Prevention of colonic aberrant crypt foci and modulation of large bowel microbial activity by dietary coffee fiber, inulin and pectin |
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Authors: | Rao CV; Chou D; Simi B; Ku H; Reddy BS |
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Institution: | Chemoprevention Program, American Health Foundation, Valhalla, NY 10595, USA. |
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Abstract: | The present experiments were aimed at developing novel dietary fibers to
aid in reduction of colon cancer risk. We assessed the effects of coffee
(non-fiber fraction), coffee fiber (arabino-galactose polymer) and inulin
(oligo-fructose) in male F344 rats using formation of azoxymethane
(AOM)-induced aberrant crypt foci (ACF) in the colon as the measure of
preventive efficacy (or lack of such). At 5 weeks of age, groups of rats
were fed the AIN-76A (control) and experimental diets that contained 1%
coffee, 10% coffee fiber, 10% inulin, 10% pectin (positive control for
fiber) or 200 p.p.m. piroxicam (a known ACF inhibitor). At 7 weeks of age,
all animals were s.c injected with AOM (15 mg/kg body wt) once weekly for 2
weeks. All rats were killed 8 weeks after the last AOM injection and ACF
were counted. The contents of the cecum were analyzed for bacterial
beta-glucuronidase activity and short-chain fatty acids (SCFAs). Dietary
administration of coffee fiber significantly suppressed AOM-induction of
colonic ACF, in terms of total number, as well as crypt multiplicity and
number of ACF/cm2 colon (P < 0.01-0.001). Inulin diet had no significant
effect on total ACF, but had reduced the number of ACF/cm2 (P < 0.05).
Whereas coffee had no effect on ACF formation, 10% pectin diet and 200
p.p.m. piroxicam significantly suppressed colonic ACF (P < 0.001) as had
been expected. A significant reduction of cecal beta-glucuronidase activity
was observed in the rats fed coffee, coffee fiber and pectin diets.
Further, coffee fiber, inulin and pectin increased cecal SCFA levels 3- to
5-fold. These results suggest that coffee fiber can prevent colon cancer
risk. Further studies are warranted to determine the full potential of this
fiber in pre-clinical efficacy studies.
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