High tin intake reduces copper status in rats through inhibition of copper absorption

The mechanism underlying the reduced Cu status in rats fed on a high-Sn diet was investigated. Male rats aged 4 weeks were fed ad lib. on purified diets containing either 1 or 100 mg Sn/kg and demineralized water for a period of 4 weeks. The high-Sn diet had no effect on feed intake, body-weight gain or weight of liver and kidney but significantly reduced Cu concentrations in plasma, liver and kidney. Biliary Cu excretion was decreased significantly in rats fed on the high-Sn diet. Apparent Cu absorption (Cu intake-faecal Cu) was not affected by the high-Sn diet, but the estimate of true Cu absorption (Cu intake-(faecal Cu-biliary Cu)) was significantly reduced. We conclude that high Sn intake reduces Cu status in rats through inhibition of Cu absorption. The decreased biliary Cu excretion observed on the high-Sn diet is a result of the reduced Cu absorption.