Guest guest Posted November 24, 2004 Report Share Posted November 24, 2004 It seems to me that insoluble fiber (bran category) carries the most protection from colon cancer, while soluble fiber (guar category) provides minimal protection (if any). Do you think the following studies are saying the same thing? http://snipurl.com/av7v PMID: 8759370 Dietary guar gum alters colonic microbial fermentation in azoxymethane-treated rats. Our results show that patterns of short-chain fatty acid production may affect the results of fiber-carcinogenesis experiments. Dietary addition of hydrolyzed guar is associated with fecal fermentation low in propionate and high in butyrate; short-chain fatty acid concentrations are greater proximally than distally. These results suggest that butyrate protects against colonic neoplasia, whereas propionate enhances it, and demonstrate that colonic microbiota adapt to produce more butyrate if given time and the proper substrate. ~~~~~~~~~~ http://snipurl.com/av7z PMID: 8386131 Butyrate production from dietary fibre and protection against large bowel cancer in a rat model. These findings indicate that fibre which is associated with high butyrate concentrations in the distal large bowel is protective against large bowel cancer, while soluble fibres that do not raise distal butyrate concentrations, are not protective. Thus, butyrate production in vivo does bear a significant relationship to suppression of tumour formation. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 24, 2004 Report Share Posted November 24, 2004 Hi Apricot: Yes. My impression is the same. But ................. " Slow-release pellets of sodium butyrate do not modify azoxymethane (AOM)-induced intestinal carcinogenesis in F344 rats. Caderni G, Luceri C, De Filippo C, Salvadori M, Giannini A, Tessitore L, Dolara P. Department of Pharmacology of the University of Florence, Viale G. Pieraccini, 6, 50139, Florence, Italy. gioca@... Butyrate exerts anti-tumour effects in vitro, but not consistently in vivo. We previously demonstrated that the administration of slow- release gastro-resistant pellets of sodium butyrate increases apoptosis in the colon mucosa of rats, an effect which may protect against carcinogenesis. Therefore, we studied whether the administration of butyrate pellets could protect rats against experimental colon carcinogenesis. Four to 5 week old male F344 rats were fed a high-fat (HF) diet (230 g/kg corn oil w/w) and treated s.c. with two injections (one week apart) of azoxymethane (AOM) at a dose rate of 15 mg/kg body weight or saline. Rats were then divided into two groups: one group received sodium butyrate pellets mixed into the diet (1.5% w/w) for 33 weeks (150 mg butyrate/day) and the second group received the high-fat diet with no butyrate. Administration of sodium butyrate pellets in the diet did not significantly affect colon carcinogenesis: the number of intestinal tumours/rat was 1.6 +/- 0.2 in controls and 2.1 +/- 0.2 in butyrate- fed rats (means +/- SE; P = 0.22, by ANOVA), while the incidence of intestinal tumours was 79 (23/29) and 90% (27/30) in controls and in butyrate-fed rats, respectively (P = 0.29 by Fisher's exact test). The level of apoptosis in the tumours was not affected by butyrate, nor was the expression of p21(CIP), a cell cycle-related protein. In conclusion, the current study indicates that butyrate does not protect against AOM-induced colon carcinogenesis in rats. PMID: 11238196 [PubMed - indexed for MEDLINE] " So who knows? Rodney. --- In , apricot85 <apricot85@a...> wrote: > It seems to me that insoluble fiber (bran category) carries the most > protection from colon cancer, while soluble fiber (guar category) > provides minimal protection (if any). Do you think the following > studies are saying the same thing? > > http://snipurl.com/av7v PMID: 8759370 > Dietary guar gum alters colonic microbial fermentation in > azoxymethane-treated rats. > > Our results show that patterns of short-chain fatty acid production may > affect the results of fiber-carcinogenesis experiments. Dietary addition > of hydrolyzed guar is associated with fecal fermentation low in > propionate and high in butyrate; short-chain fatty acid concentrations > are greater proximally than distally. These results suggest that > butyrate protects against colonic neoplasia, whereas propionate enhances > it, and demonstrate that colonic microbiota adapt to produce more > butyrate if given time and the proper substrate. > ~~~~~~~~~~ > http://snipurl.com/av7z PMID: 8386131 > Butyrate production from dietary fibre and protection against large > bowel cancer in a rat model. > > These findings indicate that fibre which is associated with high > butyrate concentrations in the distal large bowel is protective against > large bowel cancer, while soluble fibres that do not raise distal > butyrate concentrations, are not protective. Thus, butyrate production > in vivo does bear a significant relationship to suppression of tumour > formation. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 24, 2004 Report Share Posted November 24, 2004 Hi Apricot: So, if bran truly is beneficial, PERHAPS it is not the butyrate that is responsible? But also, did not one Harvard study from about a year ago show no relationship between 'fiber' and colon cancer? So, whatever it is we decide to do, it is in the nature of placing bets, I think. Hopefully, fifty years from now we will have more consistent evidence. By which time some of us will be 112, and still arguing about it here. Rodney. > > It seems to me that insoluble fiber (bran category) carries the > most > > protection from colon cancer, while soluble fiber (guar category) > > provides minimal protection (if any). Do you think the following > > studies are saying the same thing? > > > > http://snipurl.com/av7v PMID: 8759370 > > Dietary guar gum alters colonic microbial fermentation in > > azoxymethane-treated rats. > > > > Our results show that patterns of short-chain fatty acid production > may > > affect the results of fiber-carcinogenesis experiments. Dietary > addition > > of hydrolyzed guar is associated with fecal fermentation low in > > propionate and high in butyrate; short-chain fatty acid > concentrations > > are greater proximally than distally. These results suggest that > > butyrate protects against colonic neoplasia, whereas propionate > enhances > > it, and demonstrate that colonic microbiota adapt to produce more > > butyrate if given time and the proper substrate. > > ~~~~~~~~~~ > > http://snipurl.com/av7z PMID: 8386131 > > Butyrate production from dietary fibre and protection against large > > bowel cancer in a rat model. > > > > These findings indicate that fibre which is associated with high > > butyrate concentrations in the distal large bowel is protective > against > > large bowel cancer, while soluble fibres that do not raise distal > > butyrate concentrations, are not protective. Thus, butyrate > production > > in vivo does bear a significant relationship to suppression of > tumour > > formation. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 24, 2004 Report Share Posted November 24, 2004 Hi Apricot: Two studies on colon cancer, disputing supposed causes: " Prospective study of bowel movement, laxative use, and risk of colorectal cancer among women. Dukas L, Willett WC, Colditz GA, Fuchs CS, Rosner B, Giovannucci EL. Department of Nutrition, Harvard School of Public Health, Boston, MA, USA. The authors prospectively examined the association between bowel movement frequency, laxative use, and the risk of colorectal cancer in 84,577 women of the Nurses' Health Study living in the United States, 36-61 years of age and free of cancer in 1982. Between 1984 and 1996, 611 incident cases of colorectal cancer were documented. After controlling for age, body mass index, fiber intake, postmenopausal status and hormone use, physical activity, and use of laxatives, the relative risks associated with having bowel movements every third day or less, compared with those with bowel movements once daily, were 0.94 (95% confidence interval (CI): 0.69, 1.28) for colorectal cancer, 0.88 (95% CI: 0.62, 1.26) for colon cancer, and 1.18 (95% CI: 0.63, 2.20) for rectal cancer. Compared with women who never used laxatives, the multivariate relative risks associated with weekly to daily laxative use were 1.00 (95% CI: 0.72, 1.40) for colorectal cancer, 1.09 (95% CI: 0.76, 1.57) for colon cancer, and 0.68 (95% CI: 0.29, 1.57) for rectal cancer. These findings do not support an association between infrequent bowel movement, laxative use, and risk of colorectal cancer and indicate that simple questions directed at bowel movement frequency are unlikely to enhance our ability to predict colorectal cancer risk. PMID: 10853634 [PubMed - indexed for MEDLINE] " And ............................ " Dietary fiber and the risk of colorectal cancer and adenoma in women. Fuchs CS, Giovannucci EL, Colditz GA, Hunter DJ, Stampfer MJ, Rosner B, Speizer FE, Willett WC. Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. BACKGROUND: A high intake of dietary fiber has been thought to reduce the risk of colorectal cancer and adenoma. METHODS: We conducted a prospective study of 88,757 women, who were 34 to 59 years old and had no history of cancer, inflammatory bowel disease, or familial polyposis, who completed a dietary questionnaire in 1980. During a 16- year follow-up period, 787 cases of colorectal cancer were documented. In addition, 1012 patients with adenomas of the distal colon and rectum were found among 27,530 participants who underwent endoscopy during the follow-up period. RESULTS: After adjustment for age, established risk factors, and total energy intake, we found no association between the intake of dietary fiber and the risk of colorectal cancer; the relative risk for the highest as compared with the lowest quintile group with respect to fiber intake was 0.95 (95 percent confidence interval, 0.73 to 1.25). No protective effect of dietary fiber was observed when we omitted, adjustment for total energy intake, when events during the first six years of follow-up were excluded, or when we excluded women who altered their fiber intake during the follow-up period. No significant association between fiber intake and the risk of colorectal adenoma was found. CONCLUSIONS: Our data do not support the existence of an important protective effect of dietary fiber against colorectal cancer or adenoma. PMID: 9895396 [PubMed - indexed for MEDLINE] " Rodney. > > > It seems to me that insoluble fiber (bran category) carries the > > most > > > protection from colon cancer, while soluble fiber (guar category) > > > provides minimal protection (if any). Do you think the following > > > studies are saying the same thing? > > > > > > http://snipurl.com/av7v PMID: 8759370 > > > Dietary guar gum alters colonic microbial fermentation in > > > azoxymethane-treated rats. > > > > > > Our results show that patterns of short-chain fatty acid > production > > may > > > affect the results of fiber-carcinogenesis experiments. Dietary > > addition > > > of hydrolyzed guar is associated with fecal fermentation low in > > > propionate and high in butyrate; short-chain fatty acid > > concentrations > > > are greater proximally than distally. These results suggest that > > > butyrate protects against colonic neoplasia, whereas propionate > > enhances > > > it, and demonstrate that colonic microbiota adapt to produce more > > > butyrate if given time and the proper substrate. > > > ~~~~~~~~~~ > > > http://snipurl.com/av7z PMID: 8386131 > > > Butyrate production from dietary fibre and protection against > large > > > bowel cancer in a rat model. > > > > > > These findings indicate that fibre which is associated with high > > > butyrate concentrations in the distal large bowel is protective > > against > > > large bowel cancer, while soluble fibres that do not raise distal > > > butyrate concentrations, are not protective. Thus, butyrate > > production > > > in vivo does bear a significant relationship to suppression of > > tumour > > > formation. Quote Link to comment Share on other sites More sharing options...
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