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It was examined whether undigested protein, namely resistant protein, affects glucagon-like peptide-1 (GLP-1) secretion in rats fed high amylose corn starch (HACS). Rats were fed one of three experimental diets for 28 d: casein without HACS, casein with HACS or dashigara with HACS. Dashigara is produced from Katsuobushi (smoke-dried skipjack tuna) treated with microbial protease. The apparent digestibilities of casein and dashigara are 96.0% and 84.5%, respectively. The amount of rat cecal butyric acid and propionic acid were as follows: the dashigara with HACS group > the casein with HACS group > the casein without HACS group. The dashigara with HACS group had significantly greater cecal butyric acid and lower cecal succinic acid than the casein with HACS group. The GLP-1 concentration in portal vein blood increased as the amount of butyric acid and propionic acid in the cecal contents increased. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments showed that the composition of cecal microbiota differed among the three groups. These results suggest that resistant protein contained in dashigara promotes GLP-1 secretion by controlling fermentation efficiency as well as the fermentation profile of HACS through the changes in cecal microbiota in rats fed HACS.

Background: It was reported to be associated with intake of dietary fiber and gut hormone. We compared the effect of dietary fiber on the plasma concentration of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). Methods: Firstly, male Wistar rats (10 wk old) were fed a fiber-free diet (FF diet, AIN-93G-based diet without cellulose) or one of nine FF diets with 5% dietary fiber for 21 days. Cellulose, guar gam (GG), partially hydrolyzed guar gum (PHGG), sugar beet fiber (BF), konjac mannnan (KM), raffinose (RF), hydroxypropyl starch (HPS), hydroxypropyl distarch phosphate (HPDP) and Akamoku (AK) were used as dietary fiber sources. Secondly, we then determined whether the concentrations of GLP-1 and PYY in portal and aorta plasma and microbiota in cecal contents responded to an altered diet. Male Wistar rats (10 wk old) were fed the PHGG diet for 20 days before being changed to the FF diet. Results: The amount of short chain fatty acids (SCFA) in the cecal contents markedly increased in rats fed the GG, PHGG, BF, KM, RF, HPS or HPDP diets compared with SCFA in rats fed the FF, CL or AK diets. The concentrations of GLP-1 and PYY in portal plasma positively correlated with the concentration of SCFA in the cecal contents and cecal tissue weight. The concentrations of GLP-1 and PYY, in the altered diet group decreased to the same concentration as that measured in the FF group. However, it was low the similarities in the cecal bacteria population. Conclusion: The plasma concentrations of GLP-1 and PYY increased with increasing the amounts of SCFA, the products of DF fermentation, in the cecal contents. GLP-1 and PYY plasma concentrations and SCFA concentrations in the cecal contents rapidly responded to the altered diet, but the cecal bacteria population did not.

The present study was designed to investigate the effect of pectin on Fe bioavailability in ileorectomised rats or caecectomised rats. In Expt 1, rats were divided into the following two groups: ileorectomised rats fed a fibre-free diet (FF diet) and ileorectomised rats fed a FF diet supplemented with 5 % (w/w) pectin (pectin diet). Apparent Fe absorption in ileorectomised rats fed the pectin diet was significantly lower compared with ileorectomised rats fed the FF diet. In Expt 2, caecectomised rats and sham-operated rats were given one of the following diets for 3 weeks: diet containing ferrous iron (FeII diet), diet containing pectin at 50 g/kg diet (pectin diet) and diet containing a mixture of FeII and product prepared by the enzymatic degradation of pectin (FeII–OGA diet), which were presumed to be oligomers of galacturonic acid. The Fe content of these diets was 7·6, 8·1 and 7·7 mg/kg diet, respectively. The bioavailability of Fe in rats fed the FeII diet was not affected by caecectomy. In contrast, in rats fed the pectin diet, where Fe bound to pectin was the only Fe source, Hb gain and Hb regeneration efficiency were significantly decreased by caecectomy. The bioavailability of Fe from the FeII–OGA complex was not affected by caecectomy. These results suggest that Fe in pectin might be released by microbial degradation and subsequently made available for absorption in the large intestine, although pectin might decrease Fe absorption in the small intestine.

The present study investigated whether the hypocholesterolaemic effect of water-insoluble fish protein (IFP) from Alaska pollock in ovariectomised (OVX) rats was affected by methionine (Met) addition. OVX rats (6 months old) were fed a cholesterol-free diet containing casein, IFP or IFP+Met as a protein source for 28 d. The ratio of Met:glycine was lower in the IFP and IFP+Met diets compared with the casein diet. Body-weight gain, food intake and liver lipids were not affected by the diet. Plasma total cholesterol concentration was lower in OVX rats fed the IFP diet compared with those fed the casein diet. The hypocholesterolaemic effect of the IFP diet was not abolished by Met addition. Amount of bile acids in the small-intestinal content and faecal excretion of bile acids were higher in OVX rats fed the IFP and IFP+Met diets compared with those fed the casein diet. Ileal bile acid transporter (IBAT) mRNA level and faecal excretion of bile acids were significantly lower and higher, respectively, in OVX rats fed the IFP diet compared with those fed the casein diet, but not in those fed the IFP+Met diet. Thus, the hypocholesterolaemic effect of the IFP diet seems to be mediated by increased faecal excretion of bile acids coupled with decreased reabsorption of bile acids from the ileum through a decrease in IBAT and the change in cholesterol metabolism linked to the amino acid profile.

In the present in vitro study, the effects of pH and ionic strength on the release of iron from pectin and the ability of pectin to reduce ferric iron to ferrous iron were examined. The bioavailability of Fe bound to pectin was evaluated in rats. The amount of Fe released from pectin was at a maximum at pH 2·0 and decreased as the pH value increased. At pH 2·0, the amount of Fe released from pectin increased as the ion length increased; at pH 5·0, ion length had no effect on pectin release. Pectin effectively reduced Fe from the ferric form to the ferrous form. In rats fed a pectin diet, where Fe bound to pectin was the only Fe source, the final Hb concentration using diets containing 4·4–5·7, 7·2 or 11·5 mg Fe/kg diet was equal to the concentration in rats fed diets containing 4·5, 7·6 or 13·5 mg ferrous iron/kg diet, respectively. Hb regeneration efficiencies in rats fed pectin diets were significantly different from rats fed a diet containing 13·5 mg ferrous iron/kg diet. In rats fed a diet with or without pectin, where ferric iron was the only Fe source, pectin increased the final Hb concentration. These results suggest that Fe bound to pectin is utilised by rats.

In vitro and in vivo digestibilities of hydroxypropyl starch were investigated to determine an appropriate nondigested carbohydrate assaying method for hydroxypropyl starch. Hydroxypropyl tapioca starch (HPTS), with a 0.338 degree of substitution, was used as a hydroxypropyl starch source. Practically all nondigested carbohydrate in HPTS was low molecular weight and was not precipitated in 78% ethanol. The contents of nondigested carbohydrate in HPTS and in effluents of ileorectomized rats fed the HPTS diet obtained by the AOAC 2001.03 (enzyme-gravimetric-HPLC method) were almost the same, 56% and 59%, respectively. The recovery of hydroxypropyl groups from ileorectomy effluents was 98%. The AOAC 2001.03 method is suggested to be appropriate in determining the content of nondigested carbohydrates in hydroxypropyl starch.

The effect of dietary high-amylose corn starch (HACS) of varying dietary fiber (DF) content on plasma cholesterol was examined in ovariectomized (OVX) rats. Gelatinized normal corn starch (G-CS) was used as a reference. OVX rats were fed a fiber-free purified diet containing G-CS, HACS, gelatinized high-amylose corn starch (G-HACS), or heat-moisture treated HACS (HM-HACS) at 400 g starch/kg diet for 21 d. The DF content of G-CS, HACS, G-HACS, and HM-HACS measured by the AOAC method was 0.1, 19.3, 2.4, and 64.5 g/100 g, respectively. The dry weight of cecal contents, cecal wall weight, the amount of short chain fatty acids in cecal contents, the amount of bile acids in small intestinal contents, and fecal excretion of neutral sterols increased logarithmically with increasing DF, while total plasma cholesterol concentration decreased. On the other hand, hepatic CYP7A1 activity, fecal dry weight, and fecal excretion of bile acids increased linearly with increasing DF, while body weight gain decreased. The hypocholesterolemic effect of HACS in OVX-rats appeared to be more effective by heat-moisture treatment.

我々はグァーガム分解物 (partially hydrolyzed guar gum, PHGG) 単回摂取による食後血清中性脂肪上昇抑制作用ならびにその作用機序が腸管内における脂質乳化の破壊によることを報告しているが, 本研究ではPHGGを長期摂取したときにその作用に変化があるかを動物実験およびin vitro 実験で検証した。マウスに5%PHGGを含むまたは含まない市販粉末飼料を12週間摂取させ, 摂取前後に脂肪負荷試験を行った。脂肪負荷試験は, マウスを16時間絶食後に25%PHGG溶液 (3.3mL/kg BW) または水を投与後, ただちにオリーブ油 (6.6mL/kg BW) を投与することによって行った。投与前および投与2, 4, 6時間後に尾静脈より採血し, 中性脂肪を測定した。その結果, PHGGを長期摂取した後でも血清脂質上昇抑制作用は確認された。また, 乳化破壊に及ぼす影響をin vitro で検討した。胆汁酸を0.1, 0.5, 1.0%に変更して調製したオリーブ油乳化液とPHGG溶液 (1, 2, 3, 5%) を混合して振とうし, さらに振とう速度を80, 160回/分とし, PHGGによる乳化安定性に対する影響を検討した。PHGGによる乳化破壊作用は胆汁酸濃度および振とう速度に影響されなかった。これらの結果より, PHGGによる食後脂質上昇抑制作用は長期間摂取後でも減弱せず, PHGGを長期摂取しても腸管内の胆汁酸濃度が高くなったり, 蠕動運動が活発になったとしても影響を受けないことが示唆された。

The effect of dietary high amylose cornstarch (HACS) on plasma lipids was studied in ovariectomized rats (OVX-rats). OVX-rats were fed cholesterol-free purified diets containing either 0%, 5%, 10%, 20%, or 30%HACS as a percentage of total carbohydrate for 28 d. Plasma triacylglycerol (TAG) concentration and apparent starch digestibility were found to decrease as the dietary level of HACS increased. On the other hand, the amount of small intestinal bile acids, cecal tissue weight, the amount of cecal short-chain fatty acids, primary:secondary ratio of fecal bile acids, and fecal weight were found to increase. However, plasma total cholesterol concentration, excretion of fecal bile acids, cholesterol 7α-hydroxylase activity, liver lipids, body weight gain, liver weight, and the weight of cecal contents were not affected by the diets. The amount of propionic acid in the cecal content increased as the dietary level of HACS increased. HACS might lower lipogenesis in liver and adipose tissue and lower very low density lipoprotein secretion by increasing propionic acid production, consequently leading to a decreased plasma TAG concentration.

The physiological effects of hydroxypropyl-distarch phosphate (HDP) were examined in rats. Male rats were fed a fiber-free purified diet containing gelatinized potato starch (PS, 50 g/kg diet) that was not modified chemically or gelatinized, chemically modified potato starch (CMS, 50 g/kg diet) for 21 d. PS was used as the control. Six kinds of gelatinized HDP from potato with 2 different degrees of hydroxypropylation and 3 different degrees of cross-linking were used as CMS. The wet weight and moisture of the fecal output of the rats fed highly hydroxypropylated HDP was 70% and 30% greater, respectively, than that in the control rats. The weights of the cecal wall and content of the rats fed highly hydroxypropylated HDP were 15% and 30% higher, respectively, than those of the control rats. The apparent absorption of Mg was 15% higher in the rats fed highly hydroxypropylated HDP than in the control rats. On the other hand, the apparent absorptions of Ca, Zn, and Fe were not affected by the diet. Cross-linking did not influence the above-mentioned physiological effects of HDP. Fecal excretion of bile acids and the plasma cholesterol concentration were not affected by the diet. These results show that the physiological effects of HDP depend on the hydroxypropylation but not the cross-linking.

We studied the effect of taurine on ovarian hormone deficiency-induced hypercholesterolemia in 6-month-old, ovariectomized rats fed with coconut oil. Rats were fed 1 of 4 diets for 28 days: purified diet based on coconut oil without or with taurine (10, 30, or 50 g/kg, called the C, 10T, 30T and 50T diets, respectively). Coconut oil is rich in lauric and myristic acids, which are saturated fatty acids that reduce the level of hepatic low-density lipoprotein receptor activity. Plasma cholesterol level was not affected by the diet. The low-density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA levels in the liver increased by feeding the 50T diet compared with the C diet. As the dietary level of taurine increased, the levels of cholesterol 7 α -hydroxylase activity, and fecal bile acids excretion logarithmically increased. Our results showed that taurine increased fecal bile acids excretion but did not prevent ovarian hormone deficiency–induced hypercholesterolemia in rats fed with coconut oil.

The purpose of this study was to examine whether retrograded tapioca starch (RS3-tapioca) prevents ovarian hormone deficiency-induced hypercholesterolemia. Six-month-old Wistar female rats were subjected to sham-operation or ovariectomy, and fed a cholesterol-free purified diet with or without RS3-tapioca (150 g/kg diet) instead of digestible cornstarch for 28 d. Body weight gain and food intake increased in ovariectomized rats (OVX-rats). Plasma total cholesterol concentration was lowered by RS3-tapioca in OVX rats, but not in sham-operated rats. Liver lipids increased in OVX-rats, but liver cholesterol concentration was not affected by ovariectomy and RS3-tapioca. CYP7A1 activity, small intestinal and cecal bile acid content, and fecal bile acid excretion were increased by RS3-tapioca. The ratio of cholic acid groups to chenodeoxycholic acid groups in the bile acid of the small intestine was increased by RS3-tapioca. Thus, the preventive effect of RS3-tapioca on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration appears to be mediated by accelerated fecal excretion of bile acid and an increase in the intestinal pool of bile acid.

The hypocholesterolemic effects of smoke-dried bonito undigested fractions remaining after microbial proteases treatment (SDBR), SDBR undigested fractions remaining after pepsin treatment (P-SDBR), SDBR undigested fractions remaining after alcalase treatment (A-SDBR), and defatted A-SDBR (A-SDBR/DF) were studied in 6-month-old, ovariectomized rats. Casein was used as the control. Smoke-dried bonito, Katsuobushi, is a traditional Japanese food. SDBR, P-SDBR, and A-SDBR contain mainly 2 components: bonito oil and protease-undigested proteins. In comparison with casein, SDBR, P-SDBR, and A-SDBR decreased plasma cholesterol concentration and increased fecal bile acid excretion and fecal output, whereas A-SDBR/DF increased fecal bile acid excretion and fecal output, but did not decrease plasma cholesterol concentration. In addition, SDBR, P-SDBR, and A-SDBR, when compared with casein, decreased plasma triglyceride (TG) concentration and increased hepatic total lipid concentration, free cholesterol, and TG concentrations and CYP7A1 mRNA levels. Yet, these effects were not observed in rats fed A-SDBR/DF. These results suggest that the hypocholesterolemic effect of SDBR, P-SDBR, and A-SDBR is mediated by an increase in bile acid excretion through a combination of promoted secretion of bile acids by bonito oil and binding of bile acids to resistant proteins. The hypotriglyceridemic effect may be mediated by reduced hepatic TG synthesis and secretion due to the intake of bonito oil.

Modulation of the activity and content of cytochrome P-450 (CYP) in hepatic microsomes may be important to human health since these enzymes activate and inactivate a wide range of xenobiotics and food components. Regulation of the inducibility of most CYPs involves transcriptional regulation and post-transcriptional mRNA stabilization. We examined in the present study the effect of dietary soy isoflavone (0-300 mg of isoflavone/kg of diet) on the mRNA abundance of rat hepatic CYP1A1, CYP1A2, CYP2B1/2, CYP2C11, CYP2E1, CYP3A1, CYP3A2 and CYP4A1 by quantitative competitive RT-PCR and real-time monitored RT-PCR. A fermented soy extract containing 155 mg/g of genistein, 127 mg/g of daidzein, and other minor isoflavones was used as the isoflavone source. The dietary soy isoflavone had no affect on the hepatic mRNA abundance of these CYPs. The results by both methods were well matched and indicate that the dietary soy isoflavone did not cause the induction of CYPs by transcriptional step-up regulation or post-transcriptional mRNA stabilization.

We studied the effect of the particle size of corn brain (CB) on the plasma cholesterol concentration, fecal output, and cecal fermentation. Rats were fed a fiber-free diet (FF) or FF containing CB (50 g/kg diet) of six different particle sizes (500, 350, 250, 177, 149, 105 μm in diameter) for 21 days. The fecal wet weight and wet weight of cecal content were significantly higher in the rats fed CB than in those fed FF. Liver total lipids, fecal moisture, fecal bile acids excretion and moisture of cecal content were significantly lower in the rats fed CB than in those fed FF. As the particle size decreased, the plasma cholesterol concentration, fecal wet weight, and fecal bulking effect decreased, while the liver cholesterol concentration, cecal wall weight, wet weight of cecal content, and total organic acids, acetic acid and n-butyric acid in the cecal content increased.

The effect of sugar beet fiber (SBF) in reducing the ovariectomy-induced elevation in plasma cholesterol concentration was studied in 6-week-old, female ovariectomized (ovx) rats. Rats were subject to ovariectomy or sham operation, and fed a fiber-free diet (FF diet) or FF diet containing SBF (100 g/kg diet, SBF diet) for 42 days. The food intake, intake of nutrient fraction, body weight gain and liver weight were significantly higher in the ovx-rats than in the sham-operated rats. Among the ovx-rats, the plasma total and non-HDL cholesterol concentrations were significantly lower (by 29% and 47%, respectively) in those fed the SBF diet than in those fed the FF diet. The following parameters among the ovx-rats were significantly higher in those fed the SBF diet than in those fed the FF diet: cholesterol 7α-hydroxylase activity, fecal excretion of bile acids, and cecal pool of propionic acid.

The effect of taurine and glycine on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration were studied in ovariectomized (ovx) 10-month-old retired breeder female rats. Rats was randomly assigned to four treatment groups: sham-operated+a casein-based cholesterol-free diet (C-diet, sham-C); ovx+C diet (ovx-C); ovx+C diet supplemented by taurine (50 g/kg diet, ovx-T); and ovx+C diet supplemented with glycine (50 g/kg diet, ovx-G). Rats were fed these diets for 28 d and killed at midnight in a fed state. Plasma and liver cholesterol concentrations in ovx-C were significantly higher than in sham-C. Bile flow, biliary bile acid secretion and fecal bile acid excretion were not significantly different between sham-C and ovx-C. Plasma cholesterol concentrations in ovx-T and ovx-G were significantly lower than those in ovx-C. Liver cholesterol concentration in ovx-G was significantly higher than in ovx-C but not in ovx-T. Cholesterol 7a-hydroxylase, bile flow, biliary bile acid secretion and fecal bile acid excretion in ovx-T were significantly higher than in ovx-C, but not in ovx-G. These results indicate that in the case of taurine but not glycine, increased fecal bile acid excretion is one of the factors in the prevention of the ovarian hormone deficiency-associated increase in plasma cholesterol concentration.

Estradiol is metabolized through two mutually exclusive pathways. 2-Hydroxyestrone (2-OHE,) is antiestrogenic, while 16alpha-hydroxyestrone (16alpha-OHE1) is a potent estrogen. It is suggested that a high urinary 16alpha-OHE1-to-2-OHE1 rato is a biomarker of increased mammary tumor risk. Mice were fed one of the test diets for 21 days. Indole-3-carbinol (2,500 mg/kg diet) increased the cytochrome P-450 content of hepatic microsomes and liver weight and reduced the urinary 16alpha-OHE1-to-2-OHE1 ratio in comparison with the respective value in the control mice. Fermented soy extract (100, 200, or 400 mg isoflavonoid/kg diet), genistein (200 mg/kg diet), and daidzein (200 mg/kg diet) each reduced the urinary 16alpha-OHE1-to-2-OHE1 ratio without increasing the cytochrome P-450 content of hepatic microsomes or liver weight. The combination of genistein and daidzein (100 mg and 100 mg/kg diet) did not have a synergistic effect on the reduction in urinary 16alpha-OHE1-to-2-OHE1 ratio. These data suggest that the soy isoflavonoid aglycones genistein and daidzein and indole-3-carbinol each exert a cancer-preventive effect by shifting metabolism away from the production of genotoxic metabolites toward the production of inactive metabolites.

Mice (4-week-old, male ddy) were fed four isonitrogenic diets for 21 days: purified diet (C diet); fermented soybean (400 mg of soy isoflavonoids/kg; FSB); fermented soybean extract (400 mg of soy isoflavonoid aglycones/kg; FSBE); C with indole-3 carbinol (I3C) (2500 mg of I3C/kg; I3C). The I3C and FSB diets significantly increased the cytochrome P-450 content of hepatic microsomes in comparison with the C diet, while the FSBE diet did not. Other mice were fed seven diets for 21 days: C; C with 100 mg or 200 mg of genistein, 100 mg or 200 mg of daidzein, or 100 mg of genistein + 100 mg of daidzein/kg; I3C diet. Genistein and daidzein did not change the liver cytochrome P-450 content. There was no synergistic effect of the combined feeding of genistein and daidzein. The increase in the cytochrome P-450 content with the FSB diet depends on chemicals other than genistein and daidzein. Genistein and daidzein do not induce cytochrome P-450.

The effect of taurine on plasma cholesterol and liver lipid levels, and on the level of fecal bile acid excretion, was examined in ovariectomized (ovx) 10-month-old retired breeder female rats. In the first experiment, ovx-rats were fed a casein-based cholesterol-free diet (C diet) or a C diet supplemented with different amounts of taurine (5 g, 10 g, 30 g and 50 g taurine/kg diet, respectively) for 21 days, and sacrificed at midnight in a fed state. Taurine reduced the ovx-induced increase in plasma total cholesterol level in a dose-dependent manner. Taurine increased the liver cholesterol level and level of fecal bile acids excretion in a dose-dependent manner. In the second experiment, ovx-rats were fed a C diet or a C diet supplemented with 50 g taurine/kg diet (C+50T diet) for 28 days, and killed at midnight in a fed state. The plasma total cholesterol, HDL-cholesterol, and LDL+VLDL-cholesterol levels of ovx-rats fed the C+50T diet were lower than the respective level of ovx-rats fed the C diet. There was a higher level of bile acids in the cecum of ovx-rats fed the C+50T diet than in the cecum of ovx-rats fed the C diet. In the third experiment, ovx-rats were fed the C diet for 8 days, then switched to the C+50T diet for the following 10 days, and then switched back to the C diet for 10 d. Blood samples were collected from the tail vein every two days between day 8 and day 28 at midnight in a fed state. The switch from the C diet to the C+50T diet resulted in a decrease in plasma cholesterol and an increase in fecal bile acid excretion. In contrast, switching from the C+50T diet to the C diet resulted in an increase in plasma total cholesterol and a decrease in fecal bile acid excretion. These data indicate that taurine can effectively prevent the ovarian hormone deficiency-associated increase in plasma cholesterol, and that an increased level of fecal bile acid excretion is one of factors involved in the hypocholesterolemic effect of taurine.

The effect of dietary fibers on the digestive tract mass, diamine oxidase (DAO) activities in the small intestine and plasma and pool of ammonia and organic acids such as acetic, propionic, butyric, lactic and succinic acid in the cecum in rats fed a liquid formula diet was compared. Rats were fed an elemental liquid diet (ED) or ED containing 3g/100 ml of dietary fiber either a mixture of crystal cellulose and carboxymethyl cellulose sodium salt (CC), sugar-beet pectin (BP) or hydrolyzed xyloglucan (HXG) for 14 days. The mass of colon plus rectum was higher in rats fed CC, but not in rats fed BP and HXG than in rats fed ED. Cecal tissue mass was higher in rats fed BP and HXG, but not in rats fed CC, than in rats fed ED. Cecal contents and cecal pH were higher and lower in rats fed CC, BP and HXG than in rats fed ED. DAO activities in the small intestine and plasma were higher in CC than in rats fed ED. Cecal ammonia were lower in rats fed CC, BP and HXG than in rats fed ED. Production of organic acids was similar between rats fed ED and CC except for acetic acid that was much lower in rats fed CC. Diarrhea and loose feces were also improved in rats fed CC. The results suggest that the addition of a combination of water -soluble and -insoluble dietary fiber to a liquid formula diet would have more beneficial effects on the bowel function than water-soluble dietary fiber alone.

The effect of a peptide prepared from corn gluten meal (CP) by proteolysis with alkaline protease on 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumor progression were investigated in female Sprague-Dawley rats. At 6 weeks of age, rats were allowed free access to one of the four diets, 20% casein (CAS), 15% casein + 5% CP (5-CP), 10% casein + 10% CP (10-CP) or 10% casein + 10% free amino acid mixture simulated CP (AA) for 10 weeks. Rats were given 5 mg DMBA in 0.5 ml corn oil by stomach tube at two times (day 7 and 21). Tumor incidence was significantly lower in the 10-CP group, but not in the 5-CP and AA groups, than the CAS group. Total number and total weight of tumors were greater in the CAS group compared with 5-CP, 10-CP or AA groups. No changes were observed in serum 17β-estradiol concentrations among the three groups (CAS, 10-CP and AA). © 1997 Elsevier Science Inc.

It was examined whether the physiological effects of high-amylose maize starch (HAMS) are influenced by hydroxypropylation. Rats were fed one of the following three diets: an AIN-93-based diet with waxy maize starch (WMS) as a starch source, or this diet with 150 g of WMS replaced by either HAMS or hydroxypropylated HAMS (HP-HAMS). The activities of amylase in bile-pancreatic juice and sucrose, maltase and isomaltase of the jejunum and ileum were not affected by diet, but the digestibility of HAMS was decreased by hydroxypropylation. The amounts of SCFA in caecal content and H2excreted in the breath and flatus for HAMS were decreased by hydroxypropylation. Plasma glucagon-like peptide-1 (GLP-1), glucose and insulin concentrations were not affected by diet. On the basis of PCR-denaturing gradient gel electrophoresis (DGGE) profiles, the similarity in caecal bacteria population of the HP-HAMS group and HAMS group was low, but that of the HP-HAMS and WMS groups was high. The amount of caecal IgA was not affected by hydroxypropylation, but those in the HAMS and HP-HAMS groups were greater than that in the WMS group. Plasma and liver concentrations of TAG and cholesterol for HAMS were not affected by hydroxypropylation. These results show that the small intestinal digestibility and fermentation-dependent parameters such as caecal SCFA and H2productions and caecal bacterial profile of HAMS were affected by hydroxypropylation, but parameters of glucose metabolism such as GLP-1 and insulin, those of lipid metabolism such as plasma TAG and cholesterol and the amount of caecal IgA were not.

The effect of lactic acid or sodium lactate on the glycemic response was studied in rats. The lightly anesthetized, overnight-fasted rats were administered a glucose solution (200 g/L) with or without lactic acid or sodium lactate by a stomach tube to provide 250 mg of glucose per 100 g body weight. The addition of lactic acid (300 mmol/L) to a glucose solution reduced the initial rise in plasma glucose and insulin concentrations, slowed the rate of gastric emptying and brought a drop of pH in gastric contents. However, such effects were not recognized in the addition of sodium lactate (300 mmol/L as the lactate ion). Lactic acid stimulated cholecystokinin (CCK) and secretin release, but inhibited gastrin release. The study suggests that lactic acid is effective in modulating postprandial plasma glucose concentration, which is due to delayed gastric emptying accompanied by the increase of secretin and CCK release following the fall in intraduodenal pH.

The bioavailability of ferrous and ferric iron following cecal infusion was compared by assessing the hemoglobin regeneration method in ileally fistulated anemic rats. Rats were fed an iron-deficient diet (8 mg Fe/kg diet) for 14 days after recovery from surgery. The anemic rats were then divided into three groups of 11 rats. Group 1 (control) was fed an iron-adequate diet (45 mg Fe/kg diet) and infused with NaCl solution (150 mM). Group 2 and 3 were fed an iron-deficient diet and infused with ferrous sulfate [Fe(II)] suspension or ferric sulfate [Fe(III)] solution (800 ppm as Fe, pH 6.8) to provide the same amount of iron as that consumed one day before by the control group. NaCl, Fe(II) and Fe(III) were infused through the fistula as two times (1000h and 1800h) for 14 days. The volume of NaCl infused was about equal to the volume of Fe(II) suspension and Fe(III) solution infused. Hemoglobin regeneration efficiency, hematocrit, plasma iron concentration, transferrin saturation, total iron-binding capacity, iron contents in organs (liver, spleen and kidney), body weight gain and food intake were almost the same among groups. These results suggest that inorganic iron is absorbed from the large intestine and is not influenced by forms of iron, ferrous iron or ferric iron.

The objective of this study was to determine glycemic and breath hydrogen responses in 10 healthy men in response to highly cross-linked starch phosphate (HXLS), made of tapioca starch (TS). Plasma glucose concentration was analyzed at baseline and at 30, 60, 90, 120, 150, and 180 min postprandially. In addition, breath hydrogen excretion was measured at baseline and at hourly intervals, over 10 h, after test substance challenge. When compared with unmodified TS easily digested, the area under the curve of plasma glucose of HXLS was 64% smaller, and was almost the same as that of microcrystalline cellulose. When compared with fructo-oligosaccharide rapidly fermented by the microbial bacteria, the area under the excretion curve of breath hydrogen gas of HXLS was 93% smaller, and was almost the same as that of water only. These results show that HXLS is harder to digest and ferment than unmodified TS in men.

The comparison of ferrous and ferric iron bioavailability following cecal infusion was studied in ileally fistulated rats. Rats were divided into four groups of 10 rats after recovery from surgery. Group 1 (control) was given an iron-adequate diet (45 mg Fe/kg diet) and infused with NaCl solution (150 mM). Group 2 was given an iron-deficient diet (8 mg Fe/kg diet) and infused with NaCl solution. Group 3 and 4 were given an iron-deficient diet and infused with ferrous sulfate [Fe(II)] suspension or ferric sulfate [Fe(III)] solution (800 ppm as Fe, pH 6.8) to provide the same amount of iron as that consumed one day before by the control group. NaCl, Fe(II) and Fe(III) were infused through the fistula at two times (1000h and 1800h) for 28 days. The volume of NaCl infused was about equal to the volume of Fe(II) and Fe(III) suspension or solution infused. Compared with the control group, body mass gain and food intake for Group 3 and 4 did not decrease. However, the hematological indices and total iron contents in the liver and spleen for Group 3 and 4 showed 20 to 30% and 30 to 40% lower, respectively, compared with those of the control group. There was no significant difference between Group 3 and 4 on iron bioavailability. These results suggest that the lower part of the digestive tract plays an important role in iron absorption.

We examined whether lipid metabolism in orchiectomised (ORX) rats was affected by fructose ingestion and the amount of ingested fructose. Sucrose was used as a fructose source. Sham-operated and ORX rats were fed one of the following three diets for 28 d: a maize starch-based diet without sucrose (SU0), a diet by which half or all of maize starch was replaced by sucrose (SU50 or SU100). Body-weight gain and food intake were increased by sucrose ingestion, but decreased by ORX. Plasma total cholesterol concentration was increased by ORX and dose-dependently by sucrose ingestion. Plasma TAG concentration was decreased by ORX, but was increased dose-dependently by sucrose ingestion. Plasma insulin concentration was decreased by ORX, but was not affected by sucrose ingestion. Liver TAG was increased by sucrose ingestion and ORX; however, liver cholesterol concentration was not affected by sucrose ingestion and ORX. The hepatic activity of cholesterol 7α-hydroxylase 1 was not affected by sucrose ingestion and ORX; however, faecal excretion of bile acids was decreased. The mRNA level of microsomal TAG transfer protein, which is the gene related to hepatic VLDL production, was increased by ORX and sucrose ingestion. The mRNA level of uncoupling protein-1 was decreased by ORX, but not by sucrose ingestion. Plasma insulin concentration tended to correlate with the level of sterol-regulatory element-binding protein-1c mRNA (r0·747,P = 0·088). These results show that lipid metabolism in ORX rats would be affected by the consumption of fructose-rich sweeteners such as sucrose and high-fructose syrup.

A comparison of the hypocholesterolemic effects of propionic acid (PA) and sodium propionate (N-PA), infused into the stomach or cecum, was made in rats fed a cholesterol-free, casein diet. Rats received infusions of a 0.5 ml portion of either PA (100 mM), N-PA (100 mM) or NaCl (150 mM) twice a day during the experimental period. PA moderated the increase of plasma cholesterol caused by the feeding of the casein diet, but N-PA did not.

The effect on plasma and liver lipids of intracecal infusion of propionic acid (PA) was studied in ileally fistulated rats fed a cholesterol-free, casein purified diet (casein diet) for 5 weeks. Rats received intracecal infusions of a 0.5 ml portion either PA (100 mM) or NaCl (150 mM) twice a day for 5 weeks or during days 10–17. PA moderated the increase in plasma cholesterol concentration (p-chol) caused by the feeding of the casein diet. Though p-chol immediately decreased after changing NaCl to PA, it gradually returned toward its starting concentration by changing to NaCl again. Total lipids and cholesterol in the liver were not affected by PA infusion. Fecal excretions of neutral sterols and bile acids were also not affected.

Fish protein is a source of animal protein that is consumed worldwide. Although it has been reported that the intake of Alaska pollack protein (APP) reduces serum triglyceride and body fat accumulation in rats, the mechanisms underlying these effects are poorly understood. In the present study, we fed 5-week-old male Sprague-Dawley rats a high-fat diet with APP or casein for 4 weeks. We reconfirmed that the intake of APP decreases serum triglycerides and inhibits visceral body fat accumulation in rats. We found that APP had a higher non-digestive protein content than casein, and the amount of protein in feces was higher in the APP group than in the casein group. However, the amount of total lipids in feces did not differ significantly between the groups. We also found that the gastrocnemius muscle, a fast-twitch muscle, tended to increase in weight, and that the epididymal fat weight correlated negatively with gastrocnemius muscle weight in the APP group. These results imply that the enhancement of basal energy expenditure by fast-twitch muscle hypertrophy, rather than the enhancement of lipid excretion via feces, partly causes APP-induced inhibition of lipid accumulation in rats.

化工デンプン (ヒドロキシプロピル化・リン酸架橋デンプン, 酸化デンプン) をパンクレアチンで加水分解処理することにより難消化性部分を調製し, ヒトの腸内常在細菌118株による資化性を検討した。化工デンプンの難消化性部分の有用腸内細菌による資化性はフラクトオリゴ糖よりも劣っていた。化工デンプンにおいてはヒドロキシプロピル化・リン酸架橋デンプンが酸化デンプンよりも資化されにくかった。ヒドロキシプロピル化・リン酸架橋デンプンの種類の間に資化性についての特徴的な差は認められなかった。酸化デンプンについても同様であった。以上のように加工デンプンの難消化性部分が腸内細菌の基質となることが本研究から明らかにされた。

The purpose of the present study was to investigate whether water-insoluble fish protein (IFP) from Alaska pollock (Theragra chalcogramma) prevents hypercholesterolaemia induced by ovarian hormone deficiency. Wistar female rats, aged 6 months, were subjected to sham-operation or ovariectomy, and fed a cholesterol-free diet containing casein or IPF as a protein source for 28 d. Body-weight gain and food intake increased in the ovariectomised rats as compared with the sham-operated rats. Plasma total cholesterol concentration was decreased and faecal bile acid excretion was increased by IFP in the ovariectomised rats, but not in the sham-operated rats. Plasma homocysteine concentration was decreased by IFP in the ovariectomised rats, but not in the sham-operated rats. Liver lipids and liver cholesterol concentrations were increased and cholesterol 7α-hydroxylase (CYP7A1) activity was decreased by ovariectomy, but not by diet. Bile acid content and the ratio of cholic acid groups to chenodeoxycholic acid groups in bile were increased by ovariectomy, but decreased by IFP. Bile acid content in the small intestine was increased by IFP in the ovariectomised rats, but not in the sham-operated rats. 3-Hydroxy-3-methylglutaryl-CoA reductase and microsomal TAG transfer protein mRNA levels were decreased by ovariectomy and IFP, whereas LDL-receptor mRNA level was decreased by ovariectomy but unaffected by diet. Thus, the preventive effect of IFP on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration seems to be mediated by accelerated faecal excretion of bile acids, coupled with an increase in the intestinal pool of bile acids.

The effect of particle size on the surface area, cation-exchange capacity (CEC) and zinc-binding capacity of refined corn hull (RCH) was studied. The surface area was determined by the EGME method, and the specific surface area did not change substantially with particle size. CEC also did not change with particle size, and about half of the cation exchangeable group was strongly acidic. Zinc binding by RCH could be described by the Lungmiur’s equation. While the zinc-binding capacity also did not change with particle size, it was highly pH-dependent, being greater at pH 6 than at pH 3.

The effect of amylose content on digestibility of starch in the small intestine and on the concentration of plasma lipid were studied in ileorectostomized rats and in ovariectomized rats, respectively. Seven kinds of starch with different amylose content (0, 27, 54, 62, 76, 79, 86 %) were used as test starch, which contained 0·4, 5·6, 37·1, 40·2, 45·6, 36·9 and 36·1 % resistant starch (RS), respectively. Rats were fed one of test diets containing 30 % test starch with different amylose content for 14 d in ileorectostomized and for 21 d in ovariectomized rats. Food intake was not significantly different among the groups. In ileorectostomized rats, the small intestinal starch digestibility decreased with increasing intakes of amylose and RS. In ovariectomized rats, body weight gain was lower on the higher amylose maize starch diets. The concentrations of plasma TAG and cholesterol decreased with increasing intake of RS. The concentrations of liver total lipids and TAG decreased with increasing intake of RS, but that of liver cholesterol did not. There was significant positive correlation between the level of sterol regulatory element-binding protein-1c mRNA and concentration of liver TAG. Total SCFA amount in the caecum increased logarithmically with increasing dry weight of caecal contents. The amount of bile acids in the small intestinal content and the excretions of bile acids and neutral steroids in faeces increased with increasing RS intake. These results show that starch rich in RS is more effective in preventing ovarian hormone deficiency-induced hyperlipidaemia.

We examined whether the effects of high-amylose cornstarch (HACS) on lipid metabolism in ovariectomized (OVX) rats were affected by high-fructose feeding. Sucrose (482 g/kg diet) was used as fructose source. OVX rats were fed one of the following four diets for 21 days: a sucrose-based or cornstarch-based cholesterol-free diet with or without HACS (150 g/kg diet). Body weight and food intake were increased by sucrose. Plasma total cholesterol and low-density lipoprotein cholesterol concentrations were increased by sucrose and decreased by HACS in cornstarch-fed rats, but not in sucrose-fed rats. Liver total lipids and concentrations of plasma and liver triacylglycerol (TAG) were increased by sucrose, whereas plasma TAG concentration was decreased by HACS, in sucrose-fed rats. However, liver cholesterol concentration was not affected by diet. The amount of cholesterol in small-intestinal contents was increased in sucrose-fed rats, but not in cornstarch-fed rats, but that of bile acids was not affected by diet. Fecal excretions of bile acids and neutral sterols were increased by HACS. The level of sterol-regulatory element-binding protein-1c mRNA was increased by sucrose and decreased by HACS in sucrose-fed rats, but not in cornstarch-fed rats. The level of farnesoid X receptor mRNA was decreased by sucrose and increased by HACS in cornstarch-fed rats, but not in sucrose-fed rats, as was the level of cholesterol 7alpha-hydroxylase mRNA. These results show that the effect of HACS on hyperlipidemia induced by ovarian hormone deficiency would be affected by the consumption of fructose-rich sweeteners such as sucrose and high-fructose syrup.

Objective: Estrogens downregulate eating behavior, and soy isoflavones are known to be estrogenic agents. We aimed to examine whether the estrogenic property of soy isoflavones can affect food intake and body weight. Methods and Procedures: Seven-week-old male, female, and ovariectomized (OVX) Sprague-Dawley rats were given free access to a diet containing 100–300 mg total isoflavone/kg diet, or to a control diet, either with or without concurrent administration of estradiol by subcutaneous implantation. Results: Dietary soy isoflavone was shown to lower food intake in female rats, whether or not the animals had undergone ovariectomy. Administration of estradiol lowered the food intake in male rats and in OVX female rats. The decrease in weekly food intake in female rats led to a reduction in their weekly gain in body weight. Dietary soy isoflavone significantly increased the concentration of serum isoflavones, especially equol (a metabolite of daidzein), regardless of gender or ovariectomy. Dietary soy isoflavone did not affect either serum estradiol concentration or uterine and didymus weights, but estradiol administration improved the uterine atrophy in OVX rats, and decreased the didymus weight in male rats. Discussion: Soy isoflavone lowers the food intake in female rats, but not in the male animals. Contrary to the hypothesis currently in vogue, the reduction in food intake caused by soy isoflavone may not be a purely estrogenic effect. This follows from the finding that the effects of soy isoflavones on food intake and on the reproductive organs differ from the corresponding effects produced by estrogen.

The purpose of this study was to examine which component in the microbial protease-resistant fraction of Katsuobushi (KBR), smoke-dried bonito, is hypocholesterolemic in ovariectomized rats (OVX-rats). KBR contains two major components: oil and protease-resistant protein. Oil extracted from KBR (EX) was rich in palmitic, oleic and docosahexaenoic acids. OVX-rats were fed one of the following diets for 28 d: diets containing casein as the protein source (C or C+EX diet), a diet containing KBR as the protein source (KBR diet) or diets containing degreased KBR as the protein source (DF/KBR or DF/KBR+EX diet). The C and DF/KBR diets contained soybean oil as the oil source. In the C+EX, KBR and DF/KBR+EX diets, soybean oil was replaced by oil extracted from KBR (EX). Plasma total- and low density lipoprotein-cholesterol concentrations in the C+EX, KBR and DF/KBR+EX groups, but not in the DF/KBR group, were significantly lower than that in the C group. Fecal bile acid excretion was significantly greater in the C+EX, KBR, DF/KBR and DF/KBR+EX groups in comparison to the C group, whereas excretion in the KBR and DF/KBR+EX groups was significantly greater than in the C+EX and DF/KBR groups. Cholesterol 7alpha-hydroxylase activity was higher in the C+EX, KBR, DF/KBR and DF/KBR+EX groups than the C group. In OVX-rats fed C, C+EX or KBR for 28 d, bile acid flux into the small intestine increased in KBR and C+EX groups in comparison to the C group. The hypocholesterolemic effect of KBR in OVX-rats reflected in increased fecal bile acid excretion may be mediated by increased bile acid flux caused by EX and the binding of bile acids by protease-resistant proteins.

Blood ethanol concentrations are decreased by the oral administration of ethanol with acetic acid. The slowing of gastric emptying is supposed to be one of the mechanisms for the blood ethanol-lowering effect. In the present study, to further clarify the contribution of gastric emptying to this effect, we investigated the blood ethanol concentration, and the amounts of ethanol remaining in the stomach and in the small intestine, after orally administering ethanol with acetic acid or various salts of acetic acid. This was done under two conditions in which the osmolarity or concentration of the acetate ion in each administered solution was equalized.The blood ethanol-lowering effect of acetic acid was weakened by replacing acetic acid with sodium, potassium, or calcium acetate. There was a good negative correlation between the blood ethanol concentration and the amount of ethanol remaining in the stomach one hour after administering the sample solutions. The amount of ethanol remaining in the small intesti...

The purpose of this study was to examine whether katsuobushi, smoked-dried bonito (KB), which is a traditional Japanese food, prevents ovarian hormone deficiency-induced hypercholesterolemia. In experiment 1, ovariectomized rats (OVX-rats) were fed a purified diet containing casein or KB. Compared with the casein diet, the KB diet reduced the plasma cholesterol concentration and apparent protein digestibility, and increased the fecal dry weight and fecal bile acid excretion. In experiment 2, OVX-rats were fed one of the following four diets: casein diet containing corn oil or fish oil (CA/CO or CA/FO), or a diet containing the digested or undigested fraction of KB after treatment with microbial protease (KBE or KBR). KBR contains mainly two components: oil and protease-undigested protein of KB origin. In comparison with the CA/CO diet, the KBE diet did not affect the plasma and liver lipids concentrations, apparent protein digestibility nor fecal bile acid excretion. However, the KBR and CA/FO diets reduced the plasma cholesterol and triacylglycerol (TAG) concentrations and the liver total lipid and TAG concentrations, but increased the liver total and esterified cholesterol concentrations. The KBR diet increased fecal bile acid excretion and fecal dry weight, whereas the CA/FO diet did not. Thus, the preventive effect of KB on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration appears to be mediated by an increase in bile acid excretion through a promoted secretion of bile acids by the binding of bile acids to resistant proteins.

Oxidative stress is a major cause of cardiovascular tissue fibrosis. We evaluated the effects of daily doses of soy isoflavones, genistein and daidzein on cardiovascular tissue fibrosis in Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rats and Long-Evans Tokushima Otsuka (LETO) non-diabetic rats as a severe or mild oxidative stress model, respectively. Glucose and lipid metabolisms did not improve with genistein or daidzein treatment. However, genistein decreased hydroxyproline concentrations in the heart. Hydroxyproline reductions as a result of genistein were mildly stronger than those of daidzein. Thus, genistein significantly suppressed the progression of myocardial fibrosis in LETO rats despite the insignificant changes in OLETF rats. Although a daily dosage of isoflavone was not sufficient to prevent tissue fibrosis under marked oxidative stress in the early stage of diabetes, isoflavones might promise significant clinical benefits by reducing oxidative stress in the heart during aging.

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.

We evaluated the body energy accumulation as fat and protein from ingestion of difructose anhydride III (DFAIII). Male Wistar rats were fed 0, 0.25, 0.5, 1.0, or 1.5 g per d of sucrose or DFAIII added to a 7 g of basal diet for 20 d. Supplements of DFAIII did not increase whole body or peripheral fat or total body energy, whereas sucrose increased them in a dose-dependent manner. Dose-dependent increases in body water were observed in both groups. The body protein was influenced by the dose of sugars. The estimated available energy value of DFAIII was 0.263 kcal per gram; this value is one-fifteenth that of sucrose. Ingestion of DFAIII dose-dependently increased the cecal SCFA pool. DFAIII was not detected in feces, showing complete degradation of DFAIII in the intestine. These results indicate that DFAIII is a fermentable saccharide with quite low available energy for fat accumulation.

Objective Non-alcoholic steatohepatitis (NASH) is one of the most important emerging health issues. Insulin resistance and metabolic syndrome play a central role in the pathogenesis of NASH. Intake of nutrients strongly affects insulin resistance, carbohydrate and lipid metabolism, and hepatic steatosis. However, there are few reports about the intake of various nutrients in non-alcoholic fatty liver disease. In this work, we identified the characteristics of dietary habits and nutrient intake in patients with NASH. Methods Twenty-eight patients with NASH and 18 with simple steatosis (FL) were diagnosed from histologic findings, and their dietary habits and intake of nutrients were analyzed by detailed questioning by physicians and dieticians. Results There was an excess intake of carbohydrates/energy in patients with NASH 20–59 y of age compared with patients with FL. Among carbohydrates, intake of simple carbohydrates was higher in those with NASH. There also was a low intake of protein/energy in patients with NASH 40–59 y of age and a low intake of zinc in those 20–59 y of age compared with patients with FL. Ratio of intake of polyunsaturated fatty acid to saturated fatty acid was lower in patients with NASH and those with FL compared with the general Japanese subjects. Conclusion These results suggest that imbalanced diets play important roles in development and progression of NASH and correction of these diets may be necessary in patients with NASH.

We studied whether the type of dietary fatty acid influences the preventive effect of taurine on the ovarian hormone deficiency-induced increase in plasma cholesterol concentration in 6-mo-old ovariectomized rats. Rats were fed one of the following four diets for 28 d: purified diets based on corn oil, which is rich in linoleic acid, with or with out taurine (50 g/kg) or purified diets based on coconut oil, which is rich in lauric and myristic acids, with or without taurine. Body mass gain, food intake, liver weight and plasma apolipoprotein (apo) A-I, apo B, LDL and VLDL concentrations were not affected by the diets. On the other hand, taurine lowered the plasma total cholesterol concentration (P < 0.02) in rats fed corn oil, but not in those fed coconut oil. In rats fed both types of oils, taurine increased the LDL receptor mRNA level (P < 0.01), hepatic cholesterol 7alpha-hydroxylase activity (P < 0.01) and fecal bile acid excretion (P < 0.01). Taurine increased the HMG-CoA reductase mRNA level (P < 0.02) in the liver of rats fed coconut oil, but not in those fed corn oil. Taurine increased liver total lipid (P < 0.05) and triglyceride (P < 0.05) concentrations in rats fed corn oil, but not in those fed coconut oil. These results indicate that the effect of taurine on ovarian hormone deficiency-induced changes in cholesterol metabolism is influenced by the type of dietary fatty acids.

We examined the effect of dietary taurine on the concentrations of serum cholesterol and apolipoprotein in lipoprotein fractions of Six-month-old ovariectomized, which were used as a model of hypercholesterolemia in postmenopausal woman, or sham operated rats. Taurine significantly reduced the serum total and low-density lipoprotein cholesterol concentrations only in the ovariectomized rats. In contrast, taurine significantly lowered the serum apolipoprotein B concentration and serum very low-density lipoprotein-apolipoprotein E concentration only in the sham operated rats. The serum total and high density lipoprotein-apolipoprotein E concentrations were significantly lower in the rats fed taurine than in those fed the control diet regardless of whether they had undergone ovariectomy. The esterified cholesterol level in the liver was significantly lower and the level of hepatic cholesterol 7α-hydroxylase activity was significantly higher in the rats fed taurine than in those fed the control diet. The total bile acids concentration in the feces and intestinal contents of rats fed taurine were significantly higher than those in rats fed the control diet regardless of whether they had undergone ovariectomy. In the sham-rats, taurine accelerated bile acid synthesis and excretion, thereby increasing cholesterol consumption. The increased cholesterol consumption might be compensated by accelerating cholesterol synthesis and/or reducing the synthesis and release of very low-density lipoprotein from the liver. But in the ovariectomized rats, although taurine also accelerated bile acid synthesis and excretion, cholesterol demand might be compensated by excess cholesterol in the blood.

Sham-operated and cecectomized rats were fed for 21 d a cholesterol-free purified diet containing (200 g/kg) either normal cornstarch (CS) or high amylose cornstarch (HACS). In both types of rats, those fed the HACS diet had a significantly lower plasma total cholesterol concentration and a significantly larger intestinal bile acid pool than those fed the CS diet. In cecectomized rats, those fed the HACS diet had significantly lower plasma HDL and LDL cholesterol concentrations, a significantly greater fecal bile acid excretion and a significantly lower hepatic 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase mRNA concentration than those fed the CS diet. The plasma triglyceride concentration and LDL-receptor mRNA concentration were not affected by the diet or cecectomy. In sham-operated rats, the propionate concentration in the cecal contents was significantly greater in those fed the HACS diet than in those fed the CS diet. Compared with sham-operated rats, cecectomized rats had significantly enhanced cholesterol 7alpha-hydroxylase activity. In intact rats, biliary bile acid flux into the small intestine was significantly greater in those fed the HACS diet than in those fed the CS diet. Thus, the hypocholesterolemic effect of HACS appears to be mediated by accelerated fecal excretion of bile acids and increases in the intestinal pool and biliary flux of bile acids, and not by cecal fermentation products.

To examine whether the physiologic effects of high amylose cornstarch (HACS) are affected by gelatinization or heat moisture treatment, male rats were fed for 21 d a fiber-free purified diet containing 40 g/100 g gelatinized normal cornstarch (G-CS), HACS, gelatinized high amylose cornstarch (G-HACS) or heat moisture-treated HACS (HMCS). Dietary fiber (DF) content in G-HACS was 87% lower than that in HACS. The apparent starch and protein digestibilities were higher in the G-HACS group than in the HACS group. Fecal wet weight and fecal bile acid excretion were lower in the G-HACS group than in the HACS group. The cecal tissue weight, cecal surface area, cecal content weight and cecal pH were lower in the G-HACS group than in the HACS group. The cecal n-butyric acid and succinic acid concentrations were higher and lower, respectively, in the G-HACS group than in the HACS group. The plasma cholesterol and triacylglycerol concentrations did not differ between the G-HACS group and the HACS group. On the other hand, the DF content in HMCS was 330% higher than that in HACS, but the HMCS and HACS groups generally did not differ except in cecal surface area. Dietary starch did not affect fecal moisture, fecal neutral sterol (cholesterol + coprostanol) excretion, liver cholesterol level, total short-chain fatty acid (SCFA) concentration or apparent Ca, Fe, Mg and Zn absorptions. These results show that the heat moisture treatment of HACS for the most part does not alter its physiologic effects despite the greater DF content.