REPLACEMENT OF DIGESTIBLE BY RESISTANT STARCH LOWERS DIET-INDUCED THERMOGENESIS IN HEALTHY-MEN

The present study describes the effect of replacement of digestible st arch by resistant starch (RS) on diet-induced thermogenesis (DIT), pos tprandial glucose and insulin responses, and colonic fermentation. Ten healthy males consumed three test meals, consisting of diluted, artif icially-sweetened fruit syrup and either 50 g raw potato starch (550 g RS/kg), or 50 g pregelatinized potato starch (0 g RS/kg) or 30 g preg elatinized potato starch plus 20 g lactulose (670 g indigestible disac charide/kg). The meals were served in the morning after an overnight f ast. Each volunteer consumed each meal twice on six separate days in r andom order. Metabolic rate was measured by indirect calorimetry in th e fasting state for 15 min and postprandially for 5 h. Shortly before and hourly up to 7 h after consumption of the test meal, end-expirator y breath samples were obtained for H-2 and CH4 analysis. Shortly befor e the meal and 30, 60, 180, and 300 min postprandially, blood samples were taken for glucose and insulin analyses. Postprandial increases in glucose and insulin levels were proportional to the amount of digesti ble carbohydrate in the meal. Breath H-2, and CH4 concentrations indic ated that the pregelatinized starch was not fermented and that lactulo se was fermented rapidly. Fermentation of the raw starch started only 6 to 7 h after consumption, resulting in a rise in breath H-2 but not in CH4. The replacement of 27 g digestible starch by RS in a single me al lowered DIT by on average 90 kJ/5 h, as could also be calculated by assuming that RS does not contribute to DIT. The ingestion of lactulo se resulted in a substantial rise in DIT which was most probably cause d by its fermentation.