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Flax Council of Canada
Ventricular arrhythmias are the leading cause of death from acute myocardial infarction (AMI). In Canada, there were more than 12,000 deaths from AMI in 1995. Each year in the United States, about 250,000 people reportedly die within one hour of an AMI, mostly due to arrhythmia. Developing simple methods of preventing such fatal arrhythmias would provide a substantial benefit to public health.

There is growing evidence that a simple dietary change—increasing the dietary intake of omega-3 fatty acids—may help prevent arrhythmias. The major omega-3 fatty acids are alpha-linolenic acid (ALA), the essential, parent fatty acid of the omega-3 family, and the long-chain derivatives of ALA—namely, eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA). ALA is found mainly in flaxseed (the richest source of ALA in the North American diet), other oilseeds such as soybean, canola and wheat germ, some nuts (e.g., walnuts), and red and black currant seeds. EPA and DHA are found mainly in cold-water fish such as mackerel, salmon, herring, trout and blue fin tuna. (Most species of fish contain very little ALA and low levels of EPA and DHA.) The omega-3 fatty acids exhibit antiarrhythmic effects in cell cultures and laboratory animals and are associated with a reduced risk of fatal ventricular arrhythmia in humans.

Normal Physiology of Cardiac Muscle:
Cardiac muscle fibres generate electrical impulses and contract when stimulated. These actions are the result of changes in the transmembrane potential gradient that occur within each cardiac cell. Nonpacemaker cells—that is, the atrial and ventricular muscle cells that are not involved in setting cardiac impulse or rhythm—must reach a threshold potential before responding to electrical signals. The complex sequence of depolarization and repolarization of cardiac cell membranes depends on many mechanisms, including membrane permeability and the actions of specialized molecular pumps that transfer sodium out of the cell and potassium into the cell (the so-called Na+–K+ ATPase pump).

Arrhythmias occur when there is a disturbance in the electrophysiologic properties of the cardiac muscle. During an ischemic episode, for example, myocytes become slightly depolarized due to a reduction in the Na+–K+ ATPase pump. This change in the potential of the cell membrane makes it sensitive to triggering an action potential prematurely, leading to ventricular fibrillation and arrhythmias.
Proposed Mechanism of Action of Omega-3’s Omega-3 fatty acids appear to protect against arrhythmia by enhancing the electrical stability of heart cells and increasing their resistance to becoming “hyperexcitable”. In cultured cardiac myocytes of rats, for example, omega-3 fatty acids terminated toxininduced arrhythmias mainly by reducing the electrical excitability of the heart cell. Omega-3 fatty acids also prolong the relative refractory period of the cardiac cycle, thus reducing arrhythmia risk. Alpha-Linolenic Acid Is As Effective as EPA and DHA Pure preparations of ALA, EPA and DHA are equally effective in protecting against fatal arrhythmias in dogs.

In one study, intravenous infusion of pure ALA, EPA and DHA reduced significantly the incidence of ventricular flutter-fibrillation and protected a majority of dogs from fatal arrhythmias. Infusion of the control lipid (soybean oil) failed to protect any animals from fatal arrhythmias.

These findings suggest that omega-3 fatty acids help regulate cardiac function. Furthermore, it is the free, unesterified forms of ALA, EPA and DHA that confers cardioprotective effects by virtue of their being readily available to regulate ion channels and membrane excitability. In other words, omega-3 fatty acids bound in membrane phospholipids show no protective effect until they are released as free fatty acids.
Tags: Flax, Flax seed, Flaxseed, Health Benefits, Omega 3, essential fatty acids, omega EFAs