Many believe that atherosclerosis, the thickening of artery walls that can lead to heart attack and stroke, results from oxidative damage to tissue in the artery wall caused by fats in the blood.
Epidemiological studies had supported the idea that vitamin E protected against atherosclerosis by fighting oxidative damage, but results from the Vitamin E Atherosclerosis Prevention Study call that into doubt, researchers report in the Sept. 17 issue of Circulation.
"The study showed that vitamin E could reduce the oxidation of LDL cholesterol-the so-called bad cholesterol-in the blood, but that didn't translate into a slower progression of atherosclerosis," says Howard N. Hodis, M.D., professor of medicine and preventive medicine at the Keck School of Medicine of USC and the study's lead author.
More than 300 healthy men and women age 40 or older enrolled in the study, and each took either a daily dose of 400 international units of vitamin E or a placebo. (Drugstore vitamin E supplements typically range from 50 I.U. to 1,000 I.U.) They visited the clinic every six months for three years, and investigators measured the intima-media thickness of their carotid arteries on each visit through ultrasound.
After three years, participants who took the vitamin E showed significantly less oxidized LDL in the blood, but had comparable progression of atherosclerosis to those who took no vitamin E.
"This means there's either something wrong with the hypothesis about oxidative damage and atherosclerosis, or we haven't found the right clinical trial to prove it," says Hodis, director of the USC Atherosclerosis Research Unit.