Fructans of Jerusalem artichokes: intestinal transport, absorption, fermentation, and influence on blood glucose, insulin, and C-peptide responses in healthy subjects

Fructans are naturally occurring plant oligosaccharides with sweetening properties. Fructans (FAs) isolated from Jerusalem artichokes (Helianthus tuberosus) were studied with respect to intestinal handling and influence on blood glucose (BG), insulin, and C-peptide responses in eight healthy subjects. The responses were compared with those for fructose ingestion. The effect of FAs added to a wheat-starch meal was also studied. Standardized breath-hydrogen excretion indicated that FAs were completely malabsorbed and, after a 20-g dose, traces of FA were detected in 24-h urine collections in one subject only. Orocecal transit times were longer for FAs than for lactulose and fructose. The BG and insulin increments were very low after FA ingestion, lower than after fructose ingestion, whereas hydrogen production was much higher. Areas under BG curves tended to be smaller when 10 g FA was added to a 50-g wheat-starch meal, but there was no apparent interference with starch absorption.