Effect of sun-dried raisins on bile acid excretion, intestinal transit time, and fecal weight: a dose-response study.

The effect of increasing doses of sun-dried raisins (SDR) on intestinal transit time (TT), fecal weight (FW), and fecal bile acids (FBA) was investigated in 16 healthy adults (6 men and 10 women). In three cycles of 2 weeks each, subjects consumed 84, 126, or 168 g/day of SDR. Four-day fecal collections were performed during the second week of each cycle, and TT, FW, and FBA were measured. FW (mean +/- SEM), increased from 168 +/- 14 g/day without raisins (cycle 1), with a TT of 54 +/- 6 hours, to 200 +/- 24 g/day with 168 g/day raisins (cycle 4), with a TT of 42 +/- 6 hours. Intermediate increases in FW and decreases in TT were observed for cycles 2 and 3. A physiologically meaningful decrease in TT (less than 2 days), to 44 +/- 6 hours, was reached at cycle 2 (not statistically significant). FBA, a possible indicator of colon cancer risk, showed a significant decrease, from 1.00 +/- 0.18 mg/g wet feces at baseline to 0.38 +/- 0.07 mg/g in cycle 2 (P <.005), and remained low in cycles 3 and 4. Major decreases were observed in cycle 2 for fecal lithocholic (P <.02), deoxycholic (P <.002), chenodeoxycholic, and cholic acids, and their concentrations remained low in cycles 3 and 4. Two servings of raisins per day (84 g/day), a relatively small change in diet, can cause beneficial changes in colon function and may decrease the risk for colon cancer.