Age-Related Macular Degeneration (AMD) is an acquired vision disorder and, together with cataracts, a leading cause of legal blindness in the over 60s. Since AMD affects the central part of the retina (macula), which is responsible for acuity of vision, many activities, including reading, writing, sports and driving can become extremely difficult tasks for sufferers to perform. What part, then, can nutrition play in relation to this eye disease? Given that approximately 10 million Americans suffer from early onset AMD and half-a-million from significant loss of vision due to late-stage AMD, the question is an urgent one. The disease's severity and irreversibility adds to the urgency. Research has suggested that AMD develops with the reduction of pigment in the macula. This retinal layer plays a dual role: it filters out harmful blue wavelengths of light and mops up free radicals found in large concentrations in this area. Free radicals damage the cell membranes and the macular pigment. The theory goes that nutrition, in particular certain antioxidant compounds, can reduce the harmful effects of free radicals and, as a consequence, may act to slow the progression of AMD. A recent large clinical trial conducted by the National Eye Institute (NEI) supports this theory. Let's examine its methods and findings. The effect of a high dose antioxidant, vitamin combination (C & E) plus zinc, was tested on participating patients with advanced signs and symptoms of AMD. The doses tested were as follows: 500 mg. Vitamin C 400 IU Vitamin E 15 mg. Beta-Carotene ( a carotenoid and antioxidant effective in building and maintaining the thickness of the retinal pigment layer) 80 mg. Zinc 2 mg. Copper (high dosage of zinc can cause anemia and copper acts as a corrective.) The findings supported the hypothesis that high levels of antioxidants are an effective treatment in slowing the progression of AMD. For this high-risk group of patients it was found that the supplement reduced the risk of developing advanced AMD by about one-quarter and reduced vision loss by about one-fifth. The NEI concluded that, for people over the age of 55 who display signs of intermediate to late vision loss due to AMD, taking a high-dose vitamin combination plus zinc similar to that used in the clinical trial, is highly desirable. 300,000 people at high risk from AMD- associated vision loss would benefit from the treatment. It has indeed proven to be an effective means of limiting the disease in patients with advanced signs and symptoms of AMD. Given this positive association between nutrition and AMD, it is interesting and helpful to compare the levels of Vitamin C and E provided by eating five daily servings of nuts and seeds, with the dosage taken in the trial. Choosing pigment-rich fruits and vegetables (oranges, strawberries, green peppers, broccoli) can provide more than 100 mg. Vitamin C daily. Two daily servings of nuts and seeds (almonds, peanuts, sunflower seeds) can provide 8-14 mg. Vitamin E (11.9-20.8 IU). The above recommended dietary allowances (RDA), however, fall well short of the levels associated with health benefits to vision (see doses above) illustrated by the WEI's Age-Related Eye Disease Study. This is not to say, though, that good food sources of antioxidants should be overlooked in favor of supplements: the bowels and colon benefit from the anti-carcinogenic properties of fiber-rich foods. The wisest option for those who display early signs of AMD, have a genetic predisposion for the disease and are over 50, is to eat a healthy diet and supplement this with good-quality, organically-sourced nutrients. Such a dietary regime is vitally important when put into the context of current average intake. Over half of Americans get much less than 100% of their Vitamin C RDA from their diet and more than 90%, less than 100% of their Vitamin E RDA. Finally, it is important to emphasise that the use of good nutrition based on high levels of antioxidants cannot turn back the clock and reverse the damage already caused by AMD. However, many patients with AMD can experience a delay in the advancement of their condition if a diet high in antioxidant-rich foods and supplements is adopted. |
