The imbalance between the production of reactive oxygen species (ROS) and antioxidant defenses determines a state known as oxidative stress. Higher levels of pro-oxidants compared to antioxidant defenses may generate oxidative damage, which, in turn, may lead to modifications in cellular proteins, lipids, and DNA, reducing functional capacity and increasing the risk of diseases. Nevertheless, the clearance of harmful reactive chemical species is achieved by the antioxidant defense systems. These protection systems are referred to as the first and second lines of defense and comprise the classic antioxidants, enzymatic and nonenzymatic defenses, including glutathione. This book presents and discusses the advancement of research on health and diseases and their underlying mechanisms, exploring mainly aspects related to the glutathione antioxidant system.

One of the major biomedical triumphs of the post-World War II era was the defmitive demonstration that hypercholesterolemia is a key causative factor in atherosclerosis; that hypercholesterolemia can be effectively treated; and that treatment significantly reduces not only coronary disease mortality but also all cause mortality. Treatment to lower plasma levels of cholesterol - primarily low density lipoprotein (LDL) cholesterol - is now accepted as best medical practice and both physicians and patients are being educated to take aggressive measures to lower LDL. We can confidently look forward to important decreases in the toll of coronary artery disease over the coming decades. However, there is still uncertainty as to the exact mechanisms by which elevated plasma cholesterol and LDL levels initiate and favor the progression of lesions. There is general consensus that one of the earliest responses to hypercholesterolemia is the adhesion of monocytes to aortic endothelial cells followed by their penetration into the subendothelial space, where they differentiate into macrophages. These cells, and also medial smooth muscle cells that have migrated into the subendothelial space, then become loaded with mUltiple, large droplets of cholesterol esters . . . the hallmark of the earliest visible atherosclerotic lesion, the so-called fatty streak. This lesion is the precursor of the more advanced lesions, both in animal models and in humans. Thus the centrality of hypercholesterolemia cannot be overstated. Still, the atherogenic process is complex and evolves over a long period of time.

Recognition that aging is not the accumulation of disease, but rather comprises fundamental biological processes that are amenable to experimental study, is the basis for the recent growth of experimental biogerontology. As increasingly sophisticated studies provide greater understanding of what occurs in the aging brain and how these changes occur

Due to that at present, the majority of diseases are associated with alterations in oxidative stress and inflammatory processes, and in that Nrf-2 is a modulator of these processes; knowing how this transcriptional factor functions and is regulated opens a therapeutic window to diverse diseases. Therefore, the efforts of various investigation groups are centered on finding activators and/or inhibitors of Nrf-2 to prevent or control diverse diseases, for example, cancer, where it would be important to regulate Nrf-2 in order for it to activate apoptosis pathways in cancerogenous cells, or in neurodegenerative diseases where cell death is predominant, it would be important for Nrf-2 to activate antiapoptotic pathways.

Atherosclerosis, the underlying cause of heart attacks, strokes and peripheral vascular disease, is one of the major killers in the world. By 2020 WHO statistics indicate that it will be the most common cause of morbidity and mortality in both the industrialised world and the underdeveloped world. The disease develops slowly over many years in the innermost layer of large and medium-sized arteries (Fig. 1) (Scott, 1995; Ross, 1999; Naumova and Scott, 2000; Glass and Witztum, 2001; Libby, 2001). It does not usually become manifest before the fourth of fifth decade, but then often strikes with devas tating suddenness. Fifty per cent of individuals still die (25 per cent immedi ately) from their first heart attack; and morbidity from coronary heart disease and stroke is very significant. The disease has a profound impact on health care services and on industrial economies. The lesions of atherosclerosis Autopsy studies show that in humans atherosclerosis begins in the first and second decade of life. A similar disease can be produced in experimental animals, where diet and genetics can be manipulated to produce identical lesions. The earliest lesions are fatty streaks. These consist of an accumulation of lipid-engorged macrophages (foam cells) and T and B lymphocytes in the arterial intima. With time, the fatty streaks progress to intermediate lesions, composed of foam cells and smooth muscle cells.

Oxygen represents only 20% of the Earth's atmosphere, yet it is vital for the survival of aerobic organisms. There is a dark part of the use of oxygen that consists in generating reactive species that are potentially harmful to living organisms. Moreover, reactive oxygen species can combine with nitrogen derivatives and generate many other reactive species. Thus, living organisms are continuously assaulted by reactive species from external or internal sources. However, the real danger comes in the case of high concentrations and prolonged exposure to these species. This book presents an image of the mechanisms of action of reactive species and emphasizes their involvement in diseases. Inflammation and cancer are examined to determine when and how reactive species turn the evolution of a benign process to a malignant one. Some answers may come from recent studies indicating that reactive species are responsible for epigenetic changes.

The use of antioxidants in sports is controversial due to existing evidence that they both support and hinder athletic performance. Antioxidants in Sport Nutrition covers antioxidant use in the athlete ́s basic nutrition and discusses the controversies surrounding the usefulness of antioxidant supplementation. The book also stresses how antioxidants may affect immunity, health, and exercise performance. The book contains scientifically based chapters explaining the basic mechanisms of exercise-induced oxidative damage. Also covered are methodological approaches to assess the effectiveness of antioxidant treatment. Biomarkers are discussed as a method to estimate the bioefficacy of dietary/supplemental antioxidants in sports. This book is useful for sport nutrition scientists, physicians, exercise physiologists, product developers, sport practitioners, coaches, top athletes, and recreational athletes. In it, they will find objective information and practical guidance.