Dr Beaumont brings up a very important point. In my practice, I have two patients who had significant zinc toxic side effects due to excessive intake of zinc, and this is related to the point that Dr Beaumont is making.In the study by Dr Newsome, 200 mg of zinc sulfate (not zinc acetate, Zn[C4H6O4]) was given daily to patients. This provides 81 mg of elemental zinc, which is 5.4 times the recommended amount. The amount of zinc indicated on the various forms of supplement preparations sold over the counter in the United States usually indicates (and rightly so) the amount of elemental zinc contained in those preparations. For example, if a patient is told to take 200 mg of zinc sulfate daily and if this patient goes to a drugstore to buy zinc tablets and starts to take four tablets, each containing
Trempe CL. Zinc and Macular Degeneration-Reply. Arch Ophthalmol. 1993;111(8):1023. doi:10.1001/archopht.1993.01090080017004
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