Replacement of glycaemic carbohydrates by inulin-type fructans from chicory (oligofructose, inulin) reduces the postprandial blood glucose and insulin response to foods: report of two double-blind, randomized, controlled trials

Inulin-type fructans are recognized as prebiotic dietary fibres and classified as non-digestible carbohydrates that do not contribute to glycaemia. The aim of the present studies was to investigate the glycaemic response (GR) and insulinaemic response (IR) to foods in which sucrose was partially replaced by inulin or oligofructose from chicory. In a double-blind, randomized, controlled cross-over design, 40-42 healthy adults consumed a yogurt drink containing oligofructose or fruit jelly containing inulin and the respective full-sugar variants. Capillary blood glucose and insulin were measured in fasted participants and at 15, 30, 45, 60, 90, and 120 min after starting to drink/eat. For each test food, the incremental area under the curve (iAUC) for glucose and insulin was calculated and the GR and IR determined. Consumption of a yogurt drink with oligofructose which was 20% reduced in sugars significantly lowered the glycaemic response compared to the full-sugar reference (iAUC(120min) 31.9 and 37.3 mmol/L/min, respectively; p < 0.05). A fruit jelly made with inulin and containing 30% less sugars than the full-sugar variant likewise resulted in a significantly reduced blood glucose response (iAUC(120min) 53.7 and 63.7 mmol/L/min, respectively; p < 0.05). In both studies, the postprandial insulin response was lowered in parallel (p < 0.05). The reduction of postprandial glycaemia was positively correlated to the proportion of sugars replaced by inulin-type fructans (p < 0.001). In conclusion, the studies confirmed that substitution of glycaemic sugars by inulin or oligofructose from chicory may be an effective strategy to reduce the postprandial blood glucose response to foods.