Vitamin E Supplements: Good in Theory, but Is the Theory Good?

Much of the U.S. public has a deep, and seemingly unshakable, faith in the health benefits of nutritional supplements (1). Use of these products has increased so rapidly in recent years that a third of all adults, and half of those older than 55 years of age, report taking at least 1 supplement daily (2). The shelves of pharmacies, grocery stores, and “nutrition centers” are well stocked with a dazzling variety of nutritional supplements, and for sound business reasons; supplements accounted for an estimated $18.8 billion in sales in the United States in 2003 alone (3). Many of these supplements are promoted to the public as “antioxidants,” a fuzzily defined category that includes vitamins C and E, some carotenoids, and many other phytochemicals and plant extracts. Vitamin E is the most widely used of the individual products, and it is taken daily as a specific supplement (usually containing 400 IU of α-tocopherol) by 22% of U.S. adults older than 55 years of age (2).

The touted benefit of antioxidants is prevention of the major chronic diseases that affect modern adults. Belief in the preventive value of antioxidants rests largely on 2 bodies of evidence. The first is epidemiologic observation, which has been interpreted as showing a decreased risk for disease among persons who consume relatively greater amounts of antioxidants in their diets or as supplements (4). The second is laboratory experiment, which has implicated oxidative chemical processes in the pathogenesis of conditions such as atherosclerotic cardiovascular disease, cancer, neurodegenerative diseases, and chronic lung disease (5, 6). Clinical trials of antioxidant supplements have not shown a clear benefit from taking these …