Omega-3 heart benefits confirmed; 500mg/day recommended



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March 10, 2008  
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salmon.gifCM NEWS – Omega-3 fatty acids from oily fishes or capsules can reduce cardiovascular risk by up to 45%, according to a review of major scientific data. Experts recommend dosage of 500mg a day for healthy persons and 1 g for patients with coronary artery diseases.

Two omega-3 fatty acids that have been associated with cardiovascular benefit, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are found in fish oils. The best source for DHA and EPA are fatty coldwater fish such as herring, mackerel, salmon and tuna. Fish oil supplements or algae supplements also can provide omega-3 fatty acids.

What are omega-3 fatty acids? Omega-3 fatty acids are considered essential fatty acids. They are essential to human health but cannot be manufactured by the body. For this reason, omega-3 fatty acids must be obtained from food. Omega-3 fatty acids can be found in fish, such as salmon, tuna, and halibut, other marine life such as algae and krill, certain plants (including purslane), and nut oils.

Also known as polyunsaturated fatty acids (PUFAs), omega-3 fatty acids play a crucial role in brain function as well as normal growth and development. The American Heart Association recommends eating fish (particularly fatty fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon) at least 2 times a week.

omega_3_oil1.jpgThere are three major types of omega 3 fatty acids that are ingested in foods and used by the body: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3 fatty acids more readily used by the body. Extensive research indicates that omega-3 fatty acids reduce inflammation and help prevent risk factors associated with chronic diseases such as heart disease, cancer, and arthritis.

These essential fatty acids are highly concentrated in the brain and appear to be particularly important for cognitive (brain memory and performance) and behavioural function. In fact, infants who do not get enough omega-3 fatty acids from their mothers during pregnancy are at risk for developing vision and nerve problems. Symptoms of omega-3 fatty acid deficiency include extreme tiredness (fatigue), poor memory, dry skin, heart problems, mood swings or depression, and poor circulation.

Thousands of research studies have documented how the oils known as omega-3 fatty acids can benefit the cardiovascular system, particularly among people diagnosed with coronary artery disease. The incredible volume of research on this topic creates difficulty for many physicians and patients to stay current with findings and recommendations related to these oils.

In the March issue of Mayo Clinic Proceedings, contributors briefly summarize current scientific data on omega-3 fatty acids and cardiovascular health, focusing on who benefits most from their protective effects, recommended guidelines for administration and dosing, and possible adverse effects associated with their use.

Author James O’Keefe, M.D., a cardiologist from the Mid America Heart Institute in Kansas City, Mo., cites the results of several large trials that demonstrated the positive benefits associated with omega-3 fatty acids, either from oily fish or fish oil capsules.

“The most compelling evidence for the cardiovascular benefit provided by omega-3 fatty acids comes from three large controlled trials of 32,000 participants randomized to receive omega-3 fatty acid supplements containing DHA and EPA or to act as controls,” explains Dr. O’Keefe. “These trials showed reductions in cardiovascular events of 19% to 45%. Overall, these findings suggest that intake of omega-3 fatty acids, whether from dietary sources or fish oil supplements, should be increased, especially in those with or at risk for coronary artery disease.”

How much fish oil should people attempt to incorporate into their diets? According to Dr. O’Keefe, people with known coronary artery disease should consume about 1 gram per day, while people without disease should consume at least 500 milligrams (mg) per day.

“Patients with high triglyceride levels can benefit from treatment with 3 to 4 grams daily of DHA and EPA,” says Dr. O’Keefe. “Research shows that this dosage lowers triglyceride levels by 20 to 50%.”

About two meals of oily fish can provide 400 to 500 mg of DHA and EPA, so patients who need to consume higher levels of these fatty-acids may choose to use fish oil supplements to reach these targets.

Dr. O’Keefe also notes that research supports the effectiveness of combining the consumption of fish oil with the use of cholesterol-lowering medications called statins. Combination therapy with omega-3 fatty acids and a statin is a safe and effective way to improve lipid levels and cardiovascular health beyond the benefits provided by statin therapy alone. Blood DHA and EPA levels could one day be used to identify patients with deficient levels and to individualize therapeutic recommendations.

Dr. O’Keefe found little evidence of serious adverse effects associated with fish oil consumption. “In prospective placebo-controlled trials, no adverse effects were observed to occur at a frequency of more than 5%, and no difference in frequency was noted between the placebo and omega-3 fatty acid groups,” he says.

The most commonly observed side effects include nausea, upset stomach and a “fishy burp.” Taking the supplement at bedtime or with meals, keeping fish oil capsules in the freezer or using enteric-coated supplements may help reduce burping and upset stomach symptoms.