Polyol-mineral interactions in the diet of the rat with special reference to the stabilities of polyol-metal complexes

Abstract

Sugar alcohols (polyols) form complexes of high chemical stability with Cu(II) and of moderate stabilities with Ca(II) and Fe(III), contrasting the weak Zn(II)- and Mg(II)-polyol complexes. The effect of these complexes on mineral metabolism was studied in adult Long-Evans male rats fed diets containing glucose, sorbitol or xylitol (final level 20% in the diet) or the basal diet for 4 weeks. The analyses of serum, liver and urinary Ca, Mg, Fe, Zn and Cu showed a 35% increase in the serum Cu levels of the polyol-fed rats (P<0.001), whereas the liver Cu levels and the urinary Cu excretion decreased in these animals. Serum and liver Fe, and the urinary Fe excretion were higher in the polyol-fed rats, whereas the serum and liver Zn levels were similar in all groups. The polyols increased urinary Ca excretion 8-to 10-fold and Mg excretion 2-fold, and caused diuresis in the rats. The above mineral responses were observable to a certain extent also in rats fed low levels of xylitol (5% diet) for 4 weeks. These results most likely reflect increased intestinal absorption of polyol-metal complexes. The formation of the highly stabile polyol-Cu complex was considered inhibitory for the utilization of Cu by the rats.