How valid is the concept of antioxidants and cell injury?

Abstract

In the struggle for life, humans as every mammal and other living species, have to face two main dangers: (1) the competition against other individuals or other living species, including parasites, bacteria and viruses, and (2) the extreme toxicity of oxygen. The so-called ‘degenerative diseases’, which include the process of aging, are also related to both oxygen toxicity and immune defense against other living species, although some specific genetic characteristics may also be involved. The existence of a family of chemical compounds, called free radicals, has long been recognized as well as their harmful effects on biological molecules [1–5]. But, despite very active research concerning this field of reactive oxygen species (ROS) and extended work in both basic and clinical fields, we are still facing severe morbidity probably related to abnormalities on this pathway [6–12]. Several experimental studies have reported successful attempts to prevent or to counteract the deleterious effects of ROS [13–18] but, aside from important exceptions, the results so far have not produced the degree of evidence we are expecting [6, 19–25]. This relative lack of efficacy of the therapeutic approaches regarding oxidative stress and antioxidant treatments is probably related to the high degree of complexity of the ROS pathway and the antioxidant family, as well as the limitations for investigating oxidative stress and antioxidant status in patients. Besides several pharmacological approaches to such disorders [6, 22–26], which could be very promising, nutritional intake represents the most important way of providing an adequate antioxidant status in daily clinical practice.