Inhibitory Effects of Psyllium on Rat Mineral Absorption Were Abolished by Reduction of Viscosity with Partial Hydrolysis

Psyllium husk, a highly viscous fiber, has beneficial effects for health, but has been reported to inhibit absorption of calcium. The present study found the effects of fiber viscosity on calcium, magnesium, and zinc absorption with partially degraded psyllium preparations to be one fifth viscosity (LD-HP) and one seventieth viscosity (HD-HP) using normal and ovariectomized rats. Magnesium absorption was reduced with ingestion of intact psyllium (50 g/kg diet) for 4 weeks but this reduced absorption was increased with lower viscous psyllium preparations. Moreover, the absorption in the HD-HP group was higher than in the control group (100 g cellulose/kg diet) in ovariectomized rats. Changes in calcium and zinc absorption were similar to those in magnesium absorption. Cecal pH was reduced only in rats fed HD-HP in both normal and ovariectomized rats. These results indicate that reduction of psyllium viscosity tends to counter inhibitory effects on mineral absorption.