Journal of Nutrition OpenSOurce Diets- www.ResearchDiets.com

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
 QUICK SEARCH:   [advanced]


     


This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kishida, T.
Right arrow Articles by Ebihara, K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kishida, T.
Right arrow Articles by Ebihara, K.
(Journal of Nutrition. 2001;131:294-300.)
© 2001 The American Society for Nutritional Sciences


Articles

Hydroxypropyl-Distarch Phosphate from Tapioca Starch Reduces Zinc and Iron Absorption, but not Calcium and Magnesium Absorption, in Rats

Taro Kishida, Yuka Nakai and Kiyoshi Ebihara1

Department of Biological Resources, Faculty of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama 790, Japan

1To whom correspondence should be addressed. E-mail: ebihara{at}agr.ehime-u.ac.jp


    ABSTRACT
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Male rats were fed a fiber-free, purified diet containing either gelatinized tapioca starch that was not modified chemically (TS, 50 g/kg diet) or gelatinized chemically modified tapioca starch (CMS, 50 g/kg) for 21 d. TS was used as the control. The six kinds of gelatinized hydroxypropyl distarch phosphate (HDP) from tapioca with two different degrees of substitution (DS) and three different degrees of cross-linking (DC) were used as CMS sources. The wet weight and moisture of fecal output of the rats fed HDP with higher DS were 100 and 20% greater than that in the control rats, respectively. The weights of cecal wall and cecal contents were also 30 and 50% higher in the rats fed HDP with higher DS than those in the control rats. The pH of the cecal contents was more acidic in the rats fed HDP with higher DS than that in the control rats. Fecal excretion of bile acids was 40% higher in the rats fed HDP with higher DS than in the control rats. These effects of HDP were only slightly affected by the DC. The plasma cholesterol concentration was 16% lower in the rats fed HDP with higher DS and highest DC than in the control rats. The concentrations of liver lipids and plasma triglycerides and the cecal pool of organic acids were not affected by diet. The apparent absorptions of Ca and Mg were not affected by diet, but those of Zn and Fe were 75 and 70% lower in the rats fed HDP with higher DS than in the control rats. These results suggest that the physiological effects of HDP depend on the DS but not on the DC.


KEY WORDS: • tapioca starch • hydroxypropyl distarch • phosphate • physiological effect • rats


    INTRODUCTION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Chemically modified starches (CMS)2are more resistant to retrogradation, have higher viscosity and are more stable in response to acid and high temperature than is native starch. Therefore, CMS are increasingly used by the food industry to improve the physical properties of various food items, including baby food. The consumption of CMS is increasing as the consumption of processed foods increases. Many investigators have observed that CMS have reduced susceptibility to enzymes in vitro and in vivo compared with the corresponding unmodified starch (1Citation 2Citation 3Citation 4Citation 5Citation ,51Citation ,52)Citation . Therefore, CMS would be expected to exert physiological effects similar to those of dietary fiber. The presence of CMS in the gut digesta may influence the digestion of other nutrients and absorption of other compounds. CMS may influence cholesterol and bile acid metabolism and the absorption of minerals as a result of fermentation. It has been reported that the large intestine may represent a major site of Ca and Mg absorption when acidic fermentations take place (6)Citation . Therefore, CMS would be expected to exert physiological effects similar to those of dietary fiber.

The physiological effects of dietary fibers are due to their physico-chemical properties. The enzymatic susceptibility of a CMS is affected by the type of modification, such as substitution or cross-linking. However, there are only a few reports on whether different types of CMS have different physiological effects. Hydroxypropyl distarch phosphate (HDP), a starch that can be modified by a combination of substitution and cross-linking, is one of the CMS used extensively in the food industry. Therefore, we evaluated the physiological effects of six different types of HDP from tapioca starch that have two different degrees of substitution and three different degrees of cross-linking.


    MATERIALS AND METHODS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Types of HDP.

The following six kinds of gelatinized HDP with two degrees of substitution (LS or HS) and three degrees of cross-linking (LC, MC or HC) were used: LS-LC, LS-MC, LS-HC, HS-LC, HS-MC and HS-HC (Table 1Citation ). The hydroxypropyl substituents were introduced by causing the tapioca starch to react with propylene oxide at pH 9–10 in the presence of Na2SO4. Cross-linking of the etherified starch was performed with Na3(PO3)3 (0.02, 0.12 or 0.5 g/100 g etherified starch) at pH 9–10. All derivatives, as well as the unmodified tapioca starch, were delivered to the rats in a gelatinized form. The DS was measured according to the method of Johnson (7)Citation . The DSP of each HDP was measured using a slight modification of the method described by Leach et al. (8)Citation . Briefly, 1 g of a dry HDP sample was accurately weighed and placed into a 50-mL graduated centrifuge tube. After adding 1 mL of methanol, distilled water that had been kept at 25°C was added while mixing with a glass rod until the total volume was 50 mL. The graduated centrifuge tube was occasionally shaken in a water bath at 25°C over 20 min to prevent the precipitation of HDP. After centrifugation at 1200 x g at room temperature for 30 min, the volume of the aqueous supernatant was measured. Then, the total sugar content in the aqueous supernatant was analyzed with phenol/H2SO4 reagent (9)Citation . The weight of the precipitate of swollen granules was measured. The DSP of each HDP was calculated as follows:


where A is total sugar content in the supernatant (mg), B is precipitate (mg) and S is solubility (%).


View this table:
[in this window]
[in a new window]
 
Table 1. Properties of tapioca starch (TS) and hydroxypropyl distarch phosphate (HDP)1

 
The degree of swelling power (DSP) decreased with increasing DC. Kainuma et al. (10)Citation showed that there is an inverse relationship between the DC and the DSP of starch granules. Therefore, the DC of the three HDPs increased in the following order: LC < MC < HC.

Measurement of the level of amylase-resistant starch.

Amylase-resistant starch is starch that cannot be hydrolyzed to glucose by amylolytic enzymes. To determine the level of amylase-resistant starch in each HDP, 1-g triplicate samples were incubated with heat-stable {alpha}-amylase (Termamyl 120L; Novo Nordisk, Copenhagen, Denmark) at pH 6.0 at 100°C for 30 min and then allowed to cool. After cooling, the pH was adjusted to 4.5 by HCl, and the samples were incubated with amyloglucosidase (Sigma A-9913; Sigma Chemical, St. Louis, MO) at 60°C for 30 min. After the incubation, the amount of glucose in the hydrolysate was enzymatically determined using pyranoseoxidase (Determiner GL-E; Kyowa Medix, Tokyo, Japan). The concentration of amylase-resistant starch was calculated as follows:

where wt. sample is the initial weight (g), and G is the weight of the hydrolysate (g).

Animals and diets.

This study was approved by the Laboratory Animal Care Committee of Ehime University, and the rats were maintained in accordance with the "Guidelines for the Care and Use of Laboratory Animals" of Ehime University.

Male Wistar rats (Japan SLC, Hamamatsu, Japan) with an initial weight of ~80 g were used in these experiments. The rats were housed individually in cages with screen bottoms of stainless steel in a room maintained at 23 ± 1°C with a 12-h light/dark cycle (light, 0700–1900h). The rats were acclimated by feeding a commercial solid diet (MF; Oriental Yeast, Osaka, Japan) for 7 d. After acclimation, the rats were divided into seven groups of six rats each (each group had a similar mean body weight). The composition of diets used in the experiment is shown in Table 2Citation . The rats were given free access to the experimental diet and water for 21 d. The body weight and food intake were recorded daily for each rat in the morning before the diet was replaced. Then, the condition of the feces of each rat was observed.


View this table:
[in this window]
[in a new window]
 
Table 2. Compositions of control and test diets

 
Sampling and analytical procedures.

Before the rats were killed, feces were collected on the final 3 d of the experimental period from each rat. The feces were freeze-dried, weighed and milled. The level of nitrogen (N) in the diet and feces of each rat was analyzed in duplicate for each collection according to the Kjeldahl method (11)Citation . The apparent digestibility of protein (N x 6.25) was calculated by measuring the N content in the food and feces. To determine the levels of Ca, Zn, Fe and Mg, the powdered feces (~70 mg) and diet (~500 mg) were wet-ashed in HNO3/HClO4 (3:1). The concentrations of Zn, Fe and Mg in the ashed solutions were measured by atomic absorption spectrophotometry (AA-6400F; Shimadzu, Kyoto, Japan) after dilution with deionized water. The calcium concentration in the ashed solutions was measured by atomic absorption spectrophotometry after dilution with 10 mol lanthanum chloride/L. The apparent absorption of Zn, Fe, Mg or Ca was calculated as the difference between the dietary intake and fecal excretion of Zn, Fe, Mg or Ca, respectively. Fecal steroids were extracted with a mixture of chloroform/methanol (1:1, v/v) at 70°C for 60 h (12)Citation . Total fecal bile acids were determined enzymatically by the 3{alpha}-hydroxysteroid dehydrogenase assay method of Sheltaway and Losowsky (13)Citation using taurocholic acid as the standard.

Blood was collected from the abdominal aorta of rats under sodium pentobarbital (50 mg/kg body mass, Nembutal; Abbot Laboratories, North Chicago, IL) anesthesia in a blood collection tube (Vacutainer; Becton Dickinson, Franklin Lakes, NJ) that contained heparin as an anticoagulant. The plasma was separated by centrifugation at 1400 x g at 4°C for 15 min and was stored at -50°C until analysis. The liver was removed, weighed and stored at -50°C for further analysis.

After blood collection, the cecum was removed and weighed. The contents were transferred to a cooled 50-mL vial and homogenized under CO2 gas. The water content of the cecal content was determined as the difference between the wet mass and the dry mass of the cecal content after freeze-drying. The cecal pH was measured immediately after removal with a compact pH meter using a sampling sheet (model C-1; Horiba, Tokyo, Japan; calibrated at 20°C). The cecal wall was flushed with ice-cold saline (9 g NaCl/L, 4°C), blotted onto filter paper and weighed. The level of cecal ammonia was determined spectrophotometrically in the deproteinized [4 mL of 0.25 mol sulfuric acid and 50 g sodium tungsten dihydrate per L, 1:1 (v/v), for ~50 mg contents] supernatant (1500 x g, 10 min) of the cecal content (14)Citation .

The levels of cecal organic acids (acetic, propionic, n-butyric, succinic and lactic acids) were measured using HPLC (LC-6A; Shimadzu, Kyoto, Japan) by the internal standard method. Approximately 300 mg of the cecal content was homogenized by ultrasonication (USC-6; Iwaki Glass Ltd., Chiba, Japan) in 2 mL of 10 mmol sodium hydroxide/L aqueous solution, containing 0.5 g crotonic acid/L (Nakarai, Kyoto, Japan) as an internal standard, in an ice-water bath, and then centrifuged at 10,000 x g for 15 min. The fat-soluble substances in the supernatant were removed by extraction with chloroform. Neutralization of the cecal content with sodium hydroxide prevented the extraction of the individual target organic acid or crotonic acid by chloroform. The aqueous phase was filtered through a membrane filter (cellulose acetate, pore size 0.45 µm; DISMIC-13cp; Toyo Roshi, Ltd., Tokyo, Japan). These samples were subject to HPLC for analysis of the organic acids. The organic acids were separated with an ion exclusion column and detected according to the postcolumn pH-buffered electroconductivity detection method (16)Citation using an H-type cation exchanger column (shim-pack SCR-102H, 8 mm i.d. x 30 cm long; Shimadzu, Kyoto, Japan), column temperature 45°C, with a mobile phase of 2 mmol perchloric acid/L (flow rate: 1 mL/min, 45°C). They were then reacted with a commercial detection reagent (ST3-R; 15 mmol disodium hydrogen phosphate/L), 5 mmol p-toluene sulfonic acid/L aqueous solution (flow rate, 0.8 mL/min, 45°C), an electroconductivity detector of positive polarity at 45°C (CDD-6A; Shimadzu) and a detection reagent of 20 mmol bis-Tris/L aqueous solution containing 5 mmol p-toluene sulfonic acid/L and 100 µmol EDTA/L (flow rate 0.8 mL/min, 45°C).

The levels of triglyceride and total cholesterol in the plasma were enzymatically determined with commercial kits (Triglyceride E-Test Wako and Cholesterol E Test Wako; Wako Pure Chemical Industries, Osaka, Japan). The level of liver total lipids was determined gravimetrically after extraction according to the method of Folch et al. (15)Citation . The levels of liver triglyceride and total cholesterol were also measured. Lipids were extracted from 500 mg liver with chloroform/methanol (2:1, v/v) according to the method of Folch et al. (15)Citation . After extraction, the volume of the lipid solution was adjusted to 20 mL with the same solution of chloroform/methanol (2:1, v/v). One mL of this extract was dried under a nitrogen stream, and the obtained residue was mixed with 100 µL isopropyl alcohol containing 100 g Triton X-100/L (Wako Pure Chemical Industries). Thirty µL of this mixture was mixed with 3 mL of aqueous enzyme solution according to the standard procedure of the assay kit (Triglyceride E-Test Wako and Cholesterol E-Test Wako; Wako Pure Chemical Industries), and the triglyceride and cholesterol concentrations were determined colorimetrically. In a preliminary study, 30 µL of isopropyl alcohol containing 100 g Triton X-100/L did not affect the enzymatic reactions (data not shown).

Statistical analysis.

Data are expressed as means ± SEM. The statistical significance of a difference between the control group and each HDP group was evaluated by one-way analysis of variance followed by Student-Newman-Keuls test using the Super ANOVA statistical software package (Abacus Concepts, Berkeley, CA).

The effects of the DS and DC were analyzed by two-way ANOVA, using a computer software package (StatView Version 4.5; Abacus Concepts), and the difference among groups was examined using Duncan’s new multiple range test when the F-value was significant. Differences were considered to be significant at P < 0.05. Correlation coefficients were determined by linear regression (17)Citation .


    RESULTS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The content of amylase-resistant starch in the LS and HS diets was markedly greater than that in the TS diet, which was used as the control (Table 1)Citation . The level of amylase-resistant starch in the HS diets was more than twice as much as that in the respective LS diet with the same DC. The level of amylase-resistant starch slightly increased with increasing DC.

Loose stools or diarrhea was observed in the rats fed the LS and HS diets, but intestinal adaptation took place during the 1st wk of feeding. The severity of diarrhea was not affected by the DS of the HDP, but increased with increasing DC. Body mass gain, food intake and feed efficiency were not affected by the type of diet (Table 3Citation ). The weight of the cecal contents and cecal wall of the rats fed the HS diets was significantly higher than the respective weight in the control rats and was also significantly higher than the respective weight in the rats fed the LS diets. The moisture in the cecal contents of rats fed the LS-MC, LS-HC or HS diets was significantly lower than that in the control rats, and the moisture in the cecal contents of rats fed the HS diets was significantly lower than that in the rats fed the LS diets; however, the level of moisture in the cecal content was not related to the DC. The wet weight of the fecal output of the rats fed the LS-HC diet or the HS diets was significantly higher than that of the control rats. The wet weight of the fecal output of the rats fed the HS diets was significantly greater than that of the rats fed the LS diets, and it increased with increasing DC. The moisture of the fecal output was significantly higher in the rats fed the LS-HC diet or the HS diets than in the control rats. The moisture absorbed in the colon was significantly lower in the rats fed the LS-HC or HS diets than in the control rats, and the moisture absorbed in the colon of the rats fed the LS and HS diets gradually decreased with increasing DC.


View this table:
[in this window]
[in a new window]
 
Table 3. Effect of the degree of substitution and cross-linking in hydroxypropyl distarch phosphate (HDP) on body mass gain, food intake, wet mass of cecal contents, cecal wall weight, fecal output and apparent moisture absorption in the colon of rats12

 
The pH of the cecal contents in rats fed each HS diet was significantly lower than that in the control rats; however, the pH of the cecal contents in rats fed the LS diets was not (Table 4Citation ). The concentration of ammonia in the cecal contents was not affected by the diet. The concentrations of total organic acids and acetic, propionic and lactic acids in the cecal contents were not affected by the diet. However, the concentration of n-butyric acid in the cecal contents was significantly lower in the rats fed the LS or HS diets than in the control rats. The concentration of succinic acid in the cecal contents of rats fed the HS-HC diet was significantly lower than that in the control rats.


View this table:
[in this window]
[in a new window]
 
Table 4. Effect of the degree of substitution and cross-linking of hydroxypropyl distarch phosphate on the pH of the cecal contents and cecal pool of principal organic acids in rats12

 
The apparent protein digestibility in the rats fed the HS-MC or HS-HC diet was lower than that in the control rats (Table 5Citation ). The plasma cholesterol concentration in the rats fed the HS-HC diet was significantly lower than that in the control rats and was significantly lower than that in the rats fed the LS diets. The plasma triglyceride concentration, the liver weight and concentrations of liver total lipids, cholesterol and triglyceride were not affected by the diet (data not shown). The levels of bile acids in the cecal contents and fecal excretion of bile acids were higher in the rats fed the HS diets than in the control rats and in the rats fed the LS diets.


View this table:
[in this window]
[in a new window]
 
Table 5. Effect of the degree of substitution and cross-linking in hydroxypropyl distarch phosphate on plasma cholesterol, cecal bile acids and fecal excretion of bile acids in rats1

 
The apparent absorptions of Ca and Mg were not affected by diet (Table 6Citation ). However, the apparent absorption of Zn in the rats fed the HS-MC or HS-HC diet was significantly lower than that in the control rats and in the rats fed the LS diets. The apparent absorption of Fe in the rats fed the LS or HS diets was significantly lower than that in the control rats. The apparent absorption of Fe slowly decreased with increasing DC. The apparent absorption of Fe in the rats fed the HS diets was significantly lower than that in the rats fed the LS-LC or LS-MC diet.


View this table:
[in this window]
[in a new window]
 
Table 6. Effect of the degree of substitution and cross-linking in hydroxypropyl distarch phosphate on the apparent absorption of calcium, magnesium, zinc and iron12

 

    DISCUSSION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The in vitro digestibility of gelatinized hydroxypropyl starches decreases with increasing substitution of hydroxypropyl groups (18Citation , 19Citation ). On the other hand, it has been reported that cross-linking with phosphate has no effect on the in vivo digestibility of HDP from tapioca starch (20)Citation or potato starch (1)Citation . In the present study, the level of amylase-resistant starch in HS was more than twice as great as that in LS with the respective DC; however, the level of amylase-resistant starch was only slightly affected by the DC in the HDP.

A summary of investigations concerning the in vivo digestibility of various CMS was published by FAO/WHO (21)Citation . In some studies, reduced digestibility, often in association with diarrhea and cecal enlargement, was observed after modification of starches, particularly at high levels of intake. We previously reported that the severity of diarrhea increased with increasing DS and with increasing DC in rats fed hydroxypropylated potato starch or HDP (DS = 0.01) from potato starch at 100 g/kg (19)Citation . In the present study, diarrhea was observed in the rats fed all LS and HS diets, but the degree of diarrhea was not affected by the DS. Cecal enlargement was observed in the rats fed the HS diets but not in the rats fed the LS diets. However, among the rats fed the HS diets, the degree of cecal enlargement was not affected by the DC. It has been demonstrated that enlargement of the cecum is due to an increased load of osmotically active substances in the caudal part of the intestinal tract (22Citation , 23Citation ). In the case of carbohydrates, it would primarily be associated with short-chain fatty acids (SCFA) produced by the gut microflora from the undigested part of the carbohydrate. However, the SCFA concentration in the cecum of the rats fed the LS and HS diets did not significantly differ from that in the control rats. On the other hand, Oku et al. (24)Citation speculated that cecal enlargement depends on the amount of maldigested materials that reach the cecum. The level of amylase-resistant starch in the HS diet was greater than that in the LS diet. The wet weight of the cecal content of the rats fed the HS diet was significantly greater than that of the control rats; however, the wet weight of the cecal content of the rats fed the LS diet was not. Therefore, the cecal enlargement caused by the HS diet may be due to increased influx of the unabsorbed starch fraction into the cecum. The cecal tissue weight of the rats fed the HS diet was heavier than that in the control rats. Til et al. (25)Citation showed that feeding HDP (DS = 0.075) from potato starch led to an increase in the tissue weight of the cecum. Feeding nonfermentable bulk to rats predominantly increased the thickness of the muscularis externa (26)Citation . There was a positive correlation between the cecal content and cecal tissue weight among rats fed diets containing resistant starch (27)Citation . Thus, the increase in cecal content may have contributed to the heavier cecal tissue weight in the rats fed the HS diet. Til et al. (25)Citation showed that feeding HDP (DS = 0.075) from potato starch leads to an increase in the weight of the colon. However, in the present study, the LS and HS diets did not lead to an increase in the colon tissue weight. Enlargement of the large intestine is known to readily occur in rats fed CMS (28)Citation .

The apparent protein digestibility in the rats fed the HS-MC or HS-HC diet was lower than that in the control rats. A reduction in feed efficiency is generally caused by reduced digestibility of proteins and/or energy sources and by reduced retention of nutrients resulting from various metabolic disturbances. However, the feed efficiency and body mass gain in the rats fed the HS-MC or HS-HC diet did not differ from those in the control rats. Thus, it does not appear that HS-MC and HS-HC interfere with the digestion and absorption of protein and energy sources. On the other hand, the fecal N excretion (data not shown) and fecal output were greater in the rats fed the HS-MC or HS-HC diet than in the control rats. The greater fecal N excretion is caused by reduced protein digestibility and by increased production of endogenous protein (e.g., digestive enzymes and sloughed cells) and/or by greater fecal biomass. The bacteria in the large bowel play a major role in fecal bulking and constitute a large proportion of fecal N (29)Citation . However, the amylase-resistant starch in HDP is not a good substrate for bacteria in the large bowel (1Citation , 30Citation ). Thus, the greater fecal N excretion and the lower apparent protein digestibility in the rats fed the HS-MC or HS-HC diet may be due to increased fecal output as a result of a shorter transit time in the large bowel.

The fecal wet weights and fecal moistures in the rats fed the LS-HC and HS diets were significantly greater than those of the control rats, but those in the rats fed the LS-LC or LS-MC diet were not. If the magnitude of the laxative effect is calculated as the increase in fecal wet weight per gram of amylase-resistant starch consumed, the effect was as follows (g/g): 0.028 for the LS-LC diet, 0.049 for the LS-MC diet, 0.289 for the LS-HC diet, 0.835 for the HS-LC diet, 1.267 for the HS-MC diet and 1.310 for the HS-HC diet. The laxative effect of the LS and HS diets increased as the level of amylase-resistant starch increased (r = 0.969, P = 0.0014). Therefore, the increase in fecal output in the rats fed LS-HC and HS diets is due to the increases in fecal moisture and level of amylase-resistant starch. The amount of absorbed moisture in the colon of rats fed the LS-HC and LS diets was significantly lower than that in the control rats. The contents in the colon of the rats fed the LS-HC and HS diets felt stickier and more viscous to the touch compared with those of the rats fed the TS diet. Therefore, the reduced moisture absorption in the colon of rats fed the LS-HC and HS diets would be due to inhibition of diffusion.

The plasma cholesterol concentration in the rats fed the HS-HC diet was significantly lower than that in the control rats, and that in the rats fed the HS-LC or HS-MC diet was slightly (P = 0.097) but not significantly lower than that in the control rats. Because the experimental diets were not supplemented with cholesterol, the hypocholesterolemic effect of the HS diet must involve changes in endogenous sterol metabolism. One possibility is increased fecal excretion of cholesterol and bile acids. Bile acids may bind to HS in the small intestine, because starch has been shown to bind bile acids in vitro (31)Citation . The cecal contents and fecal excretion of bile acids in the rats fed the HS diet were significantly larger than the respective values in the rats fed the LS diet. By inhibiting the reabsorption of bile acids and enhancing fecal bile acid excretion, the HS may cause increased hepatic synthesis of bile acids, thereby reducing the serum cholesterol concentration. However, it is still unclear whether each type of HS can effectively bind bile acids. Another possible explanation concerns propionic acid production from fermentation of HS in the large bowel. When propionic acid was fed to rats, it significantly reduced the serum cholesterol concentration (32)Citation . Propionic acid infused into the cecum prevented the increase in plasma cholesterol concentration in rats fed a cholesterol-free casein diet (33)Citation . Furthermore, in vitro studies using rat liver cells have shown that propionic acid may attenuate hepatic cholesterol synthesis (34)Citation . On the other hand, other studies have shown that propionic acid has no hypocholesterolemic effects (35Citation , 36Citation ). However, in the present study, the concentration of propionic acid in the cecal content was not affected by the diet. Further studies are needed to elucidate the mechanism of the hypocholesterolemic effect of HS.

A strong negative correlation has been found between the cecal pH and the cecal pool of SCFA (37)Citation . However, despite a similar cecal pool size of organic acids, the cecal pH in the rats fed the HS diet was lower than that in the control rats. Lactic acid is poorly and slowly absorbed (38Citation , 39Citation ). Hoshi et al. (40)Citation suggested that the higher concentration of cecal succinic acid predominantly appears to contribute to the lower cecal pH. However, in the present study, the concentration of lactic acid was not affected by the diet. Moreover, the concentration of succinic acid in the rats fed HS-HC diet was lower than that in the control rats.

A recent in vitro study examined carbohydrate fermentation in human fecal slurries and found that starch fermentation increased n-butyric acid production (41Citation , 42Citation ). In the present study, the LS and HS diets did not increase the concentration of n-butyric acid compared with that in the control rats. Also, the LS and HS diets did not increase the concentration of propionic acid in comparison with that in the control rats. These are in agreement with the result of our previous study in rats fed HDP (DS = 0.01, 100 g/kg diet) from potato starch (19)Citation . The lower concentration of n-butyric acid can be explained by the cecal enlargement, because butyric acid is readily oxidized by cecal and colonic epithelial cells (43)Citation . Also, this lower concentration of n-butyric acid can be explained by the lower concentration of butyric acid–producing bacteria. The amylase-resistant starch in LS and HS may not be a good substrate for butyric acid–producing bacteria. The concentration of acetic, lactic or succinic acid in the rats fed the LS or HS diet was not higher than that in the control rats. However, in a previous study, we found that rats that were fed HDP (100 g/kg diet) with a molar substitution of 0.01 from potato starch had higher concentrations of acetic, lactic and succinic acids than the control rats fed potato starch (19)Citation . On the other hand, it has been reported that the pancreatin-indigested fractions in HDP are not good substrates for lactic acid–producing bacteria in in vitro bacterial fermentation (30)Citation . The apparent digestibility of CMS and the structure of the maldigested fraction in feces after CMS administration depend on the type of modification (1)Citation . Therefore, the difference in the results between the present study and our previous study is due to the differences in the quality and quantity of HDP.

The apparent absorptions of Ca and Mg were not affected by the diet. Mineral absorption generally occurs in the upper part of the intestine. However, in rats, the large intestine has a high capacity for Mg and Ca absorption (44)Citation . Moreover, it has been reported that SCFA also contribute to enhance the absorption of Ca and Mg from the cecum (45Citation 46Citation 47)Citation . On the other hand, the apparent absorption of Zn in the rats fed the HS diet was significantly lower than that in the control rats, but the apparent absorption of Zn in the rats fed the LS diet was not. The apparent absorption of Fe in the rats fed the LS or HS diet was significantly lower than that in the control rats. Bruns and Hood (48)Citation reported that HDP bound iron in vitro. Hood et al. (49)Citation reported that feeding HDP resulted in marked depression in iron retention in iron-deficient rats.

These results show that the characteristics of amylase-resistant starch in HDP are similar to dietary fiber, with respect to increases fecal bulking and fecal excretion of bile acids, an change in pH of cecal content, decreases in absorption of Fe and Zn and an decrease in apparent protein digestibility. The dietary fiber–like effects of CMS would be affected by the type of modification. In fact, dietary fiber–like effects of HDP depend on the DS but not the DC.


    FOOTNOTES
 
2 Abbreviations: CMS, chemically modified starch; DC, degree of cross-linking; DS, degree of substitute; DSP, degree of swelling power; HDP, hydroxypropyl distarch phosphate; SCFA, short-chain fatty acid. Back

Manuscript received July 17, 2000. Initial review completed August 11, 2000. Revision accepted October 20, 2000.


    REFERENCES
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

1. Björck I., Gunnarsson A, Östergrd K. A study of native and chemically modified potato starch 1989 Part II Digestibility in the rat intestinal tract. Starch/Stärke 41 128–134.

2. Ebihara K. In vitro {alpha}-amylase hydrolysis of modified starch and postprandial plasma glucose response. J. Jpn. Soc. Nutr. Food Sci. 1992a;45:551-553(in Japanese)

3. Östergrd K., Björck I., Gunnarsson A. A study of native and chemically modified potato starch 1988 Part I Analysis and enzymic availability in vitro. Starch/Stärke 40 58–66.

4. Whistler R. L., Belfort A. M. Nutritional value of chemically modified corn starch. Science 1961;133:1599-1600[Abstract/Free Full Text]

5. Wootton M., Chaudhry M. A. In vitro digestion of hydroxypropyl derivatives of wheat starch. I. Digestibility and action pattern using porcine pancreatic alpha-amylase. Starch/Stärke 1981;33:135-137

6. Younes H., Demige é C., Rémésy C. Acidic fermentation in the caecum increases absorption of calcium and magnesium in the large intestine of the rat. Br. J. Nutr. 1996;75:301-314[Medline]

7. Johnson D. P. Spectrophotometric determination of the hydroxypropyl group in starch esters. Anal. Chem. 1969;41:859-860

8. Leach H. W., McCowen L. D., Schoch T. J. Structure of the starch granule. I. swelling and solubility patterns of various starches. Cereal Chem. 1959;36:534-544

9. Dubois M., Gilles K. A., Hamilton J. K., Rebers P. A., Smith F. Calorimetric method for determination of sugars and related substances. Anal. Chem. 1956;28:350-356

10. Kainuma K., Miyamoto S., Suzuki S. Studies on structure and physico-chemical properties of starch. Part 2. Reaction of epichlorohydrin with corn starch. Denpun Kagaku 1975;22:66-71

11. Miller L., Houghton J. A. The micro-Kjeldahl determination of the nitrogen content of amino acids and proteins. J. Biol. Chem. 1945;159:373-380[Free Full Text]

12. Eneroth P., Hellstrom K., Sjovall J. A method for quantitative determination of bile acids in human feces. Acta Chem. Scand. 1968;22:1729-1744[Medline]

13. Sheltaway M. J., Losowsky M. S. Determination of fecal bile acids by an enzymic method. Clin. Chem. Acta 1975;64:127-132[Medline]

14. Okuda H., Fujii S. Kettyu anmonia tyokusetsu hisyoku teiryouhou. Saishin-igaku 1966;21:622-627(in Japanese)

15. Folch J., Less M., Sloane-Stanley G. H. A simple method for the isolation and purification of total lipids from animal tissue. J. Biol. Chem. 1957;226:497-509[Free Full Text]

16. Hayashi M. Determination of organic acids in foods by HPLC with post-column pH buffered electroconductivity detection. Shimazu Hyoron 1992;49:59-64

17. Snedecor, G. W. & Cochran, W. G. (1967) Statistical Methods, 6th ed., pp.166–190, Iowa State University Press, Ames, IA.

18. Leegwater D. C., Luten J. B. A study on the in vitro digestibility of hydroxypropyl starches by pancreatin. Starch/Stärke 1971;23:430-432

19. Ebihara K., Shiraishi R., Okuma K. Hydroxypropyl-modified potato starch increases fecal bile acid excretion in rats. J. Nutr. 1998;128:848-854[Abstract/Free Full Text]

20. Hood L. F., Arneson V. G. On vitro digestibility of hydroxypropyl distarch phosphate and unmodified tapioca starch. Cereal Chem 1976;53:282-290

21. World Health Organization (1972) Food Additive Series No 1. Toxicological evaluation of some enzymes, modified starches and other substances. World Health Organization, Geneva, Switzerland.

22. Leegwater D. C., de Groot A. P., van Kalmthout-Kuyper M. The aetiology of caecal enlargement in the rat. Food Cosmet. Toxicol. 1974;24:11-15

23. Walker R. Some observations on the phenomenon of caecal enlargement in the rat. Chemical Toxicology of Food 1st ed. 1978:339 Elsevier Amsterdam.

24. Oku T., Konishi F., Hosoya N. Effect of various unavailable carbohydrate and administration periods on several physiological functions of rats. J. Jpn. Soc. Nutr. Food Sci. 1981;34:437-443(in Japanese)

25. Til H. P., Feron V. J., Immel H. R., Vogel W. F. Chronic (89-week) feeding study with hydroxypropyl distarch phosphate, starch acetate, lactose and sodium alginate in mice. Food Chem. Toxicol. 1986;24:825-834[Medline]

26. Dowling R. H., Riecken E. O., Laws J. W., Booth C. C. The intestinal response to high bulk feeding in the rat. Clin. Sci. 1967;32:1-9[Medline]

27. Verbeek M.J.F., De Deckere E.A.M., Tijburg L.B.M., Van Amelsvoort J.M.M., Beynen A. C. Influence of dietary retrograded starch on the metabolism of neutral steroids and bile acids in rats. Br. J. Nutr. 1995;74:807-820[Medline]

28. De Groot A. P., Til H. P., Feron V. J., Dreef-van der Meulen H. C., Willems M. I. Two-year feeding and multigeneration studies in rats on five chemically modified starches. Food Cosmet. Toxicol. 1974;12:651-663[Medline]

29. Scheppach W., Fabian C., Ahrens F., Spengler M., Kasper H. Effect of starch malabsorption on colonic function and metabolism in humans. Gastroenterology 1988;95:1549-1555[Medline]

30. Ebihara K. Utilization of pancreatin-indigestible parts of modified starch by various intestinal bacteria. J. Jpn. Soc. Nutr. Food Sci. 1992b;45:554-559(in Japanese)

31. Bianchini F., Caderni G., Dolara P., Fantetti L., Kriebel D. Effect of dietary fat, starch and cellulose on fecal bile acids in mice. J. Nutr. 1989;46:S121-S122

32. Illman R. J., Topping D. L., McIntosh G. H., Trimble R. P., Storer G. B., Taylor M. N., Cheng B.-Q. Hypocholesterolemic effects of dietary propionate Studies in whole animals and perfused rat liver. Ann. Nutr. Metab. 1988;32:97-107

33. Ebihara K., Miyada T., Nakajima A. Hypocholesterolemic effect of cecally infused propionic acid in rats fed a cholesterol-free, casein diet. Nutr. Res. 1993;13:209-217

34. Wright R. S., Anderson J. W., Bridges S. R. Propionate inhibits hepatocyte lipids synthesis. Proc. Soc. Exp. Biol. Med. 1990;195:26-29[Medline]

35. Beaulieu K. E., McBurney M. I. Changes in nutrient digestibility and sterol excretion during caecal infusion of propionate. J. Nutr. 1992;122:241-245

36. Venter C. S., Vorster H. H., Cummings J. H. Effects of dietary propionate on carbohydrate and lipid metabolism in healthy volunteers. Am. J. Gastroenterol. 1990;85:549-553[Medline]

37. Berggren A. M., Björck I.M.E., Nyman E.M.G.L., Eggum B. O. Short-chain fatty acid content and pH in caecum of rats given various sources of carbohydrates. J. Sci. Food Agric. 1993;63:397-406

38. Giesecke D., Stangassinger M. Lactic acid metabolism. Ruckebush Y. Thivend P. eds. Digestive Physiology and Metabolism in Ruminant 1980:523-539 M.T P. Press, Lancaster, U.K.

39. Macfarlane, G. T. & Cummings, J. H. (1991) The colonic flora, fermentation, and large bowel digestive function. In: The Large Intestine: Physiology, Pathophysiology, and Disease (Phillips, S. F., Pemberton, J. H. & Shorter, R.G. eds.), pp. 51–91,. Raven Press, New York, NY.

40. Hoshi S., Sakata T., Mikuni K., Hashimoto H., Kimura S. Galactosylsucrose and xylosylfructoside alter digestive tract size and concentrations of cecal organic acids in rats fed diets containing cholesterol and cholic acid. J. Nutr. 1994;124:52-60

41. Høverstad T., and Bjørneklett A. Scand. J. Gastroenterol. 1984;19:1059-1065

42. Cummings J. H., Macfarlane G. T. The control and consequences of bacterial fermentation in the human colon. J. Appl. Bacteriol. 1991;70:443-459[Medline]

43. Roediger W.E.W. Utilization of nutrients by isolated epithelial cells of the rat colon. Gastroenterology 1982;83:424-429[Medline]

44. Karbach U, Feldmeier H. The cecum is the site with the highest calcium absorption in rat intestine. Dig. Dis. Sci. 1993;38:1815-1824[Medline]

45. Behar J. Magnesium absorption by rat ileum and colon. Am. J. Physiol. 1977;227:334-340

46. Rayssinguier Y., Remesy C. Magnesium absorption in the cecum of rats related to volatile fatty acids production. Ann. Rech. Vet. 1977;8:105-110[Medline]

47. Lutz T., Scharrer E. Effect of short chain fatty acids on calcium absorption by the rat colon. Exp. Physiol. 1991;76:615-618[Abstract]

48. Bruns P., Hood L. F. Binding of metal cations and sodium cholate by modified tapioca starch. Cereal Sci. Today 1973;18:299(abs.)

49. Hood L. F., Vancampen D. R., House W. A., Szatkowski E. Effect of modified and unmodified tapioca starches on 59Fe retention in rats. J. Nutr. 1976;106:1768-1772

50. American Institute of Nutrition Report of the American Institute of Nutrition Ad Hoc Committee on Standards for Nutritional Studies. J. Nutr. 1977;107:1340-1348

51. Leegwater D. C., Luten J. B. A model for the structure of hydroxy-propyl starch. Starch/Stärke 1972;24:11-15

52. Wootton M., Chaudhry M. A. Enzymic digestibility of modified starches. Starch/Stärke 1979;31:224-228




This article has been cited by other articles:


Home page
J. Nutr.Home page
T. Kishida, H. Nogami, H. Ogawa, and K. Ebihara
The Hypocholesterolemic Effect of High Amylose Cornstarch in Rats Is Mediated by an Enlarged Bile Acid Pool and Increased Fecal Bile Acid Excretion, Not by Cecal Fermented Products
J. Nutr., September 1, 2002; 132(9): 2519 - 2524.
[Abstract] [Full Text] [PDF]


Home page
J. Nutr.Home page
T. Kishida, H. Nogami, S. Himeno, and K. Ebihara
Heat Moisture Treatment of High Amylose Cornstarch Increases Its Resistant Starch Content but Not Its Physiologic Effects in Rats
J. Nutr., October 1, 2001; 131(10): 2716 - 2721.
[Abstract] [Full Text] [PDF]


This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kishida, T.
Right arrow Articles by Ebihara, K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kishida, T.
Right arrow Articles by Ebihara, K.


Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Copyright © 2001 by American Society for Nutrition