Antioxidants: benefits and risks for long-term health.

The oxidative modification hypothesis postulates that oxidative stress is one of the major factors in aging and the development of age-related disorders, including cardiovascular diseases. In this scenario, the oxidative modification of lipids, proteins and nucleic acids in vascular walls contributes to the etiology of cardiovascular disease, implying that consumption or therapeutic use of antioxidants could prevent the onset of such pathological disorders. Because of this, a number of studies have been conducted to address the question of whether cardiovascular diseases can be modulated by antioxidant treatment or consumption. Although some of the earliest data, collected in animal studies and epidemiologic studies have shown a measure of success, numerous clinical trials indicate that this approach is of minimal or no benefit. These conclusions represent a challenge to design more sensitive antioxidant trials in order to confirm or alter these conclusions. The focus of this review is on the benefits and disadvantages associated with the use of antioxidants, such as vitamins C and E, polyphenols, or antioxidant therapies, including hormone replacement therapy and iron reduction therapy, on overall vascular health.