Utilization of Orally Administered D-[14C]Mannitol via Fermentation by Intestinal Microbes in Rats

To investigate the available energy of orally administered [14C]mannitol via intestinal microbes, [14C]mannitol (222 kBq, 105 mg) or [14C]glucose (222 kBq, 105 mg) was administered to conventional rats and antibiotics-treated rats whose intestinal microbes were depleted by drinking water containing antibiotics, respectively. The exhausted CO2, feces and urine were then separately collected at 2, 4, 6, 8, 10, 12 and 24 h after administration of the test solution. In the conventional rats, 45% of administered radioactivity was recovered as 14CO2 in the administration of [14C]mannitol, while 57% of administered radioactivity was recovered as 14CO2 following the administration of [14C]glucose for 24 h. The time sequence for the 14CO2 excretion from [14C]mannitol was delayed as compared to [14C]glucose by about 4-6 h (p