Dietary prevention of age-related macular degeneration.
Age-related macular degeneration (ARMD) is the leading cause of blindness in people over the age of 65, and the prevalence of ARMD is expected to increase as the population ages. Although the incidence of ARMD increases sharply with age, recent studies indicate that prevention measures and dietary changes, implemented early in life, can reduce an individual's risk of ARMD. Several dietary components have been proposed and studied with regard to their ability to protect against ARMD; these components include antioxidant vitamins and specific carotenoids. In particular, consumption of dark green, leafy vegetables has been shown in clinical studies to reduce the risk of ARMD. Biochemical studies of such vegetables have found that they contain several nutrients that may account for this effect, including high concentrations of the related carotenoids lutein and zeaxanthin. Structural and clinical studies have shown that these carotenoids are concentrated in the retinal macular pigment and that such accumulation is dependent on dietary intake. Further studies have indicated that the density of the macular pigment is related to preservation of visual sensitivity and (possibly) protection from ARMD. Large-scale clinical trials will be necessary to demonstrate that specific agents can reduce the incidence of ARMD. Nevertheless, specific dietary components--particularly, the carotenoids found in dark green, leafy vegetables--have shown great promise. While lifestyle modifications such as smoking cessation, reduction of alcohol consumption, and the wearing of sunglasses may reduce the risk of ARMD, it is likely that consumption of specific dietary components can reduce the risk further.