Vitamins & Exercise: Heart Attack Prevention Series - Antioxidants
Do you take antioxidants to prevent a heart attack?
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What about antioxidants for heart attack prevention?
Antioxidants are food supplements that have been promoted as preventing heart disease and stroke. An important early event in the development of a cholesterol plaque in atherosclerosis is the oxidative modification of LDL cholesterol (low density lipoprotein) particles in the blood and the subsequent interaction of this modified LDL with the wall of the coronary artery. This process initiates the formation of the cholesterol plaque.
Antioxidants that block the oxidative modification of LDL have been shown to slow the progression of atherosclerosis in animal experiments. Examples of antioxidants include vitamin E and beta carotene. In humans, observational studies (studies that observe the frequency of related conditions) have found a relationship between the dietary intake of vitamin E and lower rates of heart attacks.
Observational studies provide only circumstantial evidence, however, and credible evidence is obtained only by way of controlled trials (discussed at the beginning of this article). Several controlled trials performed to date have yielded conflicting results on the benefits of antioxidant therapy. These results may possibly be due to the low doses of vitamin E used, the small number of patients in the study, or the limited duration of treatment.
The Heart Outcomes Prevention Evaluation study used a high dose (400 IU per day) of vitamin E over a span of five years in patients with significant risk factors for heart disease or stroke. This study found no difference in the occurrence of heart attack or stroke in the group treated with vitamin E versus those given the placebo. This study demonstrated that antioxidant therapy does not have any benefit in persons who have or are at high risk for having atherosclerosis.