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August 1993

Zinc and Macular Degeneration

Author Affiliations

Sydney, Australia

Arch Ophthalmol. 1993;111(8):1023. doi:10.1001/archopht.1993.01090080017003

I am surprised to see Drs Trempe1 and Newsome2 making the common mistake of referring to doses of zinc without indicating whether they are referring to elemental zinc or complex zinc. For instance, zinc citrate, Zn(C4H4O4), has a molecular weight of 183.46 and consists of 35.64% zinc. Two hundred milligrams of zinc citrate contains 71 mg of elemental zinc.

The use of zinc to create a negative copper balance has been of interest to those who treat Wilson's disease. The dose of elemental zinc required to create a negative copper balance is between 100 and 150 mg of elemental zinc.3 I agree with Dr Newsome that 200 mg of zinc acetate, ie, some 71 mg of elemental zinc, is unlikely to lead to significant toxic effects over a period of years. I also agree with Dr Trempe that 200 mg of elemental

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