Editorial: Never Underestimate The Power of ROS - The Controversial Role of Oxidative Stress in Health and Disease [ Oxidative Stress in Disease Guest Editor: Prof. Alessandro Laviano ]

There is general agreement that the most powerful step in the evolution of life on planet Earth was the acquisition of mitochondria, and thus of oxidative phosphorylation, by primordial cells. This achievement provided cells with larger amount of energy, which significantly contributed to the evolution of unicellular organisms into more complex and specialized living forms. However, this progress did not occur without any expenses. The use of oxygen in energy metabolism increased the production of energy as ATP, but toxic and potentially lethal substances were also produced, the reactive oxygen species (ROS), which should be rapidly detoxified to prevent molecular and cellular damages. As a consequence, antioxidant systems developed to counteract the negative effects of ROS, and living organisms adapted to strive by maintaining a specific redox state, i.e. a balance between ROS production and antioxidants' scavenger activity. During the last two centuries, the life expectancy significantly increased, mostly because of improved nutrition, since medical advances contributed to this progress when mortality rates had already fallen substantially [1]. However, longer life results in longer exposure to toxic agents, including ROS. Also, age- and/or disease-related inefficiency of antioxidant systems and reduced intake of antioxidants with the diet due to age- and/or disease-related anorexia increase oxidative stress, which in turn may promote molecular damages triggering the onset of degenerative diseases, worsening the clinical condition of patients and preventing healthy aging. Based on these premises, it is not surprising that considerable scientific efforts have been put into the investigation of the role of oxidative stress in the aging process, in the pathogenesis of degenerative diseases, and in influencing the outcome of patients. Consequently, a large number of papers have been published in these areas during the last few years, making difficult to people not directly involved in the study of oxidative stress to get a comprehensive view of the scientific and clinical problems. In this light, the aim of this special issue of Current Nutrition & Food Science is to provide the readers with an authoritative update on the clinical implications of oxidative stress. Leading researchers in their respective fields reviewed the available evidence to delineate the role of oxidative stress in cancer [2], diabetes [3], atherosclerosis [4], critically ill patients [5] and in the aging process [6]. From their reviews, it appears that oxidative stress play a role in the pathogenesis of many diseases, yet we have very few clues on how we can develop an effective antioxidant therapeutic strategy [7]. Indeed, many clinical trials testing the effects of antioxidant supplementation yielded controversial and even negative results [8], underlying our limited knowledge on the optimal timing and dosing of antioxidant therapy, and even on the best antioxidant(s) to be given. Therefore, further research should be conducted in order to fully explore the role of oxidative stress in health and disease. Yet, we can say that although oxidative stress is involved in the pathogenesis of many diseases, its complete annihilation may lead to even worse clinical effects. We have evolved and adapted to “symbiotically” leave with mitochondria and mitochondria-related persistent, yet low-grade, oxidative stress, which in turn may contribute to the physiological functioning of the cell. Thus, reducing oxidative stress to levels below the physiological threshold may trigger intracellular signalling pathways further damaging cellular machinery. This could represent a critical area for future scientific investigations, with tremendous social implications. Indeed, vitamin supplements are regularly taken all over the world because their prescription is just based on the media-driven assumption that oxidative stress is harmful for health and supplements are beneficial. However, when considering antioxidant therapy, it should be remembered that “more” not necessarily means “better”.