In vitro intestinal glucose uptake is inhibited by galactomannan from Canadian fenugreek seed (Trigonella foenum graecum L) in genetically lean and obese rats

Galactomannan, a soluble fiber, has been reported to reduce postprandial blood glucose response. Using this fiber, extracted from Canadian-grown fenugreek seeds (Trigonella foenum graecum L), we conducted an in vitro study to determine if galactomannan affects intestinal glucose uptake in genetically determined lean and obese rats. The segments of jejunum and ileum from these animals were incubated with labeled glucose (2 or 32 mmol/L) in the presence of different concentrations of galactomannan ranging from 0.1% to 0.5% (wt/wt). The uptake of low or high concentration of glucose was significantly and progressively reduced by increasing concentrations of galactomannan in both lean and obese rats. No significant difference was observed in the uptake of glucose between the 2 groups. The viscosity of various concentrations of galactomannan solutions was determined after stirring for 60 minutes at a temperature-controlled (37°C) fixed sheer rate of 1.29 (1/s). The inhibitory effect of galactomannan on glucose uptake was found to be in parallel with the degree of viscosity of the fiber solutions. These results suggest that the galactomannan, because of its viscous property, has the potential to reduce intestinal absorption of low or high concentrations of glucose and hence for the benefit of blood glucose management.