Does too much zinc increase your risk for macular degeneration?

Have you ever wondered why virtually every vision supplement on the market contains zinc? It has to do with zinc's ability to slow macular degeneration. In 2001, a study from the National Eye Institute found that high doses of zinc supplements combined with antioxidants may slow down the progression to blindness in patients with macular degeneration. But is it such a good idea to take so much zinc?

The authors of one surprising study suggest that taking a zinc supplement might be the exact opposite of what you want to do if you have macular degeneration.

The authors note that one of the classic findings in macular degeneration is the accumulation of deposits under the retina. When you go to the eye doctor, be sure to ask him if he sees any retinal deposits. Because if he does, this is a sign that macular degeneration may be on the way. But exactly how these deposits get there and what they mean is not fully understood. So while scientists are busy trying to find the answers, these researchers wondered if zinc had anything to do with the deposits. Here's what they did.

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First, they collected autopsy specimens from patients who had macular degeneration and patients who didn't. Then they examined their eyes for the presence of zinc deposits in the retinas. And guess what? According to the authors, the eyes of the patients with macular degeneration contained "unexpectedly high concentrations of zinc." And, "Zinc accumulation was especially high in the maculae of eyes of the patients with macular degeneration." After finding this out, they concluded, "Based on the evidence provided here, we suggest that zinc plays a role in sub-RPE [retinal] deposit formation in the aging human eye and possibly also in the development and/or progression of macular degeneration." Whoops, that doesn't sound too good. So what does it all mean?

The first thing to note here is that just because a substance is in a tissue that's damaged does not mean that it caused the damage. Often, the body will send certain minerals to an injured area in order to counter the damage. For example, the body will send calcium to areas of inflammation to reduce the inflammation. So finding excessive calcium deposits in inflamed tissues is the result of the inflammation not the cause of it. In this case, the high zinc deposits in the maculas of these patients with macular degeneration might not be the cause of macular degeneration. They may be there in order to slow down the processes involved in macular degeneration. Right now we just don't know.

Second, zinc is an essential mineral. Unless you take too much, and that means really high doses, I can't see how it could cause a disease process. But what if your supplement does contain an inordinately high dose of zinc?

The National Eye Institute study I referred to above was called the AREDS (Age Related Eye Disease Study) trial. The formula used in the study is called the AREDS formula. And it contains a whopping 80 mg of zinc. This is more than two times as much zinc than is generally recommended for any long-term use. And it is dangerously close to the 100 mg dose that has been shown to suppress the immune system. That's why in my Super Immune QuickStart the maximum zinc you would be getting is a very safe and effective 15 mg.

Yours for better health,

Frank Shallenberger, MD

Source:

Lengyel I, Flinn JM, et al. High concentration of zinc in sub-retinal pigment epithelial deposits. Exp Eye Res. 2007 Apr;84(4):772-80.