Abstract
Oxidative stress is considered to be an adverse bodily event. Antioxidants are considered to be healthful because they may protect the body from oxidative damage. This simple paradigm is much more complicated in practice, however. Reactive oxygen species are a physiological necessity but too much of them can be harmful. Whether antioxidants are really beneficial to health is not clear. Observational studies suggest either no effect or a beneficial effect of antioxidants on risks of major diseases, whereas intervention studies indicate no, beneficial, or adverse effects. Although the advice to increase the consumption of fruits and vegetables because of their beneficial effects on health remains secure, the evidence is lacking for beneficial effects of individual constituents such as antioxidants