Absorption of Copper from the Digestive Tract

Abstract

Copper may be one of those rare nutrients for which at least some minimal absorption occurs already in the stomach. In 1965, Van Campen and Mitchell reported that in rats a substantial portion of a dose of ⁶⁴Cu(II) was absorbed over 2 h, when placed in the stomach ligated at the pyloric valve (Table 2-1). Indeed, a greater percentage was absorbed there than in 7-cm segments of various parts of the small intestine. This contrasted sharply with findings for ⁶⁵Zn and ⁵⁹Fe salts, which showed almost no absorption when administered to the gastric fluid (in the tied-off stomach). However, Fields et al. (1986c) recently failed to confirm this effect, reporting less than 0.1% of the dose in the blood and nongastrointestinal tissues between 0.5 and 4 h after gastric or oral intubation of ⁶⁴Cu(NO₃)₂ (with the stomach ligated at the pylorus). (Three to 7% of the dose appeared in the washed stomach wall.) Van Barnefeld and Van den Hamer (1984), on the other hand, found 22% of an oral dose in the (washed) stomach wall of mice after 2 h, of which none remained at 6 h. The earlier data of Van Campen and Mitchell (1965) for rats also suggested that there is a lower rate of absorption of copper, the farther down the small intestine one goes. This disagreed with studies of Crampton et al. (1965) (also in rats), in which there was a trend in the opposite direction, with maximum absorption in the third and fourth segment before the cecum (see later).