MODULATION OF FECAL MARKERS RELEVANT TO COLON-CANCER RISK - A HIGH-STARCH CHINESE DIET DID NOT GENERATE EXPECTED BENEFICIAL CHANGES RELATIVE TO A WESTERN-TYPE DIET

In a randomized, crossover dietary intervention study, 12 Australians (of white descent) consumed a diet typical of low-income communities i n China and an average. Australian diet so that effects on fecal marke rs thought to be relevant to colon cancer risk could be compared. The Chinese diet contained 35.3 g starch/MJ daily [including 2 g resistant starch (RS)/MJ and 1.5 g nonstarch polysaccharides (NSPs)/MJ]: the Au stralian diet contained 12 g starch/MJ daily (including 0.8 g RS and 2 .7 g NSPs/MJ). Subjects followed each diet for 3 wk. Serum cholesterol concentrations were significantly lower after the low-fat, high-starc h Chinese diet than after the Australian diet ((x) over bar +/- SEM: 4 .17 +/- 0.30 compared with 5.04 +/- 0.28 mmol/L, respectively, P < 0.0 5), a difference indicative of dietary compliance. Fecal pH was lower after the Chinese diet (6.51 +/- 0.04) than after the Australian diet (6.63 +/- 0.05, P < 0.05). For all other fecal markers examined. howev er, the Chinese diet produced less favorable changes, including lower fecal bulk (86 +/- 11 compared with 141 +/- 20 g wet wt/d, P < 0.01). slower transit through the gut (69 +/- 6 compared with 56 +/- 7 h, P = 0.06), lower fecal concentrations of short-chain fatty acids [72.8 +/ - 7.3 compared with 98 +/- 7.6 mmol/L (including butyrate: 12.2 +/- 1. 3 compared with 18.4 +/- 2.3 mmol/L), P < 0.05]. and higher fecal conc entrations of potentially damaging ammonia (540 +/- 50 compared with 4 50 +/- 40 mg/L, P < 0.01) and phenols (109.2 +/- 13.2 compared with 68 .5 +/- 12.9 mg/L, P < 0.01). These results suggest that consumption of a high-starch diet alone is insufficient to reduce the risk of develo ping colon cancer.