ISMNT News #35. We all are looking forward to any progress made in the field of colon cancer prevention. A step in the right direction could be the finding that bacterial metabolism and associated compounds favouring cancer can be influenced by the type of starch consumed. The paper shows that during a high resistant-starch (amylomaize starch) diet, the critical fecal concentrations of total neutral sterols decreased by 30% and concentrations of 4-cholesten-3-one decreased by 36%.

The key reference is by:

Hylla S, Gostner A, Dusel G, Anger H, Bartram HP, Christl SU, Kasper H, Scheppach W

Department of Medicine, University of Wurzburg, Germany

Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention.

Am J Clin Nutr 1998 Jan;67(1):136-142

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.