Influence of resistant starch alone or combined with wheat bran on gastric emptying and protein digestion in healthy volunteers

Abstract

Objective. Resistant starch (RS) is not absorbed in the small intestine, but is partly fermented in the colon and may positively influence putative risk factors for colon cancer. The purpose of the study was to investigate the influence of RS type 3 (retrograded amylose) alone or combined with wheat bran on gastric emptying (GE) and protein assimilation. Material and methods. GE and protein assimilation were investigated by means of breath-test technology in 20 healthy volunteers who were randomly divided into two groups, each subject performing two tests. In each test, the volunteers received a labelled test meal either as such or in combination with, respectively, 15 g RS3 or 15 g RS3 combined with 6 g wheat bran (WB). Breath samples were collected during the 6 h after administration of a test meal containing egg proteins, intrinsically labelled with 13C-leucine, to measure protein digestion and sodium-14C-octanoate for measurement of GE. Results. Intake of RS3 +WB did not influence GE time compared to baseline values, whereas intake of RS3 seemed to hasten GE: from 93±32 min to 55±15 min (p=0.012). The overall protein assimilation parameters at baseline were not significantly different from those obtained after simultaneous intake of RS3 +WB, whereas RS3 significantly shortened the time of maximum excretion compared to baseline, but the extent of protein digestion after RS3 intake was not affected (12.54±3.60% versus 13.43±3.40%). Conclusions. The presence of RS3 alone or in combination with wheat bran demonstrates that there are no adverse effects on protein digestion and no influence on the nitrogen supply to the colon. © 2007 Taylor & Francis.