Before you indulge in this year’s holiday feast, take your vitamins -- C and E to be exact. A recent study found these common vitamins can temporarily block some of the harmful effects of a high-fat meal. Even a single high-fat meal can temporarily decrease endothelial function (the arteries’ ability to keep blood flowing smoothly) for two to four hours in healthy people with normal cholesterol levels. According to the Journal of the American Medical Association, this function is thought to precede hardening of the arteries, or atherosclerosis, and also is associated with several other risk factors for coronary heart disease. A study at the University of Maryland School of Medicine in Baltimore gave healthy volunteers an oral dose of vitamins C and E before a gluttonous 900-calorie breakfast loaded with 50 grams of fat. These antioxidants, which other studies indicate may help in preventing cataracts, cancer, Alzheimer's disease and aging, eliminated the decrease in endothelial function following the meal. It did not, however, increase endothelial function for the people who ate the low-fat meal (900 calories, 0 grams of fat).Here’s how the vitamins work: Cholesterol-loaded foam cells contribute to the build up of fatty plaques in blood vessels. Cholesterol, especially low-density lipoprotein (LDL), must be oxidized before it can cause foam cells. The antioxidants block the oxidative modification of LDL cholesterol, allowing arteries to keep blood flowing. The catch is you have to take 1,000 mg of vitamin C and 800 IU of vitamin E -- that’s more than 20 times the Recommended Dietary Allowance for each. Because of the high amounts, you would not be able to receive this benefit from dietary sources. To get the necessary amount of vitamin E from broccoli alone, you'd have to eat almost 100 pounds. (Don’t tell George Bush.) Excessive, prolonged use of certain antioxidant vitamins, particularly vitamin A, can be toxic. Be sure to consult your physician and pharmacist before taking supplements exceeding the daily recommended dose.