FLAX FACTS ALA AND OTHER OMEGA-3 FATS…

                              FLAX FACTS
ALA AND OTHER OMEGA-3 FATS MAY PROTECT
AGAINST ARRHYTHMIA
by Dr. Diane H. Morris
   Arrhythmias or dysrhythmias, as they are sometimes        Omega-3 Fats Protect against
called, are abnormal rhythms of the heart muscle.            Arrhythmia in Test Tube Studies
There are many different types of arrhythmias. Some
are disconcerting because they cause the heart muscle           Omega-3 fats may protect against arrhythmia by
to skip a beat or add an extra beat, but they are            helping heart muscle cells remain stable electrically
not dangerous. Others are serious, resulting in dizzy        and by preventing them from becoming
spells, shortness of breath, chest pain and other            "hyperexcitable".9 In test tube studies of rat heart
complications.1 The large number of sudden cardiac           cells, for example, omega-3 fats decreased the
deaths from coronary heart disease ­ estimated at            electrical excitability of the heart cells, making them
about 8-10% of all deaths in Canada in 19992 and             less likely to develop abnormal heart rhythms.10,11
335,000 deaths per year in the United States3 ­ are due         A test tube study of adrenal gland cells taken from
mainly to arrhythmia.                                        cows had similar findings ­ the major omega-3 fats
   Growing evidence suggests a simple dietary change         (ALA, EPA and DHA) reduced the electrical excitability
­ increasing the dietary intake of omega-3 fats ­ may        of cells. The omega-3 fats worked by blocking the
help prevent sudden death from arrhythmias. The              entry of calcium into the adrenal gland cells. DHA
major omega-3 fats are alpha-linolenic acid (ALA), the       and ALA were better than EPA at blocking calcium
essential omega-3 fatty acid, and its long-chain cousins,    entry into these cells.12 (Calcium works like a
eicosapentaenoic acid (EPA) and docosahexaenoic acid         pacemaker for cells, much like the sinus node is a
(DHA).                                                       pacemaker for the heart.) These findings suggest that
   The omega-3 fatty acids prevent arrhythmias in            the antiarrhythmic effect of omega-3 fats is partly due
heart cells grown in test tubes and also in laboratory       to their ability to control the electrical activity of cells.
animals. In humans, omega-3 fats have been shown to
reduce the risk of arrhythmias in most,4-7 but not all,8     Alpha-Linolenic Acid Is As
clinical studies.                                            Effective as EPA and DHA in
                                                             Animals
How Arrhythmias Occur in the                                    Pure preparations of ALA, EPA and DHA are equally
Heart                                                        good at protecting against fatal arrhythmias in dogs.
   The heart is a muscle that pumps blood throughout         In one study, pure solutions of ALA, EPA and DHA
the body. The pumping action of the heart is                 were infused separately. All three omega-3 fats
controlled by electrical signals, which are formed by        reduced significantly the occurrence of ventricular
a special group of cells located in the heart's right        fibrillation and protected a majority of dogs from fatal
upper chamber. These special cells are known                 arrhythmias. Infusion of a control fat (soybean oil)
collectively as the sinus node.                              failed to protect any animals from fatal arrhythmias.13
   The sinus node is a natural pacemaker for the heart.      These findings suggest that omega-3 fats help regulate
Its electrical signals travel first through the upper        heart function.
chambers of the heart (the atria), then through a
switching station called the AV node, and finally to the     Flax Protects against Ventricular
lower chambers of the heart (the ventricles). The            Fibrillation in Rabbits
ventricles route the electrical signal through special          Rabbits have long been used for the study of diet
nerve cells, and the end result is a contraction of the      and coronary heart disease. A recent study tested the
heart muscle, which pumps blood through the body.            cardioprotective effects of flax in rabbits.14 Rabbits
   Arrhythmias occur when the heart's natural                were fed a regular rabbit diet, a regular rabbit diet +
pacemaker, the sinus node, develops an unnatural             milled flax, a regular diet + added cholesterol, or a
rhythm. In some cases, the sinus node may beat too           cholesterol diet + milled flax for up to 16 weeks.
fast, producing a condition known as tachycardia. In            The diets containing milled flax increased the
other cases, the sinus node's electrical signal is totally   ALA content of heart tissue 3- to 4-fold and lowered
disorganized, causing the atria to contract too quickly.     the omega-6/omega-3 ratio in heart tissue. Ventricular
Both conditions are very serious.1                           fibrillation was prevented in rabbits fed the regular
diet + milled flax and reduced in the group fed a
cholesterol diet + milled flax. Indeed, there was                             Healthy Diets for Healthy Hearts
a negative correlation between the ALA content of                                Omega-3 fats appear to enhance the electrical
heart tissue and the incidence of arrhythmias. That is,                       stability of the heart muscle and to protect against fatal
rabbits with the greatest amount of ALA in their heart                        arrhythmia in animals and humans. Evidence suggests
tissue had the fewest arrhythmias.                                            that making a small dietary change ­ namely, regularly
   Rabbits fed milled flax, with or without added cho-                        eating foods rich in omega-3 fats from flax, other
lesterol, also had shorter QT intervals than rabbits fed                      plants and broiled or baked fish (but not fried fish) ­
diets without flax. In these rabbits, the flax diet                           helps protect against arrhythmia.
resulted in a shortened QT interval, meaning that flax
had an antiarrhythmic effect.14
                                                                              References
                                                                              1.    Heart & Stroke Foundation of Canada. Arrhythmias.
   What is a QT Interval?                                                           Available at ww2.heartandstroke.ca.
   The QT interval reflects the heart's electrical activity during an         2.    Heart & Stroke Foundation of Canada. The Growing Burden
   electrocardiogram (ECG or EKG). Electrical activity is record-                   of Heart Disease and Stroke in Canada 2003. Ottawa, ON,
   ed during the ECG as a pattern of waves. The parts of each                       2003. Available at ww2.heartandstroke.ca.
   wave are labeled by certain letters: P, Q, R, S and T. The QT
                                                                              3.    American Heart Association. Heart Disease and Stroke
   interval is the time it takes for the electrical signal to pass
   through the lower chambers of the heart. If the time is longer                   Statistics ­ 2005 Update. Dallas, TX, 2005. Available at
   than normal, a person (or animal) is said to have a long QT                      www.americanheart.org.
   interval.1                                                                 4.    GISSI-Prevenzione Investigators. Lancet. 1999;354:447-455.
                                                                              5.    Mozaffarian D, et al. Circulation. 2004;110:368-373.
                                                                              6.    Djoussé L, et al. J Am Coll Cardiol. 2005;45:1716-1722.
                                                                              7.    Calò L, et al. J Am Coll Cardiol. 2005;45:1723-1728.
Human Studies of Omega-3 Fats
                                                                              8.    Raitt MH, et al. JAMA. 2005;293:2884-2891.
and Arrhythmia                                                                9.    Leaf A, et al. Lipids. 1999;34:S187-S189.
   Heart disease can be prevented by being active, not                        10.   Kang JX and Leaf A. Eur J Pharmacol. 1996;297:97-106.
smoking, and eating a diet high in fruits, vegetables,                        11.   Kang JX and Leaf A. Biochem Biophys Res Commun.
nuts, and whole grains and also rich in omega-3 fats                                1995;208:629-636.
from plants and fish.15 Diets containing fatty fish or at                     12.   Danthi SJ, et al. Biochem Biophys Res Commun.
least one fish meal per week are associated with                                    2005;327:485-493.
reduced risk of primary cardiac arrest,16 death from all                      13.   Billman GE, et al. Circulation. 1999;99:2452-2457.
causes,17 or sudden death from a heart attack.18                              14.   Ander BP, et al. J Nutr. 2004;134:3250-3256.
   Now there is evidence that people who eat diets                            15.   Hu FB, Willett WC. JAMA. 2002;288:2569-2578.
rich in omega-3 fats from fish and plants appear to be                        16.   Siscovick DS, et al. JAMA. 1995;274:1363-1367.
protected against fatal arrhythmia. Elderly adults in one                     17.   Burr ML, et al. Lancet. 1989;8666:757-761.
study, for example, who regularly ate tuna or other                           18.   Albert CM, et al. JAMA. 1998;279:23-28.
broiled or baked fish had a lower incidence of atrial
fibrillation than those who rarely ate such fish. Eating
fried fish or fish sandwiches was not linked with a
lower risk of atrial fibrillation.5 In another study ­ the
Family Heart Study6 ­ men and women who had the
highest intakes of plant omega-3 fats had shorter QT
intervals than those with the lowest plant omega-3 fat
intakes. These findings suggest that omega-3 fats from
fish and plants have important benefits for the heart.




Flax Council of Canada, 465­167 Lombard Ave., Winnipeg, MB, Canada R3B 0T6, E-mail: flax@flaxcouncil.ca Website: www.flaxcouncil.ca   11.2005ED11.05