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Antioxidant Vitamins May Counter Effects of Triglycerides [Medical Tribune: Family Physician Edition 39(1): 1998. © 1998 Jobson Healthcare Group] Baltimore researchers report that consuming high doses of vitamins C and E before a high-fat meal may counter the ill effects of triglycerides on blood vessels. Antioxidant vitamins may somehow prevent triglycerides from blocking the release of nitric oxide in the endothelium, thereby enabling vessels to remain open and flexible, said lead researcher Gary Plotnick, M.D., a professor of medicine at the University of Maryland. In the study, the Baltimore team randomly assigned 20 healthy, normocholesterolemic hospital employees to three different breakfast groups--a high-fat meal of hash browns and egg-and-sausage muffin sandwiches totaling 50 g of fat, 14 g of which was saturated fat; a low-fat meal with 0 g of fat; and a high-fat meal with vitamin pre-treatment (1 g of vitamin C and 800 IU of vitamin E). The team also studied a fourth subgroup that was fed the low-fat meal with vitamin pre-treatment, they reported in the Journal of the American Medical Association (1997;278:1682-1686). Dr. Plotnick and colleagues then tested the dilatory response in the brachial artery with ultrasonography. Before all the meals, flow-mediated vasodilation in patients' arteries was approximately 20%. But four hours after the high-fat meal, vasoactivity fell to nearly 8%. However, when the study participants consumed 1,000 mg of vitamin C and 800 IU of vitamin E before the high-fat meal, the amount by which their arteries could dilate only fell to 18% four hours after the meal. While vitamin treatment before a high-fat meal impacted vasodilation, it had no effect when given before a low-fat meal, suggesting that a high-fat meal "impairs endothelial function through an oxidative stress mechanism that is blocked by pre-treatment with antioxidant vitamins," Dr. Plotnick and colleagues wrote. "This study suggests that a high-fat meal impairs endothelial function by an oxidative stress mechanism through the accumulation of postprandial triglyceride-rich lipoproteins. This pathway appears to be similar to the effect of hypercholesterolemia on the endothelium, but is not dependent on changes in cholesterol levels," the team wrote. Calling the findings "provocative" and "intriguing," JoAnn Manson, M.D., Dr.P.H., an associate professor of medicine at Harvard Medical School in Boston, said the study warrants further research. The study leaves the question unanswered as to the effects of other types of fats--such as monounsaturated and polyunsaturated--on endothelial-mediated vasodilation, Dr. Manson said. And the clinical significance on coronary events remains unclear, she added. "These findings do support the idea that a diet high in saturated and animal fats has deleterious effects, but I don't think the science is yet to the point that we can say vitamins C and E will prevent these deleterious effects," Dr. Manson said. --Peter Modica