Antitoxic effects of plant fiber

Influence of konjac glucomannan and its derivatives on the oral pharmacokinetics of antimicrobial agent in antibiotics cocktails: Keep vigilant on dietary fiber supplement

In this study, konjac glucomannan (KGM) and its derivatives were gavaged as dietary fiber supplements, followed by a single dose of antibiotic cocktail (Abx) containing amoxicillin, neomycin, metronidazole and vancomycin in mice. The effects of dietary fiber on the pharmacokinetics and tissue distribution of each antibiotic were investigated. The results showed that the specific effects of KGM and its derivatives on the absorption, distribution, and elimination of certain antibiotics varied and depended on the nature of the fibers and the characteristics of the antibiotics. Explicitly, the ingestion of KGM and its derivatives enhanced the absorption of metronidazole by 1.7 times and hindered that of amoxicillin by nearly 36 % without affecting the absorption of neomycin sulfate and vancomycin. KGM and its derivatives had no effect on the distribution of amoxicillin and metronidazole, but DKGM and KGM hindered the distributions of neomycin sulfate (from 1.25 h to 1.62 h) and vancomycin (from 0.95 h to 1.14 h), respectively. KGM and its derivatives promoted the elimination of amoxicillin by nearly 38 % while prolonging that of metronidazole by >50 %. KOGM boosted the elimination of neomycin sulfate and vancomycin, but KGM differed from DKGM in acting on the elimination of both.

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.

Modulation of the biological effects of glucosinolates by inulin and oat fibre in gnotobiotic rats inoculated with a human whole faecal flora

The influence of dietary fibre on the biological effects of glucosinolates was investigated in gnotobiotic rats harbouring a human whole faecal flora. Animals were fed for 6 wk with diets containing 12% rapeseed meal (RSM) supplemented or not supplemented with 10% inulin (INL) or oat fibre. Both fibre types enhanced the liver hypertrophy due to RSM to equal extents, but had different effects on the other glucosinolate-related toxic effects. INL partially restored a normal thyroid hormone status whereas kidney weight, goitre and growth deficit were increased on exposure to the diet containing oat fibre. Oat fibre and, to a lesser extent, INL modulated the alterations of digestive xenobiotic-metabolizing enzymes (XME) induced by RSM. They counter-balanced the induction of hepatic cytochrome P-450 and lessened the induction of uridine diphosphate-glucuronosyltransferase in the liver but did not modify depletion of its activity in the small intestine. On the other hand, they enhanced the induction of glutathione S-transferase in the liver and the large intestine but not in the small intestine. These findings give new evidence that the biological effects of naturally occurring non-nutrient compounds are closely dependent on the composition of the diet. Two mechanisms are proposed to explain the different influence of INL and oat fibre on RSM toxicity. Their different fermentative characteristics could lead to a modulation of the bacterial metabolism of glucosinolates in the caecum. Alternatively, their own action on the digestive XME could modify the subsequent metabolism of bacterial glucosinolate derivatives.

Comparison of cereal-based diet with purified diet by short-term feeding studies in rats, mice and hamsters, with emphasis on toxicity characteristics

Animal diets used in toxicity studies are prepared either from natural ingredients (cereal-based diet) or from more refined products (purified diet). The type of diet may influence both the outcome of the study and the values obtained with the various parameters in test and control animals. To detect the parameters sensitive to changes in diet composition, short-term (4-wk) studies were conducted in rats, mice and hamsters fed either a cereal-based diet or the AIN-76A purified diet supplemented with vitamins and minerals at the highest recommended levels for each of the species used. Although the purified diet was more palatable to rats and showed a higher protein quality, growth rate and food intake were generally slightly higher with the cereal-based diet in each of the species examined. The haematological values of the two diet groups were generally comparable. On the cereal-based diet the production of faeces was considerably higher than on the purified diet and was accompanied by a higher weight of the caecum. These findings were attributed to the relatively high level and mixed composition of the fibre fraction in the cereal-based diet. Blood levels of cholesterol and phospholipids were clearly lower on the cereal-based diet than on the purified diet. Because the differences were probably due to the level and composition of the fibre fraction, they support the suggestion to replace the 5% cellulose of the AIN-76A diet by a higher level of a more composite but well defined source of dietary fibre.

The effect of wheat bran on the excretion of cadmium in rats

The influence of wheat bran as a source of dietary fibre on the excretion of ingested cadmium from diet was studied. The cadmium contents in the diets, faeces, urine, liver, kidney and spleen were determined, as well as the weight gains, the relative weights of the cited organs, and the levels of alkaline phosphatase in serum. No evidence is provided that an increasing portion of wheat bran in the diets induced an increase in cadmium excretion. Changes in the studied toxicity parameters were not found.

Diet-induced alterations in theobromine disposition and toxicity in the rat

To assess the potential influence of diet on theobromine (TBR) disposition and the development of TBR-induced thymic and testicular toxicity, male Sprague-Dawley rats were given the following diets ad libitum for 28 days: (1) semipurified (S); (2) commercial chow (Ch); (3) semipurified + 0.6% TBR (S + TBR); or (4) commercial chow + 0.6% TBR (Ch + TBR). Toxicity endpoints determined in each TBR group indicated that Ch + TBR-treated animals did not exhibit the marked reduction in body weight or testicular atrophy induced by the S + TBR diet, although thymic weight was lower regardless of diet. Metabolic studies performed after the 28-day feeding period using 5 mg/kg TBR + 10 microCi [8-14C]TBR revealed an overall inductive effect of Ch on TBR metabolism as shown by increased urinary excretion (0-24 hr) of the major TBR metabolite, 6-amino-5[N-methylformylamino]-1-methyluracil (6-AMMU), as well as 7-methylxanthine + 3-methylxanthine (7-MX + 3-MX) and 3,7-dimethyluric acid (3,7-DMU). Consumption of 0.6% TBR for 28 days in either S or Ch diets also induced its own metabolism, as shown by decreased urinary excretion of unchanged TBR and increased conversion primarily to 3,7-DMU. Fecal 14C elimination (0-24 hr) was similar between animals fed S and Ch diets, indicating no effect of control diet on TBR bioavailability. Since serum TBR concentrations and overall toxicity were lower in Ch + TBR-treated animals than in S + TBR treated animals, yet TBR bioavailability was similar, this effect was attributed to the inducing potential of the Ch diet on TBR metabolism and clearance. Investigators are cautioned to consider the potential effect of diet on metabolism when performing and evaluating toxicological studies.

Effect of mixtures of dietary fibres on the enzyme activity of the rat caecal microflora

The enzyme activity of the caecal microflora from weanling rats was determined after feeding 1 of 3 basal diets (purified fibre-free; purified plus cellulose; and stock), with or without additional dietary fibre (pectin, i-carrageenan or carboxymethylcellulose 5% w/w). The wet weight of caecal contents and total bacterial numbers were similar for the purified fibre-free and purified plus cellulose diets, yet were significantly higher in animals fed the stock diet. Pectin supplementation of the basal diets had no effect of caecal bacterial numbers, but significantly increased total nitrate reductase activity per caecum except when added to stock diet. Carrageenan decreased caecal bacterial numbers and most enzyme activities with both purified diets, and to a lesser extent with the stock diet. Carboxymethylcellulose increased bacterial numbers and enzyme activities, particularly beta-glucosidase and nitrate reductase when added to the purified diet but not when added to either the purified diet plus cellulose or the stock diet. The results demonstrate that the effects of dietary fibre components on the rat caecal microflora are dependent upon the initial fibre content of the diet base.

Influence of wheat bran on some reductive and hydrolytic activities of the rat cecal flora

For 30 days, male weanling rats were fed a semipurified, fiber-free diet or a diet that contained 5, 15, or 30% (wt/wt) wheat bran. The activities of four cecal microbial enzymes were determined. Wheat bran significantly increased the wet weight content of the cecum and total bacterial count per cecum at the intermediate- and high-treatment levels, but it had no effect on bacterial concentration per gram wet weight of cecal contents. Total beta-glucosidase and beta-glucuronidase activities per cecum were generally increased. Wheat bran decreased total nitrate reductase activity, but there was no change in total nitroreductase activity. Wheat bran significantly decreased enzyme activities for nitro-and nitrate reduction per gram of cecal contents but increased beta-glucosidase activity. The activities of the enzymes per 10(11) bacteria followed a similar pattern to that noted per gram of cecal contents. Such fiber-dependent changes in enzyme activity may alter the steady-state concentration of toxic and genotoxic chemicals in the lumen of the hindgut.

The effect of diet on the mammalian gut flora and its metabolic activities

The review will encompass the following points: A brief introduction to the role of the gut flora in the toxicology of ingested food components, contaminants, and additives, including known pathways of activation and detoxication of foreign compounds and the implication of the flora in enterohepatic circulation of xenobiotics. The advantages and disadvantages of the various methods of studying the gut flora (classical bacteriological techniques, metabolic and enzymological methods) will be critically discussed with special reference to their relevance to dietary, toxicological, and biochemical studies. Sources of nutrients available to the gut flora will be described including host products (mucus, sloughed mucosal cells, hormones, proteins) and exogenous nutrients derived from diet. An account of the problems involved in studies of dietary modification with special reference to the use of stock laboratory animal diets, purified diets, and human dietary studies. The influence of dietary modification on the flora will be assessed on the basis of changes in numbers and types of bacteria and their metabolic activity, drawing on data from human and animal studies. The effects of manipulation of the quantity and quality of protein, fat, and indigestible residues (fiber) of the diet will be described together with their possible implications for toxicity of ingested compounds.

Dietary fibers and supplementary iron in a milk replacer for veal calves

Thirty 1-wk-old male Holstein calves were allotted randomly to six groups into a 3 X 2 factorial design. The control diet was skim milk, whey, tallow, vitamins, and minerals. Either Alpha-Floc or pectin was added at 5% dry matter. Supplementary iron was added at 30 and 50 ppm (dry basis). The six diets were fed for 14 wk. Calves without supplementary iron were mildly anemic at 6 wk and severely at 14 wk (7 and 5 g/dl hemoglobin). At 14 wk, both fibers had decreased blood hemoglobin in calves given supplementary iron. Feed refusal began at 8 wk with the appearance of anemia for calves unsupplemented with iron, but both Alpha-Floc and pectin decreased feed refusal. Supplementary iron practically eliminated feed refusal. Supplementary iron improved average daily gain and feed conversion, but dietary fibers had no effect. Adding Alpha-Floc and pectin to the diets reduced frequency of diarrheic feces. Mean carcass weight of calves fed supplementary iron was 11.6% higher than that of unsupplemented calves. Supplementary iron decreased liver lipids and increased glutamic oxaloacetic transaminase activity in blood plasma.

Alleviation in the rat of a GABA-induced reduction in food intake and growth

Cold exposure and diet dilution which stimulate food intake of normal rats lessened depressions of food intake and growth induced by dietary GABA. During a 3-day adaptation to the cold, rats fed a diet containing 4.5% GABA lost weight; thereafter, food intake and growth rate differed little from those of cold control rats and were usually greater than those of normal rats fed GABA. Hepatic GABA-aminotransferase activity of cold-exposed rats fed the GABA diet increased to about twice that of normal control rats. Rats fed a control diet diluted by half with cellulose ate 50% more of this diet than of the undiluted diet but gained only 20% less weight. Rats ate twice as much of a diluted, 9% GABA diet as of an undiluted, 4.5% GABA diet (thus doubling their GABA intake) and gained three times as much weight. A novel food (condensed milk) barely lessened the adverse responses to GABA. These results show that conditions requiring rats to increase their food intake in order to maintain body weight can also increase their acceptance of a diet high in GABA.

Effect of diet on T-2 toxicosis

T-2 toxin is an emetic trichothecene mycotoxin produced by Fusarium molds. This compound causes feed refusal, emesis and lesions in the gastrointestinal tract of livestock, poultry and man. Studies in our laboratory have indicated that the feeding of high fibre diets, non-nutritive mineral additives and high fat diets can largely overcome feed refusal caused when T-2 toxin is fed to rats. Subsequent experiments were designed to determine the mechanism by which such diets exert this effect. Rats were fed for two weeks diets containing varying levels of alfalfa meal, bentonite or corn oil in a casein-based semi-purified diet. Rats were then orally dosed with [3H] T-2 toxin and urine and feces were collected for 21 hours after which all animals were killed and tissues excised. Diet had no significant effect on the fraction dose of 3H excreted in the urine. Significant increases in fecal excretion of 3H were seen, however, with all test diets. Only high fat diets reduced hepatic residues of 3H while alfalfa had a similar effect in kidney and both alfalfa and bentonite lowered muscle residues. It was concluded that such dietary treatments overcome T-2 toxicosis mainly by promoting fecal excretion of toxin thereby reducing absorption and biological half-life.

Effect of dietary cellulose on the metabolic activity of the rat caecal microflora

Alpha-cellulose, added to a purified diet at six levels [0%, 2.5%, 5%, 10%, 20%, and 40% (w/w)] and fed to weanling rats for 3 weeks, had no effect on body weight, but it increased the weight of caecal contents and decreased the numbers of bacteria per total caecal contents. Caecal microbial azoreductase, nitroreductase, beta-glucosidase and nitrate reductase activities per total caecal contents were also significantly decreased by 10% dietary cellulose and above, yet beta-glucuronidase activity was only affected significantly by 40% dietary cellulose. Azoreductase and nitroreductase activities were highly correlated with one another and showed a similar response to cellulose.

Interaction of diet and toxicity--the future role of purified diet in toxicological research

There is a growing awareness of the importance of diet as a determinant of the toxicity of many compounds. This paper briefly reviews some of the ways in which diet affects toxicity, and draws some conclusions regarding the ideal diet for toxicological investigations. Then the two competing types of diet, stock and purified (including those frequently called semi-synthetic and semi-purified), are described and their characteristic strengths and weaknesses are discussed. Stock diets are very variable commodities, may be nutritionally poorly balanced, and also contain many non-nutritive components that influence toxicity. The formulation and preparation of purified diet are discussed. It is concluded that investigations of the mechanisms of toxicity, as well as studies of absorption, distribution and metabolism of toxic compounds, could benefit from the use of well-defined purified diets.

Dietary fibre, bacterial metabolism and toxicity of nitrate in the rat

1. A semi-synthetic diet, the semi-synthetic diet plus pectin, and a stock diet were fed to rats, and three metabolic functions of the caecal bacteria (reduction of amaranth, p-nitrobenzoic acid and nitrate) were measured in vitro. 2. No consistent differences were noted between diets for the reduction of amaranth and p-nitrobenzoic acid. 3. No consistent differences in nitrate reductase activity were noted for rats maintained on a stock diet or a fibre-free diet. However, the addition of 5% pectin to the latter diet resulted in a several-fold increase in nitrite production. 4. This increased nitrite production in vitro was associated with methaemoglobinaemia following the oral administration of nitrate to rats fed the diet containing pectin. Animals receiving the basal fibre-free diet were unaffected by nitrate.

The effect of pectin on the structure and function of the rat small intestine

1. The effect of pectin on the structure and function of the rat small intestine was compared with that of a standard pellet diet and of a fibre-free basal diet. 2. The length and wet weight of the small bowel was significantly greater inpect in-fed rats than in either pellet- or basal-diet-fed rats. 3. Histological measurements of longitudinal sections from the small bowel showed a significantly greater crypt depth and muscle layer thickness in the mid-jejunum and ileum of the pectin fed rats. Villous height showed less variation. 4. The specific activity of alkaline phosphatase (EC 3.1.3.1) and leucyl-beta-naphthylamidase (EC 3.4.11.1) in mucosal scrapings was significantly lower in the upper jejunum of pectin-fed rats compared with either of the other dietary groups. The differences were not so marked in mid-jejunum or ileum. 5. Glucose absorption measured in vivo from jejunal and ileal loops was similar in all three dietary groups. 6. With two minor exceptions there were no significant differences in any of these measurements between the pellet- and basal-diet-fed rats. 7. These findings could be explained by increased epithelial cell turnover caused by pectin. The possible mechanisms of this are discussed. 8. The effect of pectin on the human small bowel requires study before it can be widely prescribed in man.

The effect of wheat bran and pectin on paracetamol absorption in the rat

1. The absorption of an oral dose of paracetamol was measured in rats given either a basal fibre-free diet, or the basal diet with either pectin or bran added. 2. Urinary excretion of the oral dose was significantly greater during the first 8 h in the pectin-fed rats compared with those on basal diet, though cumulative excretion after 72 h was the same. 3. Free paracetamol levels in the plasma were significantly higher in the pectin-fed rats compared with those on basal diet at 30, 60, 90 and 120 min after the oral dose. 4. The plasma half-life of intravenously-injected paracetamol was shorter in the pectin-fed rats than in those on basal diet alone, but the antipyrine half-lives were not significantly different. 5. Pectin feeding had no effect on either the apparent volume of distribution of paracetamol and antipyrine, or on the rate of gastric empyting. 6. Perfusion of the whole length of the small bowel showed a significantly greater capacity for paracetamol absorption in the pectin-fed rats. 7. Bran had no effect on paracetamol absorption. 8. It was concluded that dietary fibre intake affects drug absorption and that the effect varies with the type of fibre. Unexpectedly pectin accelerates rather than retards absorption of paracetamol, though the mechansim of this effect is unknown.

Recent progress in dietary fiber (plantix) in human nutrition

Dietary fiber was extensively discussed in an article by G.A. Spiller and R.J. Amen in this journal in 1975 (Volume 7 Issue 1). The progress in this field has been tremendous in the past 2 years. What was an uncertain field in 1975 and what at that time to some investigators still appeared as a hypothesis or fad without much proof has turned into a much more respected part of nutritional sciences. The scientific quality of recent studies on dietary fiber in human nutrition shows a great deal of sophistication and care. Improved analytical methodologies are being used more extensively. Many nutritionists and clinicians have accepted the fact that a reasonable increase in the dietary fiber intake in the U.S. and U.K would be advisable. In this article, the possible beneficial effects of dietary fiber on health, the possible harmful side effects, and the food science aspects are carefully discussed after an update on chemistry, analytical procedures, and nomenclature. Undoubtedly, dietary fiber has found a new niche in the sciences of nutrition, medicine, epidemiology, and foods.

Potential for the use of germinated wheat and soybeans to enhance human nutrition

Wheat and soybeans are the major agricultural exports of the United States. The U.S. sells more of each crop than any other nation. Soybeans are the main staple in China, but the U.S. sells more soybeans than China grows. For hundreds of millions of other people, wheat is the main staple. And yet, most Americans eat whole grains of neither wheat nor soybeans. In the United States, many nutrients of wheat and soybeans are lost in processing or are fed to animals. A highly significant share of the wheat nutrients are lost from the main foodstream when the germ and bran (with aleurone) portions are separated. Whole soybeans are carefully processed for food by only a handful of Americans.

The effect of wheat bran upon bile salt metabolism and upon the lipid composition of bile in gallstone patients

When raw wheat bran was added to the diet of six subjects for 4-6 weeks, chenodeoxycholate (CDC) synthesis increased from 0.46 +/- 0.12 to 0.57 +/- 0.17 mmol/day pool increased from 1.72 +/- 0.47 to 2.19 +/- 0.74 mmol (rho less than 0.05). Deoxycholate (DC) pool size diminished from 1.20 +/- 0.29 to 0.80 +/- 0.16 mmol, but cholate synthesis and pool size were unaffected. Overall, the size of the bile salt pool did not change. In spite of this, when 10 patients with probable cholesterol gallstones took bran supplements for 4-6 weeks, their gallbladder bile aspirated from the duodenum became less saturated with cholesterol. The molar percentage of cholesterol fell from 10.1 +/- 3.1% to 8.6 +/- 2.7% (rho less than 0.01), and the saturation index of bile fell from 1.49 +/- 0.40 to 1.29 +/- 0.38 (rho less than 0.005). Bran probably operates primarily on the colon, reducing the formation or absorption of the bacterial metabolite DC, a substance which impairs CDC synthesis.