Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention.
Recent evidence suggests that resistant starch (RS) is the single most important substrate for bacterial carbohydrate fermentation in the human colon. During two 4-wk periods. 12 healthy volunteers consumed a controlled basal diet enriched with either amylomaize starch (55.2 +/- 3.5 g RS/d; high-RS diet) or available cornstarch (7.7 +/- 0.3 g RS/d; low-RS diet). Approximately 90% of the RS consumed disappeared during intestinal passage; increased fermentation was verified by elevated breath-hydrogen excretion. During the high-RS diet, fecal wet and dry weight increased 49% and 56%, respectively (P < or = 0.005), whereas stool water content did not change significantly. Fecal concentrations and daily excretion of short-chain fatty acids were not different in the two study periods. During the high-RS diet, bacterial beta-glucosidase activity decreased by 26% (P < or = 0.05). Fecal concentrations of total and secondary bile acids were significantly lower during the high-RS than during the low-RS period [a decrease of 30% (P < or = 0.05) and 32% (P < or = 0.01), respectively, in total and secondary bile acids] whereas concentrations of primary bile acids were unaffected by RS consumption. During the high-RS diet, fecal concentrations of total neutral sterols decreased by 30% (P < or = 0.005) and fecal concentrations of 4-cholesten-3-one decreased by 36% (P < or = 0.05). These data suggest that RS has potentially important effects on bacterial metabolism in the human colon that may be relevant for cancer prevention.
Hylla
S
S
Department of Medicine, University of Würzburg, Germany.
Gostner
A
A
Dusel
G
G
Anger
H
H
Bartram
H P
HP
Christl
S U
SU
Kasper
H
H
Scheppach
W
W
D000328:Adult; D001419:Bacteria / Q000201:enzymology / Q000378:metabolism; D001647:Bile Acids and Salts / Q000032:analysis; D001944:Breath Tests; D015331:Cohort Studies; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D003110:Colonic Neoplasms / Q000517:prevention & control; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000737:chemistry* / Q000201:enzymology / Q000382:microbiology; D005260:Female; D005285:Fermentation / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D013213:Starch / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D013261:Sterols / Q000032:analysis; D013997:Time Factors
D001647:Bile Acids and Salts; D004040:Dietary Carbohydrates; D005232:Fatty Acids, Volatile; D013261:Sterols; D013213:Starch