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

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 mumol (51 mg), or HB iron, 480 mumol (26 mg), inhibited 65Zn absorption from 92 mumol (6 mg) of zinc chloride. When 610 mumol of iron (34 mg) was added to a turkey test meal containing 61 mumol of zinc (4 mg), 65Zn absorption was not inhibited. Tin, 306 mumol (36 mg), given with zinc chloride or turkey test meals (61 mumol, 4 mg, of Zn) significantly reduced 65Zn absorption. Copper, 79 mumol (5 mg), had no significant effect on the 65Zn absorption from 7.9 mumol (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.

Inhibition of iron and copper uptake by iron, copper and zinc

“…However, when Zn increased, intracellular Cu did not change. These results confirm previous studies in which Fe was shown to decrease zinc absorption in humans in a dosedependent way when given in a water solution but not when given with a meal (Valberg et al, 1984;Sandstrom 1985) and when oral iron therapy impaired zinc absorption and thus zinc status in a doseindependent fashion, without affecting copper absorption (Troost, 2003).…”

Parameters Influencing Zinc in Experimental Systems in Vivo and in Vitro

“…Some divalent cations like copper, iron, cobalt, manganese and tin also decrease the intestinal zinc absorption in animal models [82], whereas heme iron in physiological doses does not inhibit zinc uptake in humans [83]. High doses of non-heme iron [83], or zinc and non-heme iron together as supplements [67] could notably decrease the absorption of zinc in humans.…”

Improvement of zinc intestinal absorption and reduction of zinc/iron interaction using metal bound to the caseinophosphopeptide 1-25 of β-casein

“…But [31] and by interactions with substances in the gut which enhance absorption, such as proteins and glucose polymers [27,29], or inhibit it such as phytates or other trace elements (Fe) which compete for common carriers [7].…”

“…Thus, lactose and citric acid [23,29] facilitate Zn uptake by the enterocyte, whereas phytates decrease Zn absorption [22]. Iron (Fe) inhibits Zn uptake and metabolism and Zn has a similar effect on Fe absorption [3,11,13,17,31].…”