Patricia A. Judd

Association between Faecalibacterium prausnitzii and dietary fibre in colonic fermentation in healthy human subjects

The intestinal microbiota are a complex ecosystem influencing the immunoregulation of the human host, providing protection from colonising pathogens and producing SCFA as the main energy source of colonocytes. Our objective was to investigate the effect of dietary fibre exclusion and supplementation on the intestinal microbiota and SCFA concentrations. Faecal samples were obtained from healthy volunteers before and after two 14 d periods of consuming formulated diets devoid or supplemented with fibre (14 g/l). The faecal microbiota were analysed using fluorescent in situ hybridisation and SCFA were measured using GLC. There were large and statistically significant reductions in the numbers of the Faecalibacterium prausnitzii (P < or = 0.01) and Roseburia spp. (P < or = 0.01) groups during both the fibre-free and fibre-supplemented diets. Significant and strong positive correlations between the proportion of F. prausnitzii and the proportion of butyrate during both baseline normal diets were found (pre-fibre free r 0.881, P = 0.001; pre-fibre supplemented r 0.844, P = 0.002). A significant correlation was also found between the proportional reduction in F. prausnitzii and the proportional reduction in faecal butyrate during both the fibre-free (r 0.806; P = 0.005) and the fibre-supplemented diet (r 0.749; P = 0.013). These findings may contribute to the understanding of the association between fibre, microbiota and fermentation in health, during enteral nutrition and in disease states such as Crohns disease.

The effect of consuming instant black tea on postprandial plasma glucose and insulin concentrations in healthy humans

Objective: To determine the effects of black tea on postprandial plasma glucose and insulin concentrations in healthy humans in response to an oral glucose load. Methods: A four-way randomised, crossover trial was designed in which 16 healthy fasted subjects would consume 75g of glucose in either 250ml of water (control), 250ml of water plus 0.052g of caffeine (positive control) or 250 ml of water plus 1.0g or 3.0g of instant black tea. Blood samples were collected at fasting and at 30min intervals for 150min from commencement of drink ingestion. Glucose and insulin concentrations were measured using standard methodology. The tea was chemically characterised using colorimetric and HPLC methods. Results: Chemical analysis showed that the tea was rich in polyphenolic compounds (total, 350mg/g). Results from only 3 treatment arms are reported because the 3.0g tea drink caused gastrointestinal symptoms. Plasma glucose concentrations <60min in response to the drinks were similar, but were significantly reduced at 120min (P<0.01), following ingestion of the 1.0g tea drink, relative to the control and caffeine drinks. Tea consumption resulted in elevated insulin concentrations compared with the control and caffeine drinks at 90min (P<0.01) and compared with caffeine drink alone at 150min (P<0.01). Conclusions: The 1.0g tea drink reduced the late phase plasma glucose response in healthy humans with a corresponding increase in insulin. This may indicate that the attenuation in postprandial glycemia was achieved as a result of an elevated insulin response following stimulation of pancreatic β-cells. This effect may be attributable to the presence of phenolic compounds in the tea

Randomized trial of the effects of cholesterol-lowering dietary treatment on psychological function.

PURPOSE Epidemiological studies have suggested that cholesterol lowering could affect psychological functioning. This study was designed to test whether cholesterol-lowering diets adversely affect mood and cognitive function.5.2 mM [198 mg/dL]) to either a low-fat diet, a Mediterranean diet, or a waiting-list control. Cholesterol levels, psychological well-being (depression, anxiety, hostility), and cognitive function were assessed at baseline, 6 weeks, and 12 weeks. RESULTS Total serum cholesterol levels fell significantly more in the intervention groups (8.2% reduction) than in the control group (P <0.001). All three groups showed a modest improvement in psychological well-being during the 12-week treatment period, but there were no differences among the groups. There were no between-group differences on three measures of cognitive function, but for a fourth measure, which involved the task with the greatest processing load, the two intervention groups did significantly worse (P <0.001) than the control group. The change in performance was correlated with the change in total serum cholesterol level (r = 0. 21, P = 0.01). CONCLUSIONS Two dietary interventions that successfully lowered serum cholesterol levels had no adverse effect on mood. There was some evidence for a relative impairment in cognitive function in the treated groups in one of four cognitive tests, but additional studies will be required to determine the relevance of this finding.

Fecal microbiota in patients receiving enteral feeding are highly variable and may be altered in those who develop diarrhea.

BACKGROUND 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. OBJECTIVE 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. DESIGN 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. RESULTS 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). CONCLUSION Intestinal dysbiosis occurs in patients who develop diarrhea during enteral feeding and may be involved in its pathogenesis.

Enteral feeding: the effect on faecal output, the faecal microflora and SCFA concentrations

Enteral tube feeding is common in both the hospital and community environment; however, patients can suffer alterations in faecal output that can have serious clinical sequelae. Problems associated with accurate characterisation of faecal output and definition of diarrhoea impede the comparison of research studies and prevent standardised assessment of therapeutic interventions in clinical practice. The colonic microflora may protect the patient against diarrhoea by preventing enteropathogenic infection and by producing SCFA that stimulate colonic water absorption. However, studies in healthy volunteers suggest that the composition of the enteral formula may have a negative impact on the microflora and SCFA concentrations. The addition of fructo-oligosaccharides to the enteral formula may partially prevent negative alterations to the microflora, although conclusive data from studies in patients are not yet available. Modification of the microflora with probiotics and prebiotics may hold potential in prophylaxis against diarrhoea during enteral tube feeding.

Appetite during consumption of enteral formula as a sole source of nutrition: the effect of supplementing pea-fibre and fructo-oligosaccharides

Liquid enteral formulas are commonly used as a sole source of nutritional support of patients in hospital and community settings. Their effect on appetite has important consequences for dietary management of such patients and is likely to be affected by the formula composition. The aim of the present study was to compare appetite within healthy subjects consuming both a standard formula and one supplemented with pea-fibre (10 g/l) and fructo-oligosaccharide (FOS; 5 g/l) as a sole source of nutrition. Eleven healthy subjects consumed a standard formula or a pea-fibre/FOS formula as a sole source of nutrition for 14 d in a double-blind, cross-over trial. Appetite was recorded using standard 100 mm lines anchored at each end by a phrase denoting the most extreme appetite sensation. Consumption of the pea-fibre/FOS formula resulted in higher mean fullness (46 v. 37 mm, P=0.035), minimum fullness (13 v. 9 mm, P=0.024) and minimum satiety (12 v. 8 mm, P=0.012) compared to the standard formula. As there were no differences in macronutrient intake between formulas, these differences are likely to be due to supplementation with pea-fibre and FOS. The effect on appetite of the composition of an enteral formula, both with respect to nutrient content and functional components such as pea-fibre and FOS, may be an important aspect to consider in the dietary management of patients consuming enteral formula as a sole source of nutrition.

Assessment of fecal output in patients receiving enteral tube feeding: validation of a novel chart

Objective: To develop a practical, valid and reliable chart to assist in the accurate visual characterization of fecal output in patients receiving enteral tube feeding (ETF).Design: A chart incorporating verbal and pictorial descriptors of fecal output was developed. Validity and reliability were assessed by a questionnaire survey of health professionals and a clinical study of patients commencing ETF. Content validity was assessed from the results of the questionnaire, construct validity by contrasting groups analysis, concurrent validity by comparison of the chart with actual fecal weight and inter-rater reliability by independent characterization of the same fecal sample by two nurses.Setting: St Georges Hospital, London, UK.Subjects: In all, 35 health professionals completed a questionnaire with respect to the chart. The chart was then used to monitor fecal output in 36 patients commencing ETF for a total of 171 patient-days, during which time nurses used the chart to characterize 269 fecal samples, of which 59 were subsequently weighed.Results: The results of the questionnaire suggested good content validity. The chart demonstrated statistically significant differences in fecal frequency, fecal consistency, fecal score and incidence of diarrhea for contrasting patient groups expected to have different fecal output (P<0.05). The inter-rater reliability was almost perfect for fecal consistency (95% agreement, κ=0.91) and substantial for fecal weight (83%, κ=0.75). In all, 83% of fecal samples were assigned to the correct weight category (κ=0.75).Conclusion: The chart has good content, construct and concurrent validity and inter-rater reliability, and is suitable for both research and clinical use.Sponsorship: This research was jointly supported by Kings College London and Nestlé, UK.

Night eating syndrome: implications for severe obesity

Night eating syndrome (NES) was first identified in 1955 by Stunkard, a psychiatrist specialising in eating disorders (ED). Over the last 20 years considerable progress has been made in defining NES as a significant clinical entity in its own right and it has now been accepted for inclusion in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) due for publication in 2013. NES is considered a dysfunction of circadian rhythm with a disassociation between eating and sleeping. Core criteria include a daily pattern of eating with a significantly increased intake in the evening and/or night time, as manifested by one or both of the following: at least 25% of food intake is consumed after the evening meal or at least two episodes of nocturnal eating per week. An important recent addition to core criteria includes the presence of significant distress and/or impairment in functioning. Stunkard’s team recommend further investigation on the pathogenesis of NES, in particular its relationship with traumatic life events, psychiatric comorbidity, the age of onset of NES and course of NES over time. The relationship between NES and other ED also requires further clarification as night-eaters exhibit some features of other ED; previous guidance to separate NES from other ED may have hindered earlier characterisation of NES. Evidence from European and American studies suggests NES features strongly in populations with severe obesity. The complex interplay between depression, impaired sleep and obesity-related comorbidity in severely obese individuals makes understanding NES in this context even more difficult. This review examines evidence to date on the characterisation of NES and concludes by examining the applicability of current NES criteria to individuals with severe obesity.

African plant foods rich in non-starch polysaccharides reduce postprandial blood glucose and insulin concentrations in healthy human subjects

The effects of two vegetable flours, prepared from the African plants Detarium senegalense Gmelin, a legume, and Cissus rotundifolia, a shrub, on postprandial blood glucose and insulin concentrations in human subjects, were investigated. Chemical analysis indicated that these flours contained significant amounts of NSP. The detarium in particular was found to be a rich source of water-soluble NSP (SNSP). The flours were incorporated into two types of breakfast meal, a stew meal and a wheat bread meal, containing 50 g and 70 g available carbohydrate respectively. Both meals also contained 10-12 g NSP, the major fraction of which was SNSP. Control and fibre-rich meals were consumed on separate days in randomized order by two different groups of subjects (n 5, stew meals; n 10, bread meals). Venous blood samples were taken at fasting (0 min) and postprandially at 30 min intervals for 2.5 h and the plasma analysed for glucose and insulin. Compared with the controls, detarium and cissus meals elicited significant reductions (P < 0.006) in plasma glucose levels at most postprandial time points and for area-under-the-curve (AUC) values (AUC reductions 38-62%). Significant reductions (P < 0.002) in plasma insulin levels at various postprandial time points and for AUC values were also seen after detarium and cissus breads (AUC reductions 43 and 36% respectively), but not after the fibre-rich stew meals. SNSP and starch are possibly the main, but not the only, components responsible for the glucose- and insulin-lowering effects of cissus flour. The main SNSP fraction of detarium, identified as a high-molecular-weight xyloglucan, is likely to be a primary factor in determining the physiological activity of detarium flour.

Covert Assessment of Concurrent and Construct Validity of a Chart to Characterize Fecal Output and Diarrhea in Patients Receiving Enteral Nutrition

BACKGROUND An accurate and convenient method for characterizing fecal output and a consistent threshold for classifying diarrhea in patients receiving enteral nutrition are required. The aim of this study is to covertly assess the construct and concurrent validity of a chart for characterizing fecal output and classifying diarrhea in patients receiving enteral nutrition. METHODS The chart was used to monitor fecal output in patients receiving enteral nutrition for a total of 280 patient days. Nurses characterized 291 fecal samples, of which 84 underwent measurement of fecal water using lyophilization and 60 underwent Clostridium difficile enterotoxin analysis using enzyme-linked immunosorbent assay. Construct and concurrent validity was assessed covertly to measure the true performance of the chart in a real-life clinical and research context. RESULTS Use of the chart demonstrated higher fecal frequency (P <or= .04), heavier stools (P <or= .167), more unformed stools (P <or= .001), higher daily fecal scores (P <or= .001), and higher incidence of diarrhea (P <or= .002) on days when patients had severe hypoalbuminemia, were receiving antibiotics, or had a recent positive C difficile assay, demonstrating construct validity. The water content of samples assigned to hard and formed (62.0%), soft and formed (72.1%), loose and unformed (79.3%), and liquid (87.9%) categories was significantly different (P < .001), demonstrating concurrent validity. CONCLUSIONS Under covert assessment, the chart demonstrated construct validity for characterizing fecal output, daily fecal score, and diarrhea, together with concurrent validity for characterizing fecal consistency. Use of the chart in clinical practice and research will standardize the characterization of fecal output and classification of diarrhea in patients receiving enteral nutrition.