Established cardiovascular benefits of omega-3 EPA/DHA.Omega-3 fatty acids were unheard of just a few decades ago. But, a report on Greenland Inuits (who ate a high-fat diet of seal meat and fish) that showed they experienced a curiously low incidence of heart disease quickly changed that. In fact, in the early 1970s, while heart disease accounted for 40% of deaths among US males aged 46-64, it claimed only 5% of deaths among Greenland males. (1) In 1975, three Danish researchers solved the apparent mystery when they identified two long-chain fatty acids that were present in high concentrations in the Inuits' blood: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The Inuits' diet was high in fat: omega-3 fatty acids.
Today, "omega-3 fatty acids" is a household term, with a recent survey showing that 88% of consumers surveyed have heard of omega-3. (2) That huge spike in awareness is directly related to the mountain of research published on omega-3 during the past 40 years, which has identified at least seven different ways that EPA and DHA promote cardiovascular wellness.
Most fats in food, as well as in the body, occur in the form of triglycerides. Triglycerides provide an important source of fuel between meals; however, elevated triglycerides may increase the likelihood of developing coronary artery disease. Triglyceride levels below 150 mg/dL are considered to be normal, with levels 150-199 mg/dL considered to be borderline high and levels above 200 mg/dL considered to be high. It may seem counterintuitive that ingesting one type of fat could lower the levels of another in the bloodstream. However, human clinical trials show that fish oil supplements supplying omega-3 EPA/ DHA can, on average, lower triglycerides by about 25-30% in hyperlipidemic (excessive amounts of fats in the blood) subjects. In a 2008 meta-analysis, which reviewed 47 randomized trials, researchers concluded: "Fish oil supplementation produces a clinically significant dose-dependent reduction of fasting blood triglycerides." (3) Lovaza, formerly Omacor, a highly refined form of fish oil, is an FDA-approved prescription medication for reducing very high triglycerides that is 46% EPA and 38% DHA.
Lowered Blood Pressure
As blood travels through the arteries, it creates pressure against the artery walls. Normal blood pressure is anything below 120 (systolic) or higher than 80 (diastolic) mmHg. Doctors get concerned when blood pressures enter the range of 120-139 over 80-89 mmHg. And, readings of 140 over 90 or higher are considered to be high. High blood pressure can damage the blood vessels and organs, and may lead to coronary heart disease, heart failure and stroke. Fish oil has been shown to cause significant improvements in blood pressure. A 1993 meta-analysis found that the mean reduction in blood pressure attributed to fish oil consumption was -3.0/-1.5 mmHg. (4) The higher the dose of omega-3, the more notable the drop in blood pressure. Significantly, researchers noted that the hypotensive effect appeared to be strongest in hypertensive patients and those with clinical atherosclerotic disease or hypercholesterolemia--in other words, the people who most needed a drop in blood pressure.
Arrhythmia is an abnormal or irregular heartbeat. Most arrhythmias are minor. However, in some people, arrhythmia can lead to heart disease, stroke or sudden cardiac death. Omega-3 EPA/DHA supplementation has been shown to reduce the frequency of irregular heartbeats. A 2005 meta-analysis, which reviewed results from 30 randomized, double-blind, placebo-controlled human clinical trials, found that in studies with a baseline heart rate of 69 beats per minute (bmp) or greater, fish oil produced an average decrease in heart rate of 2.5 bpm. (5) Interestingly, fish oil only exerted its heart rate-lowering effects in populations with a faster-than-normal heart rate. In trials with a baseline heart rate of less than 69 bpm--about average for an adult male--fish oil did not lower heart rate further. The researchers concluded: "These findings provide firm evidence that fish oil consumption directly or indirectly affects cardiac electrophysiology in humans."
Reduced Risk of Sudden Cardiac Death
Although sudden cardiac death has received less attention than heart attack, it is responsible for about half of all deaths from coronary heart disease in the United States. (6) It occurs when the heart abruptly stops functioning owing to a malfunction of its electrical system, as opposed to a heart attack, which is caused by the blockage of blood flow in one or more coronary arteries. Several studies indicate that omega-3 EPA/ DHA is associated with a lower risk of sudden cardiac death. The Italian GISSI-Prevenzione study found that among patients who had recently survived a heart attack, omega-3 EPA/DHA supplementation reduced the risk of sudden cardiac death by 46.7% after just 4 months compared with a placebo. (7) Fish oil's protective ability does not appear to be limited to those with a history of cardiovascular disease, however. The Physicians Health Study, which followed apparently healthy men for 11 years, found that those who ate just one fish meal per week had a 48% reduction in risk of sudden cardiac death compared with men who rarely ate fish. (8) A separate article, which compared blood levels of omega-3 among men who had died of sudden cardiac death with controls matched for age and smoking status, found that participants with the highest blood levels of omega-3 EPA/ DHA had a 90% risk reduction for sudden cardiac death compared with those with the lowest levels. (9)
For years, high cholesterol, triglycerides and blood pressure were considered to be the primary risk factors for heart disease. Recently, however, another biomarker was identified that may be even more important than the traditional risk factors: C-reactive protein (CRP), a marker of systemic inflammation in the body. One study found that women with high CRP levels had double the risk of dying from heart disease or stroke than those with high cholesterol. (10) Several studies have demonstrated a fish oil-CRP link. The ATTICA trial found that people who ate fish once a week had 33% lower CRP levels than non-fish eaters. (11) How does eating fish lower inflammation? The omega-3 fatty acid, EPA, which is abundant in coldwater fatty fish, regulates the effects of the pro-inflammatory omega-6 fatty acid, arachidonic acid (ARA), which is found in meat, eggs and dairy products. Fish oil capsules have been shown to improve ARA:EPA ratios in healthy people as well as in patients with coronary artery disease. (12) The landmark JELIS trial, which studied the drug Epadel (98% pure EPA), found that a more balanced ARA:EPA ratio reduced major coronary events. (13)
Slowed Build-Up of Atherosclerotic Plaque
Atherosclerosis is characterized by the build-up of plaque inside the arterial wall. The plaque causes the arteries to narrow, which restricts blood flow and oxygen supply to the heart. The real danger, however, is when this arterial plaque ruptures, as it may lead to heart attack and the formation of stroke-inducing blood clots. Several studies have found that fish oil slows the build-up of atherosclerotic plaque--and may even reverse it. A recent German study reported that increased supplementation with EPA is successful in the primary and secondary prevention of atherosclerosis. (14) And, a double-blind clinical trial found that when people with pre-existing atherosclerosis supplemented with fish oil, they experienced significant regression of atherosclerotic plaques and reduced their risk of heart attack and stroke compared with those who took a placebo. (15)
Reduced Risk of Stroke
The human brain can go without oxygen for 5 minutes before brain cells start to die. Strokes can cause permanent brain damage because, when a blood clot gets caught in a vessel leading to the brain, the brain's oxygen supply gets cut off. (16) As a matter of public health concern, strokes do not get as much attention as heart attacks; however, stroke is the third largest cause of death in the United States after heart disease and cancer. (17) Evidence is mounting that people who consume fish regularly have greater protection from stroke than fish abstainers. A study published in the Journal of the American Medical Association in 2001 examined the relationship between fish and omega-3 intake with risk of stroke as part of the Nurses' Health Study. The study followed nearly 80,000 women for 14 years, finding that compared with women who ate fish one to three times per month, those who ate fish five or more times per week cut their risk of stroke by 52%. (18) The GISSI-Prevenzione trial also found that long-term supplementation with one gram of omega-3 EPA/DHA daily was beneficial for the prevention of stroke in patients who had recently had a heart attack. (19)
Supplements and Functional Foods
As research continues to accumulate in favour of the role that omega-3 EPA/ DHA can play in promoting cardiovascular health, the popularity of omega-3 fish oil supplements and fortified foods has exploded. Ocean Nutrition Canada (ONC) is a leading global supplier of omega-3 EPA and DHA ingredients from fish oil. Its pure, high-quality MEG-3 omega-3 EPA/DHA is available as MEG-3 fish oil concentrates for dietary supplements and MEG-3 powder for functional foods. Thanks to ONC's patented microencapsulation technology, Powder-loc, MEG-3 Omega-3 powder allows a wide range of food products to benefit from the goodness of fish, without the taste of fish. To date, MEG-3 ingredients have been included in more than 40 billion servings of food and supplement products worldwide, from pizza to peanut butter and from margarine to milk.
(1.) S. Daniells, "The Inventor of Omega-3," www.foodnavigator.com (27 November 2007).
(2.) E. Sloan, "Emerging Health and Wellness Markets: Health Concerns and Product Interests of Boomers, Hispanics and Children Reveal the Up-and-Coming Markets of Tomorrow," Nutraceuticals World (1 September 2007), available online at www.thefreelibrary.com.
(3.) G.D. Eslick, et al., "Benefits of Fish Oil Supplementation in Hyperlipidemia: A Systematic Review and Meta-Analysis," Int. J. Cardiol. (Published online: 5 September 2008).
(4.) M.C. Morris, et al., "Does Fish Oil Lower Blood Pressure? A Meta-Analysis of Controlled Trials," Circulation 88(2), 523-533 (1993).
(5.) D. Mozaffarian, et al., "Effect of Fish Oil on Heart Rate in Humans: A Meta-Analysis of Randomized Controlled Trials," Circulation 112(13), 1945-1952 (2005).
(6.) American Heart Association, "Sudden Cardiac Death," www.americanheart.org/presenter. jhtml?identifier=4741.
(7.) R. Marchioli, et al., "Early Protection Against Sudden Death by n-3 Polyunsaturated Fatty Acids After Myocardial Infarction: Time-Course Analysis of the Results of the Gruppo Italiano per lo Studio della Sopravvivenza nell' Infarto Miocardico (GISSI)-Prevenzione," Circulation 105(16), 1897-1903 (2002).
(8.) C.M. Albert, et al., "Fish Consumption and Risk of Sudden Cardiac Death," JAMA 279(1), 23-28 (1998).
(9.) C.M. Albert, et al., "Blood Levels of Long-Chain n-3 Fatty Acids and the Risk of Sudden Death," N. Engl. J. Med. 346(15), 1113-1138 (2002).
(10.) Associated Press/ USAToday, "Study: Inflammation Twice as Bad as Cholesterol for the Heart," 13 November 2002 (www.usatoday.com/news/health/2002-11-13-heartinflammation_ x.htm).
(11.) A. Zampelas, et al., "Fish Consumption Among Healthy Adults is Associated with Decreased Levels of Inflammatory Markers Related to Cardiovascular Disease: The ATTICA Study," J. Am. Coll. Cardiol. 46(1), 120-124 (2005).
(12.) T. Burns, et al., "Effect of Omega-3 Fatty Acid Supplementation on the Arachidonic Acid: Eicosapentaenoic Acid Ratio," Pharmacotherapy 27(5), 633-638 (2007).
(13.) M. Yokoyama, et al., "Effects of Eicosapentaenoic Acid on Major Coronary Events in Hypercholesterolaemic Patients (JELIS): A Randomised Open-Label, Blinded Endpoint Analysis," Lancet 369, 1090-1098 (2007).
(14.) O. Adam, et al., "Omega 3 Fatty Acids and Arteriosclerosis," Ernahrung & Medizin 18(4), 205-210 (2003).
(15.) C. von Schacky, et al., "The Effect of Dietary Omega-3 Fatty Acids on Coronary Atherosclerosis. A Randomized, Double-Blind, Placebo-Controlled Trial," Ann. Intern. Med. 130, 554-562 (1999).
(16.) National Institute of Neurological Disorders and Stroke, "NINDS Cerebral Hypoxia Information Page," updated 7 May 2008 (www.ninds.nih.gov/disorders/anoxia/ anoxia.htm).
(17.) American Heart Association, "Stroke Statistics," www. americanheart.org/presenter.jhtml?identifier=4725.
(18.) H. Iso, et al., "Intake of Fish and Omega-3 Fatty Acids and Risk of Stroke in Women," JAMA [section](3), 304-312 (2001).
(19.) R. Marchioli, et al., "Efficacy of n-3 Polyunsaturated Fatty Acids After Myocardial Infarction: Results of GISSI-Prevenzione Trial," Lipids 36(Suppl.), S119-126 (2001).
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