TABLE 3.
Summary of zinc-nutrient interactions when consumed with food1
| Nutrient interaction | Possible mechanism | Key features of interactions | Effect of interaction on zinc biomarkers |
| Copper | Copper may compete for intestinal zinc transport and influence zinc bioavailability; copper may also compete for binding to metallothionein. | Zinc interferes with copper absorption when intakes are very high (≥50 mg/d). High copper intakes have no reported adverse effect on zinc absorption (136). | Usual intakes of copper in normal individuals appear to have no effect on zinc biomarkers, such as PZC (21). |
| Iron | The mechanism of interaction between iron and zinc is not fully understood. Iron and zinc may compete for a shared absorptive pathway through DMT-1 (137) and/or another common pathway located in the apical membrane of the intestinal cell (138). | Supplemental iron beyond normal amounts of dietary intake may decrease zinc absorption (139, 140). This may be of concern when high-dose prenatal iron supplements (≥60 mg elemental iron/d) are taken routinely. | PZCs may be reduced as a result of high amounts of supplemental iron (i.e., ≥60 mg elemental iron/d) (141). The effect is diminished when lower amounts (≤10 mg) of iron supplements are given during early childhood (142) or when both minerals are provided in a food matrix (112). |
| Additional zinc may be warranted in conjunction with high-dose prenatal iron-supplementation programs (141). | |||
| Calcium | Calcium per se has no detrimental effect on zinc absorption. In the presence of phytate, calcium may form insoluble calcium-zinc-phytate complexes in the intestinal tract that cannot be absorbed (143). | Calcium does not impair zinc absorption from diets adequate in zinc irrespective of whether diets have a low (440 mg/d) or high (1800 mg/d) phytate content (144). Whether calcium has an adverse effect in phytate-containing diets low in zinc is uncertain. | There is no evidence of reduced PZCs as a result of prolonged supplementation with high calcium intakes (1000 mg) in women (145). |
1
DMT-1, divalent metal transporter 1; PZC, plasma zinc concentration.