![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
CSIRO (Australia) Division of Human Nutrition, Adelaide 5000, Australia
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
ACKNOWLEDGMENT
FOOTNOTES
LITERATURE CITED
ABSTRACT 
Young male pigs consumed a diet of fatty minced beef, safflower oil, skim milk powder, sucrose, cornstarch and wheat bran. Starch provided 50% of total daily energy either as low amylose cornstarch, high amylose (amylomaize) cornstarch or as a 50/50 mixture of corn and high amylose starch. Neither feed intake nor body weight gain as affected by dietary starch. Final plasma cholesterol concentrations were significantly higher than initial values in pigs fed the 50/50 mixture of corn and high amylose starch. Biliary concentrations of lithocholate and deoxycholate were lower in pigs fed high amylose starch. Large bowel length correlated positively with the dietary content of high amylose starch. Concentrations of butyrate in portal venous plasma were significantly lower in pigs fed high amylose starch than in those fed cornstarch. Neither large bowel digesta mass nor the concentrations of total or individual volatile fatty acids were affected by diet. However, the pool of propionate in the proximal colon and the concentration of propionate in feces were higher in pigs fed amylose starch. Concentrations of starch were uniformly low along the large bowel and were unaffected by starch type. In pigs with cecal cannula, digesta starch concentrations were higher with high amylose starch than with cornstarch. Electron micrographic examination of high amylose starch granules from these animals showed etching patterns similar to those of granules obtained from human ileostomy effluent. It appears that high amylose starch contributes to large bowel bacterial fermentation in the pig but that its utilization may be relatively rapid.
Key words: pigs, volatile fatty acids, large bowel, starch, steroid metabolism.INTRODUCTION
The fermentation of carbohydrates by human large bowel microflora is a focus of considerable interest. In large part, this is due to recognition that the resulting volatile fatty acids (VFA)8 contribute substantially to the health and integrity of the colon (Cummings and Macfarlane 1991
). In addition to general effects such as lowering of colonic pH and prevention of diarrhea, two of the three major VFA (acetate, propionate and butyrate) appear to have specific benefits. Propionate enhances colonic muscular contraction in vitro (Yajima 1985) and also may promote large bowel blood flow through relaxation of the vasculature (Mortensen et al. 1991). Butyrate is probably even more important for the maintenance of colonic health. This acid is recognized as a major metabolic fuel for normal colonocytes (Roediger 1982), and its infusion promptly relieves ulcerative colitis (Scheppach et al. 1992). Butyrate also assists in the maintenance of a normal cell phenotype through a number of mechanisms that involve the repair of damaged DNA and suppression of the growth of transformed cells (Kruh et al. 1994).
Factors that control VFA production are of some significance and, until relatively recently, it was thought that non-starch polysaccharides (NSP, major components of dietary fiber) were the principal fermentative substrates for the colonic microflora. This is not surprising, given the resistance of NSP to the digestive action of human gastrointestinal enzymes and the assumption that starch, the major polysaccharide in humans diets, is digested completely in the human small intestine. Now, there is evidence that a considerable fraction of dietary starch enters the human large bowel, undigested (Cummings and Macfarlane 1991). This fraction is termed resistant starch (RS) through its resistance to amylase degradation. In the large bowel, RS is fermented by the microflora, and data from in vitro fermentation studies with human fecal inocula suggest that starch fermentation may be especially useful because it favors the production of butyrate (Weaver et al. 1992).
Resistant starch offers an opportunity to increase the fermentable polysaccharide content of carbohydrate-based foods without necessarily altering their organoleptic properties. However, in marked contrast to NSP (in which resistance to human enzymic digestion is a matter of polymer structure), RS occurs for a number of chemical, technological and physiological reasons (Annison and Topping 1994). This means that the RS content of a food, measured as resistance to enzymic hydrolysis in vitro, need not reflect the starch in the food that resists amylolysis in vivo. From the standpoint of food manufacture, there is a clear advantage in the availability of starch types for which the RS content of the starting material is known and is retained in the food product through the human small intestine. Studies in humans have shown that with one such starch (Hylon VII), there was a significant increase in breath H2 evolution and the excretion of total and individual VFA (van Munster et al. 1994). High amylose starches are found in a variety of cereal cultivars and offer another opportunity to modify the RS content of foods. The crystalline structure of amylose means that it gelatinizes less readily than amylopectin when heated with water so that with appropriate processing, foods containing high amylose starches can be enriched in RS. High amylose starches obtained from corn (often referred to as amylomaize starches) seem to be useful in this regard. Studies in humans with ileostomy have shown a significant excretion of starch when products containing one such high amylose starch are consumed (Muir et al. 1994). These authors showed also that the "dietary fiber" content of this starch was ~30% on analysis.
Although there is support for greater large bowel fermentation with consumption of RS, there are data indicating that this does not necessarily increase fecal VFA excretion (Tomlin and Read 1990). Thus, there is a degree of uncertainty about the change in colonic VFA following RS ingestion. Investigating changes in the proximal human colon in situ is difficult for a number of reasons including ethical and anatomical considerations. The pig is considered to be a good model for human fiber metabolism (Graham and Aman 1982) and provides a useful way of probing effects of such dietary treatment on large bowel VFA. Studies in pigs fed different foods varying in fat and NSP have shown that VFA determined in the distal colon need not reflect those in the proximal large bowel (Topping et al. 1993), so that concentrations could be raised in the proximal colon with little or no change in the distal region or in feces. We decided to compare the effects of a high amylose (RS) and high amylopectin starch (both from corn) on the distribution of VFA and related variables throughout the colon in pigs fed a diet based on human foods. This appears to be the first time that such a study has been conducted. Because pigs resemble humans also in their responses in plasma lipids following dietary change (Siebert et al. 1987), we examined effects on plasma lipids. In view of the fact that dietary RS alters fecal bile acids (van Munster et al. 1994), biliary bile acids were measured as well to determine whether there was any effect on the enterohepatic circulation of bile acids.
MATERIALS AND METHODS
). All of the procedures described were approved formally by the Animal Care and Ethics Committees of Division of Human Nutrition and conformed to published guidelines (National Health and Medical Research Council, CSIRO and Australian Agricultural Council 1985).
Dietary study
Diets and feeding procedures. Twenty-four pigs were used for this experiment and were fed a diet comprised of commercially available human foods that has been described previously (Topping et al. 1993). In brief, the diet was formulated from minced beef, corn oil and cornstarch with 50 g of NSP/d provided as a wheat bran product (All Bran, Kellogg Australia, Pagewood, NSW, Australia). Allowance was made for the fat, protein and carbohydrate in the latter product. The diet provided 37.5% of energy as fat, 50% of energy as carbohydrate (of which 48.2% was as starch) and 12.5% of energy as protein. A commercial vitamin and mineral supplement was also added to the diet (Topping et al. 1993). The starch, corn oil, wheat bran, vitamins and minerals were mixed and pelleted and then weighed into individual meals. The minced beef was frozen in individual portions and thawed overnight before mixing with the pellets and feeding to the animals. There were three experimental groups, each consisting of eight pigs. One group was fed the diet with all of the cornstarch as a low amylose starch (diet C). In the second group, 56% of the starch (or 28% of total energy) was fed as cornstarch and the remainder as a high amylose starch (Hi-maizeTM, Starch Australasia, Botany, NSW, Australia; diet CHA). The third group of pigs was fed the diet containing 94% of starch as high amylose starch (the remainder of the starch being in the wheat bran; diet HA). The pigs were fed one meal daily (at 0900-1000 h) with sufficient food to provide an intake of 16 MJ/d. They were allowed free access to water. On the day before sampling the pigs were given 5 g of polyethylene glycol (PEG) in 200 mL of water with the meal as a marker of fluid phase transit (Malawer and Powell 1967).
Sampling procedures.
The pigs were fed the experimental diets for 3 wk. After 5 d of feeding, fresh feces were collected at approximately 1000 h from the pigs fed the low and high amylose diets. These samples were analyzed for VFA concentrations. At the end of the 3-wk feeding period, the pigs were sampled as described previously (Topping et al. 1993). In brief, food was withdrawn on the morning of sampling and the pigs were sedated with ketamine (Ketapex; Apex Laboratories, St Mary's, NSW, Australia) and then anesthetized with halothane in O2. After a midline laparotomy, the stomach and intestines were retracted to expose the hepatic portal vein. Blood was drawn from that vessel by syringe, collected into ice-cold tubes containing EDTA as anticoagulant; plasma was prepared by centrifugation at 3000 × g for 10 min and stored at 
20°C prior to analysis. The gall bladder was identified and drained of bile by needle and syringe. The volume of bile was measured and a portion frozen and stored for analysis of bile acids and neutral sterols. The esophagus and the rectum were ligated and the whole gut excised. The cecum was tied off from the terminal ileum, the whole large bowel was separated from the mesentery and laid out to approximately the same tension and its total length measured; then the colon was subdivided into five sections of equal length which were isolated with ligatures (starting at the proximal region). These sections were numbered 1-5 from the proximal colon and their contents and that of the cecum were extruded and weighed. The first animal was anesthetized at 0830 h and sampled at 0900 h; each pig took ~40 min to process. Six pigs were sampled daily and the same sequence was maintained throughout the sampling period; thus, a pig from each group was sampled at 0900, 0945, 1030, 1115, 1200 and 1245 h. One animal (fed high amylose starch) suffered damage to a leg 5 d before the end of the experiment and required analgesics. This pig was sampled with the others to maintain the balance of the feeding and sampling procedures but the data were not used for statistical evaluation.
Cecostomized pigs
Surgical preparation of animals. Four pigs were fitted with a cannula in the cecum to allow continuous sampling of gut contents. After overnight food deprivation, the pigs were sedated as described above. When they were unconscious, the hair was removed from around the surgical site. A 10-cm incision was made in the right flank behind the last rib, and the large bowel was exposed carefully. The cecum was located and a small incision made in its extremity. A 500-mm silastic tube (13 mm o.d., 8 mm i.d.) was inserted through this hole to a depth of ~90 mm. The tube was tied in place with purse-string sutures on either side of two plastic cuffs cemented to the tube. To add extra support, a disc of high density polyethylene (diameter 45 mm, thickness 1.5 mm) was slipped down the tube and sutured to the cecum. The cannula was exteriorized through a stab wound, dorsal to the incision, anchored to the skin with nonabsorbable sutures and sealed with a removable plastic plug. Two milliliters of a 5 g/L solution of bupivacaine hydrochloride, (Marcain; Astra Pharmaceuticals, North Ryde, NSW, Australia) was used as a postoperative nerve block for pain relief on the dorsal side of the incision. Recovery from surgery was rapid; pigs returned to normal food intake within 2-3 d during which time they were maintained on standard ration. Feeding and sampling procedures. During the recovery period the pigs were fed once daily at 900-1000 h. To determine starch concentrations in cecal digesta, two pigs were fed a single meal of the diet containing high amylose starch and two were fed a meal of the low amylose starch diet at 0930 h. Samples were taken from the cecum at 1300, 1500, and 1700 h and transferred promptly to a chilled centrifuge tube. Sampling was achieved by passing a Ryles tube (FG 18, Adelaide Surgical Supply, Somerton Park, SA, Australia) down the cannula into the cecum and drawing up 10 mL of contents with a syringe using gentle suction.Analytical procedures
Concentrations of total cholesterol, VFA in portal venous plasma and digesta, and bile acids and neutral sterols in bile were determined by gas-liquid chromatography as described previously (Topping et al. 1993). Digesta from each region of the large bowel of intact animals were extruded, diluted with 2-3 volumes of water and aliquots taken for measurement of VFA (Topping et al. 1993). A similar procedure was used for the measurement of VFA in fresh feces. PEG was determined spectrophotometrically in digesta samples, and starch was measured by determination of free glucose using a commercial kit (Boehringer Mannheim, Germany) after amylase (Sigma, St Louis, MO) and amyloglucosidase digestion (Boehringer Mannheim). To ensure complete recovery of starch, samples were dispersed in dimethylsulfoxide. Samples from cannulated pigs were freeze-dried for determination of total starch. Portions of the freeze-dried samples were sprinkled carefully onto double-sided adhesive tape attached to an aluminium stub (Lineback and Ponpipom 1997). The samples were coated thinly with gold (4 min at 20 mA) using a Polaron E5100 Sputter Coater (Polaron Equipment, Watford, Hertfordshire, U.K.) and viewed under electron microcopy (JSM-35-35, Japan Electron Optics Laboratory, Nakagami, Akishima, Japan). These images were recorded on black and white photographic film. Samples of native amylomaize starch, amylomaize starch after incubation with thermostable bacterial 
-amylase and pullulanase were processed; in vitro and high amylose starch granules recovered from human ileostomy effluent were processed in the same way.
Statistical methods.
Data for intact animals are shown as the means for eight observations per group with the exception of the high amylose group (7 pigs) with a pooled standard error of the mean. The statistical significance of differences between treatments was established by ANOVA incorporating a test for least significant difference using a computer (AMR, Adelaide, SA, Australia). Comparison of initial and final concentrations of plasma lipids was conducted using a repeated measures ANOVA. Effects of diet and colonic region on the distribution of starch and VFA along the large bowel were analyzed by ANOVA (Genstat 1988) using a Sun Sparc Station (Sun Microsystems, Sydney, NSW). Simple correlations between variables were calculated by linear regression analysis. A value of P < 0.05 was taken as the criterion of significance. Individual data are shown for the starch concentrations in cannulated animals.
RESULTS
Dietary adaptation to high amylose starch
Food consumption and body weight gain. At the start of the experiment the pigs were allocated randomly to each group and the mean body weight (all groups combined) was 44 kg (pooled SEM = 2, n = 24). The pigs found the diets palatable and all food was consumed promptly after presentation. At the end of the experiment, there were no differences in body weight with means of 53 (group C), 52 (group CHA) and 52 kg (group HA) (pooled SEM = 2). Plasma lipids. Plasma cholesterol concentrations at the start of the experiment did not differ among groups with means of 1.88, 1.93 and 1.87 mmol/L in groups C, CHA and HA, starch, respectively (pooled SEM = 0.10, n = 24). Initial plasma cholesterol was a significant covariate (P < 0.001) with an apparently linear relationship between initial and final values. Final values (adjusted for initial concentrations) were 2.05, 2.25 and 1.92 mmol/L (SEM of the difference = 0.15). Only in pigs fed the CHA diet were final plasma cholesterol concentrations significantly (P < 0.02) higher than the initial value.|
Table 1. Concentrations of individual bile acids in gall bladder bile of pigs fed diets containing cornstarch (C), high amylose (amylomaize) starch (HA) or a mixture of corn and high amylose starch (CHA)1 |
|
Table 2. Concentrations of total and individual volatile fatty acids in portal venous plasma of pigs fed diets containing cornstarch (C), high amylose (amylomaize) starch (HA) or a mixture of corn and high amylose starch (CHA)1 |
|
Table 3. Concentrations of total and individual volatile fatty acids in feces of pigs after consuming diets containing cornstarch (C) or high amylose (amylomaize) starch (HA) for 51 |
Fig. 1.
Colon length vs. dietary content of high amylose cornstarch in pigs. Data are shown as the means for each group (pooled SEM = 0.08).
[View Larger Version of this Image (11K GIF file)]
Studies in cannulated pigs
Starch in cecal digesta. In pigs fed the standard pig ration, concentrations of starch in cecal digesta were low with mean values of 1.8 (±0.6), 1.8 (±1.0) and 1.8 (±0.8) mg/g of wet weight (mean ± SEM, n = 4). These samples were taken at the same times as those at which the pigs were fed the test meals (i.e., 3.5, 5.5 and 7.5 h after feeding). In pigs fed those test meals containing cornstarch, concentrations were low at all sampling times in one animal and somewhat higher in the other (Table 4). Concentrations were much higher in pigs fed the HA diet although at 7.5 h after feeding, it was not possible to obtain a sample from one animal as the cecum appeared to be empty. Samples could not be drawn from the cecum on the following morning.|
Table 4. Concentrations of starch in cecal digesta of pigs with cecal cannula fed diets containing either cornstarch (C) or a high amylose (amylomaize) starch (HA)1 |
DISCUSSION
Fig. 2.
Electron micrographs of a) native high amylose starch, ×3000; b) high amylose starch after digestion with thermostable bacterial -amylase and pullulanase, ×6000; c) high amylose starch granules recovered from pig cecum, ×4800; and d) high amylose starch granules recovered from human ileostomy effluent, ×7500.
[View Larger Versions of these Images (122 + 133 + 150 + 138K GIF file)]
). Given the physicochemical properties of high amylose cornstarches (which can increase the viscosity of dispersions), it might have been possible that they resemble soluble NSP (Brown 1993). Further, it has been reported that undigested starches from complexes with bile acids which might increase their fecal excretion (Abadie et al. 1994). These possibilities have been supported with a reduction of plasma cholesterol and increased lipoprotein catabolism in rats fed a hypercholesterolemic diet containing a high amylose starch (Mazur et al. 1990). However, another study in rats failed to show any change in plasma cholesterol although plasma triacylglycerols were significantly lower (Goda et al. 1994). In the present experiment, there was no effect of starch type on either plasma cholesterol or total biliary steroids. Indeed, in pigs fed the mixture of starches, total plasma cholesterol was significantly higher than in those fed high amylose starch
a finding for which we have no explanation. The lack of a clear effect of dietary level of high amylose starch on plasma cholesterol and biliary steroids in animals fed human foods in the present study suggests that it is unlikely to be a major agent for lowering plasma cholesterol. This conclusion supports recent studies in humans by Noakes et al. (1996) who used the same high amylose starch as that used in the present study. The lack of effect may be explained by the fact that high amylose starches form viscous solutions only when gelatinized fully (Brown 1993). This could occur during the production of rat diets.
. Their data suggested that 30% of the starch would resist digestion by human gut enzymes. Coupled with the high concentrations of starch in the cecum of cannulated pigs, this justifies the description of this starch as RS.
) and VLDL triacylglycerols (Mazur et al. 1990). Lipogenesis is a major determinant of hepatic VLDL secretion (Windmueller and Spaeth 1967), so that the lower plasma concentrations are consistent with diminished production. The reason for the difference between the present data and those published in the rat may be due to species differences in lipoprotein production. In the pig plasma, triacylglycerol concentrations are relatively low, partially as a consequence of hepatic secretion of a triacylglycerol-poor intermediate density lipoprotein (IDL) (Huff et al. 1985). Thus, altered hepatic fatty acid synthesis might not limit triacylglycerol secretion as much as in species such as the rat in which triacylglycerol-rich particles are the main lipoprotein exported by the liver.
, Topping et al. 1993). However, they conflict with other data from the same species which showed that rice raised butyrate excretion (Marsono et al. 1993), suggesting that the type of starch affects the VFA which are excreted.
, Topping et al. 1993). In those experiments, some foods (e.g., navy beans, brown rice) gave much greater digesta and VFA masses than would be predicted from their NSP contenta difference that may be explained through the presence of resistant starch. In marked contrast, there were no effects of dietary inclusion of high amylose starch on total digesta or VFA in this experiment. Concentrations of starch in the large bowel were also extremely low. The lack of effect of dietary treatment, coupled with the very low starch concentrations in the large bowel, suggested that the character of the starch was altered by the means of incorporation into the diet so as to render it more susceptible to amylolysis in the small intestine. This possibility may be discounted by the observations of shifts in propionate excretion in intact animals and the fact that cecal starch levels were much higher in cannulated pigs fed high amylose starch than in animals fed low amylose starch (although it must be noted that in the latter, starch was detected in digesta).
) and rice in the large bowel of cannulated pigs. Digesta samples could be drawn from all pigs with little or no difficulty 5 h after feeding, but at 9 h, the cecum of one animal fed high amylose starch appeared to be empty and sampling was not possible the next morning. These data are different from those obtained in similar studies with rice in which the concentration of starch in cecal digesta as raised for at least 14 h after feeding (Marsono, Y., Davies, D. A., Illman, R. J., Gooden, J. M. and Topping, D. L., unpublished observations). It appears that either the transit of high amylose starch is particularly rapid or that it was fermented very quickly compared with other foods and that the VFA may be absorbed in the proximal colon. The first choice is not supported by the similarity of distribution of PEG between the groups, whereas rapid fermentation is supported by the low starch levels in colonic digesta in the present studies. Complete fermentation in the proximal colon is consistent also with the data of Tomlin and Read (1990) obtained from intact humans eating RS as cornflakes. In these volunteers, there was an increase in colonic fermentative activity as measured through breath H2 evolution but no change in fecal parameters. The rise in breath H2 occurred 1-2 h after feeding and returned to base-line values within several hours. Therefore, it seems that RS is fermented relatively quickly and that the resulting VFA are absorbed in the proximal colon leaving fecal parameters relatively unchanged. This suggestion would account for the rather small differences in fecal bulk seen by van Munster et al. (1994) in humans fed relatively large quantities of RS. If so, then it has important implications for physiological effects of RS because most degenerative large bowel disease is found in the distal colon. In terms of experimental design, it may be especially important, with measurement of colonic VFA taking place a relatively short time after feeding. It is equally possible that in the present experiment there was another influence on the speed of fermentation, i.e., the presence of wheat bran. NSP mixtures are fermented rather more effectively in the large bowel than are single polysaccharides (Storer et al. 1984) so that fermentation might have been slower if the diet contained no additional fiber.
), and the present electron microscopic data show that this is true also for starch digestion. Native high amylose cornstarch granules exhibit rounded or polyhedral shapes with some having an irregular or filamentous appearance (Sandstedt 1965). The degree of irregularity increases with the amount of amylose in the granule (Wolf et al. 1964). Exposure in vitro of these starch granules to amylolysis by bacterial -amylase and pullulanase produces a pattern of surface erosion often resulting in a pit that extends to a hollow core. This seems to be due to the fact that the core regions are more susceptible to hydrolysis, possibly because of conformational differences between the core and the outer regions. Similar erosion patterns were observed in the granular material recovered from cecal digesta of pigs fed the amylomaize starch. These patterns occur through the sequential actions of gut and bacterial amylases. The electron micrographs show great similarity between the granules recovered from the pig cecum and those from the effluent of human ileostomates who had consumed high amylose starch (Muir et al. 1994).
, Marsono et al. 1993, Topping et al. 1993). A similar profile was noted in the present experiment and is consistent with higher fermentative activity (through greater substrate availability) in the proximal large bowel. Previous studies have shown that the exact distribution of these variables cannot be predicted from their values in the distal colon (Topping et al. 1993). The same was true in the present experiments in that propionate was not distributed normally. Although there were no overall differences in VFA and digesta, concentrations and pools of propionate in the proximal large bowel of animals fed the high amylose starch were greater. These data are consistent with fecal propionate excretion and with data from previous studies with beans in which it was shown that in the proximal large bowel the molar proportion of butyrate was lower (Fleming et al. 1989) and the absolute quantities of propionate were greater (Topping et al. 1993).
). These increases are accompanied by histological changes in the gut wall with increases in crypt numbers and their depth. Similar results have been obtained in pigs whose adaptation to dietary NSP increased the mass of the colon (Pond and Varel 1989); it is thought that these trophic effects were mediated (at least in part) by VFA. The present data show that there appears to be a dose-dependence in the lengthening in the large bowel of pigs fed high amylose starch. The implications for colonic health are not entirely certain but may be of benefit in preventing degenerative bowel disease. Greater colon length has been noted in rats fed this high amylose starch, whereas in other animals with experimentally induced colitis, the injured area was reduced (Ikai, M., Morita, T. and Kiriyama, S., Yamanouchi Pharmaceutical, personal communication). It is possible that the greater length of the bowel could have provided an explanation for the lower concentrations of butyrate in portal venous plasma. Because butyrate is believed to be a preferred substrate for colonocytes, it may be presumed that greater cell numbers would mean more demand for this substrate and, hence, less butyrate available for transport via the portal vein. However, this is not the case because linear regression analysis showed no relationship between colon length and portal venous butyrate (r = 0.19, P > 0.0.5).
). It appears that ~7.6 kJ/g starch might be available as VFA produced through RS fermentation compared with 16.4 kJ/g from glucose released by starch hydrolysis in the small intestine. This is a substantial difference and is probably the reason for the lower rates of lipogenesis (Goda et al. 1994, Mazur et al. 1990) and adipose tissue weights (Goda et al. 1994) in rats fed high amylose starches. It might have been expected that body weights would be lower in pigs fed the high amylose starches. In fact, no difference was detected and it may be beyond the power of the experiment to do so. Assuming that all starch escaped into the colon of pigs fed the high amylose diet, then the energy value of the diet would have been only 45% lower than that of the cornstarch diet. On this basis, the pigs would have gained 3.6 kg as opposed to the 8-kg gain of those fed the cornstarch diet. However, it has been reported by Muir et al. (1994) that only 30% of high amylose starch is measurable as "dietary fiber." On that basis, the high amylose diet would have provided 80% of the energy of the control diet. This would have led to a difference of 1 kg in weight gaina difference too small to be measured with accuracy.
ACKNOWLEDGMENT
FOOTNOTES
Manuscript received 30 October 1995. Initial reviews completed 18 December 1995. Revision accepted 3 December 1996.
LITERATURE CITED
-glucan-enriched oat fraction enhances butyrate production in the large intestine of pigs.
J. Nutr.
1993;
123:1235-1247
This article has been cited by other articles:
|
|
 |
|
  A. R. Bird, C. Flory, D. A. Davies, S. Usher, and D. L. Topping A Novel Barley Cultivar (Himalaya 292) with a Specific Gene Mutation in Starch Synthase IIa Raises Large Bowel Starch and Short-Chain Fatty Acids in Rats J. Nutr., April 1, 2004; 134(4): 831 - 835. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. K. Le Leu, I. L. Brown, Y. Hu, and G. P. Young Effect of resistant starch on genotoxin-induced apoptosis, colonic epithelium, and lumenal contents in rats Carcinogenesis, August 1, 2003; 24(8): 1347 - 1352. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Claus, D. Losel, M. Lacorn, J. Mentschel, and H. Schenkel Effects of butyrate on apoptosis in the pig colon and its consequences for skatole formation and tissue accumulation J Anim Sci, January 1, 2003; 81(1): 239 - 248. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Martinez-Puig, J. F. Perez, M. Castillo, A. Andaluz, M. Anguita, J. Morales, and J. Gasa Consumption of Raw Potato Starch Increases Colon Length and Fecal Excretion of Purine Bases in Growing Pigs J. Nutr., January 1, 2003; 133(1): 134 - 139. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. L. Topping and P. M. Clifton Short-Chain Fatty Acids and Human Colonic Function: Roles of Resistant Starch and Nonstarch Polysaccharides Physiol Rev, July 1, 2001; 81(3): 1031 - 1064. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. W. Lopez, M.-A. Levrat-Verny, C. Coudray, C. Besson, V. Krespine, A. Messager, C. Demigné, and C. Rémésy Class 2 Resistant Starches Lower Plasma and Liver Lipids and Improve Mineral Retention in Rats J. Nutr., April 1, 2001; 131(4): 1283 - 1289. [Abstract] [Full Text]
|
|
|
|
|
|
H.-H. Cheng and M.-H. Lai Fermentation of Resistant Rice Starch Produces Propionate Reducing Serum and Hepatic Cholesterol in Rats J. Nutr., August 1, 2000; 130(8): 1991 - 1995. [Abstract] [Full Text]
|
|
|
|
|
|
A. R. Bird, T. Hayakawa, Y. Marsono, J. M. Gooden, I. R. Record, R. L. Correll, and D. L. Topping Coarse Brown Rice Increases Fecal and Large Bowel Short-Chain Fatty Acids and Starch but Lowers Calcium in the Large Bowel of Pigs J. Nutr., July 1, 2000; 130(7): 1780 - 1787. [Abstract] [Full Text]
|
|
|
|
 |
|
 M J A P Govers, N J Gannon, F R Dunshea, P R Gibson, and J G Muir Wheat bran affects the site of fermentation of resistant starch and luminal indexes related to colon cancer risk: a study in pigs Gut, December 1, 1999; 45(6): 840 - 847. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Morita, S. Kasaoka, K. Hase, and S. Kiriyama Psyllium Shifts the Fermentation Site of High-Amylose Cornstarch toward the Distal Colon and Increases Fecal Butyrate Concentration in Rats J. Nutr., November 1, 1999; 129(11): 2081 - 2087. [Abstract] [Full Text]
|
|
|
|
|
|
J. R. Pluske, Z. Durmic, D. W. Pethick, B. P. M. and, and D. J. Hampson Confirmation of the Role of Rapidly Fermentable Carbohydrates in the Expression of Swine Dysentery in Pigs after Experimental Infection J. Nutr., October 1, 1998; 128(10): 1737 - 1744. [Abstract] [Full Text]
|
|
|
|
|
|
T. Morita, S. Kasaoka, A. Oh-hashi, M. Ikai, Y. Numasaki, and S. Kiriyama Resistant Proteins Alter Cecal Short-Chain Fatty Acid Profiles in Rats Fed High Amylose Cornstarch J. Nutr., July 1, 1998; 128(7): 1156 - 1164. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
