Contrasting effects of the stomach and small intestine of rats on copper absorption

Since the severity of copper deficiency has been shown to be enhanced by feeding diets containing fructose but ameliorated by diets containing starch, we decided to investigate the effect of fructose or starch on copper absorption. As copper transport has been reported to occur also from the stomach, it was possible that copper absorption is inhibited by fructose already from that tissue. Under anesthesia, stomachs of 72 rats fed copper-deficient or supplemented diets containing fructose or starch were ligated prior to the oral administration of ⁶⁴Cu. Gastric absorption of ⁶⁴Cu was studied when the isotope was administered by gastric tube either in diet containing fructose or starch or in water. ⁶⁴Cu was not absorbed from the stomach regardless of the type of dietary treatment, copper status or whether the copper was administered either in diet or in water. In addition, the absorption of ⁶⁴Cu from a diet containing either fructose or starch or from a saline solution was studied using the isolated ligated duodenal loop. When ⁶⁴Cu was administered with dietary fructose ⁶⁴Cu retention and absorption were impaired when compared to starch. When ⁶⁴Cu was administered in saline solution, differences in retention and absorption between the four dietary groups disappeared. It is suggested that the requirements for copper rather than the decreased absorption of copper are responsible at least in part for the more pronounced severity of copper deficiency in rats fed fructose compared to those fed starch.