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A diet low in fat and supplemented with antioxidant vitamins, in conjunction with hypercholesterolemic therapy, helps prevent and manage coronary heart disease, according to a recent report in JAMA. It appears that eating a high-fat meal leads to the accumulation of postprandial triglyceride-rich lipoproteins, which creates oxidative stress.

The authors conducted a clinical investigation of seven men and 13 women, none of whom had a history of hypertension, diabetes mellitus, or tobacco use. Studies began after a 12-hour fast. The subjects ate either a high-fat meal, an isoenergetic low-fat meal, or the high-fat meal immediately following oral ingestion of antioxidant vitamin C (1 g of ascorbic acid) and vitamin E (800 IU). Lipoprotein and glucose determinations were repeated 2 and 4 hours after eating and endothelial function was measured hourly for 6 hours after eating. Hourly assessments of blood pressure and heart rate were also taken.

Study results indicate a correlation between an increase in serum triglyceride levels and a decrease in vasodilation among the subjects given the high-fat meal. A similar increase in triglycerides was seen following the ingestion of the high-fat meal accompanied by the vitamins. No such increase was seen after the low-fat meal. The test went on to show that while triglyceride levels rose in subjects who consumed a high-fat meal alone or with vitamins, flow-mediated vasodilation in these groups fell. However, subjects who ate the high-fat meal followed by vitamins C and E, or the low-fat meal, showed no change in vasodilation in the same time period.

According to the authors, these findings indicate that a single high-fat meal transiently decreased endothelial function through an oxidative stress mechanism. However, the failure of endothelial function to decrease after the same meal was consumed together with vitamins C and E suggests that oxidative stress is blocked by pretreatment with antioxidant vitamins.

The authors note that the clinical value of vitamins and other antioxidants has been inconsistent. Other limitations to their study include a subject population that tended to have smaller brachial arteries, all of which can contribute to flow-mediated vasodilation.