Key Findings:
This research further explores that anti-atherogenic effects of flaxseed using animals fed high cholesterol diets. Atherosclerotic plaques on the aortic luminal surface were significantly reduced with dietary flaxseed supplementation. A note of caution is raised as both the cholesterol and flax group also developed extensive atherosclerotic lesions after long periods of high cholesterol feeding. These results suggest that flaxseed should not be viewed a as a magic bullet to counter the effects of a bad diet. In conjunction with this novel finding, was the first every reported observation that dietary flaxseed can improve endothelium-dependent vascular relaxation in the presence of a high-cholesterol diet. The authors do reinforce the notion that flaxseed may be an effective and safe dietary strategy to reduce both atherogenesis and vascular dysfunction associated with atherosclerosis.
ABSTRACT:
Dietary flaxseed has significant anti-atherogenic effects. However, the limits of this action and its effects on vascular contractile function are not known. We evaluated the effects of flaxseed supplementation on atherosclerosis and vascular function under prolonged hypercholesterolemic conditions in New Zealand White rabbits assigned to one of four groups for 6, 8, or 16 wk of feeding: regular diet (RG), 10% flaxseed-supplemented diet (FX), 0.5% cholesterol-supplemented diet (CH), and 0.5% cholesterol- and 10% flaxseed-supplemented diet (CF). Cholesterol feeding resulted in elevated plasma cholesterol levels and the development of atherosclerosis. The CF group had significantly less atherosclerotic lesions in the aorta and carotid arteries after 6 and 8 wk than the CH animals. However, the anti-atherogenic effect of flaxseed supplementation was completely attenuated by 16 wk. Maximal tension induced in aortic rings either by KCl or norepinephrine was not impaired by dietary cholesterol until 16 wk. This functional impairment was not prevented by including flaxseed in the high-cholesterol diet. Aortic rings from the cholesterol-fed rabbits exhibited an impaired relaxation response to acetylcholine at all time points examined. Including flaxseed in the high-cholesterol diet completely normalized the relaxation response at 6 and 8 wk and partially restored it at 16 wk. No significant changes in the relaxation response induced by sodium nitroprusside were observed in any of the groups. In summary, dietary flaxseed is a valuable strategy to limit cholesterol-induced atherogenesis as well as abnormalities in endothelial-dependent vasorelaxation. However, these beneficial effects were attenuated during prolonged hypercholesterolemic conditions. (Authors Abstract)