Expression of apolipoprotein A-I mRNA in liver and intestine of cecectomized rats fed beet fiber

Sham-operated and cecectomized rats were fed a cholesterol-free diet with no added fiber (fiber-free) for 10 days, followed by the diet of 15% beet fiber for 10 days. The plasma cholesterol concentrations in rats fed the fiber-free diet were not significantly different between sham-operated and cecectomized groups. Plasma cholesterol concentrations in sham-operated rats were decreased by feeding the beet fiber diet, whereas those in cecectomized rats did not change. Final plasma total cholesterol concentrations in cecectomized rats were significantly higher than in sham-operated rats. This difference was due mainly to lower HDL cholesterol concentrations. The cecectomized rats also tended to have higher apolipoprotein A-I concentrations in plasma. Northern blot analysis revealed that the relative concentrations of ileal apolipoprotein A-I mRNA were the same in the two groups, while hepatic apolipoprotein A-I mRNA levels were significantly higher in cecectomized rats than in sham-operated rats. These data demonstrate that the cecectomy abolished the hepatic apolipoprotein A-I mRNA-lowering effect of dietary beet fiber, and it is suggested that the cecum plays an important role in the regulation of hepatic apolipoprotein A-I expression which seems to be responsible for the hypocholesterolemic effect of dietary beet fiber.     

Effect of pectin and amidated pectin on cholesterol homeostasis and cecal metabolism in rats fed a high-cholesterol diet

Two experiments were performed to compare the effect of pectin and its hydrophobic derivatives on homeostasis of cholesterol and cecal metabolism in male young rats. Control rats were fed a diet supplemented with palm fat and cholesterol (50 and 10 g/kg, respectively). Rats of other groups were fed the same diet containing citrus pectin or octadecylpectinamide (60 g/kg). Diets were fed for 4 weeks. In experiment I, pectinamide of lower degree of amidation (30 %) increased serum HDL cholesterol from 1.20 to 1.43 micromol/ml (p>0.05) at the expense of other cholesterol fractions. In experiment II, pectinamide of a higher degree of amidation (53 %) significantly decreased total serum cholesterol from 2.08 to 1.67 micromol/ml. Amidated pectins at both levels of substitution significantly decreased hepatic concentrations of cholesterol and fat. In both experiments the relative weight of cecum in the pectinamide group was significantly lower than in pectin group. The highest cecal concentrations of short-chain fatty acids (SCFA) were found in rats fed a diet with pectin (133.2 and 129.3 micromol/g in experiment I and II, respectively). In other groups, cecal SCFA was significantly (pectinamide groups) or non-significantly (controls) lower. In wet feces, SCFA concentrations were higher and butyrate molar proportions lower than in corresponding cecal contents. Pectinamide of a lower or higher degree of substitution significantly increased fecal content of cholesterol from 18.5 and 17.3 micromol/g in controls to 31.8 and 28.0 micromol/g, respectively. Corresponding concentrations of coprostanol were decreased. Effects of pectin on cholesterol homeostasis were absent or marginal. Histological examination revealed that hepatic tissue of control and pectin-fed rats was infiltrated with lipids. The Sudan black-positive material was absent in the liver of rats fed pectinamides. No pathological changes of liver tissue were apparent. In summary, hydrophobic amidated pectins significantly altered cholesterol homeostasis in rats and might be considered as a clinically effective hypocholesterolemic agent. Low cecal SCFA concentrations in rats fed pectinamides suggest that amidation of pectin had decreased its fermentability.     

Effect of sugar alcohols on gut function and body composition in normal and cecectomized rats.

The effects of two sugar alcohols on feed utilization, digesta retention, gut fermentation and serum lipid profiles were compared in normal and cecectomized rats to examine the possibility of the cecectomized rat as an experimental animal with relevance to humans. Semi-purified diets containing no sugar alcohol, 7% sorbitol or 7% lactitol were fed to normal and cecectomized rats for 16 days. The digestibility of the crude fat and the compositions of the carcass dry matter and crude fat were significantly decreased by feeding sugar alcohols in both groups, but the effects were relatively higher in the cecectomized rats than in the normal rats. Diarrhea, faster transit times and shorter retention times of digesta were noted in the cecectomized rats fed sugar alcohols, while the inverse results were observed in the normal rats fed similar diets. The concentration of cecal organic acids was increased in the normal rats, whereas the concentration of colonic organic acids was decreased in the cecectomized rats fed sugar alcohols, compared with their corresponding control groups. The concentration of serum total cholesterol was decreased in both the normal and cecectomized rats fed diets containing sugar alcohols. The tendencies for diarrhea, faster digesta transit and reduced body fat induced by the fermentable materials in the cecectomized rat have good relevance to the parallel effects of fermentable materials in humans, suggesting the possibility of using the cecectomized rat as a model to study some of the physiological effects of sugar alcohols in humans.     

Cholesterol-lowering effects of maitake (Grifola frondosa) fiber, shiitake (Lentinus edodes) fiber, and enokitake (Flammulina velutipes) fiber in rats

The effects of mushroom fibers on serum cholesterol and hepatic low-density lipoprotein (LDL) receptor mRNA in rats were investigated. Rats were fed a cholesterol-free diet with 50 g/kg cellulose powder (CP), 50 g/kg maitake (Grifola frondosa) fiber (MAF), 50 g/kg shiitake (Lentinus edodes) fiber (SF), or 50 g/kg enokitake (Flammulina velutipes) fiber (EF) for 4 weeks. There were no significant differences in the body weight, food intake, liver weight, cecum weight, and cecum pH among the groups. Cecal acetic acid, butyric acid, and total short-chain fatty acid (SCFA) concentrations in the SF and EF groups were significantly higher than those in the other groups. The serum total cholesterol concentration in the CP group was significantly higher than that in the MAF and EF groups. The very LDL (VLDL) + intermediate-density lipoprotein (IDL) + LDL-cholesterol concentration in the CP group was significantly higher than that in the MAF, SF, and EF groups, whereas the high-density lipoprotein (HDL)-cholesterol concentration in the EF group was significantly lower than that in the other groups at the end of the 4-week feeding period. The hepatic LDL receptor mRNA level in the EF group was significantly higher than that in the CP group. The fecal cholesterol excretion in the MAF, SF, and EF groups was significantly higher than that in the CP group. The results of this study demonstrate that MAF and EF lowered the serum total cholesterol level by enhancement of fecal cholesterol excretion, and in particular, by enhancement of hepatic LDL receptor mRNA in EF group.     

Effects of soluble corn bran arabinoxylans on cecal digestion, lipid metabolism, and mineral balance (Ca, Mg) in rats

The effects of soluble corn bran arabinoxylans on cecal digestion, lipid metabolism, and mineral utilization [calcium (Ca) and magnesium (Mg)] were investigated in rats adapted to semipurified diets. The diets provided either 710 g/kg wheat starch alone (control) or 610 g/kg wheat starch plus 100 g/kg corn soluble fiber (arabinoxylans) and either 0 or 2 g/kg cholesterol (control + cholesterol and arabinoxylans + cholesterol, respectively). Compared with rats fed the control diets, rats fed the arabinoxylan diets had significant cecal hypertrophy (+50% after 3 days of the fiber adaptation) and an accumulation of short-chain fatty acids, especially propionic acid (up to 45% in molar percentage). Arabinoxylans enhanced the cecal absorption of Ca and Mg (from 0.07 to 0.19 micromol/min for Ca and from 0.05 to 0.23 micromol/min for Mg). Mg balance was enhanced by arabinoxylans (+25%). The arabinoxylan diet markedly reduced the cholesterol absorption from 50% of ingested cholesterol in controls up to approximately 15% in rats adapted to the arabinoxylans diet. Arabinoxylans were effective in lowering plasma cholesterol (approximately -20%). There was practically no effect of the diets on cholesterol in d > 1.040 lipoproteins (high density lipoproteins) whereas arabinoxylans were very effective in depressing cholesterol in d < 1.040 lipoproteins (especially in triglyceride-rich lipoproteins). Corn fermentable fiber decreased the accumulation of cholesterol in the liver. In parallel, the arabinoxylan diet counteracted the downregulation of 3-hydroxy-3-methylglutaryl-CoA by cholesterol. These data suggest that arabinoxylans may have a great impact on intestinal fermentation, mineral utilization, and cholesterol metabolism.     

Effect of dietary short-chain fructooligosaccharides on the cecal microflora in gastrectomized rats

Total gastric resection is known to lead to changes in the microflora in the whole gastrointestinal tract. Dietary short-chain fructooligosaccharides (Sc-FOS) have been shown to also induce a change in the microflora in the large bowel by promoting an increase in the numbers of Bifidobacterium and Lactobacillus which have beneficial effects on the host. In the present study, 4-week-old male Sprague-Dawley rats received total gastrectomy or laparotomy, and each of these surgically treated groups was randomly divided into two experimental diet groups and given a 7.5% Sc-FOS diet or control diet. Enumeration and identification of the cecal bacteria was performed by using selective and non-selective media. In the gastrectomized rats, the total bacterial count, and the counts of Bacteroidaceae and Enterobacteriaceae were higher than those in the sham-operated rats. Sc-FOS promoted an increase in the numbers of Bifidobacterium and Lactobacillus, In the rats fed on the Sc-FOS diet, the predominant type of bacteria was Lactobacillus and in the rats fed on the control diet, it was Bacteroidaceae irrespective of gastrectomy. We confirmed that both gastrectomy and dietary Sc-FOS changed the composition of cecal microflora in the rats. Dietary Sc-FOS in the gastrectomized rats increased the proportions of Lactobacillus relative to other types of bacteria to levels similar to those seen in healthy normal rats, and decreased the proportion of Bacteroidaceae.     

Potato powders prepared by successive cooking-process depending on resistant starch content affect the intestinal fermentation in rats

The effects of resistant starch (RS) in dry potato powders prepared by various processes on intestinal fermentation in rats were assessed. Rats were fed raw potato powder (RP), blanched potato powder (BP), steamed potato powder (SP), or drum-dried potato powder (DP) for 4 weeks. The cecal RS content was significantly higher in the RP group than in the control diet (CN) group and other dry potato powder groups. Cecum pH was significantly lower in the RP group compared to the CN group, and was also significantly lower than that in the SP, BP, and DP groups. Lactic acid bacteria levels in the RP group were significantly higher than those in the CN group, and levels in the SP group also increased relative to the control group. Lactobacillus levels in the RP group were higher than in the CN and other dry potato powder groups. Cecal short-chain fatty acid (SCFA) concentrations in the RP group followed by the SP group exhibited significantly higher levels relative to the control levels. Dry potato powders containing RS produced during the cooking process may represent a useful food material that increases intestinal concentrations of SCFA and enhances the growth of certain lactic acid bacteria.     

Effect of White Wheat Bread Containing Sugar Beet Fiber on Serum Lipids and Hepatic mRNA in Rats Fed on a Cholesterol-Free Diet

We examined the effects of white wheat bread powder (BP) and white wheat bread powder containing sugar beet fiber (BBP) on serum cholesterol. The total cholesterol (?11%, ?16%), HDL-cholesterol (?12%, ?11%), non-HDL-cholesterol (?9%, ?18%) and triacylglycerol (?44%, ?58%) concentrations in the BP and BBP groups, respectively, were significantly different from those in the control group. The fecal excretion of neutral sterols in the BP and BBP groups and of acidic sterols in the BBP group was significantly higher than that in the control group. The hepatic cholesterol 7α-hydroxylase (CYP7A1) mRNA level in the BP and BBP groups was significantly higher than that in the control group. The cecal total short-chain fatty acid concentrations in the BBP group were significantly higher than those in the control group. These results indicate that the observed changes in serum lipid levels in the BP and BBP groups were due to the increased fecal lipid and CYP7A1 mRNA levels.     

Resistant starch fraction prepared from kintoki bean affects gene expression of genes associated with cholesterol metabolism in rats

Feeding rats beans with resistant starch reduces the serum cholesterol concentration; however, the mechanism is not fully understood. We examined the effects of resistant starch of kintoki (Phaseolus vulgaris, variety) bean on serum cholesterol and hepatic mRNAs in rats. Male F344/Du Crj rats were fed a cholesterol-free diet either with 5 g of cellulose powder (control)/100 g or 5 g of pancreatin-resistant fraction prepared from kintoki bean (kintoki)/100 g diet for 4 weeks. There were no differences in the body weight gain, food intake, liver weight, and mass of cecum contents between the groups. Serum total cholesterol, very low density lipoprotein (VLDL) + intermediate density lipoprotein (IDL) + low density lipoprotein (LDL)-cholesterol, and high density lipoprotein (HDL)-cholesterol levels in the kintoki group were significantly (at least P < 0.05) lower than in the control group throughout the feeding period. There was no difference in the serum triglyceride concentration between two groups throughout the feeding period. Total hepatic cholesterol in the control group was significantly (P < 0.01) lower than in the kintoki groups. Fecal bile acid, cecal acetate, propionate and n-butyrate concentrations in the kintoki group all were significantly (P < 0.05) higher than in the control group. Likewise, hepatic cholesterol 7alpha-hydroxylase, LDL receptor, and SR-B1 mRNA levels in the kintoki group were significantly (P < 0.05) higher than in the control group. The results suggest that resistant starch of kintoki bean reduces serum cholesterol level by increasing hepatic LDL receptor, SR-B1, and cholesterol 7alpha-hydroxylase mRNAs.     

Ameliorating effects of short-chain inulin-like fructans on the healing stage of trinitrobenzene sulfonic acid-induced colitis in rats

We evaluated the ameliorating effects of short-chain inulin-like fructans (SIF) with different degrees of polymerization (DP) on the healing stage of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. The rats were assigned to 3 groups 10 d after the colitis induction, and fed for 24 d on a control diet or diet including 60 g of DP4 or DP8/kg. The fecal myeloperoxidase (MPO) activity and IgA concentration were monitored every 7 d. The colonic MPO activities and cecal concentrations of organic acids, lactobacilli, bifidobacteria, mucin and IgA were measured at the end of the study. DP4, but not DP8, significantly reduced the colonic inflammation accompanied by higher cecal concentrations of short-chain fatty acids, propionate in particular, and lactic acid-producing bacteria. DP4 therefore accelerated the healing process of TNBS-induced colitis, even when the treatment was initiated after inducing colitis.     

Dietary Resistant Starch Alters the Characteristics of Colonic Mucosa and Exerts a Protective Effect on Trinitrobenzene Sulfonic Acid-induced Colitis in Rats

The protective effect of a dietary high-amylose cornstarch (HAS) against trinitrobenzene sulfonic acid (TNBS)-induced colitis was examined in rats. Rats were fed a HAS-free basal diet or, a 15% or 30% HAS supplemented diet for 10 d, and then received intracolonic TNBS to induce colitis and fed the respective diets for a further 8 d. HAS ingestion significantly protected colonic injuries as evidenced by lower colonic myeloperoxidase activity. Rats fed the HAS diet showed greater cecal short-chain fatty acid (SCFA) production than those fed the basal diet. Further, just before TNBS administration, HAS ingestion dose-dependently increased fecal and cecal mucin contents, and protein and nucleic acid contents in the colonic mucosa. HAS ingestion also reduced colonic permeability. The protective effect of HAS ingestion on TNBS-induced colitis is perhaps exerted through alterations in colonic mucosa, possibly due to cecal SCFA production.     

Voluntary Running Exercise Alters Microbiota Composition and Increases n-Butyrate Concentration in the Rat Cecum

The effects of voluntary wheel-running exercise on cecal microbiota and short-chain fatty acid production were investigated in rats. The microbiota composition was notably different between the exercised and sedentary rats. Furthermore, the exercised rats showed a significantly higher n-butyrate concentration than the sedentary rats. This alteration of the cecal microbial environment may contribute to the beneficial effect of exercise on gastrointestinal disorders.     

Voluntary running exercise alters microbiota composition and increases n-butyrate concentration in the rat cecum

The effects of voluntary wheel-running exercise on cecal microbiota and short-chain fatty acid production were investigated in rats. The microbiota composition was notably different between the exercised and sedentary rats. Furthermore, the exercised rats showed a significantly higher n-butyrate concentration than the sedentary rats. This alteration of the cecal microbial environment may contribute to the beneficial effect of exercise on gastrointestinal disorders.     

Dietary resistant starch alters the characteristics of colonic mucosa and exerts a protective effect on trinitrobenzene sulfonic acid-induced colitis in rats

The protective effect of a dietary high-amylose cornstarch (HAS) against trinitrobenzene sulfonic acid (TNBS)-induced colitis was examined in rats. Rats were fed a HAS-free basal diet or, a 15% or 30% HAS supplemented diet for 10 d, and then received intracolonic TNBS to induce colitis and fed the respective diets for a further 8 d. HAS ingestion significantly protected colonic injuries as evidenced by lower colonic myeloperoxidase activity. Rats fed the HAS diet showed greater cecal short-chain fatty acid (SCFA) production than those fed the basal diet. Further, just before TNBS administration, HAS ingestion dose-dependently increased fecal and cecal mucin contents, and protein and nucleic acid contents in the colonic mucosa. HAS ingestion also reduced colonic permeability. The protective effect of HAS ingestion on TNBS-induced colitis is perhaps exerted through alterations in colonic mucosa, possibly due to cecal SCFA production.     

饵料对鹄沼枝额虫生长和生殖力的影响

鹄沼枝额虫是一种淡水小型甲壳动物,主要以细菌、有机碎屑和单胞藻等为食.用豆腐、虾片、米糠、大豆、面粉、小球藻6种饵料培养鹄沼枝额虫幼体,经11d培育,结果显示,不同饵料对鹄沼枝额虫生长、成活率有显著影响.方差分析表明,虾片组的鹄沼枝额虫体长增长显著优于其他5种饵料组(P<0.05);小球藻组的鹄沼枝额虫成活率显著高于米糠、豆腐和面粉组(P<0.05),但与虾片和大豆组没有显著性差异(P>0.05).虾片培养的鹄沼枝额虫较其他5种饵料提早1-2d产卵,且初次产卵量和卵径均为最大.用虾片、大豆、米糠、虾片+米糠、大豆+米糠5种饵料投喂性腺刚开始发育的鹄沼枝额虫,经27d培育,结果表明,不同饵料组间的鹄沼枝额虫生殖力差异显著.虾片+米糠培育的鹄沼枝额虫生殖总量显著高于米糠和大豆(P<0.05),而与虾片和大豆+米糠组没有显著性差异(P>0.05).因此,虾片和虾片+米糠是培养鹄沼枝额虫的优质饵料,对其生长和种群增殖有明显的促进作用.     

Effect of long term feeding of rice bran oil upon lipids and lipoproteins in rats

The effects of feeding two levels of rice bran oil (RBO) on the growth, lipid parameters, and fatty acid composition of the plasma and liver of rats (Wistar strain) were compared with those produced on animals which had been fed the same levels of peanut oil (PNO). The control animals were fed synthetic diets containing 5 and 20% peanut oil (PNO) and the experimental groups were fed similar diets, containing the same level of rice bran oil (RBO). There was no significant difference with respect to the organ weights between the control and the experimental groups. In general, groups fed 20% oil gained more weight than groups fed 5% oil. The animals which received rice bran oil in their diet had, in general, comparatively lower levels of cholesterol, triglycerides and phospholipids. On the other hand, animals receiving 20% rice bran oil in their diet, showed an increase of 20% in high density lipoproteins (HDL-C), within 18 weeks (p<0.05), when compared to the animals fed with peanut oil. Similarly, low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein cholesterol (VLDL-C) were lower in RBO-fed groups, than in the PNO-fed groups. There was, however, no significant differences in the cholesterol/phospholipid (C/P) ratio of the two groups. Analysis of plasma and of liver fatty acids indicated, in a general way, the type of fat consumed. There were no significant difference in the P/S ratio, nor any in the oleic/linoleic, oleic/stearic, palmitoleic/palmitic, oleic/palmitic, and oleic/palmitoleic ratios. Furthermore, levels of saturated (SAFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identical in both the groups. Thus, our results suggest that feeding a high level of rice bran oil (RBO) has no deleterious effect on the growth and blood lipid profile of rats.Abbreviations PNO peanut oil - RBO rice bran oil - HDL-C high density lipoprotein cholesterol - LDL-C low density lipoprotein cholesterol - VLDL-C very low density lipoprotein cholesterol - SAFA saturated fatty acids - MUFA mono-unsaturated fatty acids     

嗜酸乳杆菌MG2_1对大鼠血清脂质代谢的影响研究

利用从蒙古国酸马奶中分离鉴定,并通过耐酸性及体外降胆固醇能力测试筛选获得的L.acidophilusMG2_1菌制备成活菌体和热致死菌体制剂与高脂饲料同时灌喂Wistar系大鼠,研究探讨了对其血清脂质代谢的影响。结果显示,试验第14天时菌活菌体组和热致死菌体组与单纯饲喂高脂饲料对照组比较,对大鼠血清胆固醇浓度的上升分别呈现显著(p<0.05)和极显著的抑制效果(p<0.01),其热致死菌体组大鼠血清HDL_C,显著高于高脂饲料对照组(p<0.05)。并且各试验组大鼠动脉硬化指数均极显著地低于高脂饲料对照组(p<0.01)。热致死菌体组大鼠粪便中总胆汁酸含量也显著高于高脂饲料组(p<0.05)。可见,该菌株具有一定的抑制大鼠血清胆固醇含量上升和预防动脉硬化的作用。但在整个试验期内不改变灌服菌液剂量的情况下,随着试验时间的延长,该菌株对大鼠血清脂质的影响呈减弱趋势。     

Plasma cholesterol-lowering effect on rats of dietary fiber extracted from immature plants

Crude dietary fiber samples were prepared from beet, cabbage, Japanese radish, onion and mung bean sprouts (BF, CF, RF, OF and MF, respectively). These samples contained total dietary fiber at the levels of 814, 699, 760, 693 and 666 g/kg, respectively. To examine the effect of these dietary fiber sources on the plasma cholesterol concentration, male Sprague-Dawley rats were fed on a fiber-free (FF) diet or on an FF diet supplemented with 5% or 10% dietary fiber. Dietary fiber extracted from vegetables, wood cellulose (CL), pectin (PE) and guar gum (GG) were used as the fiber sources. Compared with the rats fed on the FF diet, a significant reduction in the plasma cholesterol concentration was observed in the rats fed on BF, CF, RF, MF, PE or GG after a 21-d feeding period. Cecal acetate, n-butyrate and total short-chain fatty acids were significantly higher in the rats fed on these dietary fibers, except for CF, than in those fed on the FF diet. A negative correlation was apparent between the total dietary fiber content, hemicellulose content and pectin content of each dietary fiber source and the plasma cholesterol concentration. These results suggest that some vegetable fibers exert a plasma cholesterol-lowering effect through cecal fermentation of these fibers.     

The effects of L-carnitine on some hematological parameters in rats fed a cholesterol-rich diet

We evaluated the effects of L-carnitine on the hematological characteristics of rats fed a cholesterol-rich diet. Healthy male Wistar Albino rats were assigned to four equal groups. During the 40 day experiment, group 1 was fed standard rat pellets, group 2 was fed standard rat pellets containing 7.5 % cholesterol powder, group 3 was fed standard rat pellets and water that contained 75 mg/l L-carnitine, and group 4 was fed standard rat pellets that contained 7.5% cholesterol and water that contained 75 mg/l L-carnitine. Blood samples were analyzed for red (RBC) and white (WBC) blood cells, hemoglobin, hematocrit, granulocytes, lymphocytes, monocytes, mean cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) using an automated cell counter. The RBC count in the group that received the 7.5% cholesterol diet was decreased significantly compared to the other groups. The hematocrit of the cholesterol group was lower than for the L-carnitine + cholesterol and L-carnitine groups. The MCV in the cholesterol group was significantly higher than the control group. The MCH in the cholesterol group was higher than for the other groups. There was no significant difference among the groups with regard to hemoglobin, MCHC, WBCs and leukocyte types. L-carnitine appears to have beneficial effects on erythrocyte stability, erythropoiesis and hyperlipidemia.     

Interactive Effects of Indigestible Carbohydrates,Protein Type,and Protein Level on Biomarkers of Large Intestine Health in Rats

The effects of indigestible carbohydrates, protein type, and protein level on large intestine health were examined in rats. For 21 days, 12 groups of six 12-week-old male Wistar rats were fed diets with casein (CAS), or potato protein concentrate (PPC), providing 14% (lower protein level; LP), or 20% (higher protein level; HP) protein, and containing cellulose, resistant potato starch, or pectin. Fermentation end-products, pH, and β-glucuronidase levels in cecal digesta, and ammonia levels in colonic digesta were determined. Cecal digesta, tissue weights, cecal and colon morphology, and colonocyte DNA damage were also analyzed. Digesta pH was lower, whereas relative mass of cecal tissue and digesta were higher in rats fed pectin diets than in those fed cellulose. Cecal parameters were greater in rats fed PPC and HP diets than in those fed CAS and LP diets, respectively. Short-chain fatty acid (SCFA) concentrations were unaffected by protein or carbohydrate type. Total SCFA, acetic acid, and propionic acid concentrations were greater in rats fed LP diets than in those fed HP. Cecal pool of isobutyric and isovaleric acids was greater in rats fed PPC than in those fed CAS diets. PPC diets decreased phenol concentration and increased ammonia concentration in cecal and colonic digesta, respectively. Cecal crypt depth was greater in rats fed PPC and HP diets, and was unaffected by carbohydrates; whereas colonic crypt depth was greater in rats fed cellulose. Myenteron thickness in the cecum was unaffected by nutrition, but was greater in the colon of rats fed cellulose. Colonocyte DNA damage was greater in rats fed LP diets than in those fed HP diets, and was unaffected by carbohydrate or protein type. It was found that nutritional factors decreasing cecal digesta weight contribute to greater phenol production, increased DNA damage, and reduced ammonia concentration in the colon.