Fecal bile acid excretion and composition in response to changes in dietary wheat bran, fat and calcium in the rat

Borum, Marie L.; Shehan, Kathleen L.; Fromm, Hans; Jahangeer, Saleem; Floor, Marianne; Alabaster, Oliver

doi:10.1007/bf02535579

Cited by 16 publications

(12 citation statements)

References 49 publications

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“…The results of our study are not consistent with this hypothesis and suggest that high fat levels in a diet do not consistently promote the growth of the colonic mucosa or enhance the production of bile acids in rats. Other authors have reported results consistent with ours, indicating that high-fat diets, despite the promotion of colonic cancer, do not increase bile acid concentrations (9,17) in the colonic contents of rats or increase mucosal growth (measured by cell proliferation) (26,27,52).…”

Section: Introductionsupporting

confidence: 87%

“…These secondary bile acids may be the mechanism by which dietary fat promotes the growth of the colonic mucosa, thus enhancing the development of colonic neoplasia (59). Other studies, however, have failed to show that high-fat diets elevate colonic bile acid concentration (9,17) in rats or increase epithelial cell proliferation in the colon (26,27,31,52). Other bacterial metabolites, such as ammonia and polyamines, have also been implicated in influencing mucosal growth (33,56).…”

Section: Introductionmentioning

confidence: 99%

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The Interactions of Diet and Colonic Microflora in Regulating Colonic Mucosal Growth

et al. 1996

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The colonic mucosa can adapt its growth to alterations in diet. Metabolites from colonic microflora are frequently implicated as the primary factor in mediating the colonic mucosal response to diet; however, there is also evidence indicating that diet may have a direct effect in mediating this response. The aim of this study was to determine the role of diet, microflora, and microflora metabolites in altering the growth of the colonic mucosa. Two 28-day feeding studies were conducted using Sprague-Dawley rats. The first study compared the growth of the colonic mucosa in germ-free and conventional rats fed 6 different diets. The second study compared the growth of the colonic mucosa to the concentration of bacterial-derived short-chain fatty acids (SCFAs), bile acids, and ammonia. The diets that were fed consisted of (1) AIN-76a diet without dietary fiber; (2) standard AIN-76a diet, which contained 5% cellulose; (3) AIN-76a diet with 5% guar gum; (4) a "Western" human diet with 20% fat and 10% cellulose; (5) AIN-76a diet formulated to mimic Diet 4 in fat content but with 2.5% cellulose; and (6) Purina Rodent Chow. Quantitative volumetric and stereologic analysis was used to assess changes in total colonic mucosal volume as a measure of mucosal growth. In germ-free rats, Diets 2-4 and 6 induced a significant increase (18-38%) in mucosal volume compared to Diet 1. In conventional animals, only Diets 4 and 6 induced a significant increase (up to 63%) in mucosal volume compared to Diet 1. Relative to the germ-free animals, only conventional animals on Diets 4 and 6 had an increase in mucosal volume. The increases in mucosal volume in Diets 4 and 6 were not consistently associated with increased SCFAs, ammonia, or bile acids. There was a wide range in the colonic concentrations of SCFAs (2-fold), ammonia (6-fold), and bile acids (10-fold). The presence of colonic microflora in and of itself does not lead to enhanced colonic mucosal growth. Rather, there are unique interactions between specific types of diet and microflora that lead to a growth-promoting effect. This effect could not be explained by alterations in the concentration of SCFAs, ammonia, or bile acids in colonic contents.

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Section: Introductionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

The Interactions of Diet and Colonic Microflora in Regulating Colonic Mucosal Growth

et al. 1996

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“…These enzymic activities were assayed on whole colonic contents; taking the fecal wet weight into account (table 3), their estimated total output was also reduced. Our results are consistent with the hypothesis that dietary fibre may be beneficial to the colonic mucosa by depressing bacterial enzyme levels [9], In agreement with work by others, this study also 254 Gestel/Besançon/Rouanet Rice Bran Feeding and Rat Colon shows that dietary WB is associated with a sig nificant increase in faical bile acid excretion [22][23][24][25] and additionally that RB triggers off a greater bile acid excretion. The mechanism of such an increased excretion may be bile acid binding to fibre [26,27], However, bile acid may also bind to bacteria which could account for the increased bile acid excretion [28].…”

Section: Discussionsupporting

confidence: 81%

Comparative Evaluation of the Effects of Two Different Forms of Dietary Fibre (Rice Bran vs. Wheat Bran) on Rat Colonic Mucosa and Fæcal Microflora

Gestel

Besançon²,

Rouanet³

1994

Ann Nutr Metab

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The aim of the study was to compare the physiological consequences of two dietary fibre sources on the fæcal microflora and colonic mucosal growth in rats. The studied sources, a moderately well-soluble fibre (rice bran, RB) and a less well-soluble fibre (wheat bran, WB), were included in diets of rats at a level of 10% for 3 weeks and compared with a totally fibre-deprived diet. RB significantly increased fæcal water compared to the control diet (p < 0.05). Fæcal nitrogen content and bacterial mass, as estimated from the 2,6-diaminopimelic acid (DAPA) output, were greatly and significantly increased by RB, and to a lesser extent by WB, compared to the control diet. Total bile acid excretion was significantly higher by rats fed RB than by those fed WB. Fæcal bacterial enzyme activities tested (β-glucuronidase, mucinase and nitroreductase) were significantly reduced by the two different fibre sources, but RB was more effective than WB, except for nitroreductase activity which was reduced at the same level for each fibre source. Although measurements of mucosal colonic weight and RNA content were significantly different between groups fed RB and WB (p < 0.05), DNA content and the ratio RNA/ DNA did not significantly differ between these groups. Our results indicate that the differential changes observed in β-glucuronidase and mucinase activities and DAPA and bile acid excretion may depend on the nature of the fibre consumed. They also suggest that RB, which had similar effects, sometimes more marked than WB, on the studied parameters, may be a new valuable fibre source.

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“…This is again consistent with the study by MaziyaDixon et al (23), who found total daily bile acid excretion was greater in the whole wheat groups, compared to the refined wheat groups. Diets high in wheat bran have been associated with greater bile acid excretion (24)(25)(26)(27). The greater bile acid Values as means ± SEM.…”

Section: Discussionmentioning

confidence: 99%

Wheat Color (Class), Not Refining, Influences Colon Cancer Risk in Rats

Buescher

Gallaher

2014

Nutrition and Cancer

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Epidemiological studies suggest whole grain consumption is associated with decreased colon cancer risk. However, wheat classes differ in their usage, making the influence of wheat class (red vs. white) and state of refinement (whole vs. refined) difficult to separate, leading to potential confounding. Consequently, we examined the effect of wheat class and refining on colonic precancerous lesions (aberrant crypt foci; ACF) in carcinogen-treated rats. Diets contained wheat flour as whole soft white, refined soft white, whole hard red, or refined hard red. Feeding was begun 10 days prior to carcinogen treatment and continued for 9 wk. Hard red-fed groups had significantly fewer ACF than soft white-fed groups (25-32% reduction, P = 0.013). However, state of refinement had no significant effect on ACF number. Cecal contents supernatant oxygen radical absorbance capacity and fecal bile acid concentration were significantly greater in whole wheat-fed groups than refined wheat-fed groups and did not correlate with ACF number (increase of 21-22%, P < 0.001 and 55-56%, P < 0.001, respectively). Consequently, wheat class, not state of refinement, appears to influence colon cancer risk, with hard red wheat protective relative to soft white wheat. Thus, epidemiological associations of reduced colon cancer risk with whole grain consumption may actually reflect different wheat classes.

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Fecal bile acid excretion and composition in response to changes in dietary wheat bran, fat and calcium in the rat

Cited by 16 publications

References 49 publications

The Interactions of Diet and Colonic Microflora in Regulating Colonic Mucosal Growth

The Interactions of Diet and Colonic Microflora in Regulating Colonic Mucosal Growth

Comparative Evaluation of the Effects of Two Different Forms of Dietary Fibre (Rice Bran vs. Wheat Bran) on Rat Colonic Mucosa and Fæcal Microflora

Wheat Color (Class), Not Refining, Influences Colon Cancer Risk in Rats

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Fecal bile acid excretion and composition in response to changes in dietary wheat bran, fat and calcium in the rat

Cited by 16 publications

References 49 publications

The Interactions of Diet and Colonic Microflora in Regulating Colonic Mucosal Growth

The Interactions of Diet and Colonic Microflora in Regulating Colonic Mucosal Growth

Comparative Evaluation of the Effects of Two Different Forms of Dietary Fibre (Rice Bran vs. Wheat Bran) on Rat Colonic Mucosa and F&aelig;cal Microflora

Wheat Color (Class), Not Refining, Influences Colon Cancer Risk in Rats

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Comparative Evaluation of the Effects of Two Different Forms of Dietary Fibre (Rice Bran vs. Wheat Bran) on Rat Colonic Mucosa and Fæcal Microflora