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Background: Increased consumption of non-digested, non-absorbed substrates, such as dietary fibre, can lead to an increase in colonic transit rate and stool output. The effects of dietary fibre and olestra on the consistency and water content of digesta residue within the large bowel were not known. Aim: The aim of this study was to determine the effects of dietary fibre and olestra on regional dehydration and apparent viscosity of digesta residue throughout the large bowel. Methods: Seventy-eight pigs were fed diet alone (control) or supplemented with 40 g/day or 80 g/day dietary fibre or olestra and sacrificed 24, 48, 96 or 192 h after initiation of dosing. The large bowel was removed, divided into 13 segments, and the digesta residue/stool was analysed for apparent viscosity (peak force for extrusion) and percentage water content. Results: In control animals, digesta residue occurred as a continuum, from liquid in the cecum (87.9% water) to solid in the rectum (71.5% water). The relatively small decrease in percentage water content (16.4%) resulted in a marked increase in mean apparent viscosity (liquid = 87 g peak force; solid=3919 g peak force). Dietary fibre increased the percentage water content of digesta residue throughout the large bowel. In contrast, olestra decreased the percentage water content of digesta residue in the mid and distal large bowel. At 40 g/day, dietary fibre showed a significant (P

The aim of this study was to determine the effects of olestra and sorbitol consumption on three accepted objective measures of diarrhea (stool output >250 g/day, liquid/watery stools, bowel movement frequency >3/day), and how stool composition influences reports of common gastrointestinal symptoms. A double-blind, placebo-controlled study compared the effects of sorbitol (40 g/day in candy), a poorly absorbed sugar-alcohol with known osmotic effects, with those of olestra (20 or 40 g/day in potato chips), a nonabsorbed fat, on objective measures of stool composition and GI symptoms. Sixty-six subjects resided on a metabolic ward for 12 days: 2 days lead-in, 4 days baseline, 6 days treatment. Sorbitol 40 g/day resulted in loose/liquid stools within 1-3 h of consumption. In contrast, olestra resulted in a dose-responsive stool softening effect after 2-4 days of consumption. Subjects reported "diarrhea" when mean stool apparent viscosity (peak force (PF), g) decreased from a perceived "normal" (mean +/- SE, 1355 +/- 224 g PF; firm stool) to loose (260 +/- 68 g PF) stool. Mean apparent viscosity of stool during treatment: placebo, 1363 +/- 280 g (firm); olestra 20 g/day 743 +/- 65 g (soft); olestra 40 g/day, 563 +/- 105 g (soft); and sorbitol 40 g/day, 249 +/- 53 g (loose). Of the 1098 stool samples collected, 38% (419/1098) were rated by subjects as "diarrhea," yet only 2% of treatment days (all in the sorbitol treatment group) met commonly accepted criteria for a clinical diarrhea. Sorbitol, but not olestra, increased the severity of abdominal cramping, urgency and nausea compared to placebo. Olestra consumption, at levels far in excess of normal snacking conditions, resulted in a gradual stool softening effect after several days of consumption, did not meet any of the three objective measures of diarrhea, and did not increase GI symptoms. Sorbitol consumption, at only 80% of the dose requiring a "laxative effect" information label, resulted in rapid onset loose/liquid stools and a significant increase in abdominal cramping, urgency and nausea. Overall, subjects categorized stool as "diarrhea" when stool decreased from their perceived "normal," but the vast majority of these reports were not associated with clinically significant diarrhea.

Background: Stool softening is a physician’s first step in the management of chronic constipation. Aim: To compare stool softening (stool water content) and laxative efficacy of psyllium hydrophilic mucilloid vs. docusate sodium. Methods: The multi-site, randomized, double-blind, parallel-design study of 170 subjects with chronic idiopathic constipation involved a 2-week baseline (placebo) phase followed by 2 weeks of treatment. The treatment phase compared psyllium (5.1 g b.d.) plus docusate placebo to docusate sodium (100 mg b.d.) plus psyllium placebo. Stools were collected and assessed. Results: Compared to baseline, psyllium increased stool water content vs. docusate (psyllium 2.33% vs. docusate 0.01%, P = 0.007). Psyllium also increased stool water weight (psyllium 84.0 g/BM; docusate 71.4 g/BM; P = 0.04), total stool output (psyllium 359.9 g/week; docusate 271.9 g/week; P = 0.005), and O’Brien rank-type score combining objective measures of constipation (psyllium 475.1; docusate 403.9; P = 0.002). Bowel movement (BM) frequency was significantly greater for psyllium (3.5 BM/week) vs. docusate (2.9 BM/week) in treatment week 2 (P = 0.02), with no significant difference (P > 0.05) between treatment groups in treatment week 1 (3.3 vs. 3.1 BM/week). Conclusion: Psyllium is superior to docusate sodium for softening stools by increasing stool water content, and has greater overall laxative efficacy in subjects with chronic idiopathic constipation.

Increased consumption of non-digested, non-absorbed substrates, such as dietary fibre, can lead to an increase in colonic transit rate and stool output. The effects of dietary fibre and olestra on the consistency and water content of digesta residue within the large bowel were not known.The aim of this study was to determine the effects of dietary fibre and olestra on regional dehydration and apparent viscosity of digesta residue throughout the large bowel.Seventy-eight pigs were fed diet alone (control) or supplemented with 40 g/day or 80 g/day dietary fibre or olestra and sacrificed 24, 48, 96 or 192 h after initiation of dosing. The large bowel was removed, divided into 13 segments, and the digesta residue/stool was analysed for apparent viscosity (peak force for extrusion) and percentage water content.In control animals, digesta residue occurred as a continuum, from liquid in the cecum (87.9% water) to solid in the rectum (71. 5% water). The relatively small decrease in percentage water content (16.4%) resulted in a marked increase in mean apparent viscosity (liquid = 87 g peak force; solid=3919 g peak force). Dietary fibre increased the percentage water content of digesta residue throughout the large bowel. In contrast, olestra decreased the percentage water content of digesta residue in the mid and distal large bowel. At 40 g/day, dietary fibre showed a significant (P0.05) digesta residue/stool softening effect for all time points, beginning at 24-h (single dose). Olestra 40 g/day did not significantly soften digesta residue/stool until 48 h (2 doses, P0.05), and was not different from control at 96 h. At 80 g/day, both dietary fibre and olestra significantly (P0.01) softened digesta residue/stool at all time points. There were no liquid or oily stools at any dose or time-point.Relatively small changes in water content result in large changes in digesta residue/stool apparent viscosity. Dietary fibre increased digesta residue/stool water content throughout the bowel, resulting in softer digesta residue/stool. In contrast, olestra decreased stool water content, yet had a similar stool softening effect compared to dietary fibre.

The aim of this study was to characterize propagating contractions in the unprepared colon of freely ambulating mini pigs. A telemetric method was used to record colonic motility continuously for six consecutive days in a 40-cm segment of proximal colon. Propagating contractions occurred over a wide range of propagation rates (0.4-16.7 cm/sec), peak amplitudes (10-116 mm Hg) and pressure wave durations (5.3-40.0 sec). Propagating contractions were divided into two groups by duration and wave-form: short-duration symmetrical and long-duration asymmetrical. Short-duration (7.8 +/- 0.9 sec) symmetrical wave-from propagating contractions exhibited a higher frequency (27.9 +/- 2.6 events/day), more rapid propagation rate (3-16.7 cm/sec; mean +/- SEM: 4.9 +/- 1.7 cm/sec), and a lower peak amplitude (31.2 +/- 0.9 mm Hg) compared to long-duration (19.2 +/- 5.1 sec) asymmetrical propagating contractions, which were less frequent (6.1 +/- 0.7 events/day), slower in propagation rate (0.4-2 cm/sec; mean +/- SEM: 1.5 +/- 0.7 cm/sec), and higher in peak amplitude (51.6 +/- 2.4 mm Hg). The results show that propagating contractions occur over a wide spectrum, from short-duration, low-amplitude, rapidly propagating contractions to long-duration, high-amplitude, slowly propagating contractions.

The aim of this study was to determine how bulk fibers and calcium docusate affect regional dehydration and digesta viscosity throughout the large intestine. Fifty-two pigs were fed a chow diet supplemented with a bulk laxative, placebo, or calcium docusate for three days, after which the pigs were sacrificed and the contents of the large bowel were analyzed. Digesta occurred as a continuum from liquid (cecum, 91.2% water content) to solid (rectum, 70.5% water content). The observed 20.7% difference in water content resulted in a 240-fold increase in viscosity. Half of this water is reabsorbed in the first 18% of the large bowel length where viscosity remains relatively low. Compared to placebo, calcium docusate and calcium polycarbophil had no significant effect on digesta water content or viscosity, polycarbophil exhibited significantly (P0.05) lower digesta viscosity in three bowel segments, and psyllium exhibited significantly (P0.01) lower viscosity in six bowel segments and higher water content in nine bowel segments. In conclusion, the majority of digesta dehydration occurs early in the proximal large bowel, while the greatest increases in viscosity occur in the distal bowel. Relatively small decreases in digesta water content result in large increases in digesta viscosity. Psyllium, and to a lesser extent polycarbophil, are able to resist dehydration, resulting in a softer digesta.

Regulation of colon function depends on the location of nerve cell bodies and the distribution of intrinsic nerve fibers in the myenteric plexus. The morphology and projections of myenteric neurons through colonic fiber bundles in cat colon were determined using in vivo retrograde transport of HRP and Fast blue. Myenteric neurons were found to project from at least 5 to 59 mm orad (mean: 42 mm) or aborad (mean: 54 mm) through colonic fiber bundles. Approximately 73% of labelled cells were in ganglia within 2.8 mm of colonic fiber bundles in the axis of circular muscle fibers; none was beyond 7.7 mm. There were 2 soma morphologies. One type (Dogiel type I) had a mean soma diameter of 40.5 μm and had a rough somal surface. There were few if any short, broad dendrites, but its one long process extended to a branch point of an adjacent colonic fiber bundle. The other type (Dogiel type III) had a mean soma diameter of 26.4 μm, had a smooth somal surface and had few if any fine dendrites. It also projected a single long axon to colonic fiber bundles. There were twice as many Dogiel type III neurons. We conclude that myenteric neurons in the cat colon project both orad and aborad over relatively long distances through colonic fiber bundles where they form another intrinsic neuronal connection for the myenteric plexus.