Fecal Flora (bacteria)

  The human intestinal microbiota is a complex bacterial consortium that is critical to normal health. The microflora is present at concentrations of 10(11)-10(12) cells/g of intestinal contents; the number of species present may exceed 500, although exact numbers remain to be defined, due in part to the fact that <30% of microorganisms are culturable with current microbiologic methods. Molecular tools based on 16S rDNA sequence similarities such as fluorescent in-situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), quantitative dot blot hybridization, restriction fragment length polymorphism (RFLP) and large scale 16S rDNA sequencing have helped to overcome limitations of conventional microbiological plating methods in studying the fecal microflora composition. However, these tools are just now beginning to be applied to understand the dynamics of this complex community, and its relationship to diet and human health. There is a need to understand both the limitations of the current data and the importance of moving forward with the best possible molecular and epidemiologic techniques as we deal with these critical questions.

PMID: 14747689

  The aim of the present study was to determine the effects of age and diet (breast milk, formula milk and weaning diet) on metabolic activities in faecal samples from infants aged 1 week to 1 year, and to compare these findings with activities found in samples from adults. Such activities can provide valuable information on functional changes in the microbiota that may have significance for the health of the host. Fresh faecal samples were collected from forty-four breast-fed infants (twenty-four males, twenty females) and thirteen formula-fed infants (three males, ten females) throughout the first year of life. The samples were analysed for protein-breakdown products, including the faecal concentrations of NH3, phenol and p-cresol, and faecal bacterial enzyme activities. There was wide individual variation in all variables measured; however, the values in infants were substantially lower then those found in adults. In pre-weaned infants, faecal NH3 concentration and beta-glucuronidase activity were the only endpoints that were significantly different in breast-fed and formula-fed infants (P<0.001 and P<0.05 respectively). This was not apparent after weaning. There was a significant difference between the breast-fed and formula-fed weaned groups and their pre-weaned counterparts only for NH3 (P<0.05). beta-Glucuronidase activity and phenol concentration were significantly (P<0.01) greater in weaned breast-fed infants compared with pre-weaned breast-fed infants. No differences were observed between pre-weaned and weaned formula-fed infants for any of the variables except for NH3 concentration. It can be concluded from the present study that there are significant differences in two faecal characteristics between breast- and formula-fed infants and that changes occur as the infants grow older and are weaned onto solid foods.

PMID: 12654169

  BACKGROUND: Hydrogen sulfide is a luminally acting, bacterially derived cell poison that has been implicated in ulcerative colitis. Sulfide generation in the colon is probably driven by dietary components such as sulfur-containing amino acids (SAAs) and inorganic sulfur (eg, sulfite).
  OBJECTIVE: We assessed the contribution of SAAs from meat to sulfide production by intestinal bacteria with use of both a model culture system in vitro and an in vivo human feeding study.
  DESIGN: Five healthy men were housed in a metabolic suite and fed a sequence of 5 diets for 10 d each. Meat intake ranged from 0 g/d with a vegetarian diet to 600 g/d with a high-meat diet. Fecal sulfide and urinary sulfate were measured in samples collected on days 9 and 10 of each diet period. Additionally, 5 or 10 g bovine serum albumin or casein/L was added to batch cultures inoculated with feces from 4 healthy volunteers. Concentrations of sulfide, ammonia, and Lowry-reactive substances were measured over 48 h.
  RESULTS: Mean (+/-SEM) fecal sulfide concentrations ranged from 0.22 +/- 0.02 mmol/kg with the 0-g/d diet to 3.38 +/- 0.31 mmol/kg with the 600-g/d diet and were significantly related to meat intake (P: < 0.001). Sulfide formation in fecal batch cultures supplemented with both bovine serum albumin and casein correlated with protein digestion, as measured by the disappearance of Lowry-reactive substances and the appearance of ammonia.
  CONCLUSION: Dietary protein from meat is an important substrate for sulfide generation by bacteria in the human large intestine.

PMID: 11101476

  Increasing awareness that the human intestinal flora is a major factor in health and disease has led to different strategies to manipulate the flora to promote health. The complex microflora of the adult is difficult to change in the long term. There is greater impact of diet on the infant microflora. Manipulation of the flora particularly with probiotics has shown promising results in the prevention and treatment of diarrhoea and allergy. Before attempting to change the flora of the infant population in general, a greater understanding of the gut bacterial colonisation process is required. The critical stages of gut colonisation are after birth and during weaning. [when toxic cultural diets are introduced - ljf] Lactic acid bacteria dominate the flora of the breast-fed infant. The formula-fed infant has a more diverse flora. [due to the introduction of foods not in our evolutionalry histor - ljf] The faeces of the breast-fed infant contain mainly acetic and lactic acid whereas the formula fed-infant has mainly acetic and propionic acid. Butyric acid is not a significant component in either group. The formula-fed infant also has higher faecal ammonia and other potentially harmful bacterial products. [infant 'formula' generally has animal proteins which produce toxic byproducts, just as in the meat/dairy-eating afult - ljf] The composition of the microflora diversifies shortly before and particularly after weaning. The flora of the formula-fed infant develops more quickly than that of the breast-fed infant. Before embarking on any strategy to change the flora, the following questions should be considered: Should we retain a breast-fed style flora with limited ability to ferment complex carbohydrates? Can pro- and prebiotics achieve a flora with adult characteristics but with more lactic acid bacteria in weaned infants? Are there any health risks associated with such manipulations of the flora?

PMID: 12215177

  The notion that dietary factors may influence rheumatoid arthritis (RA) has been a part of the folklore of the disease, but scientific support for this has been sparse. In a controlled, single-blind trial we tested the effect of fasting for 7-10 d, then consuming an individually adjusted, gluten-free, vegan diet for 3.5 mo, and then consuming an individually adjusted lactovegetarian diet for 9 mo on patients with RA. For all clinical variables and most laboratory variables measured, the 27 patients in the fasting and vegetarian diet groups improved significantly compared with the 26 patients in the control group who followed their usual omnivorous diet throughout the study period. One year after the patients completed the trial, they were reexamined. Compared with baseline, the improvements measured were significantly greater in the vegetarians who previously benefited from the diet (diet responders) than in diet nonresponders and omnivores. The beneficial effect could not be explained by patients' psychologic characteristics, antibody activity against food antigens, or changes in concentrations of prostaglandin and leukotriene precursors. However, the fecal flora differed significantly between samples collected at time points at which there was substantial clinical improvement and time points at which there were no or only minor improvements. In summary, the results show that some patients with RA can benefit from a fasting period followed by a vegetarian diet. Thus, dietary treatment may be a valuable adjunct to the ordinary therapeutic armamentarium for RA.

PMID: 10479237

  We have performed a number of studies including dietary interventions and cross-sectional studies on subjects consuming uncooked vegan food called living food (LF) and clarified the changes in several parameters related to health risk factors. LF consists of germinated seeds, cereals, sprouts, vegetables, fruits, berries and nuts. Some items are fermented and contain a lot of lactobacilli. The diet is rich in fiber. It has very little sodium, and it contains no cholesterol. Food items like berries and wheat grass juice are rich in antioxidants such as carotenoids and flavonoids. The subjects eating living food show increased levels of carotenoids and vitamins C and E and lowered cholesterol concentration in their sera. Urinary excretion of sodium is only a fraction of the omnivorous controls. Also urinary output of phenol and p-cresol is lowered as are several fecal enzyme levels which are considered harmful. The rheumatoid arthritis patients eating the LF diet reported amelioration of their pain, swelling of joints and morning stiffness which all got worse after finishing LF diet. The composite indices of objective measures showed also improvement of the rheumatoid arthritis patients during the intervention. The fibromyalgic subjects eating LF lost weight compared to their omnivorous controls. The results on their joint stiffness and pain (visual analogue scale), on their quality of sleep, on health assessment questionnaire and on general health questionnaire all improved. It appears that the adoption of vegan diet exemplified by the living food leads to a lessening of several health risk factors to cardiovascular diseases and cancer. Rheumatoid patients subjectively benefited from the vegan diet which was also seen in serum parameters and fecal analyses.

PMID: 10943644

  The effect of an uncooked extreme vegan diet on fecal microflora was studied by direct stool sample gas-liquid chromatography (GLC) of bacterial cellular fatty acids and by quantitative bacterial culture by using classical microbiological techniques of isolation, identification, and enumeration of different bacterial species. Eighteen volunteers were divided randomly into two groups. The test group received an uncooked vegan diet for 1 month and a conventional diet of mixed Western type for the other month of the study. The control group consumed a conventional diet throughout the study period. Stool samples were collected. Bacterial cellular fatty acids were extracted directly from the stool samples and measured by GLC. Computerized analysis of the resulting fatty acid profiles was performed. Such a profile represents all bacterial cellular fatty acids in a sample and thus reflects its microflora and can be used to detect changes, differences, or similarities of bacterial flora between individual samples or sample groups. GLC profiles changed significantly in the test group after the induction and discontinuation of the vegan diet but not in the control group at any time, whereas quantitative bacterial culture did not detect any significant change in fecal bacteriology in either of the groups. The results suggest that an uncooked extreme vegan diet alters the fecal bacterial flora significantly when it is measured by direct stool sample GLC of bacterial fatty acids.

PMID: 1482187

  We investigated the effects of a high meat mixed Western diet and a nonmeat diet, representing the dietary pattern of high and low risk areas for colon cancer, respectively, on fecal microflora dn on bile acid and neutral sterol patterns in man. The total anaerobic microflora as well as the count of Bacteroides, Bifidobacterium, Peptococcus, and anaerobic Lactobacillus were significantly higher during the period of consumption of a high meat mixed Western diet comparted with the nonmeat-diet consumption period. The difference in total fecal bile acid excretion was not significant between the two dietary periods. Fecal excretion of microbially modified bile acids and neutral sterols was decreased when subjects eating a high meat diet transferred to a nonmeat diet. These results support the fact that diet plays a modifying role on the composition of intestinal microflora, bile acids, and neutral sterols.

PMID: 1138032