Individuals at high risk of age-related macular degeneration (AMD) who took a high-dose combination of vitamins C and E, beta-carotene and the mineral zinc lowered their risk of age related macular degeneration (AMD) by 25%. The supplements had no apparent effect on those who were not at risk.
AMD, the leading cause of blindness in adults over 65, occurs when abnormal blood vessels leak fluid and blood into the tissue at the back of the eye, leading to blistering and scarring of the retina. The disease affects central vision needed for reading, driving and recognizing faces, but patients are often able to detect colors and see with their peripheral vision. While the supplements did not restore vision that had already been lost, they slowed the progression of vision loss in some individuals with intermediate or advanced AMD.
In the study, more than 3,600 people aged 55 to 80 years at risk for AMD received a daily dietary supplement. The supplement consisted of either 500 milligrams (mg) of vitamin C, 400 international units of vitamin E and 15 mg of beta-carotene; 80 mg of zinc and 2 mg of copper; antioxidants and zinc; or an inactive pill (placebo).
Study participants at high risk of developing vision loss associated with AMD who took antioxidants and zinc were less likely than those who took only antioxidants or only zinc to lose their vision over the 6-year study. Individuals who took a placebo were the most likely to develop advanced AMD and vision loss.
Individuals should consult their doctor before taking high doses of any nutrient, the researchers note. Doses used in the study were 5 to 15 times the recommended dietary allowance and may have unintended effects in some individuals such as kidney stones (vitamin C), muscle weakness and fatigue (vitamin E), anemia and upset stomach (zinc), and yellow skin (beta carotene).
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