Increasing butyrate concentration in the distal colon by accelerating intestinal transit.
BACKGROUND
Populations at low risk of colonic cancer consume large amounts of fibre and starch and pass acid, bulky stools. One short chain fatty acid (SCFA), butyrate, is the colon's main energy source and inhibits malignant transformation in vitro.


OBJECTIVE
To test the hypothesis that altering colonic transit rate alters colonic pH and the SCFA content of the stools.


METHODS
Thirteen healthy adults recruited by advertisement.


METHODS
Volunteers consumed, in turn, wheat bran, senna and loperamide, each for nine days with a two week washout period between study periods, dietary intake being unchanged. Before, and in the last four days of each intervention, whole gut transit time (WGTT), defaecation frequency, stool form, stool beta-glucuronidase activity, stool pH, stool SCFA concentrations and intracolonic pH (using a radiotelemetry capsule for continuous monitoring) were assessed.


RESULTS
WGTT decreased, stool, output and frequency increased with wheat bran and senna, vice versa with loperamide. The pH was similar in the distal colon and stool. Distal colonic pH fell with wheat bran and senna and tended to increase with loperamide. Faecal SCFA concentrations, including butyrate, increased with senna and fell with loperamide. With wheat bran the changes were non-significant, possibly because of the short duration of the study. Baseline WGTT correlated with faecal SCFA concentration (r = -0.511, p = 0.001), with faecal butyrate (r = -0.577, p < 0.001) and with distal colonic pH (r = 0.359, p = 0.029).


CONCLUSIONS
Bowel transit rate is a determinant of stool SCFA concentration including butyrate and distal colonic pH. This may explain the inter-relations between colonic cancer, dietary fibre intake, stool output, and stool pH.
Lewis
S J
SJ
University Department of Medicine, Bristol Royal Infirmary, UK.
Heaton
K W
KW
D000328:Adult; D000930:Antidiarrheals / Q000494:pharmacology; D002087:Butyrates / Q000378:metabolism*; D020148:Butyric Acid; D002400:Cathartics / Q000494:pharmacology; D003106:Colon / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D004043:Dietary Fiber / Q000008:administration & dosage*; D005232:Fatty Acids, Volatile / Q000032:analysis*; D005243:Feces / Q000737:chemistry*; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D005966:Glucuronidase / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008139:Loperamide / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D012676:Senna Extract / Q000494:pharmacology; D013686:Telemetry; D014908:Triticum
D000930:Antidiarrheals; D002087:Butyrates; D002400:Cathartics; D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D020148:Butyric Acid; D008139:Loperamide; D012676:Senna Extract; D005966:Glucuronidase