Oxidative Stress and Antioxidant Function in Relation to Risk for Cataract

Abstract

Publisher Summary The lens is composed primarily of proteins and water. The light and oxygen to which the lens is exposed are associated with extensive damage to the long-lived lens proteins and other constituents. With progressive damage, the altered proteins accumulate, aggregate, and precipitate in opacities, or cataracts. The young lens has substantial reserves of antioxidants and antioxidant enzymes that may prevent damage. Proteases may selectively remove obsolete proteins and provide a second level of defense. Compromises of function of the lens upon aging are related to deplete or diminished primary antioxidant reserves, antioxidant enzyme capabilities, and diminished secondary defenses such as proteases. Environmental stresses such as smoking and excessive light exposure appear to provide an additional oxidative challenge associated with the depletion of antioxidants as well as with enhanced risk for cataract. This chapter reviews available data and intervention trials, regarding associations between antioxidant nutrients and eye lens cataract in humans. The primary function of the eye lens is to collect and focus light on the retina. The chapter discusses public health issues regarding cataract, clinical features of cataract, role of oxidation and smoking to cataract formation, associations between antioxidants—vitamins C, E, carotenoids, antioxidant nutrient combinations—and cataract, and intervention trial designed to assess the effect of vitamin supplements on cataract risk. Nutrient intake can be optimized to delay cataract. Optimization of nutriture can be achieved through better diets and, with the aid of supplements once appropriate levels of specifically beneficial nutrients are defined. Study in terms of revealing the utility of diet indicates a significant five-fold decrease in risk ratio for cataract between persons consuming ≥1.5 servings of fruits and/or vegetables. It is also essential to know for how long or when would intake of the nutrient be useful with respect to delaying cataract.