The dietary availability of copper in the form of naturally occurring organic complexes

Abstract

Copper-deficient black-hooded rats were used to study the availability of copper in "deionized" aqueous extracts of herbage. Cu uptake by the rat was assessed by haematopoietic response, melanin-pigment regeneration, growth and measurement of liver-copper storage. Aqueous extracts of herbage passed through a cation-exchange resin to remove the Cu2+ ion still contained copper in an available form. The stable, soluble complexes of copper remaining in these extracts promoted a more rapid physiological response and a greater storage of copper in the liver than the feeding of equivalent amounts of the Cu2+ ion. These results were confirmed by comparing the uptake of Cu64 by the rat liver after feeding the isotope as the Cu642+ ion and after combining it with the complex-forming ligands of an aqueous herbage extract. To account for the rapid utilization of the Cu of the stable, soluble complexes of herbage it is suggested that Cu may be transported through the intestinal mucosa in the form of such complexes.