Oral rehydration solutions (ORS): enhancement by a soluble fiber

This study was designed to test the hypothesis that, in an animal model of protein-energy malnutrition (PEM), carboxymethylcellulose (CMC), a viscous additive for the World Health Organization Oral Rehydration Solution (WHO-ORS), previously found to be effective in rats with osmotic diarrhea as an enhancer of water and sodium absorption, would also improve the performance of the WHO-ORS. This hypothesis was based on the changes in fluid and electrolyte transport that could be induced by an increase in the viscosity.

We evaluated CMC in young rats fed a low-protein, low-energy diet for 3 weeks to induce PEM. Control (CTL) rats were fed a nutritionally complete diet. The ORS were tested with an in vivo perfusion procedure under anesthesia.

CMC addition (0, 2.5, 5.0 and 10.0 g/L) sharply increased the rates of net water and sodium absorption in both groups of rats, especially in the PEM animals. Net water absorption increased from (means +/- SEM) 0.75 +/- 0.06 to 2.21 +/- 0.18, 3.35 +/- 0.20 and 8.46 +/- 0.84 microL/min x cm in the PEM rats (0, 2.5, 5.0 and 10.0 g/L CMC, respectively). For the same CMC concentrations, sodium absorption improved from 178.8 +/- 20.3 to 402.4 +/- 18.4, 486.4 +/- 29.2 and 898.4 +/- 21.4 nmol/min x cm, respectively. CTL rats also showed marked increases. Rates of lumen-to-serosa water influx improved in both groups without major changes in water efflux. Net water and sodium absorption appeared related to the log of the ORS viscosity.

The results further support the concept that increased viscosity induced by CMC enhances the effectiveness of ORS.