Allitol Exerts Distinct Osmotic Actions in Vivo: Intravenous Diuresis and Oral Gastrointestinal Water Retention

Rare sugars have garnered interest for their unique biological properties; however, the effects of allitol on fluid and electrolyte balance remain poorly understood, particularly regarding route-dependent differences between its renal and gastrointestinal actions. In this study, we investigated the effects of the rare sugar allitol on urine formation and whole-body water and electrolyte balance. Intravenous administration of allitol in anesthetized rats induced a marked increase in urine output, accompanied by decreased urinary osmolality and relatively stable sodium and potassium excretion. In contrast, oral administration of allitol softened stools, tended to decrease urine volume in conscious mice, and did not affect total body water or whole-body sodium and potassium content. These findings indicate that orally administered allitol promotes gastrointestinal water retention, thereby limiting renal water excretion without disturbing systemic fluid or electrolyte homeostasis. These results suggest that allitol acts via a novel organ-selective mechanism, highlighting the importance of the administration route in modulating its physiological effects.