Laxative effects of wheat bran and psyllium: Resolving enduring misconceptions about fiber in treatment guidelines for chronic idiopathic constipation.

BACKGROUND: Treatment guidelines for chronic idiopathic constipation (CIC) recommend an "increase in fiber intake" as a first-line therapy, but most epidemiologic studies fail to support an association between a high-fiber diet and a reduced risk of constipation. Furthermore, randomized controlled clinical studies show that most isolated fibers (e.g., supplements) are not different from placebo for a laxative effect, and several may be constipating. OBJECTIVES: The objective of this review was to compare the effects of two isolated fibers, coarse wheat bran and psyllium, on stool output and stool water content in patients with CIC. This review will also address misconceptions about fiber that are perpetuated by treatment guidelines. DATA SOURCES: A comprehensive literature review was conducted with the use of the Scopus, SciFinder, and PubMed scientific databases, limited to the previous 50 years (1968-2018; latest date included, December 31, 2018). CONCLUSIONS: In patients with CIC, nonfermented gel-forming psyllium was 3.4 times more effective than insoluble wheat bran for increasing stool output. Both psyllium and coarse wheat bran increased stool water content, a stool-softening effect, but finely ground wheat bran decreased stool water content, a stool-hardening effect. IMPLICATIONS FOR PRACTICE: It is a misconception that dietary fiber and all isolated fibers provide a laxative effect in patients with CIC. Our analysis suggests that treatment guidelines for CIC should make specific evidence-based recommendations as it pertains to fiber. To do otherwise takes the risk of perpetuating myth and misunderstanding and depriving patients of an effective therapy for CIC. A generic recommendation to "increase fiber intake" is akin to a recommendation to "increase pill intake" without regard to therapeutic or adverse effects.

Microwave assisted synthesis of binary grafted psyllium and its utility in anticancer formulation.

A binary grafted copolymer of Psyllium mucilage (Psy) with acrylic acid (AA) and acrylonitrile (An) has been successfully synthesized under microwave conditions for in vitro drug release study. The grafting was confirmed by FTIR spectroscopy, XRD, SEM, EDX, TGA analytical techniques and the intrinsic viscosity study. The swelling behavior of grafted material has been studied in solution of different pH and time. We also prepare Psy-g-Poly (AA-co-An) based beads with anti-cancer drug [(2-Chloro-3-(4-hydroxyphenylamino) naphthalene-1, 4-dione)]. The drug release behavior of Psy-g-Poly (AA-co-An) based beads has been determined in aqueous medium at different pH. It has been observed that highest drug release at pH 1.6. The drug release kinetics was analysed using the different models. This study demonstrates that the release of drug depends on the composition of beads and pH of release medium. Kinetics of drug release from beads is best fitted by zero order and first order model.

Performance of two neutral oral contrast agents in CT enterography.

INTRODUCTION: This study compares the performance of two neutral oral contrast agents in CT enterography (CTE). Mannitol 2.5%, an oral osmotic agent, is compared with psyllium fibre (Metamucil). Both these agents are commonly used, but to our knowledge, they have not been compared in CTE. METHODS: CTE data were collected from 25 consecutive studies for both mannitol and psyllium fibre between 2011 and 2013. All images were reviewed by two radiologists and one registrar blinded to the oral contrast used. Each quadrant was assessed for maximum distension, proportion of bowel loops distended, presence of inhomogeneous content and bowel wall visibility. Overall subjective quality and whether the contrast agent reached the caecum were also assessed. Patients were invited to answer a questionnaire regarding tolerability of the preparations. RESULTS: Wall visibility was rated good in 100% of the mannitol studies, compared with 71% of the psyllium fibre studies, in the right lower quadrant (P = 0.01). No statistically significant difference between groups was observed in either maximal distension or proportion of loops distended in any quadrant. Inhomogeneous material was observed in 12% of the mannitol cases and 86% of the psyllium fibre cases (P < 0.0001). In all mannitol cases, the contrast reached the caecum, compared with 50% of psyllium fibre cases (P < 0.0001), and 36% of the mannitol studies were considered excellent, compared with 20% of the psyllium fibre studies (P = 0.03). CONCLUSION: Mannitol achieves studies of better quality and is now the preferred oral contrast for CTE studies at Auckland City Hospital.

Correlation between tissue metabolism and cellularity assessed by standardized uptake value and apparent diffusion coefficient in peritoneal metastasis.

PURPOSE: To evaluate the correlation between standardized uptake value (SUV) (tissue metabolism) and apparent diffusion coefficient (ADC) (water diffusivity) in peritoneal metastases. MATERIALS AND METHODS: Patients with peritoneal dissemination detected on (18)F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) were prospectively recruited for MRI examinations with informed consent and the study was approved by the local Institutional Review Board. FDG-PET/CT, diffusion-weighted imaging (DWI), MRI, and DWI/MRI images were independently reviewed by two radiologists based on visual analysis. SUVmax/SUVmean and ADCmin/ADCmean were obtained manually by drawing ROIs over the peritoneal metastases on FDG-PET/CT and DWI, respectively. Diagnostic characteristics of each technique were evaluated. Pearson's coefficient and McNemar and Kappa tests were used for statistical analysis. RESULTS: Eight patients were recruited for this prospective study and 34 peritoneal metastases were evaluated. ADCmean was significantly and negatively correlated with SUVmax (r = -0.528, P = 0.001) and SUVmean (r = -0.548, P = 0.001). ADCmin had similar correlation with SUVmax (r = -0.508, P = 0.002) and SUVmean (r = -0.513, P = 0.002). DWI/MRI had high diagnostic performance (accuracy = 98%) comparable to FDG-PET/CT, in peritoneal metastasis detection. Kappa values were excellent for all techniques. CONCLUSION: There was a significant inverse correlation between SUV and ADC.

Thiol modification of psyllium husk mucilage and evaluation of its mucoadhesive applications.

Thiol functionalization of psyllium was carried out to enhance its mucoadhesive potential. Thiolation of psyllium was achieved by esterification with thioglycolic acid. Thiolation was observed to change the surface morphology of psyllium from fibrous to granular and result in a slight increase in the crystallinity and swelling. Thiolated psyllium was found to contain 3.282 m moles of thiol groups/g of the polymer. Mucoadhesive applications of thiolated psylium were explored by formulating gels using metronidazole as the model drug. On comparative evaluation thiolated psyllium gels showed 3-fold higher mucoadhesive strength than the psyllium gels as determined by modified physical balance using chicken buccal pouch. The results of in vitro release study revealed that thiolated psyllium gels provided a prolonged release of metronidazole. Further, the psyllium and thiolated psyllium gels were found to release the drug following first-order kinetics by combination of polymer relaxation and diffusion through the matrix.

Dietary fibre, physicochemical properties and their relationship to health.

Dietary carbohydrates that escape digestion and absorption in the small intestine include non-digestible oligosaccharides (carbohydrates with a degree of polymerisation between three and ten), resistant starch and non-starch polysaccharides. The physiological effects of this heterogeneous mixture of substrates are partly predictable on the basis of their physicochemical properties. Monosaccharide composition and chain conformation influence the rate and extent of fermentation. Water-holding capacity affects stool weight and intestinal transit time. Viscous polysaccharides can cause delayed gastric emptying and slower transit through the small bowel, resulting in the reduced rate of nutrient absorption. Polysaccharides with large hydrophobic surface areas have potentially important roles in the binding of bile acids, carcinogens and mutagens. Ispaghula is capable of binding bile acids through a large number of weak binding sites on the polysaccharide structure, and having greatest effect on the potentially more harmful secondary bile acids deoxycholic acid and lithocholic acid.

Psyllium improves fecal consistency and prevents enhanced secretory responses in jejunal tissues of piglets infected with ETEC.

Infection with enterotoxigenic E. coli (ETEC) induces secretory diarrhea by stimulating net secretion of fluid and electrolytes. We tested the hypothesis that ETEC potentiates jejunal ion secretion induced by other agonists and also examined whether the soluble fiber psyllium ameliorates effects of ETEC-induced pathophysiology. Noninfected or ETEC-infected piglets were given oral electrolyte solution twice daily or electrolyte solution supplemented with psyllium for 48 hr. Jejunal tissues were mounted in flux chambers and basal and stimulated ion transport responses, as reflected by short-circuit current (I(SC)) were measured. The severity of ETEC-induced diarrhea was reduced by psyllium. I(SC) responses to carbachol and 5-hydroxytryptamine were greater in tissues from infected piglets compared with noninfected controls or infected piglets given psyllium. These results suggest that psyllium ameliorates ETEC-induced diarrhea and prevents the enhanced secretory responses to calcium-mediated agonists that occur in ETEC-infected piglet jejunum.