Effects of iron, tin, and copper on zinc absorption in humans

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Abstract
Zinc absorption as measured by body retention of [65Zn]zinc chloride or a turkey test meal extrinsically labeled with 65Zn was determined in human subjects by whole body counting after 7 days. Average 65Zn absorption from zinc chloride in persons with a high iron-absorbing capacity was similar to persons with a low capacity to absorb iron. Inorganic iron, 920 µmol (51 mg), or HB iron, 480 µmol (26 mg), inhibited 65Zn absorption from 92 µmol (6 mg) of zinc chloride. When 610 µmol of iron (34 mg) was added to a turkey test meal containing 61 µmol of zinc (4 mg), 65Zn absorption was not inhibited. Tin, 306 µmol (36 mg), given with zinc chloride or turkey test meals (61 µmol, 4 mg, of Zn) significantly reduced 65Zn absorption. Copper, 79 µmol (5 mg), had no significant effect on the 65Zn absorption from 7.9 µmol (0.5 mg) of zinc chloride. In summary, the capacity to absorb iron did not influence 65Zn absorption, but both inorganic iron and heme-iron inhibited 65Zn absorption from zinc chloride. Inorganic iron had no effect, however, on 65Zn absorption from the turkey test meal. Tin in a large dose also inhibited 65Zn absorption from both zinc chloride and the turkey test meal.