Differing effects of pectin, cellulose and lignin on stool pH, transit time and weight

Determinants of polycystic ovary syndrome: A matched case-control study

BACKGROUND

Polycystic ovarian syndrome (PCOS) is a multifaceted endocrine disorder of women of reproductive age with a multifactorial aetiology. Despite much research, there is still inconclusive data on the impact of dietary, lifestyle and socio-economic factors on PCOS aetiology. Thus, the present study explored the association of PCOS with diet, eating behaviour, other lifestyle and socio-economic factors.

METHODS

A matched-pair case-control study was conducted on 150 women with PCOS and 150 healthy controls. Information on diet, eating behaviour and physical activity, and also anthropometric and socio-economic data were collected through standard questionnaires. The adjusted odds ratios (AmOR) were calculated and reported using conditional multivariable logistic regression.

RESULTS

The results showed low education level (AmOR = 8.44; 95% confidence interval [CI] = 1.63-43.68), high sugar consumption (AmOR = 11.61; 95% CI = 2.05-65.72) along with higher body mass index (BMI) and inactivity to be significantly associated with PCOS. Also, a significant protective effect was found for cognitive dietary restraint (AmOR = 0.79; 95% CI = 0.66-0.93), crude fibre (AmOR = 0.61; 95% CI = 0.45-0.82) and protein intake.

CONCLUSIONS

Low education status may contribute to higher receptiveness to choosing unhealthy diets and lifestyles, resulting in adiposity and an increased risk of PCOS.

Advancing human gut microbiota research by considering gut transit time

Accumulating evidence indicates that gut transit time is a key factor in shaping the gut microbiota composition and activity, which are linked to human health. Both population-wide and small-scale studies have identified transit time as a top covariate contributing to the large interindividual variation in the faecal microbiota composition. Despite this, transit time is still rarely being considered in the field of the human gut microbiome. Here, we review the latest research describing how and why whole gut and segmental transit times vary substantially between and within individuals, and how variations in gut transit time impact the gut microbiota composition, diversity and metabolism. Furthermore, we discuss the mechanisms by which the gut microbiota may causally affect gut motility. We argue that by taking into account the interindividual and intraindividual differences in gut transit time, we can advance our understanding of diet-microbiota interactions and disease-related microbiome signatures, since these may often be confounded by transient or persistent alterations in transit time. Altogether, a better understanding of the complex, bidirectional interactions between the gut microbiota and transit time is required to better understand gut microbiome variations in health and disease.

Subchronic exposure to cellulose nanofibrils induces nutritional risk by non-specifically reducing the intestinal absorption

Previous studies of cellulose nanofibrils (CNF) in decreasing fat absorption and glucose release suggested their potential application as food additives or supplements in diets containing high contents of fat and sugars. However, the long-term effects of CNF uptake remained unknown. The purpose of this study was to determine the effects of subchronic oral CNF consumption on various health aspects of Western diets (WD)-fed mice. The results demonstrated that CNF decreased fat absorption in the jejunum and attenuated WD-induced fatty liver, but slightly decreased lean body mass and affected glucose homeostasis. Additional in vivo studies showed that CNF decreased the intestinal absorption. The in vitro studies suggested that CNF did not decrease the viability of any cells used; however, they prevented epithelial and T cells, but not macrophages, from accessing the viability dye. Taken together, CNF decreased the intestinal absorption non-specifically, which might lead to nutritional risks after long-term exposure.

Addition of plant dietary fibre to a raw red meat high protein, high fat diet, alters the faecal bacteriome and organic acid profiles of the domestic cat (Felis catus)

Commercial diets high in animal protein and fat are increasingly being developed for pets, however little is understood about the impacts of feeding such diets to domestic cats. The carbohydrate content of these diets is typically low, and dietary fibre is often not included. Dietary fibre is believed to be important in the feline gastrointestinal tract, promoting stool formation and providing a substrate for the hindgut microbiome. Therefore, we aimed to determine the effects of adding plant-based dietary fibre to a high animal protein and fat diet. Twelve domestic short hair cats were fed three complete and balanced diets in a cross-over design for blocks of 21 days: raw meat (Raw), raw meat plus fibre (2%, ‘as is’ inclusion of inulin and cellulose; Raw+Fibre) and a commercially available Kibble diet. A commercially available canned diet was fed for 21 days as a washout phase. Apparent macronutrient digestibility, faecal output, score, pH, organic acid concentrations and bacteriome profiles were determined. Diet significantly affected all faecal parameters measured. The addition of dietary fibre to the raw meat diet was found to reduce apparent macronutrient digestibility, increase faecal output, pH and score. Thirty one bacterial taxa were significantly affected by diet. Prevotella was found to dominate in the Kibble diet, Clostridium and Fusobacterium in the Raw diet, and Prevotella and a group of unclassified Peptostreptococcaceae in the Raw+Fibre diet. Our results show that diets of different macronutrient proportions can strongly influence the faecal microbiome composition and metabolism, as shown by altered organic acid concentrations and faecal pH, in the domestic cat. The addition of 2% of each fibre to the Raw diet shifted faecal parameters closer to those produced by feeding a Kibble diet. These results provide a basis for further research assessing raw red meat diets to domestic cats.

Hypocholesterolemic Effect of the Lignin-Rich Insoluble Residue of Brewer's Spent Grain in Mice Fed a High-Fat Diet

Insoluble residue (INS) is a lignin-rich fraction of brewer's spent grain (BSG) that also contains β-glucan and arabinoxylan, the major constituents of dietary fiber. We investigated the effects of INS in diet-induced obese mice in terms of lipid metabolism and metabolic diseases. Male mice (C57bl6) were fed a high-fat diet (HFD), a HFD + 20% INS, a HFD + 20% cellulose (CEL), a HFD with a combination of 20% INS-CEL (1:1), or a control diet for 14 weeks. Insulin and glucose tolerance tests were performed after 12 weeks. Fasting plasma lipids, bile acid, and fecal bile acid were measured after 14 weeks of feeding, and tissues were collected for gene expression analysis. Body weight gain was significantly reduced with all fibers, but only INS and INS-CEL decreased fasting plasma low-density lipoprotein cholesterol and total cholesterol compared to HFD. CEL and INS-CEL significantly improved insulin resistance. Fecal bile acids were significantly increased by all fibers, but there was no change in plasma bile acid. Clostridium leptum was increased with all fibers, but universal bacterial diversity was only with INS and INS-CEL. In addition, INS significantly increased the abundance of Bacteriodes, while CEL decreased Atopobium and Lactobacillus. INS feeding significantly upregulated various genes of cholesterol and bile acid metabolism, such as Srebp2, Hmgcr, Ldlr, Cyp7a1, Pparα, Fxr, and Pxr, in the liver. INS, INS-CEL, and CEL significantly attenuated liver steatosis. Our results suggest that INS from BSG induced beneficial systemic changes in mice via gut microbiota, bile acids, and gene expression in the liver.

The effect of prunes on stool output, gut transit time and gastrointestinal microbiota: A randomised controlled trial

BACKGROUND & AIM

Prunes (dried plums) are perceived to maintain healthy bowel function, however their effects on gastrointestinal (GI) function are poorly researched and potential mechanisms of action are not clear. We aimed to investigate the effect of prunes on stool output, whole gut transit time (WGTT), gut microbiota and short-chain fatty acids (SCFA) in healthy adults METHODS: We conducted a parallel group, randomised controlled trial with three treatment arms in 120 healthy adults with low fibre intakes and stool frequency of 3-6 stools/wk. Subjects were randomised to 80 g/d prunes (plus 300 ml/d water); 120 g/d prunes (plus 300 ml/d water) or control (300 ml/d water) for 4 weeks. Stool weight was the primary outcome and determined by 7-day stool collection. Secondary outcomes included stool frequency and consistency (stool diary), WGTT (radio-opaque markers), GI symptoms (diary), microbiota (quantitative PCR) and SCFA (gas liquid chromatography). Group assignment was concealed from the outcome assessors.

RESULTS

There were significantly greater increases in stool weight in both the 80 g/d (mean + 22.2 g/d, 95% CI -1-45.3) and 120 g/d (+32.8 g/d, 95% CI 13.9-51.7) prune groups compared with control (-0.8 g/d, 95% CI -17.2 to 15.6, P = 0.026). Stool frequency was significantly greater following 80 g/d (mean 6.8 bowel movements/wk, SD 3.8) and 120 g/d (5.6, SD 1.9) prune consumption compared with control (5.4, SD 2.1) (P = 0.023), but WGTT was unchanged. The incidence of flatulence was significantly higher after prune consumption. There were no significant differences in any of the bacteria measured, except for a greater increase in Bifidobacteria across the groups (P = 0.046). Prunes had no effect on SCFA or stool pH.

CONCLUSIONS

In healthy individuals with infrequent stool habits and low fibre intake, prunes significantly increased stool weight and frequency and were well tolerated. Prunes may have health benefits in populations with low stool weight.

CLINICAL TRIAL REGISTRY NUMBER AND WEBSITE

ISRCTN42793297 http://www.isrctn.com/ISRCTN42793297.

Re-evaluation of celluloses E 460(i), E 460(ii), E 461, E 462, E 463, E 464, E 465, E 466, E 468 and E 469 as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion re-evaluating the safety of microcrystalline cellulose (E 460(i)), powdered cellulose (E 460(ii)), methyl cellulose (E 461), ethyl cellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methyl cellulose (E 464), ethyl methyl cellulose (E 465), sodium carboxy methyl cellulose (E 466), enzymatically hydrolysed carboxy methyl cellulose (E 469) and cross-linked carboxy methyl cellulose (E 468) as food additives. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food (SCF) established an acceptable daily intake (ADI) 'not specified' for unmodified and modified celluloses. Celluloses are not absorbed and are excreted intact in the faeces; in addition, microcrystalline cellulose, powdered and modified celluloses could be fermented by the intestinal flora in animals and humans. Specific toxicity data were not always available for all the celluloses evaluated in the present opinion and for all endpoints. Given their structural, physicochemical and biological similarities, the Panel considered it possible to read-across between all the celluloses. The acute toxicity of celluloses was low and there was no genotoxic concern. Short-term and subchronic dietary toxicity studies performed with E 460(i), E 461, E 462, E 463, E 464, E 466 and E 469 at levels up to 10% did not indicate specific treatment related adverse effects. In chronic toxicity studies performed with E 460(i), E 461, E 463, E 464, E 465 and E 466, the no observed adverse effect level (NOAEL) values reported ranged up to 9,000 mg/kg body weight (bw) per day. No carcinogenic properties were detected for microcrystalline cellulose and modified celluloses. Adverse effects on reproductive performance or developmental effects were not observed with celluloses at doses greater than 1,000 mg/kg bw by gavage (often the highest dose tested). The combined exposure to celluloses (E 460-466, E 468 and E 469) at 95th percentile of the refined (brand-loyal) exposure assessment for the general population was up to 506 mg/kg bw per day. The Panel concluded that there was no need for a numerical ADI and that there would be no safety concern at the reported uses and use levels for the unmodified and modified celluloses (E 460(i); E 460(ii); E 461-466; E 468 and E 469). The Panel considered an indicative total exposure of around 660-900 mg/kg bw per day for microcrystalline, powdered and modified celluloses.

Re-evaluation of pectin (E 440i) and amidated pectin (E 440ii) as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient sources added to Food (ANS) was asked to deliver a scientific opinion on the re-evaluation of pectin (E 440i) and amidated pectin (E 440ii) as food additives. An acceptable daily intake (ADI) 'not specified' was allocated by the Scientific Committee for Food (SCF) for E 440i and E 440ii. Pectin and amidated pectin would not be absorbed intact, but extensively fermented by intestinal microbiota in animals and humans; products formed from pectins in the gastrointestinal tract are similar to manufactured pectin-derived acidic oligosaccharides (pAOS). There is no indication of genotoxicity for pectin and amidated pectin, although the available data were limited. No adverse effects were reported in a chronic toxicity study in rats at levels up to 5,000 mg pectin/kg bw per day, the highest dose tested. No treatment-related effects were observed in a dietary one-generation reproductive toxicity study with pAOS in rats at up to 6,200 mg/kg body weight (bw) per day, the highest dose tested. The Panel did not consider E 440i and E 440ii as having allergenic potential. A dose of 36 g/day (equivalent to 515 mg/kg bw per day) for 6 weeks in humans was without adverse effects. Exposure to pectins from their use as food additives ranged up to 442 mg/kg bw per day for toddlers at the 95th percentile (brand-loyal scenario). The Panel concluded that there is no safety concern for the use of pectin (E 440i) and amidated pectin (E 440ii) as food additives for the general population and that there is no need for a numerical ADI.

Interactions of Insoluble Residue from Enzymatic Hydrolysis of Brewer's Spent Grain with Intestinal Microbiota in Mice

Brewer's spent grain (BSG) is the major side-stream from brewing. As BSG is rich in dietary fiber and protein, it could be used in more valuable applications, such as nutritional additives for foods. Our aim was to elucidate whether an insoluble lignin-rich fraction (INS) from BSG is metabolized by mice gut microbiota and how it affects the microbiota. Our results indicated that lignin was partially degraded by the gut microbiota, degradation products were absorbed, and finally excreted in urine. Therefore, they contribute to the phenolic pool circulating in the mammalian body, and may have systemic effects on health. In addition, the effects of the test diets on the microbiota were significant. Most interestingly, diversities of predominant cecal and fecal bacteria were higher after the intervention diet containing INS than after the intervention diet containing cellulose. Since low fecal bacterial diversity has been linked with numerous diseases and disorders, the diversity increasing ability opens very interesting perspectives for the future.

Digestion-resistant maltodextrin effects on colonic transit time and stool weight: a randomized controlled clinical study

PURPOSE

Increased awareness of the importance of dietary fibre has led to increased interest in "functional" fibre components like digestion-resistant maltodextrin (RMD). This randomized, placebo-controlled, double-blind study assessed the effects of RMD in the colonic transit time (CTT) and defecation characteristics (frequency, stool volume and consistency).

METHODS

Sixty-six healthy adult volunteers (32 men) who did not have a daily defecation habit had a 7-day run-in period before the 21-day intervention period with RMD or placebo. CTT and segmental CTT (SCTT) were assessed by a single abdominal X-ray film taken at the end of both periods after radiopaque marker ingestion. Defecation characteristics and intestinal functions were also assessed, which were self-reported by patients. Intragroup comparisons were evaluated by Student's paired t test, Bonferroni test and Chi-square test, while time comparisons by analysis of variance (ANOVA) and time-by-treatment interaction by repeated-measures ANOVA.

RESULTS

Fifty-seven subjects were assessed for CTT (placebo, n = 28; RMD, n = 29). In the RMD group, the total CTT, left SCTT and rectosigmoidal SCTT decreased significantly compared to baseline (p < 0.01 each; -13.3, -4.7, -8.7 h, respectively). Significant differences between groups were observed in total CTT and left SCTT. Significant time-by-treatment interaction was observed in the RMD group for stool volume (p = 0.014), increasing 56 % compared to baseline (p < 0.01), while remained unchanged in the placebo group. Stool consistency was improved only in the RMD group (p < 0.01). No adverse effects related to study products were observed.

CONCLUSIONS

The results show that RMD improved CTT, stool volume, stool consistency and some intestinal functions in a healthy population.

Effects of young barley leaf powder on gastrointestinal functions in rats and its efficacy-related physicochemical properties

Young barley leaf is consumed as a popular green-colored drink, which is named “Aojiru” in Japan. In the present study, we examined effects of young barley leaf powder (BL) on gastrointestinal transit time (GTT) and fecal moisture and weight in comparison with wheat bran (WB) in male Sprague-Dawley rats. In addition, an attempt was made to identify BL components responsible for these effects by using various fractions of BL. Additionally, we examined the water-holding capacity and setting volume of BL in vitro. We also examined the granular structures of BL with a scanning electron microscope. As a result, BL supplementation in the diet increased the fecal weight and shortened GTT. Our results demonstrate that the active component responsible for the effect on increasing the fecal volume in BL is the water-insoluble dietary fiber fraction and that this effect is thought to be caused by stimulation of the gut tract by the pH lowering. Furthermore, the high laxative action of BL was thought to be ascribable to the high water-holding capacity due to the complicated structures of BL.

Effects of new dietary fiber from Japanese Apricot (Prunus mume Sieb. et Zucc.) on gut function and intestinal microflora in adult mice

Much attention has been focused recently on functional foods. Ume, the Japanese name for the apricot of Prunus mume Sieb. et Zucc., is an example of a Japanese traditional functional food. There are, however, few reports on the effects of fiber from this fruit on bowel function. With this objective, we prepared ume fiber to test the hypothesis that it can change gut function and intestinal flora in mice. Mice were fed an ume fiber (UF) or cellulose (CF) diet (control) for 40 days. The fecal weight, fecal lipids, plasma lipids and cecal composition of the microflora were analyzed. The amount of feces was significantly greater in the UF group than in the CF group (p < 0.01). The fecal lipids content (% DW) of the feces sampled on the final day of the experiment were significantly greater in the UF group than in the CF group (p < 0.01). Plasma non-esterified fatty acids (NEFA) concentrations tended to be lower in the UF compared to the CF group (p = 0.058). Occupation ratios of Bacteroides and Clostridium cluster IV were significantly greater in the cecal flora of the UF group. Our results suggest that ume fiber possesses the fecal lipid excretion effects and feces bulking effects.

Dietary fiber and subsequent changes in body weight and waist circumference in European men and women

BACKGROUND

Dietary fiber may play a role in obesity prevention. Until now, the role that fiber from different sources plays in weight change had rarely been studied.

OBJECTIVE

Our aim was to investigate the association of total dietary fiber, cereal fiber, and fruit and vegetable fiber with changes in weight and waist circumference.

DESIGN

We conducted a prospective cohort study with 89,432 European participants, aged 20-78 y, who were free of cancer, cardiovascular disease, and diabetes at baseline and who were followed for an average of 6.5 y. Dietary information was collected by using validated country-specific food-frequency questionnaires. Multiple linear regression analysis was performed in each center studied, and estimates were combined by using random-effects meta-analyses. Adjustments were made for follow-up duration, other dietary variables, and baseline anthropometric, demographic, and lifestyle factors.

RESULTS

Total fiber was inversely associated with subsequent weight and waist circumference change. For a 10-g/d higher total fiber intake, the pooled estimate was -39 g/y (95% CI: -71, -7 g/y) for weight change and -0.08 cm/y (95% CI: -0.11, -0.05 cm/y) for waist circumference change. A 10-g/d higher fiber intake from cereals was associated with -77 g/y (95% CI: -127, -26 g/y) weight change and -0.10 cm/y (95% CI: -0.18, -0.02 cm/y) waist circumference change. Fruit and vegetable fiber was not associated with weight change but had a similar association with waist circumference change when compared with intake of total dietary fiber and cereal fiber.

CONCLUSION

Our finding may support a beneficial role of higher intake of dietary fiber, especially cereal fiber, in prevention of body-weight and waist circumference gain.

Effect of pectin enhancement on plasma quercetin and fecal flora in rutin-supplemented mice

Few reports have considered the effects of dietary fiber on plasma quercetin and the intestinal flora. We investigated the effects of pectin on the plasma and fecal flora of mice fed a diet supplemented with the quercetin glycoside rutin. Male mice were randomly divided into 2 groups, which were fed a pectin-rutin (PR) or cellulose-rutin (CR) diet for 14 d. Plasma quercetin and isorhamnetin metabolites were measured by high-performance liquid chromatography. Feces were immediately processed with bacteriological procedures. The fecal flora was investigated. Plasma quercetin and isorhamnetin concentrations were significantly higher in the PR diet group, as was the plasma isorhamnetin/quercetin ratio. The composition of the intestinal flora differed between the 2 dietary groups. The total number of fecal bacteria was significantly larger in the PR group, in which most types of bacteria were more abundant, with the exceptions of bifidobacteria, fusiform-shaped bacteria, and staphylococci. The lower gut seemed to be the major absorption site for rutin. Pectin might thus enhance the bioavailability of quercetin from rutin by altering the metabolic activity of the intestinal flora and/or gut physiological function.

Dietary Fiber and the Relationship to Chronic Diseases

Preventative medicine is targeting chronic diseases such as heart disease, cancer, diabetes, and obesity. Populations that consume more dietary fiber have less chronic disease. Intake of dietary fiber has beneficial effects on the risk factors for developing several chronic diseases. Dietary reference intakes recommend the consumption of 14 g of dietary fiber per 1000 kcal, or 25 g for women and 38 g for men, based on the goal of protection against cardiovascular disease. Usual intake of dietary fiber is only 16 g per day. Viscous fibers decrease the glycemic response and may assist in diabetes care. High-fiber diets provide bulk, are more satiating, and have been linked to lower body weights. Evidence that fiber decreases cancer is mixed, and further research is needed. Dietary messages to increase consumption of high-fiber foods such as whole grains, legumes, fruits, and vegetables should be broadly supported by the medical profession. Consumers are also turning to fiber supplements and bulk laxatives as additional fiber sources. As many fiber supplements have not been studied for physiological effectiveness, the best advice is to consume fiber in foods.

Effects of isomalt consumption on gastrointestinal and metabolic parameters in healthy volunteers

The polyol isomalt (Palatinit®) is a well established sugar replacer. The impact of regular isomalt consumption on metabolism and parameters of gut function in nineteen healthy volunteers was examined in a randomised, double-blind, cross-over trial with two 4-week test periods. Volunteers received 30 g isomalt or 30 g sucrose daily as part of a controlled diet. In addition to clinical standard diagnostics, biomarkers and parameters currently discussed as risk factors for CHD, diabetes or obesity were analysed. Urine and stool Ca and phosphate excretions were measured. In addition, mean transit time, defecation frequency, stool consistency and weight were determined. Consumption of test products was affirmed by the urinary excretion of mannitol. Blood lipids were comparable in both phases, especially in volunteers with hyperlipidaemia, apart from lower apo A-1 (P=0·03) for all subjects. Remnant-like particles, oxidised LDL, NEFA, fructosamine and leptin were comparable and not influenced by isomalt. Ca and phosphate homeostasis was not affected. Stool frequency was moderately increased in the isomalt phase (P=0·006) without changes in stool consistency and stool water. This suggests that isomalt is well tolerated and that consumption of isomalt does not impair metabolic function or induce hypercalciuria. In addition, the study data indicate that isomalt could be useful in improving bowel function.

Pectin in pig nutrition, a comparative review

A comprehensive review is given on pectin effects in pigs. Its effects on feed passage and digestion in the small intestine, the composition of ileal digesta and fermentation in the colon are described. Pectins promote fermentation at the terminal ileum and in the first part of the colon. It is shown, that pectin opposite to cellulose is degraded to high extents in the colon. Dietetic effects in relation to composition of ileocaecal digesta, endogenous secretions, buffering and pH-stability, high fermentability of organic matter in the colon and resulting volatile fatty acids (VFA) in the cranial part of the colon and even its possible interactions to colonization of the gut by infectious bacteria are described. Pectin effects concerning volume of the intestinal tract, distribution of VFA and lactic acid, role of endogenous secretions are described. The negative effect of pectins on praecaecal digestibility, their high degradation rates in the large intestine and consequences for their dietetic effects are discussed.

Inter-relationship of microbial activity, digestion and gut health in the rabbit: effect of substituting fibre by starch in diets having a high proportion of rapidly fermentable polysaccharides

Caecal microbial activity, digestion and gut health were analysed in the young rabbit, in response to fibre substitution by starch, in diets with high proportions of rapidly fermentable polysaccharides (pectins+hemicelluloses:acid-detergent fibre (ADF) ratio of 1.7). A range of five diets corresponding to a 60 % linear reduction of the ADF level (230 to 92 g ADF/kg) without changes in the fibre quality, and to a corresponding linear increase in dietary starch, was given ad libitum to young rabbits from 18 d until 70 d of age. A one half reduction of the ADF level resulted in a sharp increase in energy digestibility (+25 units), associated with a lower feed intake (-35 %) and to an increase of the mean retention time (+6 h) in the whole digestive tract. Despite large variations in the fibre intake (20 to 59 g ADF/d), the fibre digestive efficiency remained similar among the five diets. Starch ileal concentrations were low after 4 weeks of age (<5 %), and variations with age were significant when the dietary starch level was over 19 %. A 65 % lower biomass production was measured when the ADF level progressed from 230 to 165 g/kg, and no precise relationship was found with fermentative activity. Reducing the fibre intake led to a linear decrease of caecal volatile fatty acids concentrations, and to higher pH and NH3 levels. An increased occurrence of mortality by diarrhoea was registered with the lowest fibre intake. It can be concluded that a sufficient supply of fibre, with high proportions in rapidly fermentable polysaccharides, stimulates the maturation of microbial activity and reduces the occurrence of diarrhoea.

The prevention of colon carcinogenesis in rats by dietary cellulose is greater than the promotive effect of dietary lard as assessed by repeated endoscopic observation

We developed a method which we used in the current study to observe the rat colon endoscopically. Our goal was to evaluate the entire course in the development of experimental large bowel tumors through serial observations in the same rat. We compared the effects of dietary lard and cellulose on rat colon tumorigenesis in a 2 x 3 factorial design. Sprague-Dawley rats (n = 90) were divided into 6 diet groups: rats were fed a diet without cellulose that contained 5, 10, and 15 g/100 g lard, or diets containing 15% cellulose diet (15 g cellulose/100 g diet) and the same concentrations of lard. The development of large bowel tumors induced by the administration of 1,2-dimethylhydrazine (25 mg/kg body weight) for 19 wk was examined endoscopically. Tumor induction rates in the 15% cellulose groups were lower than in the 0% cellulose groups (P = 0.008), independent of the lard concentration. These results suggest that the preventive effect of cellulose against large bowel tumorigenesis is greater than the promotive effect of fat under the current experimental conditions.

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.

Immunonutrition: the role of carbohydrates

The major role for carbohydrates in the diet is for the provision of energy. Most non-energy-related effects of carbohydrates can be related to short-chain fatty acid production or other effects of bacterial fermentation in the colon. More complex or slowly absorbed carbohydrates may also reduce glycemic index and insulin production and therefore may have a less profound effect on modification of lipid metabolism. Certain carbohydrates may promote fermentation in the colon, increasing short-chain fatty acid production and may alter bacterial flora in the small bowel and colon. Increased insoluble fiber will increase fecal bulk. Further immunomodulary effects of carbohydrates have had little attention in the literature. This would be a potential opportunity for further investigation.

Barley bran flour accelerates gastrointestinal transit time

The effect of barley bran flour on colon physiology was studied in 44 volunteers. Twenty-two subjects followed the National Cholesterol Education Program (NCEP) step 1 diet supplemented with 20 g cellulose and the other 22 followed the NCEP diet supplemented with 30 g barley bran flour. To measure gastrointestinal transit time, subjects ingested 20 polyethylene pellets impregnated with barium sulfate in two gelatin capsules. Subjects collected fecal samples for 5 days during the baseline period and again during the period of fiber supplementation. Each stool sample was radiographed, and the number of recovered markers was used to calculate mean transit time. Daily fecal weights were recorded and dry weights were determined. The group that consumed barley bran flour significantly decreased transit time by 8.02 hours from baseline, whereas the group that consumed cellulose increased transit time by 2.95 hours from baseline. Similarly, cellulose supplementation did not result in increased fecal weight, whereas daily fecal weight increased significantly by 48.6 g with supplementation with barley bran flour. This study shows that barley bran flour accelerates gastrointestinal transit and increases fecal weight.

Dietary fiber, inulin, and oligofructose: a review comparing their physiological effects

Dietary fiber is a general term. It covers a wide variety of substances that belong to the family of carbohydrates that resist hydrolysis by human alimentary enzymes but are fermented by colonic microflora. The main physiological effects of dietary fiber are primarily on gastric emptying and small intestinal transit time, resulting in an improved glucose tolerance and a decreased digestion of starch: second, on colonic transit time and large bowel functions due to fermentation by ceco-colonic microbial flora or bulking action. The so-called soluble dietary fibers are fermented to a large extent by a wide variety of anaerobic bacteria that result in an increase in bacterial biomass, an increase in fecal mass, a change in intracolonic pH, and production of short chain fatty acids and various gases as metabolic end products. The insoluble fibers are only marginally fermented: they serve almost exclusively as bulking agents that result in shorter transit time and increased fecal mass. The short chain fatty acids resulting from the colonic fermentation of dietary fiber are largely absorbed via the portal blood and reach both the liver and the peripheral tissues. They induce changes in glucose and fat metabolism leading to post-prandial hypoglycemia and long-term hypolipidemia. Inulin and oligofructose are fructans with a degree of polymerization of 2 to 60 and 2 to 20, respectively. Due to the structural conformation of their osidic bridge (beta 2-1), they both resist the hydrolysis by human alimentary enzymes. Moreover, when reaching the colon, both inulin and oligofructose are almost quantitatively fermented almost exclusively by colonic bifidobacteria and bacteroides. Such an extensive fermentation causes an increase in fecal bacterial biomass, a decrease in ceco-colonic pH, and produces a large amount of fermentation products among which the short chain fatty acids that exert systemic effects on lipid metabolism. Thus, both inulin and oligofructose have most of the characteristics of a dietary fiber and the proposal is made to classify them as such. Moreover, they are bifidogenic factors, because, due to still unknown reasons, they are primarily fermented by bifidobacteria. It is concluded from this review that "nondigestible fructo-oligosaccharides," even though they are not included in the carbohydrate fraction that is quantified as dietary fiber by classic analytical methods, have most of the physiological effects of a dietary fiber.(ABSTRACT TRUNCATED AT 400 WORDS)

Mesalazine release from coated tablets: effect of dietary fibre

Delayed-release mesalazine formulations relay on pH-dependent coat dissolution to ensure delivery of 5-aminosalicylic acid (5-ASA) to the colon. As dietary fibre acidifies the colonic lumen we have studied the effect of fibre supplementation in 10 patients with quiescent colitis. Greater intake of dietary fibre was associated with a decrease in stool pH and an increase in stool frequency and faecal mass. However, the 24 h faecal and urinary excretion of 5-ASA and N-acetyl-5-ASA was unchanged. The percentage of total faecal ASA excreted as N-acetyl-5-ASA correlated with whole-gut transit time, suggesting that prolonged transit may be disadvantageous to patients with colitis as N-acetyl-5-ASA appears to be inactive.

Use of a fiber-containing enteral formulation in an AIDS patient

The value of aggressive nutritional support in the patient with AIDS requires further study. As medical treatment modalities become more sophisticated, the etiology of complications that are associated with AIDS are more clearly understood and can be more effectively treated. Survival rates of greater than one and one-half years after an episode of pneumocystis are now more common. As clinicians become more familiar with AIDS and as new medical treatments are discovered, there is reason to believe that a gradual improvement in survival and quality of life will continue. Therefore, further research is needed to determine the point at which nutritional therapy is truly beneficial in the AIDS population.

The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet or lifestyle

Dietary intake of cholesterol has been linked to coronary heart disease. The effect of grapefruit pectin (Citrus paradisi) on plasma cholesterol, triglycerides, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and the low-density lipoprotein:high-density lipoprotein cholesterol ratio was studied. The study design was a 16-week double-blind, crossover (placebo or pectin) using 27 human volunteers screened to be at medium to high risk for coronary heart disease due to hypercholesterolemia. The study did not interfere with the subjects' current diet or lifestyle. Grapefruit pectin supplementation decreased plasma cholesterol 7.6%, low-density lipoprotein cholesterol 10.8%, and the low-density lipoprotein:high-density lipoprotein cholesterol ratio 9.8%. The other plasma lipid fractions studied showed no significant differences. We conclude that a grapefruit pectin-supplemented diet, without change in lifestyle, can significantly reduce plasma cholesterol.

Grapefruit pectin inhibits hypercholesterolemia and atherosclerosis in miniature swine

We studied the effect of dietary grapefruit pectin on plasma cholesterol and the development of atherosclerosis in 18 miniature swine. Pigs were randomized to one of three diets: no added fat (I), added fat/cellulose (II), and added fat/pectin (III). Plasma cholesterol was measured monthly. Arteries were examined for atherosclerosis at the termination of the experiment. Pectin supplementation of an added fat diet resulted in a significantly lower average plasma cholesterol than did cellulose supplementation (168 mg/dl vs. 249 mg/dl, p less than 0.05). The pectin-fed pigs also developed less atherosclerosis of their aortas (1.1% vs. 7.0%, p less than 0.05) and coronary arteries (2.9% vs. 26.2% cross-sectional narrowing, p less than 0.05). Plasma cholesterol levels correlated with the severity of aortic (r = 0.836) and coronary artery (r = 0.735) atherosclerosis. We conclude that dietary grapefruit pectin supplementation inhibits hypercholesterolemia and appears to be proportionately protective against atherosclerosis.

Enteral and parenteral nutrition in patients with enteric fistulas and short bowel syndrome

Significant advances in the use of enteral and parenteral nutrition in patients with either enteric fistulas or short bowel syndrome include increased usage of enteral nutrition because of its trophic effects on the gut and increased usage of both enteral and parenteral nutrition in the home setting. Current investigations are directed toward identifying gut-specific fuels and dietary and pharmacologic enhancement of nutrient utilization.

In vivo studies with fibre components

There are few studies in man examining the in vivo effects of dietary fibre on bile acid metabolism but divergent results have been recorded depending on the amount and type of fibre eaten. Studies in which the fibre components pectin, cellulose, and lignin were fed to normal volunteers for four weeks have been reported. The highly fermentable component pectin is associated with increased secondary bile acid formation in contrast to the partially fermentable component cellulose in which the opposite occurs. Lignin has no effect on bile acid metabolism. No component significantly alters biliary lipids. Since ordinary diets contain a mixture of different fibres the net effect will depend on the relative amounts of each. Significant changes in bile acid metabolism and biliary lipids in the longer term (greater than 4 weeks) however, are not precluded by the results of these short term studies.

Harry M. Vars award. The effect of a pectin-supplemented elemental diet on intestinal adaptation to massive small bowel resection

The effect of a pectin-supplemented elemental diet on intestinal adaptation to massive small bowel resection in the rat was investigated in this study. Sixty adult Sprague-Dawley rats underwent placement of a feeding gastrostomy and swivel apparatus. Control animals (N = 16) were then returned to their cages while the remaining animals underwent an 80% small bowel resection and anastomosis (resected, N = 44). Postoperatively, animals were randomly assigned to receive either a fat- and fiber-free elemental diet (no pectin) or the same diet supplemented with 2% pectin (pectin). After 8 days of full strength diet, samples of jejunum, ileum, and colon were obtained for analysis. The weights per unit length of the ileum and colon were significantly greater in the resected pectin group than either the resected no pectin or pectin control groups. Mucosal parameters (unit weight, DNA, RNA, and protein content) were significantly increased in the jejunum and ileum of both the resected pectin and resected no pectin groups relative to their respective control groups. However, jejunal and ileal mucosal parameters were significantly greater (1.3- to 2-fold) for the resected pectin group than for the resected no pectin group. All the mucosal parameters of the colons were significantly greater for the pectin resected group than for the pectin control group, while only colonic mucosal RNA was significantly greater for the no pectin resected group than for the no pectin control group. These data indicate that the addition of pectin to an elemental diet significantly enhanced intestinal adaptation to massive small bowel resection in the rat.

Bowel function of healthy men consuming liquid diets with and without dietary fiber

The importance of the level of dietary fiber intake on bowel function was measured in 16 healthy young males consuming self-selected and liquid enteral diets. Subjects consumed liquid Ensure as their sole nutrient source plus 0 (diet a), 30 (diet c), and 60 (diet d) g/day soy fiber, a fiber source high in hemicellulose that was added to the Ensure. Further, to examine whether heat processing affects the physiologic action of fiber, subjects consumed Enrich, an enteral formula similar to Ensure, which contains 30 g of the same soy fiber (diet b). The four diets were consumed in randomized order each for 10 days. Daily wet stool weight averaged 144.6 g on the self-selected diet and decreased significantly to 67.3 g when Ensure was consumed alone. Average stool weights on diets (b), (c), and (d) were 114.6, 100.2, and 150.3 g/day, respectively. Average fecal dry weights for the four diets were 19.1, 28.7, 25.0, and 30.3 g/day for (a-d), respectively. Gastrointestinal transit time, as measured with radiopaque pellets, was longest on the Ensure diet, 72.4 hr, and approximately 2 days on the fiber-supplemented diets and the self-selected diet. Thus, soy fiber's physiologic effect on laxation was not changed by heat processing. Also, although stool weights were larger on higher fiber intakes, transit rates were similar on all the fiber-containing diets.