International Health News

Antioxidants counteract effects of fatty meals

BALTIMORE, MARYLAND. The formation of fatty plaques and scar tissue in the arteries (atherosclerosis) is a crucial first step in the development of heart disease. The development of atherosclerosis in turn is intimately connected with high blood cholesterol levels and a dysfunction of the lining of the blood vessels (endothelium). There is now considerable evidence that endothelial dysfunction can be caused by an increase in superoxide and other free radicals in the blood. More recently, a transient accumulation of triglyceride-rich lipoproteins has also been implicated in endothelial dysfunction. Endothelial dysfunction manifests itself by a tensing of the cell lining tissue resulting in a narrowing of the artery diameter. Its extent can be determined by ultrasonically measuring the diameter of the brachial artery.

Researchers at the University of Maryland School of Medicine now report that the consumption of a fatty meal causes immediate impairment of the endothelial function and that this detrimental effect can be completely eliminated by taking antioxidants (vitamins C and E) prior to the meal. Their experiment involved 20 physically active men and women with normal cholesterol levels (<5.2 mmol/L total cholesterol). The test participants ate three different breakfasts with a one week interval between the different meals. Their brachial artery diameter was measured every hour for the six hours following ingestion of the meal. The first meal contained 50 grams of fat consisting of an Egg McMuffin, Sausage McMuffin and two hash brown patties (McDonald's), the second meal contained no fat at all consisting of orange juice, Frosted Flakes and skim milk while the third meal was identical to the first except that the participants took 1000 mg of vitamin-C (ascorbic acid) and 800 IU of vitamin-E before consuming the high- fat meal. Consumption of the high-fat meal without vitamins caused a very significant decrease in the brachial artery diameter for at least four hours after ingestion of the meal. No changes in artery diameter were observed with the low-fat meal or with the high-fat meal when vitamins were taken before eating. The researchers also noted a highly significant transient increase in triglyceride levels after ingestion of the fatty meal (with and without vitamins), but saw no other significant changes in lipoprotein or glucose levels after the different meals. The researchers conclude that a high-fat meal causes immediate impairment of the lining of the arteries through oxidative stress and that this potentially atherosclerosis-causing effect can be inhibited by taking vitamins C and E prior to consuming a fatty meal.
Plotnick, Gary D., et al. Effect of antioxidant vitamins on the transient impairment of endothelium-dependent brachial artery vasoactivity following a single high-fat meal. Journal of the American Medical Association, Vol. 278, November 26, 1997, pp. 1682-86

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