Influence of starch fermentation on bile acid metabolism by colonic bacteria

Su, Christl; Hp, Bartram; Rückert, A; Scheppach, Wolfgang; Kasper, Heinrich

doi:10.1080/01635589509514394

Cited by 15 publications

(13 citation statements)

References 34 publications

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“…It is therefore more practi cal to use in vitro models to examine the metabolism of the gut flora. We have pre viously used fecal batch cultures to study the influence of starch on BA metabolism and were able to demonstrate that the production of secondary BA was substantially reduced by the addition of starch to the incubation media [19], This effect was mainly due to a pH reduction during starch fermentation, but there was also a pH-independent inhibition of 7a-dehydroxylation which could not readily be explained. Batch cultures are relatively Bile Acid Metabolism by Colonic Bacteria in Continuous Culture simple models to study the metabolism of the colonic flora.…”

Section: Discussionmentioning

confidence: 98%

“…BA were measured by a method published by Red dy et al [20] with minor modifications as previously described [ 18,19], Two-milliliter samples were sapon ified with 10 A NaOH inethanol:w ater(3:l)by reflux ing on a heater for 1 h. Nordeoxycholic acid was added to the samples as an internal standard. After extraction of the non-sapon¡liable fraction with hexane, the Methods Schcppach/Kaspor aqueous phase was hydrolyzed by autoclaving at 100 kPa for 3 h with 10 N NaOH.…”

Section: Ba Measurementmentioning

confidence: 99%

“…Dietary fiber has been shown to reduce fecal concentrations of sec ondary BA, an effect which was mostly attrib uted to the bulking effect of fiber [15][16][17], Malabsorbed starch, however, may act in a different way. In a previous study, we have shown in healthy volunteers that during acarbose-induced starch malabsorption, less sec ondary BA were excreted in feces whereas total BA excretion remained unchanged [18], In an in vitro study using fecal batch cultures, degradation of primary to secondary BA was inhibited when starch was present in the me dia [19], To study the mechanisms of this inhibition, we have now measured BA metab olism in continuous cultures of mixed fecal bacteria. Bacteria were grown either in starch free media or with starch enrichment and at different pH values.…”

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confidence: 99%

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Bile Acid Metabolism by Colonic Bacteria in Continuous Culture: Effects of Starch and pH

Su¹,

Hp²,

Paul³

et al. 1997

Ann Nutr Metab

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Secondary bile acids (BA) have been shown to be involved as a promoting agent in the adenoma-carcinoma sequence of colorectal cancer. In previous studies, fermentation of starch has been shown to inhibit the degradation of primary to secondary BA by the colonic microflora. This study was designed to investigate BA metabolism in continuous cultures of mixed fecal bacteria to get further insights into the mechanisms of this inhibition. Fermentation vessels were fed with media containing cholic (0.6 g/l) and chenodeoxycholic acid (0.4 g/l). Cultures were either starch-free or enriched with starch (10 g/ 1). pH was controlled and adjusted to 7.0 or 6.0. Total culture duration was 28 days and concentrations of BA, short-chain fatty acids (SCFA), and starch were measured periodically. At pH 6, significantly more primary BA remained in the media and less secondary BA were produced. Total BA concentrations were lower at pH 7. SCFA concentrations were higher in the vessels supplemented with starch. Starch was completely fermented and not present in significant amounts in any fermentation vial after the first week. These data indicate that bacterial breakdown of primary to secondary BA is inhibited when starch is simultaneously fermented. This effect can be explained by the reduction of pH resulting from SCFA production. Considering these findings, resistant starch which escapes assimilation in the small bowel may be a protective factor against colorectal cancer.

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Section: Discussionmentioning

confidence: 98%

Section: Ba Measurementmentioning

confidence: 99%

mentioning

confidence: 99%

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Bile Acid Metabolism by Colonic Bacteria in Continuous Culture: Effects of Starch and pH

Su¹,

Hp²,

Paul³

et al. 1997

Ann Nutr Metab

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“…The authors speculated that RS consumption decreases colonic proliferation as a result of the decreased formation of cytotoxic deoxycholic acids, possibly mediated through acidi®cation of the large bowel through production of short-chain fatty acids. In a recent in vitro study, the effect of starch fermentation on bile acid metabolism by colonic bacteria was investigated (Christl et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

Retrograded high-amylose corn starch reduces cholic acid excretion from the small bowel in ileostomy subjects

Ekwall

Björck

et al. 1998

Eur J Clin Nutr

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Objective: To study the short-term effect of resistant starch (RS) from retrograded high-amylose corn starch (HACS) on the excretion of bile acids and nutrients from the small bowel in humans. Design: Seven healthy ileostomists were given a controlled, constant diet during three days. On days 2 and 3, 100 g/d of one of two test-productsÐdrum-dried ordinary corn starch and autoclaved retrograded HACS, providing 5 and 39 g RS/d, respectivelyÐwas given, in random order. Ileostomy ef¯uents were collected for 24 h per day and analysed for wet weight, dry weight, energy, bile acids and nutrients. Settings: In-patient study at the metabolic ward, Department of Clinical Nutrition, Sahlgrenska University Hospital, Go Èteborg. Results: Consumption of retrograded HACS caused (1) a 42% lower mean excretion of cholic acid (P 0.024); (2) a 42% lower mean wet weight concentration of bile acids (P`0.001); (3) a 70% increased excretion of dry weight (P 0.001); and (4) a 41% increased excretion of energy (P 0.036) compared with consumption of drum-dried ordinary corn starch. Conclusion: The reduced ileal excretion and concentration of cholic acid would be protective regarding colon cancer risk in addition to the increased fermentation substrate provided by RS and other energy-yielding components.

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“…The H91 diet especially increased the cecal Lactobacillus and total anaerobe populations. Furthermore, it has been suggested that a lowering of cecal pH by the fermentation of starch prevents the degradation of bile acid to cocarcinogenic agents active in the large bowel [10] or in a culture system [27,28] . Secondary bile acids are believed to act as promoters in the adenoma-carcinoma sequence of colorectal cancer [7,29] .…”

Section: Discussionmentioning

confidence: 99%

Feeding Potato Flakes Affects Cecal Short-Chain Fatty Acids, Microflora and Fecal Bile Acids in Rats

et al. 2008

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Background/Aims: Feeding rats potato resistant starch improves large bowel health; however, there is little information on the physiological effects of preprocessed starch like potato flakes in animal experiments. The present study was designed to investigate the effects of the consumption of various colored potato (white, red and purple) flakes on cecal fermentation and fecal bile acid excretions in rats. Methods: The control group was fed a basal diet (BD) containing α-cornstarch for 4 weeks. The potato flake-treated groups were fed one of the following diets containing a mixture of 299.5 g/kg α-cornstarch plus 250 g/kg Hokkai kogane flakes (HK, white), Hokkai No. 91 flakes (H91, red) or Hokkai No. 92 flakes (H92, purple). Results: There were no significant differences in the body weight, food intake and cecum weight among the groups. Cecal pH values in the HK, H91 and H92 groups were significantly lower than that in the BD group, and matter excretion in the H91 group was significantly higher than in the BD and HK groups. Cecal short-chain fatty acid (SCFA) concentrations in the HK, H91 and H92 groups were significantly higher than in the BD group, and the molar ratio of butyrate to total SCFA in the HK, H91 and H92 groups was greatly increased compared with the BD group. Rats fed the HK, H91 and H92 potato flake diets presented significantly higher counts of total anaerobes in the cecum than rats fed the BD. The cecal Lactobacillus count in the H91 group was significantly increased compared to the BD group and the Bifidobacterium count was similar for all groups. Fecal total bile acid excretion in the H92 flake group and secondary bile acid excretions in the H91 and H92 groups were significantly greater than those in the other groups and in the BD and HK groups, respectively. Conclusion: The results indicate that potato flakes act like resistant starch and raise bowel SCFA, probably through anaerobic bacterial activities and fermentation of residual starch. These actions are helpful for the improvement of the colonic environment.

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Influence of starch fermentation on bile acid metabolism by colonic bacteria

Cited by 15 publications

References 34 publications

Bile Acid Metabolism by Colonic Bacteria in Continuous Culture: Effects of Starch and pH

Bile Acid Metabolism by Colonic Bacteria in Continuous Culture: Effects of Starch and pH

Retrograded high-amylose corn starch reduces cholic acid excretion from the small bowel in ileostomy subjects

Feeding Potato Flakes Affects Cecal Short-Chain Fatty Acids, Microflora and Fecal Bile Acids in Rats

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