The impact of food contaminants on the bioavailability of trace metals.

Organic solvents, detergents, organochloric compounds, pesticides, mycotoxins, residues of veterinary drugs and metals are examples for food contaminants; they are usually present at very low concentrations. Their impact on absorption and distribution kinetics of essential trace metals, if there is any, can be mediated by three types of mechanisms: 1. In animal experiments, contaminants like T-2 mycotoxins or 2,3,7,8 tetrachlorodibenzodioxin inhibited absorptive or excretory mechanisms at high concentrations which, however, are usually not found in food. 2. Food contaminants with metal binding properties can interact with essential metals in the intestinal lumen or during transfer through the intestinal mucosa and affect their absorption according to the rules of complex chemistry. To balance the effect of endogenous metal-binding food constituents, they should be present in comparably high quantities. Usually, however, the concentration of contaminants is approx. 6 orders of magnitude lower than that of endogenous food ligands. 3. Contaminating metals may interfere with the regulated absorption, distribution, and excretion kinetics of essential metals. Such mechanisms may be amplified by vicious cycles. In general, however, food contaminations with metals are too low to have an impact on the bioavailability of essential metals.