The antioxidant protective system in the eye includes antioxidant enzymes, the antioxidant vitamins C and E, and the macular pigments Lutein and Zeaxanthin. The antioxidant enzymes form the primary defense against oxidative stress. Many of these enzymes contain the element Zinc or require the presence of Zinc to function. Vitamin E is a major antioxidant in the human body; it plays a critical role in protecting cell membranes.7
Lutein and Zeaxanthin, members of a class of naturally pigmented chemicals called carotenoids, are highly concentrated in the macula. They act not only as antioxidants but also blue light filters in the macula to protect the photoreceptors from damaging short wavelength visible light.6 Dietary intake of Lutein and Zeaxanthin have been shown to increase the density of macular pigment and reduce the risk of AMD.8,9,10,11,12
Omega-3 fatty acids play an important role in retinal function. The retina has the highest concentrations of DHA, an important structural lipid.13 EPA has the potential to regulate abnormal retinal neovascularization, vascular permeability, and inflammation.14
To protect the eye from oxidative stress, all these essential nutrients need to be maintained at adequate levels. The aging eye, however, often experiences declining levels of these nutrients. Research has shown a reduction in Zinc and in the activity of the antioxidant enzyme catalase in older RPE cells.15 The amount of vitamins C and E in the body and in the retina also drops significantly with age,1,15and the level of protective macular pigments decreases as well.5 Indeed, nutrient deficiency may be an important risk factor for the development and progression of age-related macular changes.