Dietary Polyphenols in Age-Related Macular Degeneration: Protection against Oxidative Stress and Beyond

Figure 3

Oxidative events occurring in the retina and their contribution to degeneration and death of retinal cells, an essential feature of age-related macular degeneration. High metabolic rate, intense blood flow in the retina, and its massive light exposure are physiological sources of reactive oxygen species (ROS). Phagocytosis of photoreceptor outer segments (POS) and accumulation of lipofuscin, a protein/lipid mixture, lead to further ROS production. Environmental and lifestyle factors, including additional exposure to blue light, smoking, and diet, potentiate ROS production. However, some nutritional compounds can inhibit oxidative stress associated with ROS overproduction and ameliorate retinal damage. Retinal antioxidant defense can directly inhibit oxidative stress and its intermediates, including lipid peroxidation, but it decreases with age; limited regenerative and renewal mechanisms in the retina also decline with age.