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In vitro degradation and fermentation of three dietary fiber sources by human colonic bacteria

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Although clinical benefits of dietary fiber supplementation seem to depend in part on the extent of fiber degradation and fermentation by colonic bacteria, little is known about the effect of the type of supplemented fiber on bacterial metabolism. In an experiment using a non-adapted human bacterial population from three normal subjects, in vitro fermentation of guar gum (GA) was greater than that of psyllium fiber (PSY), which was greater than that of carboxymethylcellulose (CMC). In a separate experiment, in vitro fermentation of feces of 52 subjects with fecal incontinence before and after random assignment to and consumption of one of the three fiber supplements or placebo for 20-21 days showed that the fiber consumed did not increase its degradation by fecal bacteria. Findings suggest that increased intake of a fiber source by humans is not expected to result in bacterial adaptation that would require continually larger and eventually intolerable amounts of fiber.
Donna Z. Bliss , Paul J. Weimer , Hans-Joachim G. Jung , Kay Savik
USDA Scientist Submission
Journal of Agricultural and Food Chemistry 2013 v.61
Journal Articles, USDA Authors, Peer-Reviewed
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