Doc Roc, I found this article while researching zinc. It appears researchers found high zinc deposits in the eyes of people with age-related macular degeneration. They believe "free zinc can cause lots of problems"

You may well be right that zinc can be hazardous in amounts higher than the RDA. This seems to be quite different from other research that suggests high zinc intakes reduce risk for AMD. Maybe nothing will ever be proven. I think I'll just stick to the RDA levels for all vitamins and minerals. Regards, Roger

  Dear Roger,  Thank you so much for bringing this question to my attention.  Here is a short answer, followed by a much longer reasoning process.  1) It is a confusing choice, with evidence for and against AREDS and zinc. 2) I am persuaded to avoid exceeding the Daily Value (RDA) of zinc. 3) Eating an egg a day is a convenient way to get nutrition for your eyes.

I. The ZINC Report -To see the actual article, I went to pubmed and searched for Lengyel and zinc.  Here's a good press report summary:

  High Zinc Levels in Eyes Linked to AMD A U.K. study finds that elevated levels of zinc in the eyes may play a role in the development of age-related macular degeneration (AMD), the leading cause of blindness among elderly people in the developed world, BBC News reported.

The study, led by London's Institute of Ophthalmology, found that the eyes of people with AMD have high levels of zinc in drusen, microscopic structures in the eye that are an early sign of AMD.

"Zinc had previously been shown to contribute to the formation of plaques in the brains of patients with Alzheimer's disease, so it was logical for us to test the idea that zinc might also contribute to the formation of plaque-like drusen in the eye as well," said researcher Dr. Imre Lengyel.

"AMD can be considered as the Alzheimer's disease of the eye, in that both involve the build-up of proteins and metals like zinc and copper into microscopic clumps," Lengyel said.

II. The AREDS study - Here is the link to the actual AREDS study.   This was a 5-year trial of nearly 5,000 people aged 55-80.  Here's one citation that can be found on pubmed Arch Ophthalmol. 2001 Oct;119(10):1439-52 that shows people took vitamin C, 500 mg; vitamin E, 400 IU; and beta carotene, 15 mg, zinc (80 mg of zinc as zinc oxide) and copper (2 mg of copper as cupric oxide).  This report states there was no benefit of the AREDS formula. However, at the NIH site it states that 1) there was a 25% decrease in risk for those at high risk who were developing AMD, and 2) no benefit for those who did not have signs of AMD.   

III. LUTEIN/ZEAXANTHIN - Note that the AREDS study was conducted prior to the discovery that the two key molecules in the macula are lutein and zeaxanthin.  One of my students researched these two antioxidants, and they appear to be key in preventing AMD.  Her study showed that 10mg zeaxanthin and 2mg lutein per day were optimal.  In fact, a great article in October of 2006 showed that eating an egg a day can protect your eyes and provide these two important molecules without raising cholesterol.

IV. Reasoning

The AREDS trial showed some benefit to getting antioxidants, but that benefit may well have come from the vitamin C and E which seem quite safe, and which many people do not get in their diets.  The benefit of those ingredients may well have masked any potential harm done by the zinc.  But I know that free radical damage from metals like iron is responsible for much damage leading to Alzheimer's, while vitamin C is extremely protective of eyes from cataracts and AMD.  I find this latest study of harmful effects of zinc quite persuasive.  My own risk-benefit analysis says, avoid supplements with high levels of zinc, with the possible exception of use at the initial signs of a cold.