Inhibition of intestinal uptake of amino acids by unconjugated bile salt.

The unconjugated bile salt, sodium deoxycholate, at a concentration of 0.5 mM was shown to inhibit the intestinal uptake of the amino acids L-glycine, L-leucine, L-proline, L-lysine and L-tyrosine in rats in vitro. This effect was acutely reversible except for the basis amino acid L-lysine and is therefore not simply due to tissue damage. These results, and the recent finding that sodium deoxycholate inhibits intestinal absorption of amino acids in vivo, suggest that impaired intestinal amino acid transport may contribute to hypoproteinaemia in patients with bacterial overgrowth in the upper small intestine in whom deoxycholate is present in the small intestinal lumen in excessive concentrations.