Effect of corn fiber residue supplementation on fecal properties, flora, ammonia, and bacterial enzyme activities in healthy humans

A Review of Microbiota and Irritable Bowel Syndrome: Future in Therapies

Irritable bowel syndrome (IBS), one of the most frequent digestive disorders, is characterized by chronic and recurrent abdominal pain and altered bowel habit. The origin seems to be multifactorial and is still not well defined for the different subtypes. Genetic, epigenetic and sex-related modifications of the functioning of the nervous and immune-endocrine supersystems and regulation of brain-gut physiology and bile acid production and absorption are certainly involved. Acquired predisposition may act in conjunction with infectious, toxic, dietary and life event-related factors to enhance epithelial permeability and elicit mucosal microinflammation, immune activation and dysbiosis. Notably, strong evidence supports the role of bacterial, viral and parasitic infections in triggering IBS, and targeting microbiota seems promising in view of the positive response to microbiota-related therapies in some patients. However, the lack of highly predictive diagnostic biomarkers and the complexity and heterogeneity of IBS patients make management difficult and unsatisfactory in many cases, reducing patient health-related quality of life and increasing the sanitary burden. This article reviews specific alterations and interventions targeting the gut microbiota in IBS, including prebiotics, probiotics, synbiotics, non-absorbable antibiotics, diets, fecal transplantation and other potential future approaches useful for the diagnosis, prevention and treatment of IBS.

Corn fiber oil lowers plasma cholesterol levels and increases cholesterol excretion greater than corn oil and similar to diets containing soy sterols and soy stanols in hamsters

The aims of this study were to compare the cholesterol-lowering properties of corn fiber oil (CFO) to corn oil (CO), whether the addition of soy stanols or soy sterols to CO at similar levels in CFO would increase CO's cholesterol-lowering properties, and the mechanism(s) of action of these dietary ingredients. Fifty male Golden Syrian hamsters were divided into 5 groups of 10 hamsters each, based on similar plasma total cholesterol (TC) levels. The first group of hamsters was fed a chow-based hypercholesterolemic diet containing either 5% coconut oil + 0.24% cholesterol (coconut oil), 5% CO, 5% CFO, 5% CO + 0.6% soy sterols (sterol), or 5% CO + 0.6% soy stanols (stanol) in place of the coconut oil for 4 weeks. The stanol diet significantly inhibited the elevation of plasma TC compared to all other dietary treatments. Also, the CFO and sterol diets significantly inhibited the elevation of plasma TC compared to the CO and coconut oil diets. The CFO, sterol, and stanol diets significantly inhibited the elevation of plasma non-high density lipoprotein cholesterol compared to the CO and coconut oil diets. The stanol diet significantly inhibited the elevation of plasma high density lipoprotein cholesterol (HDL-C) compared to all other dietary treatments. The sterol diet significantly inhibited the elevation of plasma HDL-C compared to the CO and coconut oil diets, whereas the CFO diet significantly inhibited the elevation of plasma HDL-C compared to the coconut oil diet only. No differences were observed between the CFO and CO for plasma HDL-C. There were no differences observed between groups for plasma triglycerides. The CO and CFO diets had significantly less hepatic TC compared to the coconut oil, sterol, and stanol diets. The CO and CFO diets had significantly less hepatic free cholesterol compared to the sterol and stanol diets but not compared to the coconut oil diet; whereas the coconut oil and sterol diets had significantly less hepatic free cholesterol compared to the stanol diet. The CFO, sterol, and stanol diets excreted significantly more fecal cholesterol compared to the coconut oil and CO diets. In summary, CFO reduces plasma and hepatic cholesterol concentrations and increases fecal cholesterol excretion greater than CO through some other mechanism(s) in addition to increase dietary sterols and stanols-possibly oryzanols.

Effect of meat and resistant starch on fecal excretion of apparent N-nitroso compounds and ammonia from the human large bowel

N-nitroso compounds are produced in the human large intestine, but little is known about the dietary modulation of their synthesis at this site. The effects of meat and resistant starch on the fecal excretion of N-nitroso compounds, measured as apparent total N-nitroso compounds (ATNC), were therefore investigated in a crossover study involving eight healthy men. Three controlled diets that differed in the amount of meat (40 or 600 g) and resistant starch (37 g added to 600 g meat diet) were fed in random order, and fecal ATNC, as well as fecal ammonia and parameters of bowel function, were measured after 19 days of dietary adaptation. Mean ATNC excretion during the high-meat period was 114 micrograms/day, three times that during the low-meat period of 35 micrograms/day (p = 0.02); ammonia excretion was twice that during the low-meat period: 2.9 vs. 1.4 mmol/day (p = 0.03). The fecal ATNC were dissolved in the fecal water, and 45% had a molecular weight < 3,000. The addition of readily fermentable resistant starch to the high-meat diet significantly increased stool output from 118 to 153 g/day and decreased fecal pH from 7.2 to 6.6 but had no significant effect on fecal ATNC (151 micrograms/day), ammonia (3.7 mmol/day), whole gut transit time, urinary nitrate, or plasma urea. ATNC produced in the large bowel in association with a high-meat intake could represent an important source of DNA-damaging alkylating agents in the human large bowel.

Pattern of metabolism and composition of the fecal microflora in infants 10 to 18 months old from day care centers

BACKGROUND

From 5 months of age, infants are progressively introduced to a variety of foods which influence the equilibrium of the intestinal microflora.

METHODS

Thirty-five children age 10-18 months from 8 day care centers in France were studied. Fecal specimens were examined for their biochemical and microbiological criteria.

RESULTS

Bifidobacteria and Bacteroides belong to the predominant populations (9.7 and 8.6 log 10 cfu/g, respectively). The mean level of enterobacteria and enterococci were 8.0 and 7.8 log 10 cfu/g, respectively. Only 10% of the infants presented a lactobacilli amount above 6 log 10 cfu/g. Most feces had similar pH values (mean 6.4), percentage of water (mean 76.4%), and short chain fatty acid, ammonia and lactic acid concentrations (means 77, 6.7 and 2.3 mumol/g, respectively). beta-galactosidase had the highest activity (106 IU/g of protein) and nitroreductase, the lowest (0.1 IU/g of protein). alpha-glucosidase and nitrate reductase showed intermediate values of 17 and 4 IU/g of protein, respectively. With the exception of 4 infants, beta-glucosidase and beta-glucuronidase values were low (4 and 2 IU/g of protein). Age and day care center were not significant factors for most parameters studied, except that rotavirus was related to day care center, with detection in 5 infants from the same center.

CONCLUSIONS

Many biochemical parameters were comparable to those found in adults, with the exception of ammonia concentration and beta-galactosidase activity. The fecal bacterial profile was different than in adults, with more Bifidobacteria than Bacteroides and higher levels of facultative anaerobes. One infant suffering from gastroenteritis had distinctive biochemical and bacterial parameters.

Colonic fermentation of complex dietary carbohydrates in short-bowel patients. No association with hydrogen excretion and fecal and plasma short-chain fatty acids

BACKGROUND

The colonic degradation of carbohydrates (fermentation) to short-chain fatty acids (SCFAs) appears to have major impacts on colonocyte function, sodium and water absorption, and large-bowel energy salvation, but how to quantify the in vivo fermentation in man is still debatable.

METHODS

Indicators of colonic fermentation, fecal and plasma SCFAs and breath hydrogen (H2), were measured in 10 short-bowel patients (mean +/- SE; 106 +/- 21 cm) with totally preserved large bowels who were on a 60% high-carbohydrate, 20% low-fat diet, compared with the reversed isocaloric 20% low-carbohydrate, 60% high-fat diet. This human model showed large differences in large-bowel fermentation, as excretions of calories were reduced (40%; 485 +/- 151 kcal/day) and excretions of carbohydrates were unchanged and low with the high-carbohydrate diet as compared with the low-carbohydrate diet, in contrast to unchanged calorie excretion in short-bowel patients with no colonic function.

RESULTS

Fecal concentrations of SCFAs did not change when the diet was changed from the high content to the low content of carbohydrates (82 +/- 11 mmol/l and 79 +/- 9 mmol/l, respectively). The ratio of acetate in feces increased (from 48 +/- 4% to 54 +/- 3%; p = 0.01) on the high-carbohydrate diet, whereas the percentage of the other SCFAs decreased proportionally. Plasma SCFAs 2 h and 6 h after breakfast were also identical when comparing the two dietary regimens. Nor were the peak H2 breath excretion and the area under the H2 excretion-versus-time curve increased by the threefold increase in the intake of dietary carbohydrates.

CONCLUSIONS

Fecal and plasma SCFAs and breath H2 excretion are of limited value in the evaluation of even large differences in colonic fermentation of complex dietary carbohydrates.