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The physiologic roles of dietary lecithin have not yet been clearly defined. We examined the effects of soybean lecithin on gastric emptying (Experiments 1 and 2) and food intake (Experiment 3) in rats. Male Wistar rats were fed 2 g of a 20 g lipid/100 g diet containing various levels of lecithin after 24 h of food deprivation; gastric contents were collected 3 h after feeding (Experiment 1). In Experiment 2, the effects of lecithin and a CCK-A receptor antagonist on gastric emptying were examined using a modified phenol red recovery technique. In Experiment 3, their effects on food intake were examined after an intraduodenal infusion of an oil emulsion containing 50 mg soybean oil (SO) or SO partially replaced by lecithin (14-50%). Gastric emptying rates of the lipid and protein in the test diet (Experiment 1) or of phenol red (Experiment 2) were lower in the groups administered lecithin. Food intake for 60 min was lower in rats infused with the oil emulsion containing lecithin (25, 50%) than in rats not administered lecithin. The suppressive effects of lecithin on gastric emptying and food intake were largely reduced by devazepide. These results demonstrate that oil containing lecithin inhibits gastric emptying and food intake, and the effects are associated in part with CCK release. KEY WORDS: * soybean phosphatidylcholine * gastric emptying * food intake * cholecystokinin * rats

We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber, on gastrectomy-induced iron malabsorption, anemia and impairment of exercise performance in rats in two separate experiments. The study was designed as a 2 x 2 factorial arrangement with operation (total gastrectomy) and diet (WSSF) under sedentary (Experiment 1) and exercised (Experiment 2) conditions. In Experiment 1, gastrectomy reduced net iron absorption, hemoglobin concentration, hematocrit and hemoglobin regeneration efficiency (P < 0.01). However, in rats fed a WSSF diet (50 g/kg diet), iron absorption and the hematological variables of the gastrectomized rats were comparable to those in the sham-operated rats, demonstrating that ingestion of WSSF promotes iron absorption and prevents anemia after gastrectomy. Feeding WSSF increased pools of organic acids and soluble iron in cecal contents and decreased the pH of the cecal contents (P < 0.001). Of the many cecal variables measured, net iron absorption in gastrectomized rats was most closely correlated (r = 0.614, P < 0.01) with the short-chain fatty acid pool in the cecum. Cecal fermentation of WSSF may contribute to improvements in gastrectomy-induced nutritional defects. In Experiment 2, we examined voluntary running exercise performance in totally gastrectomized rats fed diets with or without WSSF. Total gastrectomy severely impaired running performance (P < 0.001), and WSSF feeding largely restored the lowered performance. We conclude that feeding WSSF improves anemia and impaired voluntary running performance in totally gastrectomized rats. J. Nutr. 133: 1120-1126, 2003. KEY WORDS: * gastrectomy * iron absorption * anemia * dietary fiber * voluntary running exercise * rats

In three separate experiments, we examined the effects of feeding difructose anhydride III (DFAIII) on intestinal calcium (Ca) absorption using female Sprague-Dawley rats (6 wk old) with or without ovariectomy (OVX). In Experiment 1, we showed that Ca absorption was lower in OVX rats fed the 2.0 and 3.0 g Ca/kg diets, but not the 1.0 g Ca/kg diet, than in sham-operated rats during a 3-wk test period. In Experiment 2, we demonstrated that Ca absorption rate in sham and OVX rats fed a diet containing 3% DFAIII was higher than that in rats fed a DFAIII-free diet 4 wk after consuming the test diets. Absorptive activities of everted sacs of the colon, but not of the duodenum, in rats fed DFAIII diet for 4 wk were higher than those in rats fed the control diet. In Experiment 3, we determined which of the small and large intestines is responsible for the effects of DFAIII on Ca absorption using OVX rats with cecocolonectomy or transsection and reanastomosis (sham). Both the sham and cecocolonectomized rats were divided into four subgroups and fed a control, polyethylene glycol (PEG), 1.5% DFAIII or 3% DFAIII diet. We set up the PEG group as another control group to observe the effects of shortening transit time of the small intestine in the DFAIII groups. Promotive effects of DFAIII on Ca absorption were abolished by cecocolonectomy. However, in the cecocolonectomized rats, the Ca absorption rate was still higher in the 1.5 and 3% DFAIII groups than in the PEG group. In conclusion, ovarian hormone deficiency impaired Ca absorption, but the reduction of Ca absorption was restored by feeding DFAIII. KEY WORDS: * calcium absorption * difructose anhydride III * rats * ovariectomy

We previously showed that plasma cholesterol levels decreased following ingestion of a short-chain fatty acid (SCFA) mixture composed of sodium salts of acetic, propionic, and butyric acids simulating cecal fermentation products of sugar-beet fiber (SBF). In the present study, we investigated whether hepatic and small intestinal cholesterol synthesis is involved in the cholesterol-lowering effects of SCFA and SBF. In vitro (expt. 1) and in vivo (expt. 2) cholesterol synthesis rates and the diurnal pattern of SCFA concentrations in portal plasma (expt. 3) were studied in three separate experiments in rats fed diets containing the SCFA mixture, SBF (100 g/kg diet), or the fiber-free control diet. Cholesterol synthesis was measured using 3[H.sub.2]O as a tracer. The in vitro rate of cholesterol synthesis, measured using liver slices, was greater in the SBF group, but not in the SCFA group, than in the fiber-free control group. In contrast, the hepatic cholesterol synthesis rate in vivo was lower in the SCFA group, but not in the SBF group, than in the control group. The mucosal cholesterol synthesis rate for the whole small intestine was KEY WORDS: cholesterol synthesis; short-chain fatty acids; liver; small intestine; rats

Gastrectomy induces osteopenia. We examined the effects of feeding a diet containing soluble dietary fiber, guar gum hydrolysate (GGH, 50 g/kg diet), on intestinal calcium absorption and bone mineralization in totally gastrectomized (Roux-en-Y esophagojejunostomy) rats by comparing them with those in two control groups (laparotomized and bypassed rats). In the bypassed rats, chyme bypassed the duodenum and upper jejunum without gastrectomy. In a second separate experiment, we compared calcium absorption and bone mineralization in the gastrectomized rats fed diets containing soluble and insoluble calcium salts and in bypassed rats fed insoluble calcium. In Experiment 1, apparent absorption of calcium supplied as a water-insoluble salt was more than 50% lower in gastrectomized rats than in the intact (laparotomized) or bypassed rats 3 wk after the start of feeding the test diets (P < 0.05). Calcium absorption was higher (P < 0.05) in gastrectomized rats fed the GGH diet than in those rats fed the GGH-free diet. In Experiment 2, absorption of soluble calcium in the gastrectomized rats did not differ from the absorption of calcium from calcium carbonate by bypassed rats. The soluble calcium pool in the cecal contents was significantly lower in gastrectomized rats (Experiment 1) than in intact or bypassed control rats, and was higher (P < 0.05) in the GGH-fed gastrectomized rats than in those fed the GGH-free diet. However, calcium absorption correlated most closely (r = 0.787, P < 0.01) with cecal propionic acid concentration. The femur calcium content was significantly lower in gastrectomized rats fed insoluble calcium than in bypassed rats fed the same diet, but was partially restored in the rats fed soluble calcium (Experiment 2). Bone calcium was not increased by feeding GGH in gastrectomized rats (Experiment 1). We conclude that the severely diminished calcium absorption following total gastrectomy is totally due to a decrease in calcium solubilization, and feeding GGH partially restores calcium absorption. The decrease in bone calcium that occurs as a result of gastrectomy is mainly due to diminished intestinal calcium absorption. KEY WORDS: calcium absorption; dietary fiber; gastrectomy; osteopenia; rats

We demonstrated recently that [Gamma] -irradiation can induce aberrant crypt foci (ACF) in the rat colorectum. The aim of this study was to evaluate the effect of dietary sugar beet fiber (SBF) on the distribution of the CD8(+) intraepithelial lymphocyte (IEL) in the colorectum and on the number of [Gamma] -irradiation-induced ACF of rats administered anti-asialo GM1 ([Alpha] AGM1) as an immunosuppressant. Wistar/ST rats fed a fiber-free diet or the diet supplemented with SBF (100 g/kg diet) were administrated [Alpha] AGM1 or normal rabbit serum as a control during the initiation period with [Gamma] -irradiation. At 5 and 9 wk after the first irradiation, ACF and total aberrant crypts (AC) per area in the colorectum were counted. The numbers of ACF (P = 0.0010) and AC (P = 0.0635) per unit area were lower in the SBF-fed group than in the rats fed the fiber-free diet. [Alpha] AGM1 administration significantly raised the number of ACF (P = 0.0001) and AC (P = 0.0006) per area in the colorectum. Moreover, [Alpha] AGM1 administration during the initiation period reduced the number of CD8(+) IEL per 100 cells in the epithelial layer (P = 0.0001) of the colon. These results demonstrate that reduction of the number of CD8(+) IEL per 100 cells in the epithelial layer as a result of [Alpha] AGM1 administration promotes the formation of irradiation-induced ACF in the colorectum. The number of CD8(+) IEL per 100 cells in epithelial layer was lower in the group fed the fiber-free diet than in the SBF-fed group (P = 0.0522). These results indicated that the ingestion of dietary SBF suppressed [Alpha] -irradiation-induced ACF formation through the immune surveillance in the colorectal mucosa. J. Nutr. 130: 1682-1687, 2000. KEY WORDS: * aberrant crypt foci * anti-asialo GM1 * CD8(+) intraepithelial lymphocyte * rats * sugar beet fiber