The effect of wheat bran on intestinal transit

Chronic constipation in adults: Contemporary perspectives and clinical challenges. 2: Conservative, behavioural, medical and surgical treatment

BACKGROUND

Chronic constipation is a prevalent disorder that affects quality of life of patients and consumes resources in healthcare systems worldwide. In clinical practice, it is still considered a challenge as clinicians frequently are unsure as to which treatments to use and when. Over a decade ago, a Neurogastroenterology and Motility journal supplement devoted to the investigation and management of constipation was published (Neurogastroenterol Motil 2009;21(Suppl 2):1). In October 2018, the 3rd London Masterclass, entitled "Contemporary management of constipation" was held. The faculty members of this symposium were invited to write two reviews to present a collective synthesis of talks presented and discussions held during this meeting. The first review addresses epidemiology, diagnosis, clinical associations, pathophysiology, and investigation.

PURPOSE

The present is the second of these reviews, providing contemporary perspectives and clinical challenges regarding behavioral, conservative, medical, and surgical treatments for patients presenting with constipation. It includes a management algorithm to guide clinical practice.

Factors associated with first-line antiretroviral treatment failure in adult HIV-positive patients: a case-control study from Ethiopia

Background

Treatment failure has become a significant challenge in patients taking antiretroviral therapy (ART). The aim of the present study was to identify risk factors for first-line ART failure among patients attending clinical follow-up.

Methods

A 1:2 matched case-control study (by age, sex, and treatment duration since initiated on ART) was conducted from June 2015 to July 2017 on adult patients (aged ≥15 years) who were on ART for at least 6 months. Cases were selected from patients who were switched to second-line ART after first-line ART failure (viral load ≥1000 copies/mL). Controls were randomly selected from patients on first-line ART with viral load < 50 copies/mL. Data were collected using an interview questionnaire, reviewing chart and electronic health records and laboratory tests. Multivariate logistic regression analysis was performed to identify risk factors for treatment failure.

Results

Of the 273 patients who participated in this study, 55% were males. Ninety-one cases were compared with 182 controls. The median age of participants was 40 years and the median duration of treatment since initiated on ART was 69 months. Independent risk factors associated with first-line antiretroviral treatment failure were discontinuation of ART (adjusted odds ratio (AOR) = 9.8, 95% confidence interval (CI): 4.0–23.8), baseline CD4 lymphocyte count ≤50 cells/mm³ (AOR = 3.8, 95% CI: 1.5–9.6) and persistent diarrhea (AOR = 4.4, 95% CI: 1.5–13.2). The risk of ART failure was high and comparable whether the duration of ART discontinuation was greater or less than 1 month (crude odds ratio (COR) = 6.3 and 8. 5 respectively, p-value < 0.001). Frequent eating of a diet containing wheat or barley (AOR = 2.3, 95% CI: 0.9–5.4) showed a trend to be a risk factor for first-line ART failure (p-value = 0.064).

Conclusions

Our findings underscore the importance of avoiding ART discontinuation of any duration, early initiation of ART and diarrhea management to prevent first-line ART failure.

Chronic idiopathic constipation in adults: epidemiology, pathophysiology, diagnosis and clinical management

Chronic idiopathic constipation (CIC) is one of the most common gastrointestinal disorders, with a global prevalence of 14%. It is commoner in women and its prevalence increases with age. There are three subtypes of CIC: dyssynergic defaecation, slow transit constipation and normal transit constipation, which is the most common subtype. Clinical assessment of the patient with constipation requires careful history taking, in order to identify any red flag symptoms that would necessitate further investigation with colonoscopy to exclude colorectal malignancy. Screening for hypercalcaemia, hypothyroidism and coeliac disease with appropriate blood tests should be considered. A digital rectal examination should be performed to assess for evidence of dyssynergic defaecation. If this is suspected, further investigation with high resolution anorectal manometry should be undertaken. Anorectal biofeedback can be offered to patients with dyssynergic defaecation as a means of correcting the associated impairment of pelvic floor, abdominal wall and rectal functioning. Lifestyle modifications, such as increasing dietary fibre, are the first step in managing other causes of CIC. If patients do not respond to these simple changes, then treatment with osmotic and stimulant laxatives should be trialled. Patients not responding to traditional laxatives should be offered treatment with prosecretory agents such as lubiprostone, linaclotide and plecanatide, or the 5-HT4 receptor agonist prucalopride, where available. If there is no response to pharmacological treatment, surgical intervention can be considered, but it is only suitable for a carefully selected subset of patients with proven slow transit constipation.

Modifying wheat bran to improve its health benefits

Consumption of wheat bran (WB) has been associated with improved gastrointestinal health and a reduced risk for colorectal cancer, cardiovascular diseases and metabolic disorders. These benefits are likely mediated by a combination of mechanisms, including colonic fermentation of the WB fiber, fecal bulking and the prevention of oxidative damage due to its antioxidant capacities. The relative importance of those mechanisms is not known and may differ for each health effect. WB has been modified by reducing particle size, heat treatment or modifying tissue composition to improve its technological properties and facilitate bread making processes. However, the impact of those modifications on human health has not been fully elucidated. Some modifications reinforce whereas others attenuate the health effects of coarse WB. This review summarizes available WB modifications, the mechanisms by which WB induces health benefits, the impact of WB modifications thereon and the available evidence for these effects from in vitro and in vivo studies.

Effects of cereal fiber on bowel function: A systematic review of intervention trials

AIM

To comprehensively review and quantitatively summarize results from intervention studies that examined the effects of intact cereal dietary fiber on parameters of bowel function.

METHODS

A systematic literature search was conducted using PubMed and EMBASE. Supplementary literature searches included screening reference lists from relevant studies and reviews. Eligible outcomes were stool wet and dry weight, percentage water in stools, stool frequency and consistency, and total transit time. Weighted regression analyses generated mean change (± SD) in these measures per g/d of dietary fiber.

RESULTS

Sixty-five intervention studies among generally healthy populations were identified. A quantitative examination of the effects of non-wheat sources of intact cereal dietary fibers was not possible due to an insufficient number of studies. Weighted regression analyses demonstrated that each extra g/d of wheat fiber increased total stool weight by 3.7 ± 0.09 g/d (P < 0.0001; 95%CI: 3.50-3.84), dry stool weight by 0.75 ± 0.03 g/d (P < 0.0001; 95%CI: 0.69-0.82), and stool frequency by 0.004 ± 0.002 times/d (P = 0.0346; 95%CI: 0.0003-0.0078). Transit time decreased by 0.78 ± 0.13 h per additional g/d (P < 0.0001; 95%CI: 0.53-1.04) of wheat fiber among those with an initial transit time greater than 48 h.

CONCLUSION

Wheat dietary fiber, and predominately wheat bran dietary fiber, improves measures of bowel function.

Oats and bowel disease: a systematic literature review

Whole-grain foods such as oats may protect against colorectal cancer and have benefits on inflammatory bowel disease and coeliac disease. The present study aimed to systematically review the literature describing intervention studies that investigated the effects of oats or oat bran on risk factors for bowel disease. A literature search was conducted using Embase, Medline and the Cochrane library, which identified 654 potential articles. Thirty-eight articles describing twenty-nine studies met the inclusion criteria. Two studies carried out in participants with a history of colorectal adenomas found no effects of increased oat-bran intake on indirect risk makers for colorectal cancer. One of two interventions with oat bran in patients with ulcerative colitis showed small improvements in the patients' conditions. Most of the eleven studies carried out in adults with coeliac disease showed no negative effects of uncontaminated oat consumption. The fourteen studies carried out in volunteers with no history of bowel disease suggest that oats or oat bran can significantly increase stool weight and decrease constipation, but there is a lack of evidence to support a specific effect of oats on bowel function compared with other cereals. A long-term dietary intake of oats or oat bran could benefit inflammatory bowel disorders, but this remains to be proven. A protective effect on colorectal adenoma and cancer incidence has not yet been convincingly shown. The majority of patients with coeliac disease could consume up to 100 g/d of uncontaminated oats, which would increase the acceptability of, and adherence to, a gluten-free diet.

Fiber and functional gastrointestinal disorders

Despite years of advising patients to alter their dietary and supplementary fiber intake, the evidence surrounding the use of fiber for functional bowel disease is limited. This paper outlines the organization of fiber types and highlights the importance of assessing the fermentation characteristics of each fiber type when choosing a suitable strategy for patients. Fiber undergoes partial or total fermentation in the distal small bowel and colon leading to the production of short-chain fatty acids and gas, thereby affecting gastrointestinal function and sensation. When fiber is recommended for functional bowel disease, use of a soluble supplement such as ispaghula/psyllium is best supported by the available evidence. Even when used judiciously, fiber can exacerbate abdominal distension, flatulence, constipation, and diarrhea.

New strategies for the management of diverticular disease: insights for the clinician

Diverticulosis is one of the most common gastrointestinal conditions affecting the general population in the Western world. It is estimated that over 2.5 million people are affected by diverticular disease in the United States. The spectrum of clinical manifestations of diverticulosis ranges from asymptomatic diverticulosis to complicated diverticulitis. Treatment for symptomatic diverticular disease is largely based on symptoms. Traditional therapy includes fiber, bowel rest, antibiotics, pain control and surgery for selected cases. This review discusses recent advances in the medical treatment of diverticular disease such as the use of mesalamine, rifaximin and probiotics as our understanding of the disease evolves.

Wheat bran: its composition and benefits to health, a European perspective

Wheat bran is a concentrated source of insoluble fibre. Fibre intakes are generally lower than recommendations. This paper reviews the physiological effects of wheat bran and the health benefits it may provide in terms of the prevention of diseases such as colon and breast cancers, cardiovascular disease, obesity and gastrointestinal diseases. In recognition of the weight of evidence, the European Food Safety Authority has recently approved two health claims for wheat bran and gastrointestinal health.

Therapeutic effects of fiberform on defecation in patients after enterostomy for colorectal cancer: an analysis of 19 cases

AIM: To investigate the therapeutic effects of fiberform on defecation in patients after enterostomy for colorectal cancer.

METHODS: Nineteen patients who underwent enterostomy for colorectal cancer from January 2010 to July 2011 at our hospital were given continuous oral fiberform for 1 wk. Stool characteristics, peristomal skin appearance, and both doctor and patient satisfaction were quantitatively compared between before and after medication.

RESULTS: Fiberform could significantly improve stool frequencies and characteristics as well as peristomal skin irritations (1.09 ± 0.78 vs 2.03 ± 0.63, 4.32 ± 0.49 vs 6.01 ± 0.66, 0.44 ± 0.21 vs 1.57 ± 0.57, all P < 0.05) and was not associated with significant adverse effect during medication.

CONCLUSION: Fiberform could improve defecation status in patients after enterostomy for colorectal cancer.

Treatment of diverticular disease of the colon and prevention of acute diverticulitis: a systematic review

BACKGROUND

Diverticular disease of the colon is a common disorder, characterized by recurrent symptoms and complications such as diverticulitis, requiring hospital admissions and surgery.

OBJECTIVE

This study aimed to systematically review the evidence for medical therapy of diverticular disease in reducing symptoms and preventing acute diverticulitis.

DATA SOURCES

MEDLINE and Embase databases (1966 to February 2010).

STUDY SELECTION

The studies selected were prospective clinical trials on uncomplicated diverticular disease of the colon.

INTERVENTIONS

Four investigators independently reviewed articles, extracted data, and assessed study quality according to standardized criteria.

MAIN OUTCOME MEASURES

The main outcomes measured were improvement in symptoms, complete remission of symptoms, and prevention of acute diverticulitis.

RESULTS

We identified 31 studies, including 6 placebo-controlled trials. The methodological quality of these studies was suboptimal. Only 10 trials provided a detailed description of the patient history, 8 assessed symptoms by the use of a validated questionnaire, and 14 appropriately defined inclusion and exclusion criteria. Only one long-term double-blind placebo-controlled study was identified. This reported a significant improvement in symptoms and greater prevalence of symptom-free patients at 1 year with fiber plus rifaximin in comparison with fiber alone. The efficacy of treatment in preventing acute diverticulitis was evaluated in 11 randomized trials. Four trials compared rifaximin plus fiber vs fiber alone and failed to show a significant difference between treatments. However, cumulative data from these trials revealed a significant benefit following rifaximin and fiber (1-year rate of acute diverticulitis: 11/970 (1.1%) vs 20/690 (2.9%); P = .012), but with a number needed to treat of 57, to prevent an attack of acute diverticulitis.

LIMITATIONS

: Heterogeneity of the study design, patients' characteristics, regimens and combination of studied treatment, and outcome reporting precluded the pooling of results and limited interpretation.

CONCLUSIONS

The treatment for diverticular disease relies mainly on data from uncontrolled studies. Treatment showed some evidence of improvement in symptoms, but its role in the prevention of acute diverticulitis remains to be defined.

Systematic review: the effects of fibre in the management of chronic idiopathic constipation

BACKGROUND

Patients with chronic idiopathic constipation are often told to increase dietary fibre intake. Whether this is of any benefit remains unclear.

AIM

To conduct a systematic review of the efficacy of soluble and insoluble fibre supplementation in the management of chronic idiopathic constipation.

METHODS

MEDLINE, EMBASE, and the Cochrane central register of controlled trials were searched to identify randomised controlled trials (RCTs) comparing fibre with placebo or no therapy in adult chronic idiopathic constipation patients. Studies had to report dichotomous data assessing response to therapy, or continuous data examining either effect of therapy on mean number of stools per week, or mean symptom scores. Adverse events data were extracted where reported.

RESULTS

Six RCTs were eligible. Four used soluble fibre and two used insoluble fibre. Formal meta-analysis was not undertaken due to concern about methodological quality of identified studies. Compared with placebo, soluble fibre led to improvements in global symptoms (86.5% vs. 47.4%), straining (55.6% vs. 28.6%), pain on defaecation, and stool consistency, an increase in the mean number of stools per week (3.8 stools per week after therapy compared with 2.9 stools per week at baseline), and a reduction in the number of days between stools. Evidence for any benefit of insoluble fibre was conflicting. Adverse events data were limited, with no RCT reporting total numbers.

CONCLUSIONS

Soluble fibre may be of benefit in chronic idiopathic constipation, but data for insoluble fibre are conflicting. More data from high quality RCTs are required before the true efficacy of either fibre type in the treatment of chronic idiopathic constipation is known.

The use of a wireless motility device (SmartPill®) for the measurement of gastrointestinal transit time after a dietary fibre intervention

Historically, measurement of gastrointestinal transit time has required collection and X-raying of faecal samples for up to 7 d after swallowing radio-opaque markers; a tedious, labour-intensive technique for both subjects and investigators. Recently, a wireless motility capsule (SmartPill®), which uses gut pH, pressure and temperature to measure transit time, has been developed. This device, however, has not been validated with dietary interventions. Therefore, we conducted a controlled cross-over trial to determine whether the device could detect a significant difference in transit time after ten healthy subjects (five men and five women) consumed 9 g of wheat bran (WB) or an equal volume, low-fibre control for 3 d. A paired t test was used to determine differences in transit times. Colonic transit time decreased by 10·8 (sd 6·6) h (P = 0·006) on the WB treatment. Whole-gut transit time also decreased by 8·9 (sd 5·4) h (P = 0·02) after the consumption of WB. Gastric emptying time and small-bowel transit time did not differ between treatments. Despite encouraging results, the present study had several limitations including short duration, lack of randomisation and unusable data due to delayed gastric emptying of the capsule. With minimal participant burden, the SmartPill technology appears to be a potentially useful tool for assessing transit time after a dietary intervention. This technology could be considered for digestive studies with novel fibres and other ingredients that are promoted for gut health.

Cutoff volume of dietary fiber to ameliorate constipation in children

OBJECTIVE

To evaluate the proper ingested volume of dietary fiber for relieving constipation in children.

STUDY DESIGN

During a 3-year period, we prospectively evaluated the correlation of intake volume of dietary fiber with improvement of constipation in children. Patients were categorized into younger (3-7 years) and older (8-14 years) children. The evaluation period lasted 12 weeks. A good improvement was defined as the child exhibiting at least 60% relief of the constipation symptoms during the observation period. Freedom from constipation was observed during the last 4 weeks.

RESULTS

The study population consisted of 422 patients (213 younger, 209 older), with a mean age of 7.89 +/- 4.71 years. Baseline daily dietary fiber intake of the younger and older groups was 5.97 +/- 2.35 g and 9.83 +/- 3.51 g, respectively. 227 cases (53.8 %) showed improvement of constipation, and 49.1 % of the patients had relief of constipation. Greater intake of dietary fiber was positively associated with good improvement of constipation in both groups (P = .002, and P < .001). Cutoff volumes of daily dietary fiber intake in the relief of constipation were 10 g in the younger group and 14.5 g in the older group.

CONCLUSION

The cutoff of dietary fiber intake needed to relieve constipation increased with age, achievable in a 12-week intervention.

Enteral access options and management in the patient with intestinal failure

Intestinal failure refers to a condition in which inadequate digestion and/or absorption of nutrients leads to malnutrition and/or dehydration. Enteral access is occasionally used in patients with intestinal failure either for the purpose of providing nutrition or decompressing the gut. As a consequence, it is important that clinicians caring for these highly complex patients be knowledgeable in enteral access options and experienced in the subsequent care of these tubes. In this review, enteral access options and the potential complications associated with their use will be reviewed. Importantly, this information is relevant to both the pediatric and adult patient with intestinal failure.

Nutritional aspects in patients with functional gastrointestinal disorders and motor dysfunction in the gut. Working team report of the Swedish Motility Group (SMoG)

In reviews regarding the management of patients with functional gastrointestinal disorders and motility disturbances within the gut nutritional aspects and dietary advice is often put forward as being of great importance. However, there are relatively few high-quality, interventional studies in the literature supporting an important role for general dietary advice to improve symptoms in these patients. Nutritional supplementation to patients with malnutrition due to severe dysfunction of the gastrointestinal tract is of course less controversial, even though different views on how this should be performed exist. The content of this article is based on presentations given by the authors during the second meeting of the Swedish Motility Group held in Gothenburg in March 2005, and aims to give an overview on the role of dietary advice and nutritional supplementation to patients with gastrointestinal dysfunction of different severity.

Fiber (glucomannan) is beneficial in the treatment of childhood constipation

OBJECTIVE

Constipation and encopresis are common problems in children. Still today, the role of fiber in the treatment of chronic constipation in childhood is controversial. The aim of our study was to evaluate whether fiber supplementation is beneficial in the treatment of children with functional constipation with or without encopresis. We used glucomannan as the fiber supplement.

METHODS

We evaluated the effect of fiber (glucomannan, a fiber gel polysaccharide from the tubers of the Japanese Konjac plant) and placebo in children with chronic functional constipation with and without encopresis in a double-blind, randomized, crossover study. After the initial evaluation, the patients were disimpacted with 1 or 2 phosphate enemas if a rectal impaction was felt during rectal examination. Patients continued with their preevaluation laxative. No enemas were given during each treatment period. Fiber and placebo were given as 100 mg/kg body weight daily (maximal 5 g/day) with 50 mL fluid/500 mg for 4 weeks each. Parents were asked to have children sit on the toilet 4 times daily after meals and to keep a stool diary. Age, frequency of bowel movements into the toilet and into the undergarment, presence of abdominal pain, dietary fiber intake, medications, and the presence of an abdominal and/or a rectal fecal mass were recorded on a structured form at the time of recruitment and 4 weeks and 8 weeks later. Children were rated by the physician as successfully treated when they had > or =3 bowel movements/wk and < or =1 soiling/3 weeks with no abdominal pain in the last 3 weeks of each 4-week treatment period. Parents made a global assessments to whether they believed that the child was better during the first or second treatment period.

RESULTS

Forty-six chronically constipated children were recruited into the study, but only 31 children completed the study. These 31 children (16 boys and 15 girls) were 4.5 to 11.7 years of age (mean: 7 +/- 2 years). All children had functional constipation; in addition, 18 had encopresis when recruited for the study. No significant side effects were reported during each 4-week treatment period. Significantly fewer children complained of abdominal pain and more children were successfully treated while on fiber (45%) as compared with placebo treatment (13%). Parents rated significantly more children (68%) as being better on fiber versus 13% as being better on placebo. The initial fiber intake was low in 22 (71%) children. There was no difference in the percentage of children with low fiber intake living in the United States (70%) and Italy (71%). Successful treatment (physician rating) and improvement (parent rating) were independent of low or acceptable initial fiber intake. The duration of chronic constipation ranged from 0.6 to 10 years (mean: 4.0 +/- 2.5 years). Duration of constipation did not predict response to fiber treatment. Children with constipation only were significantly more likely to be treated successfully with fiber (69%) than those with constipation and encopresis (28%).

CONCLUSION

We found glucomannan to be beneficial in the treatment of constipation with and without encopresis in children. Symptomatic children who were already on laxatives still benefited from the addition of fiber. Therefore, we suggest that we continue with the recommendation to increase the fiber in the diet of constipated children with and without encopresis.

The irritable bowel syndrome

Symptoms of IBS are very prevalent. One quarter of symptomatic individuals present for medical care because of symptom severity and psychologic factors. The pathogenesis of IBS is multifactorial, involving abnormalities in the gut, immune system, enteric sensory and motor nerves, and the CNS. IBS is diagnosed by symptomatology according to the Rome criteria and the absence of alarm findings suggestive of organic disease. Minimal testing is advocated to confirm the diagnosis in patients presenting with typical symptoms. Therapy is based on the dominant symptom (IBS subtype). Therapeutic options include dietary modifications, counseling, medications, and psychologic treatments. Novel therapies are being investigated to correct potentially pathogenetic peripheral and CNS abnormalities in IBS.

Functional bowel disorders in the geriatric patient: constipation, fecal impaction, and fecal incontinence

Functional bowel disorders, including constipation, fecal impaction, and fecal incontinence, are common gastrointestinal diseases in the elderly and a major source of morbidity. Often the etiology is multifactorial. Evaluation should investigate presenting symptoms and important historical clues. An appropriate workup, including radiological studies, endoscopy, and physiological testing should be individualized. Therapy should be directed against relieving the major complaint and treating the underlying pathophysiological mechanism.

Wheat bran affects the site of fermentation of resistant starch and luminal indexes related to colon cancer risk: a study in pigs

BACKGROUND

Recent studies suggest that resistant starch (effective in producing butyrate and lowering possibly toxic ammonia) is rapidly fermented in the proximal colon; the distal colon especially would, however, benefit from these properties of resistant starch.

AIMS

To determine whether wheat bran (a rich source of insoluble non-starch polysaccharides), known to hasten gastrointestinal transit, could carry resistant starch through to the distal colon and thus shift its site of fermentation.

METHODS

Twenty four pigs were fed four human type diets: a control diet, or control diet supplemented with resistant starch, wheat bran, or both. Intestinal contents and faeces were collected after two weeks.

RESULTS

Without wheat bran, resistant starch was rapidly fermented in the caecum and proximal colon. Supplementation with wheat bran inhibited the caecal fermentation of resistant starch, resulting in an almost twofold increase (from 12.9 (2.5) to 20.5 (2.1) g/day, p<0.05) in resistant starch being fermented between the proximal colon and faeces. This resulted in higher butyrate (133%, p<0.05) and lower ammonia (81%, p<0.05) concentrations in the distal colonic regions.

CONCLUSIONS

Wheat bran can shift the fermentation of resistant starch further distally, thereby improving the luminal conditions in the distal colonic regions where tumours most commonly occur. Therefore, the combined consumption of resistant starch and insoluble non-starch polysaccharides may contribute to the dietary modulation of colon cancer risk.

Roughage revisited: the effect on intestinal function of inert plastic particles of different sizes and shape

The mechanisms by which dietary fiber exerts its laxative action are not fully understood. Finely grinding wheat bran reduces its effect. Inert plastic particles are equipotent to bran if they consist of flakes or sliced tubing. It is not known whether altering the size or shape of inert particles alters their effect on intestinal function. In a randomized crossover study, 18 volunteers swallowed 24 g/day of plastic as branlike flakes or as small granules for 10-12 days with a two-week washout period between interventions. Whole-gut transit time (WGTT), orocecal transit time (OCTT), defecation frequency, stool form, stool water content, stool pH, and dietary intake were assessed. The plastic flakes caused a 24% (P < 0.001) reduction in WGTT and a 19% (P = 0.002) fall in OCTT. Resultant and appropriate changes in stool form, interdefecatory intervals (IDI), and stool weight were seen. The small granules did not cause any significant change in WGTT or OCTT, although IDI did decrease and stool output and stool form score increased. The stimulant effect of solid particles in the intestinal lumen upon transit time is influenced by the morphology of the particles.

Gastric emptying and intestinal transit times of radiopaque markers in cats fed a high-fiber diet with and without low-dose intravenous diazepam

Reference ranges for gastric emptying time (GET), small intestinal transit time (SITT), and colonic transit time of 1.5-mm and 5-mm radiopaque markers in healthy cats fed a high-fiber meal were determined, and the influence of low-dose diazepam intravenous injection on the gastrointestinal transit of the markers was examined. The mean GETs and SITTs, and the mean residence times (MRTs) and geometric centers (GCs) of markers in the colon were determined. The effect of intravenous diazepam injection and marker size on these parameters was examined. Diazepam injection had no significant influence on gastrointestinal transit. The GETs of the 1.5-mm markers were significantly more rapid than those of the 5.0-mm markers. There were no significant differences between the SITTs or GCs of the 1.5-mm and 5.0-mm markers. Reference values were developed for GET, SITT, and colonic transit of radiopaque markers for cats fed a high-fiber meal. Diazepam injection had no effect on these parameters.

Confirmation of the role of rapidly fermentable carbohydrates in the expression of swine dysentery in pigs after experimental infection

Two experiments were conducted to test the hypothesis that soluble non-starch polysaccharides (NSP) and resistant starch (RS) cause swine dysentery (SD) in pigs experimentally infected with the spirochete Serpulina hyodysenteriae. In Experiment 1, a source of soluble NSP (guar gum; GG), insoluble NSP (oat chaff; OC), resistant starch (retrograde cornstarch; RS) or a combination of GG and RS (GG + RS) was added to a diet containing cooked white rice (R), soybean meal (SBM) and animal protein (meat and bone meal, bloodmeal, fishmeal). A diet containing only cooked white rice, SBM and the sources of animal protein (AP) was also fed. In Experiment 2, three rice-based diets containing different levels of RS were fed to pigs. In Experiment 1, the pH of digesta in the cecum, proximal colon and distal colon of pigs fed diets R-GG, R-RS and R-GG + RS was lower (P < 0.001), and volatile fatty acid concentration higher (P < 0.001), than in pigs fed diets R-OC and R-AP. Pigs fed diets with RS and GG + RS had greater (P < 0.05) concentrations of ATP in the large intestine than pigs fed other diets. There were no significant differences in any fermentation indices measured in Experiment 2. In Experiment 1, pigs fed diets R-GG, R-RS and R-GG + RS were colonized with S. hyodysenteriae after experimental infection. However, only pigs consuming diets R-GG (4 of 5) and R-GG + RS (5 of 5) showed clinical signs of SD. Spirochetes were isolated from the feces of all pigs fed diets containing RS in Experiment 2. However, and in contrast to Experiment 1, 80-100% of pigs infected with S. hyodysenteriae displayed clinical signs of SD. These data confirm the role of fermentable carbohydrate in the pathogenesis of SD.

Does chronic supplementation of the diet with dietary fibre extracted from pea or carrot affect colonic motility in man?

The aim of the present study was to assess, in healthy volunteers and under physiological conditions, the acceptability, clinical tolerance and effects on colonic motility of chronic supplementation of the usual diet with new dietary fibre sources. Three studies were carried out, one after a period of habitual diet, and two after randomized 3-week periods of supplementation with fibre extracted either from pea hulls or carrots, added to the meals as a fine powder. The 24 h motility was recorded on an unprepared colon at five levels to determine the initiation site and the number of high amplitude propagated contractions (HAPC) and to quantify motor activity every 30 min, particularly in the two periods following lunch and breakfast. With the habitual diet the motility pattern was an irregular alternation of quiescence and sporadic non-propagated contractions. HAPC always started from the ascending colon and occurred mainly after breakfast. With either type of fibre the 24 h motor profiles, the 24 h variations and the number of HAPC were not significantly modified but a more distal initiation of HAPC was found. The colonic postprandial motor response was more diffuse after dietary enrichment with carrot fibre than after enrichment with pea-hull fibre. In healthy volunteers the long-term addition of fibre extracted from pea hulls and carrots to the usual diet was easy and well-tolerated without clinical side-effects, but with limited colonic motor effects. However, the more distal initiation of HAPC observed could be deleterious.

Assessment of the effect of increased dietary fibre intake on bowel function in patients with spinal cord injury

It is common for constipation to occur following severe spinal cord injury (SCI). Although a bowel management program including a high fibre diet is an integral part of rehabilitation, the effect of a high fibre diet on large bowel function in SCI has not been examined. The aims of this study were to assess the nutrient intake of SCI patients, to determine baseline transit time, stool weight and evacuation time and to assess the effect of addition of bran on large bowel function. Eleven subjects, aged 32 +/- 10.5 years participated in the study. The level of injury ranged from C4 to T12; only one patient had an incomplete injury. Baseline mean energy intake was 7823 +/- 1443 kJ/d, protein intake 93 +/- 21 g/d, carbohydrate intake 209 +/- 39 g/d and mean dietary fibre intake 25 +/- 8 g/d. Mean baseline stool weight was 128 +/- 55 g/d and bowel evacuation time was 13 +/- 7.4 min/d. Three subjects who consumed < 18 g dietary fibre/d had low stool weights of 60-70 g/d and two had very delayed transit times that were too slow to enable quantitation. Mean mouth to anus transit time was 51.3 +/- 31.2 h, mean colonic transit time 28.2 +/- 3.5 h, right colonic transit time 5.9 +/- 4.5 h, left colonic transit time 14.5 +/- 5.2 h and rectosigmoid colonic transit time 7.9 +/- 5.6 h. Following the addition of bran, dietary fibre intake significantly increased from 25 g/d to 31 g/d (P < 0.001). However, the mean colonic transit time increased from 28.2 h to 42.2 h (P < 0.05) and rectosigmoid colon transit time increased from 7.9 to 23.3 h (P < 0.02). Stool weight, mouth to anus, left and right colon transit time and evacuation time did not change significantly. Results of this study suggest that increasing dietary fibre in SCI patients does not have the same effect on bowel function as has been previously demonstrated in individuals with 'normally functioning' bowels. Indeed the effect may be the opposite to that desired. This preliminary study highlights the need for further research to examine the optimal level of dietary fibre intake in SCI patients.

Effects of psyllium therapy on stool characteristics, colon transit and anorectal function in chronic idiopathic constipation

BACKGROUND

Psyllium is widely used in the symptomatic therapy of constipation. Its effects on colonic function and their correlation with symptomatic response have not been defined.

METHODS

After a 4-week baseline, placebo, run-in phase, 22 subjects with idiopathic constipation confirmed by prospectively administered stool diaries were randomly assigned to receive either psyllium (5 g b.d., 11 patients) or placebo (11 patients) for 8 weeks, followed by another 4-week wash-out, placebo phase. A colon transit study and anorectal manometry were performed at the beginning and at the end of each study phase. Subjects recorded, in diaries, their daily stool frequency, difficulty with defecation and weekly stool weight.

RESULTS

Stool frequency increased significantly after 8 weeks of psyllium treatment (3.8 +/- 0.4 vs. 2.9 +/- 0.1 stools/week, P < 0.05) as did stool weight (665.3 +/- 95.8 g vs. 405.2 +/- 75.9 g, P < 0.05). Subjects also reported an improvement in stool consistency (stool consistency score: 3.2 +/- 0.2 vs. 3.8 +/- 0.2, P < 0.05) and pain on defecation (pain score: 2.0 +/- 0.4 vs. 2.6 +/- 0.5, P < 0.05) on psyllium. Colon transit and anorectal manometry parameters were unchanged on psyllium. Subjects treated with placebo did not show any change in either subjective or objective measures of constipation.

CONCLUSIONS

Psyllium increases stool frequency and weight and improves stool consistency in idiopathic constipation. These effects are not associated with significant changes in either colonic or rectal motor function. We suggest that the beneficial effects of psyllium in constipation are primarily related to a facilitation of the defecatory process.

The effect of fiber source in enteral products on fecal weight, mineral balance, and growth rate in rats

The effect of two fiber systems in enteral formulas on fecal output, mineral balance, weight gain, and cecal short-chain fatty acid production was studied in rats. Enteral products tested had either no fiber; soy fiber (3.4 g of total dietary fiber/8 fluid oz); a fiber blend containing 75% oat fiber, 17.5% gum arabic, and 7.5% carboxymethylcellulose (3.4 g of total dietary fiber/8 fluid oz); or the same blend at 4 g of total dietary fiber/8 fluid oz. Food, feces, and urine were analyzed for nitrogen, calcium, magnesium, iron, and zinc. Cecal contents were analyzed for short-chain fatty acids. Weight gain, intake, food efficiency, and nitrogen balance were unaffected by fiber source. Fecal weight was increased by the fiber blend (p < .05). Calcium and magnesium balances were similar for all groups fed fiber-containing products but were lower for the fiber-free group (p < .05). Iron balance was significantly lower for rats fed the fiber blend at 4 g/8 fluid oz as compared with the other treatment groups (p < .05). Cecal acetate, propionate, and total short-chain fatty acid concentrations for rats fed the soy-fiber diet were significantly higher than for the other three diets (p < .05). Rats fed the fiber blend at the higher level had a significantly higher percentage of butyrate production than rats fed the other three diets (p < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Diurnal changes in large-bowel metabolism: short-chain fatty acids and transit time in rats fed on wheat bran

To investigate diurnal changes in large-bowel metabolism rats were fed once daily on a cooked maize-based diet without or with 200 g wheat bran/kg diet and containing Cr2O3 as an indigestible marker. After 17 d four rats on each diet were killed at 4, 10, 16 and 22 h postfeeding. Emptying of dry matter (DM) from the stomach occurred by an apparently zero-order process at about 0.5 g/h in both diet groups. Feeding wheat bran had little effect on caecal pH or total short-chain fatty acid (SCFA) concentration but was associated with a marked increase in molar proportion of butyrate and a fall in propionate. There were substantial changes in caecal total SCFA concentration and in the molar proportions of individual SCFA throughout the day but no evidence of an interaction between diet and time interval after feeding. Caecal transit time (TT) was significantly reduced by feeding wheat bran whilst colonic TT was unaffected. Although when averaged across both diets there were no significant time effects on caecal or colonic TT, there was a significant diet x time interaction for caecal TT. The extent of coprophagy was measured. The proportion of stomach DM derived from ingested faeces increased with time interval after feeding but it was always a minor contribution so that in these circumstances coprophagy is unlikely to result in significant bias in estimates of digesta flow-rates or TT.

Characterization of colonic transit of nondisintegrating tablets in healthy subjects

The transit of pharmaceutical dosage forms through the colon has been shown to be highly variable. The amount of fiber in the diet is known to alter gastrointestinal transit; however, the dietary intake of the subjects in previous studies was not adequately controlled. Using the technique of gamma scintigraphy, we have therefore characterized the variability in the colonic transit of nondisintegrating tablets, by strictly controlling the dietary fiber intake of the subjects. Eight healthy male subjects followed a diet containing 25 g dietary fiber per day, for six days prior to dosing. Each subject received five 6-mm nondisintegrating tablets on three consecutive days. Mouth-to-anus transit times exhibited a high degree of variability. Regional differences in colonic transit were evident. Tablet stasis appeared to occur mainly in the ascending colon and hepatic flexure. Despite the diets of the volunteers being identical, colonic transit was still observed to be highly variable, which suggests that this variability is intrinsic.

The effect of feeding xanthan gum on colonic function in man: correlation with in vitro determinants of bacterial breakdown

Xanthan gum (15 g/d) was given for 10 d to eighteen normal volunteers. In vivo measurements of stool output, transit time, frequency of defaecation and flatulence were compared with a preceding control period of 10 d. At the end of the control and test periods fresh faecal homogenate from each subject was anaerobically incubated with xanthan gum and control solutions to assess the ability of the bacteria to break down the gum. Xanthan gum was found to be a highly efficient laxative agent causing significant increases in stool output (P < 0.01), frequency of defaecation (P < 0.05) and flatulence (P < 0.01) whilst having variable effects on transit time. Before feeding xanthan gum, faecal samples from twelve of the eighteen subjects could reduce the viscosity of the gum in vitro. This rose to sixteen of the eighteen with significantly greater amounts (P < 0.05) of hydrogen and short-chain fatty acids also being produced, indicating bacterial adaptation in the presence of the substrate. Correlations between the in vivo and in vitro findings did not substantiate claims that the in vivo effect of a given polysaccharide can be predicted from its fermentation characteristics in vitro.

Study of constipation in a geriatric hospital, day hospital, old people's home and at home

A study of constipation and related factors was carried out in 439 geriatric hospital patients, 183 people living in two old people's homes, and 78 patients visiting a geriatric day hospital. In addition, a cross-sectional survey of constipation and related factors was undertaken in 138 people older than 74 years and 74 people aged 41 to 50 years living at home. Constipation and the use of laxatives were most frequent in the geriatric hospital (79% and 76% respectively), followed by the old people's homes (59% and 60%), the day hospital (29% and 31%), elderly living at home (38% and 20%) and middle-aged living at home (12% and 5%). The results suggest an increased risk of constipation for the persons walking less than 0.5 km daily [relative risk (RR) = 1.7], walking with help (RR = 3.4), chairbound (RR = 6.9) and bedbound (RR = 15.9). The relative risk of constipation increased for the persons living in the old people's homes (RR = 1.7) and the geriatric hospital (RR = 2.2), and also with advancing age (between 75 and 84 years, RR = 2.9; over 84 years, RR = 4.9). The prevalence of constipation was directly correlated to fecal and urinary incontinence.

Effects of liquid versus solid diet on colonic transit in humans. Evaluation by standard colonic transit scintigraphy

The effects of liquid versus solid diet on human colonic transit were investigated, and transit following cecal instillation of tracer was compared with transit following instillation in the proximal jejunum. In a randomized cross-over, single-blind fashion, 6 normal volunteers ingesting either normal solid foods or a liquid diet were studied using colonic transit scintigraphy. 111In-DTPA was instilled either into the cecum via a long intestinal tube or into the proximal jejunum via a feeding tube. Compared with the liquid diet, the solid diet slowed transit in the cecum and ascending colon (p less than 0.025) and delayed progression of the geometric center (p less than 0.05) during the first 4 h of the study. Transit from 18 to 48 h was similar on the 2 diets. On the solid diet, transit was similar whether 111In-DTPA was instilled into the proximal jejunum or into the cecum. Transit from the terminal ileum to the cecum was assessed in an additional 5 volunteers following jejunal instillation of 99mTc-DTPA. Cecal filling was rapid (T1/2 = 0.49 h) and complete in all subjects before the onset of cecal emptying. These results suggest that colonic transit is slower on a solid than a liquid diet and that jejunal instillation of radiopharmaceuticals should be suitable for colonic transit studies in most subjects.

Effect of exercise and physical fitness on large intestinal function

The effect of exercise on large intestinal function has been determined in 14 healthy but normally sedentary men and women, aged 22-34 yr while on a constant diet. For an initial 3-5-wk period (control) no activity was allowed. Six subjects then undertook a 9-wk training schedule by the end of which they were capable of jogging for 1 h per day, 5 days a week. A further 6 subjects undertook a similar training schedule that lasted for only 7 wk, at the end of which they were jogging for 45 min per day. Finally, 2 subjects were studied continuously while taking light exercise for 6 wk and then jogging for a further 3 wk. Physical fitness was monitored and showed significant changes with maximum aerobic capacity increasing from 2.4 +/- 0.5 to 3.1 +/- 0.4 L/min, maximum heart rate after a step test falling from 152 +/- 8 to 129 +/- 5 beats per minute, and resting pulse rate also falling from 56 +/- 4 to 50 +/- 5 beats per minute. High-density lipoprotein cholesterol also increased significantly. Colonic function was assessed by measurement of stool weight and transit time, using the continuous radiopaque marker technique, fecal pH, nitrogen excretion, and ammonia concentration. No change was observed overall in mean daily fecal weight [124 +/- 39 (control) and 129 +/- 49 g/day (exercise)], transit time [55 +/- 20 (control), 54 +/- 23 h (exercise)], nor in fecal frequency, dry stool weight, pH, ammonia, or total nitrogen excretion. Significant changes did occur in 5 individuals with significant slowing of transit time in 2 and speeding up in 3. Overall transit time increased in 9 subjects and decreased in 5; hence, when diet is constant, exercise has marked effects on physical fitness but no consistent effect on large bowel function.

Fibre and enteral nutrition

The recent launch of a number of fibre enriched polymeric diet in the United States and Europe has stimulated considerable interest in the topic of fibre and enteral nutrition, and several commercial concerns appear to be under considerable pressures from their consumers to produce similar products. As a means of identifying areas of potential application of fibre to enteral nutrition some of the recent knowledge gained about the physical properties of dietary fibre and the processes involved in the intestinal assimilation of fibre has been reviewed. Two areas of interest are identifiable. The first relates to the bulking properties of fibre and the application of this to the regulation of bowel function in enterally fed patients. It is clear from the clinical studies that have been reviewed that there remains a paucity of controlled data, and a great deal more research is needed before widespread use of fibre supplemented diets can be supported. Perhaps of greater interest academically is the potentially beneficial effects that appear to be exerted by the VFA's, liberated as a consequence of colonic bacterial fermentation of fibre, on morphology and function of ileal and colonic mucosa. Although there are a number of potential applications of fibre supplemented enteral diets in this area, more research is required before any firm recommendations can be made about recommending their use. The one exception concerns patients with the nutritionally inadequate short bowel syndrome. There does seem to be sufficient experimental evidence to suggest that clinical studies should be commenced using a pectin supplemented predigested 'elemental' diet in these patients. Overall therefore, one is forced to conclude that the increasing interest and use of fibre supplemented enteral diets is being driven more by market than scientific forces. Nevertheless, the promotion of these diets has already provided a powerful stimulus to the scientific community, and it remains entirely possible that many of the potential applications of these diets will be realised in the near future.

Effect of wheat bran on weight of stool and gastrointestinal transit time: a meta analysis

Twenty original papers that reported on the effect of wheat bran on large bowel function were analysed. Bran increased the stool weight and decreased the transit time in each study in healthy controls and in patients with the irritable bowel syndrome, with diverticula, and with chronic constipation. Statistical evaluation of the data showed, however, that constipated patients had lower stool output and slower transit whether or not they had taken bran, and they responded less well to bran treatment than controls. From these data it is concluded that bran can be expected to be only partially effective in restoring normal stool weight and transit time in patients who are constipated.

Effect of wheat bran on weight of stool and gastrointestinal transit time: a meta analysis

Twenty original papers that reported on the effect of wheat bran on large bowel function were analysed. Bran increased the stool weight and decreased the transit time in each study in healthy controls and in patients with the irritable bowel syndrome, with diverticula, and with chronic constipation. Statistical evaluation of the data showed, however, that constipated patients had lower stool output and slower transit whether or not they had taken bran, and they responded less well to bran treatment than controls. From these data it is concluded that bran can be expected to be only partially effective in restoring normal stool weight and transit time in patients who are constipated.

The effect of age, sex and level of intake of dietary fibre from wheat on large-bowel function in thirty healthy subjects

1. To evaluate the effect of age, sex and level of intake on the colonic response to wheat fibre, thirty healthy volunteers aged 17-62 years (nineteen men, eleven women) recruited from a local industry, were divided into four groups and given a controlled diet for two 3-week periods. The diet contained white bread during one period or one of four different amounts of bran-enriched wholemeal bread during the other (30, 60, 110, 170 g/d). 2. Wide variation was observed between subjects in stool weight on the basal diet and in response to wheat fibre. Stepwise regression analysis showed that the variation in stool weight was significantly related to sex (t 4.0, P less than 0.001) but not to age, height, weight or energy:fibre intakes on the basal diet. Stool weight in men (162 (SE 11) g/d) was approximately double that in women (83 (SE 11) g/d). Transit time and stool weight were closely related and the effect of sex on stool weight could be explained entirely by differences in transit. 3. The increase in stool weight with fibre was significantly related to dose (t 4.18, P less than 0.001) with approximately 1 g non-starch polysaccharides (the main component of dietary fibre) increasing stool weight by 5 g/d. Smaller increases in stool weight were seen in females, persons with initially low stool weights and small people. 4. Faecal carbohydrate excretion increased with the addition of bran mainly due to increased amounts of cellulose and pentose (arabinose + xylose), whilst digestibility of dietary non-starch polysaccharide fell from 77.6 (SE 2.3)% on the white bread diet to 65.6 (SE 2.4)% with the added bran (t 7.4, P less than 0.01, n26). 5. Faecal pH was more acid in men than in women and was related to methane production. Methane producers had higher faecal pH than non-producers (7.06 (SE 0.11) v. 6.65 (SE 0.1], lower stool weight (g/d; 93 (SE 12) v. 156 (SE 13] and slower transit times (h; 84.6 (SE 11.7) v. 48.6 (SE 6.6]. 6. These studies show that, when on similar diets, women have much lower stool weights and slower transit times than men. Furthermore, within the range of amounts of wheat fibre used in this and other published work, stool weight increases in linear proportion to the dose of fibre added to the diet. Methane excretion in breath is associated in this group of subjects with slow transit time and high faecal pH.