Reactive oxygen species (ROS) have deleterious or beneficial effects; this dual nature of ROS means that ROS act as intracellular signaling molecules and as defense mechanisms against micro-organisms. An overproduction of ROS results in oxidative stress, a deleterious process that damages cell structures, including lipids, proteins, and DNA. Oxidative stress plays a major role in various human disease states, including endocrine dysfunction. As a safeguard against oxidative stress, several endogenous nonenzymatic and enzymatic antioxidant systems exist. Antioxidants can delay or prevent oxidative stress and are widely used in the hope of maintaining health and preventing diseases. Although early studies suggested that antioxidant supplements promoted health, later clinical trials revealed that it may not be true in all cases. In this article, we provide a brief review of the pathophysiologic aspects of oxidative stress in a number of the most commonly human endocrionopathies (diabetes, male and female infertility and thyroid diseases) and review the therapeutic potentials of existing antioxidant strategies. We focus on human clinical trials and discuss the implications of their results. Based on the data reported so far, we conclude that the results reported challenge us to design better antioxidant trials in future, with a particular emphasis on identifying 1) appropriate doses 2) selecting the right populations 3) treating for optimal durations and 4) specific intracellular targeting mechanisms.

Keywords: Thyroid Diseases - drug therapy, Ubiquinone - therapeutic use, Thioctic Acid - therapeutic use, Reactive Oxygen Species - metabolism, Oxidative Stress - physiology, Infertility - drug therapy, Diabetes Mellitus - drug therapy, Ascorbic Acid - therapeutic use, Antioxidants - therapeutic use, Vitamin E - therapeutic use