Copper and zinc absorption in the rat: mechanism of mutual antagonism.
Level 5 - mechanism / opinion, no new human data
Animal ex vivo physiological experiment
PubMed 3968585 · doi:10.1093/jn/115.2.159
What was done
The researchers evaluated the mutual antagonism between copper and zinc absorption using an isolated, vascularly perfused rat intestine model across two experimental series. In the first series, rats were fed one of nine diets for one week containing low, adequate, or high levels of copper (1, 6, or 36 mg/kg) and zinc (5, 30, or 180 mg/kg), followed by intestinal perfusion with fixed metal concentrations (6 mg/L Cu, 30 mg/L Zn). In the second series, rats were maintained on standard diets (6 mg/kg Cu, 30 mg/kg Zn), while luminal perfusate concentrations were varied (Cu from 1 to 36 mg/L; Zn from 5 to 180 mg/L) to assess direct mucosal interactions.
What was found
In the diet manipulation phase, pre-feeding different mineral levels did not significantly alter the absorption of either metal; high dietary zinc increased metallothionein-bound copper without altering intracellular copper concentration. In the perfusate manipulation phase, higher luminal copper concentrations increased mucosal zinc accumulation and decreased zinc transfer to the portal perfusate at the highest luminal zinc concentration. High luminal zinc concentrations decreased cytosolic copper concentration in mucosal cells and reduced copper transfer to the portal effluent. No exact numerical values or effect sizes were reported in the abstract.
Why it matters
This study provides mechanistic evidence that copper-zinc antagonism occurs via direct competitive inhibition of uptake and exit pathways at high luminal concentrations, rather than through short-term dietary preconditioning.
Limits
The study was conducted in an isolated ex vivo rodent intestine model, limiting direct translation to intact human physiology. Sample sizes, statistical variance, and specific numerical results were omitted from the abstract.
Cited by
- supports Copper and zinc compete with each other for gastrointestinal absorption.