Use of dietary fibers in enteral nutrition of critically ill patients: a systematic review

To meet the nutritional requirements of patients admitted to intensive care units, it is necessary to establish a diet schedule. Complications associated with enteral nutrition by tube feeding are not uncommon and may reduce the delivery of required nutrient to patients in intensive care units. Research on the osmolality, fat content, caloric intensity and fiber content of formulas are under way, and a substantial number of studies have focused on fiber content tolerability or symptom reduction. We conducted a systematic review of dietary fiber use and safety in critically ill patients in 8 studies based on diarrhea, other gastrointestinal symptoms (abdominal distension, gastric residual volume, vomiting and constipation), intestinal microbiota, length of stay in the intensive care unit and death. We discussed the results reported in the scientific literature and current recommendations. This contemporary approach demonstrated that the use of soluble fiber in all hemodynamically stable, critically ill patients is safe and should be considered beneficial for reducing the incidence of diarrhea in this population.

Related papers:

title: Enteral nutrition delivery and energy expenditure in medical intensive care patients.
abstract: Delivery of enteral nutrition (EN) in critical illness is often inadequate. This prospective observational study addresses the implementation of enteral feeding in critically ill medical patients and its relation to energy expenditure.



All admissions to a university medical ICU over a period of one year were screened. Patients receiving EN for at least 7 days were followed up. The caloric target was a minimum of 20 kcal/kg/day. The feeding volume was increased daily by 500 ml and a maximum of 2000 ml/day was targeted to be achieved by day 4 of admission. Energy expenditure was measured with indirect calorimetry on day 3 or 5.



Two hundred and thirtyone patients required artificial nutrition, of which 61 patients were enterally fed for 7 days. This group was followed for a total of 750 feeding days. The gastric route was used at the start, with a post-pyloric feeding required during follow-up in 36.1% of patients due to high gastric residual. EN was interrupted in 32.1% of the feeding days. The daily administered volume was 86.2 +/- 30.4% of the prescribed. The mean enteral caloric supply in relation to energy expenditure was between 39.2 +/- 34.6% on day 1 and 83.1 +/- 31.1% on day 6. The targeted maximum feed volume was achieved on day 4 in 75.4% of the patients. Patients with a delayed target time had a higher mortality rate than those with a target time of <4 days (73.3% vs. 26.1%),



A high delivery-to-prescription rate could be achieved with a standardized enteral feeding protocol in critically ill medical patients. However, caloric delivery is much less than measured energy expenditure. Enteral feeding intolerance is associated with a high mortality rate.

title: Enteral nutrition preference in critical care: fibre-enriched or fibre-free?
abstract: This study's main aim was to observe the effects of a fibre-enriched nutrition solution on requisite feeding volume, which is directly proportional to energy intake in mechanically ventilated patients with enteral nutrition.



Some 120 patients who required mechanical ventilation and enteral nutrition with a nasogastric tube were studied. Upon ICU admission, the patient's age, gender, weight, height, comorbidities, diagnosis and APACHE II score were recorded. We assigned two diets to the patients randomly. The control group received the fibre-free nutrition solution. The study group, received the fibreenriched nutrition solution. Prescribed feeding volume and administered feeding volume, gastric residual volume (GRV), volume ratio (VR), diarrhoea score and gastrointestinal complications (GIC) were recorded, along with daily biochemistry.



The two groups did not differ with respect to age, sex, weight, BMI, APACHE II score, target caloric intake or GRV (p>0.05). On days four and five, the study group had higher VR values (p<0.05). Seventy-one (59%) patients had at least one gastrointestinal complication; 44 (73%) of them were controls and 27 (45%) of them study patients. The most commonly observed GIC was diarrhoea. Thirty-eight patients had diarrhoea in control group, and twenty-two patients had diarrhoea in study group, and this difference was statistically significant (p<0.001). There were no significant differences between the groups about vomiting and regurgitation.



We suggest that ICU staff initiate enteral nutrition with fibre-enriched formulas rather than fibre-free formulas to avoid frequent feeding interruptions that cause protein energy malnutrition in ICU patients.

title: Tolerance, Safety, and Effect on the Faecal Microbiota of an Enteral Formula Supplemented With Pre- and Probiotics in Critically Ill Children
abstract: The aim of this study was to demonstrate the tolerance and safety of an enteral formula containing prebiotics/probiotics, and its effect on the faecal microbiota in critically ill children.  Ninety-four patients between 1 and 3 years old under mechanical ventilation requiring enteral feeding were randomised to receive either a test formula containing a synbiotic blend (composed of 2 probiotic strains [Lactobacillus paracasei NCC 2461 and Bifidobacterium longum NCC 3001], fructooligosaccharides [FOS], inulin, and Acacia gum), or a control formula. Patients remained in the intensive care unit for 7 days and were examined at day 14. Tolerance was assessed by overall caloric intake and time to reach caloric goal. Safety was assessed by abdominal distention, vomiting, and stool frequency. Microbiota was analysed by culture- and molecular-based methods.  Overall caloric intake and time to reach caloric goal were similar between groups (noninferiority was shown). Abdominal distention, vomiting, and stool frequency were not affected by the supplementation with pre- and probiotics. Faecal bifidobacteria were higher in the test group at the end of the study. A similar trend was observed for total lactobacilli. L paracasei NCC 2461 and B longum NCC 3001 were detected in 80.4% and 17% of the test group patients, respectively. Enterobacteria levels remained unchanged during hospitalisation in the control group but diminished in the test group.  The enteral formula supplemented with synbiotics was well tolerated by children in intensive care units; it was safe and produced an increase in faecal bacterial groups of previously reported beneficial effects.

title: Gastrointestinal symptoms in intensive care patients
abstract: Gastrointestinal (GI) problems are not uniformly assessed in intensive care unit (ICU) patients and respective data in available literature are insufficient. We aimed to describe the prevalence, risk factors and importance of different GI symptoms.

title: Isotonic tube feeding formula induces liquid stool in normal subjects: reversal by pectin.
abstract: Diarrhea is one of the most common complications in patients who receive tube-feeding formulas. Since the colon is the final site of water and electrolyte absorption and ultimately determines fecal composition, diarrhea during tube feeding may result from altered colonic function. The lack of dietary fiber, such as pectin, in tube-feeding formulas may be one of the means by which colonic function is affected. The purpose of this study was to determine the effect of a standard, liquid, commercially available, isotonic tube-feeding formula (ITFF) and the effects of supplementing the ITFF with pectin on colonic function as measured by stool consistency and colonic fluid composition in 13 normal adults. Data were obtained when subjects consumed their regular diet, ITFF, and ITFF supplemented with pectin using the technique of in vivo dialysis of colonic fluid. Ingestion of the ITFF resulted in a significant increase in the percentage of liquid stools compared to a regular diet [median (interquartile range) = 0% (0), 60% (64); p less than 0.01]. Ingestion of the ITFF also resulted in significant decreases in the concentrations of sodium, potassium, and short-chain fatty acids, and increases in pH and osmotic gap in colonic fluid compared to the subjects' regular diet. Supplementing the ITFF with pectin significantly reduced the incidence of liquid stools [0% (0)] and promoted a normalization of colonic fluid composition. The results suggest that the addition of pectin may enhance tolerance to ITFFs.

title: Early enteral nutrition in critically ill patients with a high-protein diet enriched with arginine, fiber, and antioxidants compared with a standard high-protein diet. The effect on nosocomial infections and outcome.
abstract: This study was designed to evaluate the effects of a high-protein formula enriched with arginine, fiber, and antioxidants compared with a standard high-protein formula in early enteral nutrition in critically ill patients.



For this study, 220 patients were enrolled in a prospective, multicenter, single-blind, randomized trial in 15 Spanish intensive care units (ICUs). The primary end-points were the incidence density rates of nosocomial infections, ICU and hospital length of stay, ICU and in-hospital mortality, and mortality at 6-month follow-up.



The patients in the control and study groups had similar baseline characteristics. The study group had a lower incidence of catheter-related sepsis (0.4 episodes/1000 ICU days) than the control group (5.5 episodes/1000 ICU days), with a relative risk (RR) of 0.07 (95% confidence interval [CI] 0.01 to 0.54, p < .001). There were no differences in the incidence of ventilator-associated pneumonia, surgical infection, bacteremia, or urinary tract infections between the 2 groups. ICU mortality (16% in the study group versus 21% in the control group; RR 1.5, CI 95% 0.7 to 2.9) and in-hospital mortality (21% in the study group versus 30% in the control group; RR 1.6, CI 95% 0.9 to 3) were similar without differences in survival at 6-month follow-up (75% in the study group versus 68% in the control group, p = .15). Patients in the study group who were treated for 2 or more days showed a strong trend for better survival at 6-month follow-up (76% in the study group versus 67% in the control group, p = .06). Medical patients treated with the study diet had better survival than medical patients in the control group (76% in the study group versus 59% in the control group, p < .05).



Critically ill patients fed a high-protein diet enriched with arginine, fiber, and antioxidants had a significantly lower catheter-related sepsis rate than patients fed a standard high-protein diet. There were no differences in mortality or ICU and hospital length of stay. The subgroup of patients fed the study diet for >2 days showed a trend toward decreased mortality.

title: Soluble fiber reduces the incidence of diarrhea in septic patients receiving total enteral nutrition: a prospective, double-blind, randomized, and controlled trial.
abstract: Attempts to control enteral nutrition associated diarrhea in the critically ill tube-fed patient by implementing feeding formulas enriched with fiber were mostly unsuccessful. Recently, it was shown that enteral feeding containing soluble partially hydrolyzed guar decreased the incidence of diarrhea in a cohort of non-critically ill medicosurgical patients. We investigated whether this type of enteral feed could also influence stool production in patients with severe sepsis, a population at risk for developing diarrhea.



The study was double-blind. Patients with severe sepsis and septic shock were consecutively enrolled and at random received either an enteral formula supplemented with 22 g/l partially hydrolyzed guar or an isocaloric isonitrogenous control feed without fiber. All patients were mechanically ventilated and treated with catecholamines and antibiotics. Enteral feeding was provided through a nasogastric tube for a minimum of 6 days. A semiquantitative score based on stool volume and consistency was used for daily assessment of diarrhea.



25 patients fulfilled the criteria for data analysis. Soluble fiber was administered in 13 of them. The two groups were well-matched for gender, age, disease severity, cause of sepsis, laboratory parameters, total feeding days and time to reach nutritional goals. The mean frequency of diarrhea days was significantly lower in patients receiving fiber than in those on standard alimentation (8.8+/-10.0 % vs 32.0+/-15.3 %; P=0.001). The whole group of fiber-fed patients had less days with diarrhea per total feeding days (16/148 days (10.8%) vs 46/146 days (31.5%); P<0.001) and a lower mean diarrhea score (4.8+/-6.4 vs 9.4+/-10.2; P<0.001). The type of enteral diet did not influence sepsis-related mortality and duration of stay in the intensive care unit.



Total enteral nutrition supplemented with soluble fiber is beneficial in reducing the incidence of diarrhea in tube-fed full-resuscitated and mechanically ventilated septic patients.

title: Control of diarrhea by fiber-enriched diet in ICU patients on enteral nutrition: a prospective randomized controlled trial.
abstract: Enteral fiber-free diets alter intestinal transit and produce diarrhea or constipation. This prospective double blind, controlled study evaluates the use of guar gum, a soluble fiber and a candidate prebiotic in enteral feeds, to prevent diarrhea and potential health benefits in intensive care unit patients.



Twenty patients on enteral nutrition with persistent diarrhea were randomized to receive a new enteral feed either enriched with 2% soluble guar gum (study group, n = 10) or fiber-free (control group, n = 10) for 4 successive days.



The number of liquid stools in response to a soluble fiber-enriched diet was 2.0+/-0.9 (first day) vs. 1.0+/-0.7 (fourth day) (P < 0.01), and in the control group 1.2+/-0.7 (first day) vs. 2.1+/-0.8 (fourth day) (P < 0.05). In the fiber-enriched feed group, plasma glucose and cholesterol levels at termination of the study, respectively, reached 126+/-81 and 164+/-71 mg dl(-1), as compared to 333+/-108 and 378+/-26 mg dl(-1) on Day first (P < 0.01). In the control group, these values on the fourth day were, respectively, 267+/-94 and 263+/-79 vs. 247+/-115 and 315+/-78 on Day first (P > 0.05).



Guar gum-enriched enteral nutrition was related to a decrease of diarrheal episodes in ICU patients with preexisting diarrhea; and to a trend for lower plasma glucose and cholesterol levels.

title: Synbiotics, prebiotics, glutamine, or peptide in early enteral nutrition: a randomized study in trauma patients.
abstract: Since the hepatosplanchnic region plays a central role in development of multiple-organ failure and infections in critically ill trauma patients, this study focuses on the influence of glutamine, peptide, and synbiotics on intestinal permeability and clinical outcome.



One hundred thirteen multiple injured patients were prospectively randomized into 4 groups: group A, glutamine; B, fermentable fiber; C, peptide diet; and D, standard enteral formula with fibers combined with Synbiotic 2000 (Synbiotic 2000 Forte; Medifarm, Sweden), a formula containing live lactobacilli and specific bioactive fibers. Intestinal permeability was evaluated by measuring lactulose-mannitol excretion ratio on days 2, 4, and 7.



No differences in days of mechanical ventilation, intensive care unit stay, or multiple-organ failure scores were found between the patient groups. A total of 51 infections, including 38 pneumonia, were observed, with only 5 infections and 4 pneumonias in group D, which was significantly less than combined infections (p = .003) and pneumonias (p = .03) in groups A, B, and C. Intestinal permeability decreased only in group D, from 0.148 (0.056-0.240) on day 4 to 0.061 (0.040-0.099) on day 7; (p < .05). In group A, the lactulose-mannitol excretion ratio increased significantly (p < .02) from 0.050 (0.013-0.116) on day 2 to 0.159 (0.088-0.311) on day 7. The total gastric retention volume in 7 days was 1150 (785-2395) mL in group D, which was significantly more than the 410 (382-1062) mL in group A (p < .02), and 620 (337-1190) mL in group C (p < .03).



Patients supplemented with synbiotics did better than the others, with lower intestinal permeability and fewer infections.

title: Mixed fibers diet in surgical ICU septic patients.
abstract: Diarrhea commonly occurs in surgical critically ill patients, especially septic patients and fiber formulas have been reported to improve diarrhea. Most reports have used soluble or insoluble fiber exclusively, while the effects of a mixed fiber diet remain unclear. This study compares diarrhea scores between mixed-fiber and non-fiber diets in surgical septic patients receiving broad spectrum antibiotics. We conducted a prospective randomized control double blind study in a general surgical ICU. Patients who received broad spectrum antibiotics and no contraindication to enteral feeding were randomly allocated to a fiber or non-fiber diet for up to 14 days. Nutritional delivery and diarrhea scores were recorded daily. Intention to treat analysis was performed. Thirty-four patients were enrolled in the study, 17 in the fiber group and 17 in non-fiber group. These two patients groups were similar in demographics, disease severity, nutritional status, cause of sepsis and total feeding per day. The proportion of patients with diarrhea score ≥12 was higher in the non-fiber group than in the fiber group, but the difference was not statistically significant [8/17 (47.06%) vs. 4/17(23.53%); p=0.15]. However, the fiber group had a lower mean diarrhea score (fiber vs. non-fiber = 3.6 ± 2.3 vs. 6.3 ± 3.6; p=0.005), as well as a lower global diarrhea score from the generalized estimation equation model for repeated measurement [Coefficient -3.03 (95%CI= -5.03 to -0.92); p=0.005]. In summary, a mixed fiber diet formula can reduce the diarrhea score in surgical critically ill septic patients who received broad spectrum antibiotics.

title: Measurement and Characterization of Dietary Starches
abstract: Some factors present in the starchy foods influence the rate at which the starch is hydrolysed and absorbed in vivo . In order to predict the physiological effects of starchy foods and to complement information of food composition database, the quantification and characterization of the various components in the starch fraction must be evaluated. The contents of total starch (TS), resistant starch (RS), digestible starch (DS), amylose and dietary fibre (DF) were evaluated in 11 starchy foods cooked and cooked/stored (−20°C/30 days—conventional and domestic storage). The in vitro starch hydrolysis, the hydrolysis index (HI), rapidly digestible starch (RDS) and slowly digestible starch (SDS) were also carried out with the same samples. These storage conditions increased the RS content and decreased the HI in all studied foods, and each food showed a specific behaviour in relation to each variable. The high concentration of amylose is not the only fact involved with the starch retrogradation and the formation of RS. Therefore, the complete characterization of the starch fraction of foods subjected to different ways of preparation and storage conditions should be included in the food composition database. The highly significant positive correlation observed between the HI and RDS ( y =0.573 x −16.671, r =0.907, P ⩽0.001, n =22) suggests that the RDS, expressed as dry weight, is an alternative device to predict the digestion of starchy foods.

title: Physiological aspects of resistant starch and in vivo measurements.
abstract: Resistant starch (RS) is the sum of starch and products of starch degradation not absorbed in the small intestine of healthy individuals. There are a number of RS with different characteristics which may have a different fate in the colon. As a consequence, all RS should not be considered equivalent as far as physiological properties are concerned; indeed, they may have a different impact on colonic health. This statement may explain part of the apparent contradictions in the literature on RS and cancer or inflammatory disease prevention. RS is fermented in the large intestine into short-chain fatty acids and, among those, butyrate, which is recognized as the main nutrient of the colonocyte. This fermentation pattern seems to be responsible for most of the effects of RS on colonic health. Another important property is linked to its ability to lower colonic pH, which is usually considered as beneficial for mineral biovailability in the colon or cancer prevention. Due to their fate in the digestive tract, RS materials do not seem to have any significant impact on glucose absorption or metabolism. On the contrary, they may have a hypocholesterolemic effect, but available information is contradictory.

title: Prebiotic capacity of inulin-type fructans.
abstract: The human gut microbiota plays a significant role in human health through its ability to digest food ingredients and manufacture metabolites. This can be positive or negative for host welfare. Moreover, the microflora plays an active role in host defense whereby colonization resistance affords protection against pathogens. Prebiotics are nondigestible food ingredients that target beneficial components of the gut microflora (mainly colonic), particularly the bifidobacteria. In vitro and in vivo evidence has accumulated to confirm the prebiotic effects of inulin-derived fructans.

title: Fecal microbiota in patients receiving enteral feeding are highly variable and may be altered in those who develop diarrhea.
abstract: The pathogenesis of diarrhea in patients receiving enteral feeding includes colonic water secretion, antibiotic prescription, and enteropathogenic colonization, each of which involves an interaction with the gastrointestinal microbiota.



The objective was to investigate temporal changes in the concentrations of fecal microbiota and short-chain fatty acids (SCFAs) in patients starting 14-d of enteral feeding and to compare these changes between patients who do and do not develop diarrhea.



Twenty patients starting exclusive nasogastric enteral feeding were monitored for 14 d. Fecal samples were collected at the start, middle, and end of this period and were analyzed for major bacterial groups by using culture independent fluorescence in situ hybridization and for SCFAs by using gas-liquid chromatography.



Although no significant changes in fecal microbiota or SCFAs were observed during enteral feeding, stark alterations occurred within individual patients. Ten patients (50%) developed diarrhea, and these patients had significantly higher concentrations of clostridia (P = 0.026) and lower concentrations (P = 0.069) and proportions (P = 0.029) of bifidobacteria. Patients with and without diarrhea had differences in the proportion of bifidobacteria (median: 0.4% and 3.7%; interquartile range: 0.8 compared with 4.3; P = 0.035) and clostridia (median: 10.4% and 3.7%; interquartile range: 14.7 compared with 7.0; P = 0.063), respectively, even at the start of enteral feeding. Patients who developed diarrhea had higher concentrations of total fecal SCFAs (P = 0.044), acetate (P = 0.029), and butyrate (P = 0.055).



Intestinal dysbiosis occurs in patients who develop diarrhea during enteral feeding and may be involved in its pathogenesis.

title: Outcomes associated with enteral tube feedings in a medical intensive care unit.
abstract: Underfeeding of patients reliant on enteral tube feedings most likely is due primarily to interruptions in the infusions. Strategies to improve energy intake require an understanding of such interruptions and associated outcomes.



To compare daily energy intake with goal energy intake; to ascertain frequency, duration, and reasons for interruptions in feedings, and to determine occurrences of feeding intolerance.



A prospective, descriptive study of a convenience sample of patients admitted during a 3-month period to a medical intensive care unit. Patients were included who were expected to receive continuous enteral tube feedings for at least 48 hours. Patients were studied until discontinuation of feedings, discharge from the unit, or death.



Thirty-nine patients were studied for 276 feeding days. Patients received a mean of 64% of goal energy intake. Mean length of interruptions in feeding was 5.23 hours per patient per day. Interruptions for performance of tests and procedures accounted for 35.7% of the total cessation in feeding time. Next most time-consuming interruptions occurred with changes in body position (15%), unstable clinical conditions (13.5%), high gastric residual volume (11.5%), and nausea and vomiting (9.2%). Patients had diarrhea 105 (38%) of 276 feeding days. Gastric residual volumes exceeded 150 mL on 28 measurements in 11 patients. Five patients experienced episodes of nausea and vomiting. Four patients experienced an episode of feeding aspiration.  Precautionary interruptions in enteral feedings to decrease presumed risk of aspiration occurred frequently and resulted in underfeeding. Episodes of vomiting and of aspiration were uncommon.

title: Diarrhoea during enteral feeding in the critically ill: A comparison of feeds with and without fibre
abstract: This randomised double-blind study examined the frequency of diarrhoea in intensive care unit patients given a fibre-containing feed, Enrich, and a fibre-free feed, Ensure. A daily ‘diarrhoea score’ was calculated from the frequency, volume and consistency of the stools. A score greater than 12 indicated diarrhoea, and greater than 50 severe diarrhoea. Ninety one patients met the criteria for participation: Enrich 45, Ensure 46. The groups were similar in age, sex ratio, feed volume, antibiotic usage, upper gastro-intestinal bleeding prophylaxis and plasma albumin concentrations. Diarrhoea occurred in 16 patients given Enrich and 13 given Ensure, severe diarrhoea affecting 5 and 9 respectively (NS). Forty seven of 343 (14%) Enrich feeding days and 51 of 342 (15%) Ensure feeding days were complicated by diarrhoea — severe diarrhoea: 8 and 12 feeding days (NS). We conclude soy polysaccharide (21 g/L) did not reduce diarrhoea in intensive care unit patients given enteral feeds.

title: Soy-polysaccharide fiber: effect on diarrhea in tube-fed, head-injured patients.
abstract: In a randomized, double-blind, crossover study the effect of tube-feeding with soy-polysaccharide fiber (SPF) vs without SPF on stool weight (SW), stool consistency (SC), fecal nitrogen (FN), and incidence of diarrhea (ID) was compared in nine head-injured subjects; associations with feeding volume, albumin level, and medications were also examined. Subjects with and without SPF had (mean +/- SEM) SW of 245 +/- 47 and 277 +/- 49 g/d, SC of 2.17 +/- 0.01 and 2.52 +/- 0.13 (3 is watery) (p less than 0.01), FN of 1.35 +/- 0.45 and 1.36 +/- 0.33 g/d, and ID of 33% and 44%, respectively. Significant treatment X treatment-sequence interaction nullified results for SW and SC. Neither FN nor ID were affected by SPF. The condition of all variables tended to improve over time. Certain medications and SPF were predictive of SW and SC; albumin and tube-feeding volume were not. SPF-containing tube feedings did not seem to have an effect on bowel function in these well-nourished head-injured patients.

title: Tube feeding-related diarrhea in acutely Ill patients.
abstract: Acutely ill patients received tube feeding for an average of 15.8 days and, on average, 35% of those days were spent in the intensive care unit (ICU). Patients were prospectively assigned either a fiber-free formula (FFF-OSMOLITE HN, Ross; n = 50) or a fiber-supplemented (soy polysaccharide 14.4 g/L) formula (FSF = JEVITY, Ross; n = 50). Diarrhea was defined as three or more loose or watery stools per day and occurred in 30% of all patients. Diarrhea developed in 29 (41%) of the 71 patients who received antibiotics during, or within 2 weeks prior to, the feeding period, whereas only 1 (3%) of the 29 patients not receiving antibiotics developed diarrhea (p less than 0.005); and this patient developed diarrhea on the day of death. Among the 30 patients with diarrhea, stool Clostridium difficile (CD) toxin was positive in 15 (50%), negative in 11 (37%), and was not measured in four. The mean serum albumin was significantly lower in patients with diarrhea (2.43) than in those without diarrhea (2.75) (p = 0.043). There were no significant differences in age, sex, diagnoses, number of feeding days, and percent ICU days between patients with and without diarrhea. While not statistically significant, patients who received FSF were observed to have a lower incidence of diarrhea, a lower percentage of diarrhea days per total feeding days, and a lower frequency of positive CD toxin assays than patients who received FFF. In this patient population, antibiotic usage was the factor most strongly associated with diarrhea during tube feedings.

title: Systematic review and meta‐analysis: the clinical and physiological effects of fibre‐containing enteral formulae
abstract: Enteral nutrition can be associated with gastrointestinal side effects and fibre supplementation has been proposed as a means to normalize bowel function.

title: Plant Residue and Bacteria as Bases for Increased Stool Weight Accompanying Consumption of Higher Dietary Fiber Diets
abstract: Stool diluting effects of relatively inert material, such as unfermentable dietary fiber, has been proposed as an effect of fiber beneficial to the colon. Stool dilution by increasing bacterial mass may be beneficial or deleterious, depending on bacterial metabolic products. The purpose of this study was to determine the basis for stool weight when two stepwise increases of fiber from all classes of fiber-containing foods were consumed.  Stool from five men consuming three constant diets containing 15, 30 and 42 g/d of dietary fiber were fractionated into plant material and bacteria and analyzed for neutral and amino sugar content. Fecal nitrogen, fat and ash were measured.  Daily gravimetric yield and sugar content of the plant fraction from stool increased with each fiber addition. Compared to the low fiber diet, the medium fiber diet decreased the concentration of the bacterial mass in wet stool by 11% and the high fiber diet by an additional 32%. The high fiber diet decreased stool fat concentration; the medium and high fiber diets decreased stool nitrogen concentration to the same extent. Apparent digestibility of plant-derived neutral sugars decreased with each fiber addition.  Inherently less fermentable plant material modulates the colon environment in three beneficial ways: it is a relatively unreactive diluent of lumenal contents; it adds mass to promote distal movement of waste; it does not promote a large bacterial mass.

title: Dietary fiber, glycemic load, and risk of non-insulin-dependent diabetes mellitus in women.
abstract: To examine prospectively the relationship between glycemic diets, low fiber intake, and risk of non-insulin-dependent diabetes mellitus.



Cohort study.



In 1986, a total of 65173 US women 40 to 65 years of age and free from diagnosed cardiovascular disease, cancer, and diabetes completed a detailed dietary questionnaire from which we calculated usual intake of total and specific sources of dietary fiber, dietary glycemic index, and glycemic load.



Non-insulin-dependent diabetes mellitus.



During 6 years of follow-up, 915 incident cases of diabetes were documented. The dietary glycemic index was positively associated with risk of diabetes after adjustment for age, body mass index, smoking, physical activity, family history of diabetes, alcohol and cereal fiber intake, and total energy intake. Comparing the highest with the lowest quintile, the relative risk (RR) of diabetes was 1.37 (95% confidence interval [CI], 1.09-1.71, P trend=.005). The glycemic load (an indicator of a global dietary insulin demand) was also positively associated with diabetes (RR= 1.47; 95% CI, 1.16-1.86, P trend=.003). Cereal fiber intake was inversely associated with risk of diabetes when comparing the extreme quintiles (RR=0.72, 95% CI, 0.58-0.90, P trend=.001). The combination of a high glycemic load and a low cereal fiber intake further increased the risk of diabetes (RR=2.50, 95% CI, 1.14-5.51) when compared with a low glycemic load and high cereal fiber intake.



Our results support the hypothesis that diets with a high glycemic load and a low cereal fiber content increase risk of diabetes in women. Further, they suggest that grains should be consumed in a minimally refined form to reduce the incidence of diabetes.

title: Human studies with probiotics and prebiotics: clinical implications
abstract: Probiotic agents have been shown to have significant clinical beneficial effects in the prevention and management of gastrointestinal and non-gastrointestinal conditions. These observations have led to work demonstrating that an important mechanism of these agents is their close interaction with the gut associated lymphoid tissue (GALT) and suggested immunomodulatory effects on systemic immune response. Studies on the possibility that prebiotic agents might directly or indirectly induce similar immunomodulation have only recently begun. The preliminary findings of several recent human clinical trials reviewed in this article indicate that prebiotics may indeed prove to be a clinically beneficial dietary supplement, in the context of novel nutritional strategies for the management of gastrointestinal and systemic conditions.

title: Faecal microbiota and short-chain fatty acids in patients receiving enteral nutrition with standard or fructo-oligosaccharides and fibre-enriched formulas.
abstract: Prebiotics potentially increase the growth of bifidobacteria, which may minimise the risk of diarrhoea in patients receiving enteral nutrition (EN). The present study aimed to compare the concentrations of faecal microbiota and short-chain fatty acids (SCFA) in patients receiving EN with either a standard formula or one enriched with fructo-oligosaccharides (FOS) and fibre.



Forty-one hospitalised adult patients (25 males, 16 females) who were on exclusive EN for at least 12 days were recruited to a cross-sectional study. Faecal samples were collected and analysed for major groups of microbiota using fluorescent in situ hybridisation and SCFA concentrations were analysed using gas liquid chromatography.



There were generally low concentrations of the major bacterial groups, including bifidobacteria, in all patients receiving either standard or FOS/fibre-enriched formula  dry faecal, P=0.199]. However, faecal butyrate concentrations were higher in patients receiving the FOS/fibre-enriched formula compared to standard formula [20.5 (21.6) versus 4.6 (6.7) μmol g(-1) dry faecal, P=0.006].



Low concentrations of faecal bifidobacteria were identified in these patients, which potentially increases their risk of diarrhoea. Other microbiota groups may utilise FOS/fibre, leading to different butyrate concentrations between the two cohorts.