Effects of indigestible dextrin on glucose tolerance in rats

A recently developed indigestible dextrin (IDex) was studied for its effects on glucose tolerance in male Sprague-Dawley rats. IDex is a low viscosity, water-soluble dietary fibre obtained by heating and enzyme treatment of potato starch. It has an average molecular weight of 1600. An oral glucose tolerance test was conducted with 8-week-old rats to evaluate the effects of IDex on the increase in plasma glucose and insulin levels after a single administration of various sugars (1.5 g/kg body weight). The increase in both plasma glucose and insulin levels following sucrose, maltose and maltodextrin loading was significantly reduced by IDex (0.15 g/kg body weight). This effect was not noted following glucose, high fructose syrup and lactose loading. To evaluate the effects of continual IDex ingestion on glucose tolerance, 5-week-old rats were kept for 8 weeks on a stock diet, a high sucrose diet or an IDex-supplemented high sucrose diet. An oral glucose (1.5 g/kg body weight) tolerance test was conducted in week 8. Increases in both plasma glucose and insulin levels following glucose loading were higher in the rats given a high sucrose diet than in the rats fed a stock diet. However, when IDex was included in the high sucrose diet, the impairment of glucose tolerance was alleviated. Moreover, IDex feeding also significantly reduced accumulation of body fat, regardless of changes in body weight. These findings suggest that IDex not only improves glucose tolerance following sucrose, maltose and maltodextrin loading but also stops progressive decrease in glucose tolerance by preventing a high sucrose diet from causing obesity.