Pectin-containing Diets Research Articles

Type and Amount of Dietary Fiber Influence the Hindgut Synthesis of Organic Acids from Fermentable Material of Both Total and Nondietary Origin in a Pig Model of the Adult Human

BackgroundOrganic acid synthesis by the hindgut microbiota is commonly believed to be mainly of fermentable material of dietary origin. ObjectiveThis study aimed to determine the hindgut organic acid synthesis from fermentable material of dietary (mainly fiber) or nondietary origin for different types and amounts of dietary fiber in growing pigs used as a model for adult humans. MethodSeven fiber-containing diets were formulated: 4 fiber types (cellulose, gum acacia, oligofructose, and pectin) at 6% of the diet and 3 (gum acacia, oligofructose, and pectin) at 3% as the sole fiber source. Ileal cannulated female pigs (n = 14; Landrace/Large white) were fed the fiber-containing diets (n = 6 pigs/diet) for 11 days (fiber phase) followed by 3 days on a fiber-free diet (fiber-free phase), using a replicated Youden square. Ileal digesta for each phase were collected and fermented in vitro with a pooled fecal microbial inoculum prepared from feces collected during the fiber phase to determine the organic acids synthesized from fermentable material of dietary (fiber phase) and nondietary (fiber-free phase) origins. ResultsThe total amount of each individual organic acid synthesized during in vitro hindgut fermentation differed (P ≤ 0.05) across the types and amounts of dietary fiber intake. For example, the amount of acetate was 3.6-fold higher (P ≤ 0.05) for pigs fed the 6% pectin-containing diet than those fed the 6% oligofructose-containing diet. The nondietary substrate contributed between 36% (hexanoate) and 70% (succinate) to the total hindgut organic acid synthesis. The adaptation to the different fiber-containing diets led to different amounts of some organic acids of nondietary origin. ConclusionsThe total amount of organic acids synthesized in the hindgut by the resident microbes is influenced by the type and amount of dietary fiber consumed. This study quantifies the interaction between both dietary and nondietary fermentable materials in hindgut fermentation.

Interactive effects of dietary fibre and lipid types modulate gastrointestinal flows and apparent digestibility of fatty acids in growing pigs.

A total of eight ileal and caecal cannulated Yorkshire barrows were used to determine the interactions of dietary fibre (DF) and lipid types on apparent digestibility of DM and fatty acids (FA) and FA flows in gastrointestinal segments. Pigs were offered four diets that contained either pectin or cellulose with or without beef tallow or maize oil in two Youden square designs (n 6). Each period lasted 15 d. Faeces, ileal and caecal contents were collected to determine apparent ileal digestibility (AID), apparent caecal digestibility and apparent total tract digestibility (ATTD) of dietary components. The interactions between DF and lipid types influenced (P <0·05) the digestibility of DM and FA flows. The addition of maize oil decreased (P <0·05) AID of DM in pectin diets, and the addition of beef tallow depressed (P <0·001) ATTD of DM in cellulose diets. Dietary supplementation with beef tallow decreased (P <0·05) the AID of FA in pectin-containing diets but had no effects in cellulose-containing diets. Dietary supplementation with beef tallow increased (P <0·05) AID of SFA and PUFA and the flow of ileal oleic, vaccenic, linolenic and eicosadienoic acids and reduced the flow of faecal lauric, docosatetraenoic and docosapentaenoic acids in pectin- and cellulose-containing diets. In conclusion, the interaction between DF type and lipid saturation modulates digestibility of DM and lipids and FA flows but differs for soluble and insoluble fibre sources, SFA and unsaturated fatty acids and varies in different gastrointestinal segments.

Rheological and microstructural properties of porcine gastric digesta and diets containing pectin or mango powder

Hydrated polysaccharides and their assemblies are known to modulate gastric emptying rate due to their capacity to change the structural and rheological properties of gastric contents (digesta). In the present study, we investigated the rheological and microstructural properties of gastric digesta from pigs fed with diets incorporating mango powder or pectin, and compared results with those from hydrated diets of the same water content, in order to investigate the origins for rheological changes in the pig stomach. All of the hydrated diets and gastric digesta were particle-dominated suspensions, generally showing weak gel or more solid-like behavior with the storage modulus (G’) always greater than loss modulus (G”) under small deformation oscillatory measurements, and with small deformation viscosity greater than steady shear viscosity (i.e. non-Cox-Merz superposition). Although significant rheological differences were observed between the hydrated diets, rheological parameters for gastric digesta were similar for all diets, indicative of a rheological homeostasis in the pig stomach. Whilst the addition of gastric mucin (20mg/mL) to control and mango diets altered the rheology to match the gastric digesta rheology, the effect of mucin on the pectin-containing diet was negligible. The viscous effect of pectin also hindered the action of alpha amylase as observed from relatively less damaged starch granules in pectin digesta compared to mango and control digesta. Based on the experimental findings that the rheology of gastric digesta differs from hydrated diets of the same water content, the current study revealed composition-dependent complex behavior of gastric digesta in vivo, suggesting that the rheology of food products or ingredients may not necessarily reflect the rheological effect when ingested.

Combined dietary effects of supplemental threonine and purified fiber on growth performance and intestinal health of young chicks

Characterization of intestinal health in poultry has become imperative as specialized ingredients become more common in poultry diets. We tested whether purified fiber affects dietary Thr requirements and intestinal morphology of young chicks. In experiment 1, three diets containing 7% added silica sand (control), cellulose, or high-methoxy pectin were used. Six replicate pens of 6 chicks received dietary treatments through d 14 posthatch, at which time growth performance and nutrient digestibility were determined. In experiment 2, the effect of purified fiber on dietary Thr requirements was determined using a Thr-deficient basal diet (3.2 g of Thr/kg of diet) and 7 graded levels of supplemental Thr (0 to 9.6 g/kg of diet). Six replicate pens of 5 chicks were tested from d 8 to 21 posthatch, and ileal tissue was collected at the conclusion of the study for histological evaluation. In experiment 1, pectin reduced (P < 0.05) weight gain, feed efficiency, DM digestibility, and AME(n) compared with the control diet. In experiment 2, supplemental Thr requirements were estimated by fitting growth performance data to a 1-slope, broken-line (i.e., piece-wise) regression model. For the control and cellulose- and pectin-containing diets, supplemental Thr requirements were estimated at 3.64, 2.60, and 2.38 g of Thr/kg of diet, and at 778, 737, and 576 mg of supplemental Thr intake over the 21-d study, respectively, based on BW gain. For histological measures, crypts were deepest (P < 0.03) in the cellulose treatment; total goblet cell count and density were highest (P < 0.03) in the pectin-fed birds, and mixed goblet cell counts were highest (P < 0.03) in the control treatment. The serosa was thickest in the cellulose treatment with adequate supplemental Thr, and acidic and neutral goblet cell counts were highest in the control treatment with adequate Thr supplementation (fiber × Thr, P < 0.05). These findings suggest both dietary Thr concentration and fiber source affect growth performance, intestinal morphology, and mucin secretion in young chicks, which may directly affect poultry feeding strategies.

A Chemoprotective Fish Oil- and Pectin-Containing Diet Temporally Alters Gene Expression Profiles in Exfoliated Rat Colonocytes throughout Oncogenesis

We have demonstrated that fish oil- and pectin-containing (FO/P) diets protect against colon cancer compared with corn oil and cellulose (CO/C) by upregulating apoptosis and suppressing proliferation. To elucidate the mechanisms whereby FO/P diets induce apoptosis and suppress proliferation during the tumorigenic process, we analyzed the temporal gene expression profiles from exfoliated rat colonocytes. Rats consumed diets containing FO/P or CO/C and were injected with azoxymethane (AOM; 2 times, 15 mg/kg body weight, subcutaneously). Feces collected at initiation (24 h after AOM injection) and at aberrant crypt foci (ACF) (7 wk postinjection) and tumor (28 wk postinjection) stages of colon cancer were used for poly (A)+ RNA extraction. Gene expression signatures were determined using Codelink arrays. Changes in phenotypes (ACF, apoptosis, proliferation, and tumor incidence) were measured to establish the regulatory controls contributing to the chemoprotective effects of FO/P. At initiation, FO/P downregulated the expression of 3 genes involved with cell adhesion and enhanced apoptosis compared with CO/C. At the ACF stage, the expression of genes involved in cell cycle regulation was modulated by FO/P and the zone of proliferation was reduced in FO/P rats compared with CO/C rats. FO/P also increased apoptosis and the expression of genes that promote apoptosis at the tumor endpoint compared with CO/C. We conclude that the effects of chemotherapeutic diets on epithelial cell gene expression can be monitored noninvasively throughout the tumorigenic process and that a FO/P diet is chemoprotective in part due to its ability to affect expression of genes involved in apoptosis and cell cycle regulation throughout all stages of tumorigenesis.

A Comparison of Pectin, Polyphenols, and Phytosterols, Alone or in Combination, to Lovastatin for Reduction of Serum Lipids in Familial Hypercholesterolemic Swine

Greater than 50% of Americans use some form of a dietary supplement, and a diagnosis of coronary artery disease is associated with higher supplement use. The objective of this study was to compare nutritional supplements (pectin, polyphenols, and phytosterols) to lovastatin to reduce serum cholesterol. Familial hypercholesterolemic (FH) swine received the same amount of basal diet (control) in addition to pectin (30 g/day), polyphenols (20 g/day), phytosterols (6 g/day), and all possible combinations in contrast to lovastatin (3 mg/kg of body weight). The experimental design consisted of 4 weeks of basal diet followed by 4 weeks of basal diet plus the supplement treatment. All of the supplements, except pectin, reduced total cholesterol by an average of 71 +/- 19 mg/dL in comparison to the control diet (53 +/- 20 mg/dL) and lovastatin (143 +/- 21 mg/dL) during the 5-8-week treatment period. Serum high-density lipoprotein-cholesterol remained unchanged, while serum triglycerides changed independent of diet. During the 5-8-week treatment period serum low-density lipoprotein (LDL)-cholesterol was reduced maximally 22%, 19%, 20%, 17%, 18%, and 17% by polyphenols, phytosterols, pectin + polyphenols, pectin + phytosterols, polyphenols + phytosterols, and pectin + polyphenols + phytosterols, respectively, compared to control (8%) and lovastatin (40%). Phytosterols was the most effective supplementation, while both phytosterol and polyphenol supplements enhanced the reduction in LDL-cholesterol of pectin-containing diets. Supplements effectively reduced cholesterol in FH swine by half compared to lovastatin. Results suggest that more research on the use of dietary supplements, alone or in combination with statins, to reduce LDL-cholesterol is justified.

Intestinal morphology and enzymatic activity in newly weaned pigs fed contrasting fiber concentrations and fiber properties1

The main objective of this study was to determine the effect of fiber source and concentration on morphological characteristics, mucin staining pattern, and mucosal enzyme activities in the gastrointestinal tract of pigs. The experiment included 50 pigs from 10 litters weaned at 4 wk of age (BW 8.6 +/- 1.4 kg) and divided into 5 treatment groups. Diets containing fiber of various physico-chemical properties and concentrations were formulated to contain 73, 104, or 145 g of dietary fiber/kg of DM. The diets were based on raw wheat and barley flours. Pectin and barley hulls, representing soluble and insoluble fiber sources, respectively, were used to increase the fiber concentration. The pigs were fed the experimental diets for 9 d, and then the pigs were euthanized and the entire gastrointestinal tract was removed. Tissue samples were taken from the mid and distal small intestine and from the mid colon. Inclusion of pectin in the diets significantly decreased (P < 0.001) ADFI and ADG compared with pigs fed no pectin. The villi and the crypts were shorter in pigs fed pectin-containing diets, but the villous height/crypt depth ratio was unaltered. Pectin significantly decreased the area of mucins in the crypts of the small intestine, indicating that the pigs fed the pectin-containing diet would probably be more susceptible to pathogenic bacteria, although this cannot be separated from the impact on ADFI. The lectin-binding pattern of the intestinal mucosa was unaffected by diet. The activity of lactase and maltase was increased in pigs fed diets with high fiber content, whereas sucrase activity was increased in pigs fed the pectin-containing diets. The activity of the peptidases, aminopeptidase N and dipeptidylpeptidase IV, was increased when feeding high fiber diets, whereas the activity of gamma-glutamyl transpeptidase remained unaffected by the experimental diets. In conclusion, the reduced feed intake observed with the pectin-containing diets could explain the lower villous height and crypt depth observed in this study. However, direct effects of pectin also are possible, and thus further study is warranted. Feeding pigs high insoluble fiber diets improved gut morphology by increasing villi length and increased mucosal enzyme activity when compared with pigs fed pectin-containing diets. The mucin content as determined by staining characteristics suggests that pigs fed high insoluble fiber diets might be better protected against pathogenic bacteria than pigs fed diets high in soluble fiber.

Intestinal steroids in rats are influenced by the structural parameters of pectin

We investigated the effects of pectin with different degrees of methylation (34.5, 70.8, and 92.6%, respectively) on the composition and concentration of intestinal and fecal bile acids and neutral sterols in conventional and germfree rats. Diets containing 6.5% pectin (galacturonan) were given for 3 weeks. High concentrations of free and secondary bile acids appeared in cecum and colon of conventional rats. With increasing degree of methylation, more bile acids were transported into lower parts of intestinal tract and excreted whereas the proportion of secondary bile acids decreased. In contrast, the composition of bile acids in intestinal contents and feces was relatively unchanged in germfree rats. Exclusively cholesterol was found as a neutral sterol in germfree rats. Coprostanol appeared in cecum of conventional rats and additionally coprostanone in colon. Amounts of neutral sterols increased with increasing degree of methylation of pectin. Additionally, concentrations of bile acids in plasma decreased if the pectin-containing diets were given. Besides the degree of methylation, the molecular weight of pectin used in the diets influenced concentration and composition of intestinal and fecal steroids in rats.

DNA adducts in tissues of germ-free and conventional rats fed high- and low-esterified pectins.

Tissue samples from germ-free and conventional rats fed pectins with different degrees of esterification (DE) were tested for containing indigenous DNA adducts (I-compounds). For 21 days groups of six germ-free and 10 conventional rats each were fed either pectin-free or with diets containing 7.5% of three differently esterified pectin preparations (Pectin A, DE 92.6%; Pectin B, DE 70.8%; Pectin C, DE 34.5%). DNA was isolated from colonic mucosa, liver, lung, kidney and analysed for DNA adducts by the 32P-postlabelling assay. The experiments showed a tendency to a higher number and intensity of DNA-adduct-like spots (1) in the colonic mucosa compared with liver, lung, and kidney, (2) in germ-free compared with conventional rats, (3) with pectin-free compared with pectin-containing diets, (4) under the low-esterified compared with the higher-esterified pectins.

Effects of fiber-containing liquid diets on colonic structure and function in the rat.

Dietary fiber plays a role in maintaining colonic structure and function. Recently, fiber-supplemented liquid diets containing primarily soy polysaccharide have been marketed. However, the effects of these diets on the colon, particularly absorptive function, are not well documented. We compared Jevity (containing 1.4% soy polysaccharide) to fiber-free Osmolite. In addition, we were interested in comparing the effects of soy polysaccharide to that of pectin, which has previously been shown to facilitate adaptation. A 1% pectin-supplemented rat liquid diet was compared to the liquid diet alone. After 2 weeks of dietary treatment, rats were anesthetized and in vivo colonic absorption measured. Both Jevity and the pectin-containing diets led to a significantly greater (p less than 0.01) basal and butyrate stimulated water absorption as well as 20 mM butyrate absorption compared to their fiber-free fed controls. After perfusion, rats were killed and parameters of colonic mass measured including mucosal weight, protein, and DNA. The fiber-containing diets produced a modest, nonsignificantly greater colonic mass compared to their fiber-free controls. A commercial diet containing soy polysaccharide seems to be equally effective as pectin in maintaining colonic absorptive function.

Dietary fiber and cholesterol and bile acid metabolism in axenic (germfree) and holoxenic (conventional) rats. III. Effect of non-sterilized pectin.

Axenic (germfree) and holoxenic (conventional) rats were given a pectin-containing diet (5%) or a pectin-free diet. The diet was not sterilized and the axenic state was maintained by the addition of antibiotics. Pectin modified little or not at all the quantity of bile acids in the small intestine, fecal bile acid excretion and fecal elimination of the sum of cholesterol and bile acids. It similarly decreased the concentration of liver cholesterol and the amount of bile acids in the cecum and large intestine of both germfree and conventional rats. Pectin decreased the absorption coefficient of dietary cholesterol and its plasma concentration and increased fecal cholesterol elimination in conventional rats but not in germfree animals. The data imply that some of the actions of pectin depend on the presence of the intestinal flora but the exact nature of this relationship is unclear.

Studies on the action of pectin in depressing the growth of chicks.

Citrus pectin (40 g/kg diet) significantly depressed weight gain and food utilisation when fed to young chicks. This effect was not associated with pathological manifestations or signs of deficiency. Feeding pectin at 40 g/kg diet did not affect the retention of energy, nitrogen, lipids or calcium, but decreased serum and liver total cholesterol and altered the glucose tolerance of chicks by retarding clearance of ingested glucose from blood. Supplementation of the pectin-containing diet with penicillin (70 mg/kg), with selected essential elements and vitamins, or increasing the energy density of the diet had no ameliorating effect on the depressed growth. Pair-feeding showed that pectin depressed food intake, reduced carcase lipid content and increased carcase moisture content.

Effects of pectin-containing diets on the hepatic macromolecular covalent binding of 2,6-dinitro-[ 3H]toluene in Fischer-344 rats

The influence of diets varying in pectin content on intestinal microfloral metabolic capacity of rats has been investigated as a possible mechanism for the alteration of toxicity of 2,6-dinitrotoluene (2,6-DNT) produced by these diets. Male F-344 rats were fed a purified diet (AIN-76A), AIN-76A plus 5% or 10% citrus pectin, or either of two cereal-based diets that vary in pectin content, NIH-07 or Purina Chow 5002. After 28 days, rats were given tritium-labeled 2,6-DNT (10 or 75 mg/kg po) and killed 12 hr later. Total hepatic macromolecular covalent binding (CVB) was determined by exhaustive extraction. The CVB of 2,6-DNT was found to be independent of diet at 10 mg/kg. However, at 75 mg/kg CVB was increased 40% by feeding 5% pectin in the purified diet and 90% by feeding 10% pectin in the purified diet. Animals fed Purina 5002 and NIH-07 had 135 and 150% higher CVB, respectively, than animals fed the purified diet alone and significantly greater CVB than animals fed the pectin supplemented diets. Elevated (two- to threefold) β-glucuronidase and nitroreductase activities, microfloral enzymes proposed to be involved in the activation of 2,6-DNT to a toxicant, were found in the cecal contents of animals fed the pectincontaining diets which correlated with a two- to threefold increase in total number of cecal anaerobes. These results suggest that pectin-induced changes in microflora may enhance hepatoxicity after high doses of 2,6-DNT.

Dietary fiber and cholesterol and bile acid metabolisms in axenic (germfree) and holoxenic (conventional) rats. II. Effect of pectin.

Axenic and holoxenic rats were fed with a semi-synthetic diet containing 5 p. 100 pectin as the only fiber. Although the microbial flora of the digestive tract converted most of the bile acids in holoxenic rats, it hardly changed the other characteristics of cholesterol and bile acid metabolisms, except intestinal bile salt pools which were much larger in the axenic rats. When the pectin-containing and pectin-free diets were compared, it appeared that the former diet increased cecal weight, especially in axenic rats, but slightly modified cholesterol and bile acid metabolisms. However, the values of some characteristics of those metabolisms varied individually in the holoxenic rat fed with the pectin-containing diet, while they were very homogeneous in the other groups. This heterogeneity might result from pectin-digestive tract microbial flora interactions which would vary among individuals.