In vitro competition between calcium phytate and the soluble fraction of rat small intestine contents for cadmium, copper and zinc.

Calcium phytate precipitates were mixed with cadmium (Cd), copper (Cu), or zinc (Zn); in each case most of the trace metal was found to bind to the precipitate. In the presence of some amino acids, picolinic acid or soluble contents of rat intestine, binding was reduced. The solubility effects were low for Cd and Zn, but much higher for Cu. The extent to which Cd was solubilized by intestinal extract was correlated with calcium concentration, but for Cu and Zn it appeared that the concentration of amino groups was the most important factor.