Flaxseed Exerts Cardioprotective Effects

WINNIPEG, Manitoba--Consumption of flaxseed exerts antiarrhythmic effects in normal and hypercholesterolemic rabbits, according to a study published in the December issue of the Journal of Nutrition (134, 12:3250-3256) (www.nutrition.org).

Male New Zealand white rabbits were fed a regular diet (REG group) or diets containing 10 percent flaxseed (FLX group), 0.5 percent cholesterol (CHL group) or 0.5 percent cholesterol and 10 percent flaxseed (CHL/FLX group), for a 16-week feeding period. Plasma cholesterol was elevated significantly in the CHL and CHL/FLX groups. Plasma triglycerides were unchanged. ALA levels increased significantly in the blood and hearts of the FLX and CHL/FLX groups. Following the feeding period, rabbit hearts were isolated and subjected to 30 minutes of global ischemia (deprivation of blood flow and oxygen to the heart muscle) and 45 minutes of reperfusion (restoration of blood flow to the tissue). Ventricular fibrillation (heart arrhythmia) occurred during ischemia in 33 percent of the REG but in none of the FLX hearts, and 28 percent of CHL but only 6 percent of CHL/FLX hearts. Ventricular fibrillation incidence during reperfusion was 28 percent and 26 percent in REG and FLX hearts, respectively. The incidence of ventricular fibrillation increased considerably in CHL hearts (64 percent), and was attenuated extensively in CHL/FLX hearts (18 percent). Cholesterol markedly prolonged the QT interval (the time between electrical activation and inactivation of the ventricles), whereas flax significantly shortened the QT interval and reduced arrhythmias in FLX and CHL/FLX hearts. Flax shortened the action potential duration, an effect consistent with the QT data.

The researchers concluded dietary flaxseed exerts antiarrhythmic effects during ischemia-reperfusion in rabbit hearts, possibly through shortening of the action potential.