
-Secondary coronary disease was also reduced in follow-up to 5 years.
-Evidence of benefit for atherosclerosis has been derived from comparative studies of Japanese and Caucasians suggesting that very high intake of marine-derived omega-3 PUFA has antiatherosclerotic effects.

-Several randomized controlled trials of omega-3 PUFA suggest a benefit for arrhythmias in patients post-MI and with impaired systolic function.
-For example, use of omega-3 PUFA including high oily fish consumption has been associated with significant reductions in resting heart rate, 1-minute heart rate recovery after exercise, and improvement in heart rate variability.
-The most significant studies on arrhythmias were noted in atrial fibrillation with 30% risk reduction at 12 years of follow-up in 1 study, and a number needed to treat of 5.5 to prevent a case of AF after coronary bypass graft surgery in another study.

-Benefits of omega-3 PUFA have been extended to HF in which high fish consumption has been linked to a lower rate of incident HF.
-Doses of 850 to 882 mg of EPA with DHA have been used in combination with rosuvastatin 10 mg/day with reduction in total mortality and hospital admission rates for cardiovascular disease.

-The FDA has approved a high-dose preparation (Lovaza; GlaxoSmithKline) containing 4 g/day of omega-3 PUFA for the treatment of very high triglyceride levels (≥ 500 mg/dL).
-The dose of 3 to 4 g/day of EPA/DHA has been shown to reduce triglyceride levels by 30% to 40% with a smaller reduction in non–high-density lipoprotein (HDL) cholesterol levels of 14% and a 9% increase in HDL-cholesterol levels. However, generally there are no significant improvements in LDL cholesterol levels.

-Antiplatelet effects, anti-inflammatory effects, and triglyceride lowering require higher doses of DHA/EPA (3 - 4 g/day).

-Antiarrhythmic effects, reduction in secondary coronary events, and improvement in HF can be achieved at lower doses of 500 to 1000 mg of EPA/DHA daily.

-The most commonly observed adverse effects of omega-3 PUFA are nausea, gastrointestinal upset, and 'fishy' burp.
-Although a concern, prolonged bleeding times with clinically significant bleeding have not been noted at doses of up to 7 g of combined EPA and DHA daily, even when combined with warfarin or antiplatelet therapy.
-The FDA advises that children and pregnant or lactating women avoid fish with potentially high mercury content such as swordfish, king mackerel, and shark.
-The fish oil supplements contain negligible amounts of mercury.

Clinical Implications

-Fish oil from oily fish or supplements have been shown to be of benefit in primary and secondary cardiovascular disease prevention and for arrhythmias, HF, and hypertriglyceridemia.
-Higher doses of 3 to 4 g/day of EPA/DHA are recommended for hypertriglyceridemia, anti-inflammatory effects, and antiplatelet effects, and lower doses of 850 to 1000 mg/day for secondary cardiovascular disease prevention and HF