Acute tryptophan depletion slows gastric emptying in females

Serotonin (5-HT) is an important neurotransmitter involved in the brain-gut axis. It is possible to lower the 5-HT level in the body by means of a nutritional intervention using an amino acid mixture; the acute tryptophan depletion (ATD) method. We studied the effect of ATD on gastric emptying in healthy females, who received both ATD and placebo in a random order. Gastric emptying was measured using the [(13)C]octanoic acid breath test. The present data demonstrate significant differences in both gastric emptying and lag phase (Tlag) between the ATD and placebo experiment. Eight out of ten subjects showed a delayed gastric emptying in the ATD experiment. Both the gastric half-emptying time (T1/2) and the Tlag were significantly higher in the ATD experiment. T1/2 in the ATD experiment was 137.2 (range 76.2-634.8) min; T1/2 for the placebo experiment was 98.5 (range 63.7-168.8) min (P=0.028). Tlag in the ATD experiment was 83.7 (range 45.1-356.2) min; Tlag for the placebo experiment was 56.9 (range 23.2-101.2) min (P=0.007). We conclude that lowering the 5-HT level in the body using the ATD method leads to a significantly delayed gastric emptying of a solid meal. Nutritional manipulation of the serotonergic system in healthy volunteers may lead to alterations in gastrointestinal motility.     

Preventing gastric sieving by blending a solid/water meal enhances satiation in healthy humans

Separation of solids and liquids within the stomach allows faster gastric emptying of liquids compared with solids, a phenomenon known as sieving. We tested the hypothesis that blending a solid and water meal would abolish sieving, preventing the early rapid decrease in gastric volume and thereby enhancing satiety. We carried out 2 separate studies. Study 1 was a 2-way, crossover, satiety study of 22 healthy volunteers who consumed roasted chicken and vegetables with a glass of water (1008 kJ) or the same blended to a soup. They completed satiety visual analogue scales at intervals for 3 h. Study 2 was a 2-way, crossover, mechanistic study of 18 volunteers who consumed the same meals and underwent an MRI to assess gastric emptying, gallbladder contraction, and small bowel water content (SBWC) at intervals for 3 h. In Study 1, the soup meal was associated with reduced hunger (P = 0.02). In Study 2, the volume of the gastric contents after the soup meal decreased more slowly than after the solid/liquid meal (P = 0.0003). The soup meal caused greater gallbladder contraction (P < 0.04). SBWC showed a biphasic response with an initial "gastric" phase during which SBWC was greater when the solid/liquid meal was consumed (P < 0.001) and a later "small bowel" phase when SBWC was greater when the soup meal was consumed (P < 0.01). Blending the solid/liquid meal to a soup delayed gastric emptying and increased the hormonal response to feeding, which may contribute to enhanced postprandial satiety.     

Effects of xylitol on gastric emptying and food intake

We studied the effects of xylitol, the pentose-sugar alcohol, on gastric emptying of the solid-food component of a complex meal. Gastric emptying was measured in human volunteers by utilizing a standardized radiolabeled scrambled-egg meal. After ingestion of 25 g xylitol, gastric emptying was markedly prolonged (T-1/2 58 +/- 5 min control vs 91 +/- 7 min after xylitol [p less than 0.01]). Since delayed gastric emptying may affect food intake, we evaluated the effects of xylitol on calorie intake. Food intake after oral preloading with water resulted in intake of 920 +/- 60 kcal vs 690 +/- 45 kcal after 25 g of xylitol. In contrast, a preload of glucose, fructose, or sucrose failed to suppress food intake. Although xylitol decreased food intake and also delayed gastric emptying, these effects may be unrelated. Our data suggest a role for xylitol as a potentially important agent in dietary control.     

Camel's milk and gastric emptying

BACKGROUND & AIM: Gastric emptying is determined by food consistency, pH, osmolality, lipid and calorie content as well as the presence of different nutrients in the duodenal lumen. Control of gastric emptying is essential for ensuring optimal digestion. The present study tested the hypothesis that due to its different precipitation properties, gastric emptying of camel's milk may be quicker than that of bovine's milk with the same caloric and fat content. METHODS: Gastric emptying was studied by a scintigraphic technique in a randomized, double blind fashion in 8 volunteers after drinking 450 mL of either cow's milk or camel's milk. RESULTS: No differences in gastric emptying rates were found between the two types of milk. The percentage of retention of the meal after 60 min was 74.6+/-13.2% for cow's milk and 79.8+/-10.8% for camel's milk. The 50% emptying time (T(1/2)) was 131.8+/-37.4 min for cow's milk and 136.8+/-55.8 min for camel's milk. CONCLUSIONS: Camel's milk is most probably not a useful substitute for other types of milk to shorten gastric emptying.     

Comparison of starch digestibility of a blended food prepared with and without extrusion cooking

OBJECTIVE: To compare starch digestibility from a maize-soy blended food with and without extrusion cooking. DESIGN: Resistant starch, soluble and insoluble dietary fibres were measured in vitro before and after extrusion. Starch digestibility was assessed in 8 volunteers who took, in a randomised order, a test meal with either 100 g extruded (EF) or non-extruded (NEF) blended flour cooked 15 min at 80 degrees C in 500 ml of water. SETTING: Research ward for healthy volunteers. SUBJECTS: Healthy volunteers. MAIN OUTCOME MEASURES: Starch digestibility was measured by 13C enrichment of breath samples for 8 h. Breath H2 concentration was measured during 12 h to assess bacterial fermentation in the colon. Volunteers reported hunger on a visual scale every hour for 8 h. RESULTS: In vitro resistant starch, soluble and insoluble dietary fibers were higher in NEF than in EF (5.4 vs 1.1, 0.7 vs 0.5, and 13.3 vs 10.4% dw respectively). In vivo, the area under curve (AUC) for 13CO2 excretion during 8 h was not significantly different for NEF and EF (10.3+/-1.3 vs 9.1+/-0.5 mmol/min, respectively). AUC for H2 excretion during 12 h was significantly higher for EF than for NEF (26.9+/-5.6 vs 14.1+/-4.7 mL, P<0.05). AUC for satiety was marginally higher with EF (12.6+/-1.6) than for NEF (10.0+/-2.1) (P=0.06). CONCLUSIONS: Extrusion cooking does not seem to substantially improve blended foods digestibility. Extrusion of high fibre flours may promote carbohydrate fermentation in the colon and increase satiety.     

Slowed gastric evacuation accounts for the reduction of food intake by anorectic drugs

The effect of mazindol given orally on gastric emptying of a radiolabelled solid meal was examined in 10 obese females. The patients underwent the measurement of gastric emptying twice: 2 mg mazindol was compared with placebo according to a double-blind study protocol. Mazindol significantly delayed gastric emptying (P less than 0.02 for both the gastric half emptying time, t1/2, and emptying index, Ix). The inhibition of the late phase of gastric emptying by mazindol was reflected by a significant (P less than 0.05) decrease of the shape parameter S of the power-exponential fitted gastric emptying curves, as well as by the comparison of the amount of food retained within the stomach (P less than 0.05 at 80 min and P less than 0.02 at 90 min). Potential mechanisms and the meaning of the findings are discussed.     

A simple isotope method for studying of gastric emptying of solid foods

A simple isotope method is explained by the authors for noninvasive functional evaluation of the gastric emptying of solid meal. According to the results of in vitro measurements suitable solid phase labelling was provided by boiling the egg traced with injected Tc-99m-pertechnetate. The evaluation of gastric emptying by means of test meal containing the radiolabelled boiled egg is simple, inexpensive and the radiation hazard is minimal. In cases of intact stomach the gastric emptying of solids (T2 = 115.1 +/- 12.4 min) were significantly slower, than in cases of Billroth I (T2 : 66.7 +/- 6.9 min, p less than 0.01) and Billroth II (T2 = 28.8 +/- 3.3 min, p less than 0.001) resections. Similarly, there was a significant difference (p less than 0.001) between the mean half time values of the two operated groups.     

The effect of ethanol and alcoholic beverages on gastric emptying of solid meals in humans

AIMS: The systematic study of the effect of pure ethanol, alcoholic beverages, and their non-alcoholic components on gastric emptying of solid meals in humans. METHODS: 16 fasting healthy male subjects received once weekly 300 ml of the following solutions in random order: 4 and 10% (v/v) ethanol, beer, red wine, 5.5 and 11.4% (w/v) glucose, and water. The test solutions were given either together with a low caloric (270 kcal, n = 8) or a high caloric (740 kcal, n = 8) solid meal. Ultrasonography of the antrum was used to determine gastric emptying. RESULTS: Gastric half emptying time (t(1/2) ) of the high caloric solid meal with water was 131.3 +/- 7 min. The ingestion of 4 and 10% (v/v) ethanol (158.8 +/- 9.3 and 165.6 +/- 6.2 min, respectively), beer (163.1 +/- 11 min), and red wine (186.3 +/- 8.4 min) resulted in a significantly longer t(1/2) than water. The lag phases after 4 and 10% (v/v) ethanol, beer, and red wine were not significantly different from that of water (48.1 +/- 6.5 min). Compared with water, the ingestion of 5.5 and 11.4% (w/v) glucose resulted in a significantly longer t(1/2) (153.8 +/- 5 and 168.1 +/- 14.4 min, respectively) by increasing the duration of the lag phase. The high caloric meals resulted in a 2-fold prolongation of t(1/2) when compared with the low caloric meals. The effect of the solutions on the gastric emptying times, however, was similar for both test meals. CONCLUSIONS: (i) Ethanol in low concentrations of 4 and 10% (v/v) prolongs gastric emptying of solid meals; this inhibitory effect is not dose-dependent. (ii) Alcoholic beverages (beer and red wine) also result in a prolongation of gastric emptying. The inhibitory effect of red wine, but not of beer, is more pronounced than that of the corresponding ethanol concentration and amount. (iii) The inhibitory effect of ethanol and alcoholic beverages is mainly induced by a prolongation of the gastric emptying phase (without affecting the lag phase), whereas 5.5 and 11.4% (w/v) glucose prolong the lag phase in a dose-dependent manner. (iv) The inhibitory effect of ethanol, beer, and red wine on gastric emptying does not depend on the caloric content of the meal.     

Effect of dexfenfluramine on gastric emptying of a mixed solid-liquid meal in obese subjects

Recent studies suggest that dexfenfluramine (D-fenfluramine), because of its pure serotonergic effect, may be a more potent anti-obesity agent, associated with fewer side-effects than the racemate DL-fenfluramine. The effect of dexfenfluramine on gastric emptying of a mixed solid and liquid meal was assessed with a double-isotope scintigraphic technique in eleven obese patients. Each subject took a placebo capsule on the morning and evening of the day before, and on the morning of the first gastric emptying measurement. Dexfenfluramine was then taken at a dose of 15 mg twice daily and gastric emptying measurements were performed at 5 and at 29 d after the initiation of active treatment. Dexfenfluramine significantly slowed gastric emptying of the solid meal at both 5 and 29 d when compared with the placebo (P less than 0.05) and also delayed emptying of solid food from the proximal stomach (P less than 0.01), but no significant effect on liquid emptying was observed. No significant side-effects were reported and there was a marginal weight loss (P less than 0.005) during treatment. We conclude that inhibition of gastric emptying may contribute to the efficacy of dexfenfluramine in the treatment of obesity.     

Physical state of meal affects gastric emptying, cholecystokinin release and satiety

To verify the influence of food consistency on satiety mechanisms we evaluated the effects of the same meal in solid-liquid (SM) and homogenized (HM) form on satiety sensation, gastric emptying rate and plasma cholecystokinin (CCK) concentration. Eight healthy men, aged 21-28 (mean 24.5) years were given two meals (cooked vegetables 250 g, cheese 35 g, croutons 50 g and olive oil 25 g, total energy 2573 kJ, with water 300 ml) differing only in physical state: SM and HM. The subjects consumed the meals in randomized order on non-consecutive days. The sensations of fullness, satiety and desire to eat were evaluated by means of a questionnaire, gastric emptying was assessed by ultrasonographic measurement of antral area, and plasma CCK concentration was measured by radioimmunoassay. The vegetable-rich meal was significantly more satiating (P < 0.05) when in the HM form than when eaten in a SM state. Furthermore, the overall gastric emptying time was significantly slowed (255 (SEM 11) min after HM v. 214 (SEM 12) min after SM; P < 0.05) and CCK peak occurred later (94 (SEM 12) min after HM v. 62 (SEM 11) min after SM; NS) when the food was consumed in the HM form. Independently of the type of meal, antral area was significantly related to fullness sensations (r2 0.46, P = 0.004). These results demonstrate that meal consistency is an important physical food characteristic which influences both gastric emptying rate and satiety sensation. Moreover, the relationship observed between antral area and fullness sensation confirms that antral distension plays a part in the regulation of eating behaviour.     

Reproducibility and reliability of the 13C-acetate breath test to measure gastric emptying of liquid meal in infants

OBJECTIVE: This study assessed the noninvasive 13C-acetate breath test (13C-ABT) as a reliable and reproducible method to evaluate gastric emptying in infants METHODS: Gastric emptying was measured simultaneously by scintigraphy and 13C-ABT in 11 infants with clinical symptoms of gastroesophageal reflux to validate the method compared with the gold standard. Gastric emptying was also measured with 13C-ABT in a separate group of 14 healthy infants on 2 consecutive days to evaluate reproducibility of the method. Half-emptying times obtained with scintigraphy and 13C-ABT were correlated with Pearson's analysis. The variability of the half-emptying times obtained on 2 consecutive days was analyzed with paired t test and by the coefficient of variation as proposed by Bland and Altman. RESULTS: The mean emptying times obtained with scintigraphy and 13C-ABT were not different (89 +/- 27 min and 70 +/- 39 min, respectively, P = 0.22). Both methods correlated significantly (r = 0.75, P < 0.05). Half-emptying times measured on 2 consecutive days with 13C-ABT were 69 +/- 31 min and 68 +/- 30 min, respectively (mean difference = 1.4 +/- 12.4 min, P = 0.67). Intraindividual coefficient of variation was 6.3%. CONCLUSIONS: This study supports the 13C-ABT method as a useful tool to evaluate gastric emptying of liquids in healthy infants and in infants with gastroesophageal reflux in the field of research and in clinical evaluations.     

Investigation into the role of cephalic stimulation of acid secretion on gastric emptying and appetite following a soup meal using the gastric acid inhibitor omeprazole

We previously showed that oral administration of a liquid soup preload was associated with a slower rate of gastric emptying and suppressed appetite more compared with intragastric administration of the same soup [Appetite 31(1998)377]. The present study was designed to investigate whether these results could be explained by the cephalic stimulation of acid secretion induced by oral administration. Eight healthy male subjects took part in a double-blind placebo controlled study comparing the effects of omeprazole and placebo on gastric emptying, appetite ratings and subsequent food intake following the ingestion of a liquid soup. Subjects were administered with a single oral dose of 80 mg omeprazole or placebo 3 h prior to ingesting the radiolabelled soup preload (400 kcal; 425 ml) over 15 min. Ratings of hunger, desire to eat and fullness were recorded over 135 min and gastric emptying was measured by scintigraphy. Food intake was evaluated from a test meal (yoghurt drink) given 120 min after the end of the soup ingestion. Analysis of data showed that there was no significant difference between omeprazole and placebo in gastric emptying, appetite or subsequent energy intake from the test meal. The results suggest that gastric acid secretion is not responsible for the differences in gastric emptying and appetite observed between intragastrically infused and orally administered soup preloads.     

Gastric acid secretion, gastrin release, and gastric emptying in humans as affected by liquid meal temperature

We investigated the effect of the temperature of a liquid meal on intragastric temperature, gastric acid secretion, gastrin release, and gastric emptying in normal human subjects. Coffee (360 mL) was infused into the stomach through a nasogastric tube at 58 (steaming hot), 37, or 4 degrees C (ice cold). Intragastric temperature, measured by an intragastric temperature sensor attached to the nasogastric tube, returned to body temperature 16.7 +/- 2.7 min after the hot meal and 23.8 +/- 1.1 min after the cold meal. Gastric acid secretion increased after hot, warm, and cold coffee but the initial temperature of the meal had no effect on gastric acid secretion. The temperature of the meal also had no effect on serum gastrin concentrations, which increased significantly after all the meals. Gastric emptying of hot, warm, or cold coffee meals was similar. These findings indicate that over a wide temperature range, the temperature of a liquid meal has little effect on gastric function in humans.     

Characterisation with stable isotopes of the presence of a lag phase in the gastric emptying of liquids

Summary Background Gastric emptying of non-nutrient liquids usually lacks the presence of an initial delay phase (lag phase), and so it has been considered to be monoexponential with an initial rapid phase followed by a slower emptying phase. However a lag phase in the gastric emptying of liquids can be found if there is a high caloric density in the liquid meal. Aims of the study To characterise with stable isotopes the presence of a lag phase in the gastric emptying of non-sold meals. Methods Healthy volunteers ingested a low caloric liquid meal (345 KJ/200 mL) (LCLM), a high caloric liquid meal (1135 KJ/180 mL) (HCLM) or a semisolid meal (1403 KJ/500 mL) (SSM). Test meals were labelled with ¹³C-acetate. Breath samples were collected for ^13>CO₂ measurement and data were fitted to a power exponential function. Results Non-solid meals can have different behaviour related to the initial emptying. The presence of a lag phase in the gastric emptying of liquids was not masked by the processing of the tracer previous to its detection in breath. While the LCLM and SSM showed a rapid initial emptying phase (no lag phase), the HCLM has an initial slow emptying phase. The slower gastric emptying of the HCLM compared to the SSM was related to the presence of a lag phase in the gastric emptying of the HCLM. Conclusions The ¹³C-acetate breath test is very accurate to identify and study the lag phase if present of liquid meals.     

Pattern of gastric emptying in the pig: relation to feeding

The aims of the present study were to compare the gastric emptying of dry matter (DM) and liquids during the feeding period with that following meal consumption, to clarify the relationship between feeding and gastric emptying, and to investigate how gastric emptying changes in growing animals. The studies were performed in pigs fitted with a gastric cannula and fed on a normal finely ground solid diet mixed with water containing CrEDTA as liquid marker. Gastric emptying was measured using a gastric evacuation technique. It was observed that between 0.75 and 6 h after feeding the total amounts emptied increased, but the proportion of the meal emptied fell, with increase in meal size; emptying of both DM and liquids with large and small meals followed an exponential pattern. In contrast, while the animals were feeding, there was linear and rapid emptying of both DM and liquids following a very short (approximately 2 min) lag phase before emptying began. The rate of emptying increased linearly with body-weight (by 0.055 g DM/min and by 0.24 ml/min per kg body-weight over the range 58-200 kg) such that the emptying of digestible energy per kg metabolic body-weight (W0.75) was roughly maintained (between 2.9 and 3.2 kJ/min per kg W0.75). This suggests that the rate of emptying may be linked in some way with the metabolic requirements of the body. The biphasic pattern of gastric emptying observed is probably the intrinsic pattern of emptying of a meal which does not require breakdown of particles before emptying can occur.     

Gastrointestinal and biliopancreatic response to continuous nasogastric feeding in man: effect of increasing nutrient infusion rate

Nasogastric feeding is a safe and inexpensive procedure used in various conditions to provide artificial nutritional support. However, the effects of increasing energy load of nutrients during continuous enteral nutrition on gastric physiology, biliopancreatic secretions and intestinal absorption of nutrients are unknown. A nutrient solution (1 kcal/ml, 15% proteins, 30% lipids, 55% carbohydrates) was randomly infused at three rates, 1.5, 3.0 and 4.5 ml/min, into the gastric antrum in 6 volunteers over a 6 h period. Gastric emptying, gastric and biliopancreatic secretion, and intestinal absorption were studied using a perfusion technique. Gastric emptying rate reached the infusion rate during continuous enteral nutrition at 1.5 and 3.0 ml/min although a steady state was not reached at 4.5 ml/min. During feeding at 1.5, 3.0 and 4.5 ml/min, the median gastric pH values were 1.9, 2.3 and 3.0 respectively and the total gastric volumes at the sixth hour were 78 +/- 13, 226 +/- 43 and 539 +/- 101 ml respectively. There was a significant increase in biliary and pancreatic secretion between 1.5 and 3.0 ml/min but not between 3.0 and 4.5 ml/min. Gastric emptying became the limiting factor in lipid and in carbohydrate absorption. Our study shows that, in healthy volunteers, the maximal infusion rate of a nutrient solution infused into the stomach should be approximately 3 ml/min to avoid complications such as nausea, vomiting, regurgitation and pulmonary inhalation.     

Development of gastric emptying in premature infants. Use of the (13)C-octanoic acid breath test

OBJECTIVE: The non-invasive (13)C-octanoic acid breath test ((13)C-OABT) has recently been used to monitor gastric emptying. We evaluated (13)C-OABT as a method for assessing gastric emptying in relation to the amount of milk ingested in preterm neonates during their first days of life. METHODS: The (13)C-OABT was performed in 16 stable preterm neonates born between weeks 31 and 37 of gestation (mean +/- standard deviation: 34.0 +/- 1.5 wk). Birth weight was 1400 to 2680 g (2076 +/- 350 g); four newborns were small for gestational age. The newborns underwent (13)C-OABT three times according to the amount of (13)C-primed breast milk being fed to them (<7 mL/kg, 7-13 mL/kg, and 10-19 mL/kg per dose). (13)C-primed breast milk (the test meal) was prepared by adding (13)C-octanoic acid to pasteurized breast milk to achieve a concentration of 1 microL of (13)C-octanoic acid/mL of milk. Exhaled air samples were taken through an original nasal mask. Amounts of (13)C and (12)C in the exhaled air samples were measured by mass spectrometry. Results were expressed as delta over baseline and related to the international standard of Pee Dee Belemnite Limestone. To assess the half-life of elimination (t(1/2)E), we modeled the process of elimination with the incomplete gamma-function, which has a convenient form for the empiric plotting of breath test data. We estimated the parameters of the function, f(x) = A x(b) e(-cx), by using the moment method. The curves were determined by the t(1/2)E of (13)CO(2) and characterized by the shape of the elimination curve. The half-time of gastric emptying (t(1/2)GE) was calculated as t(1/2)E reduced by the mean metabolic half-time of octanoic acid. RESULTS: Forty-eight (13)C-OABT results from 16 premature newborns were analyzed. The mean and median of t(1/2)GE calculated from all three tests were 50.3 (+/-29.9) and 43.7 min, respectively. The t(1/2)GE did not change significantly (P = 0.6811) with the administered dose of (13)C-primed breast milk in the stomach. The coefficient of variation among the studied infants was 4.0% to 33.6% (mean, 11.5%). In 12 infants, the characteristic type of elimination curve was the same for all three tests. CONCLUSIONS: In the first hours of gastric feeding, neither the age of the neonate nor the amount of administered (13)C-primed breast milk had any effect on t(1/2)GE. The gastric emptying rate and the evacuation curve shape for individual neonates were similar and independent of milk amount.     

Gastric emptying and intestinal absorption of a low-carbohydrate sport drink during exercise

The purpose of this study was to determine if lowering carbohydrate (CHO) concentration in a sport drink influences gastric emptying, intestinal absorption, or performance during cycle ergometry (85 min, 60% VO(2peak)). Five subjects (25 +/- 1 y, 61.5 +/- 2.1 mL . kg(-1) . min(-1) VO(2peak)) ingested a 3% CHO, 6% CHO, or a water placebo (WP) beverage during exercise. Gastric emptying was determined by repeated double sampling and intestinal absorption by segmental perfusion. Total solute absorption and plasma glucose was greater for 6% CHO; however, neither gastric emptying, intestinal water absorption, or 3-mi time trial performance (7:58 +/- 0:33 min, 8:13 +/- 0:25 min, and 8:25 +/- 0:29 min, respectively, for 6% CHO, 3% CHO, and WP) differed among solutions. These results indicate lowering the CHO concentration of a sport drink from 6% CHO does not enhance gastric emptying, intestinal water absorption, or time trial performance, but reduces CHO and total solute absorption.     

Guar gum does not impair the absorption and utilization of dietary nitrogen but affects early endogenous urea kinetics in humans

BACKGROUND: Viscous gums enhance viscosity in the upper gastrointestinal lumen, quickly disturbing motility and promoting fluid secretion. OBJECTIVE: We sought to determine whether guar gum could acutely affect the absorption and utilization of dietary nitrogen and whether these luminal effects could also perturb the kinetics of urea. DESIGN: We studied the short-term effect of adding 1% of highly viscous guar gum to a (15)N-labeled protein meal (30 g soy protein isolate in 500 mL water) during the postprandial phase in humans. The effects on bioavailability were studied by using the [(13)C]glycine breath test (to assess gastric emptying) and (15)N enrichment in plasma amino acids (for systemic amino acid bioavailability). The kinetics of dietary and endogenous urea were assessed in plasma and urine. RESULTS: Guar gum modulated the gastric emptying kinetics of the liquid phase of the meal slightly (P < 0.05), but had no significant effect on either the systemic appearance of dietary amino acids or plasma and urinary dietary urea kinetics. Without significantly affecting plasma urea concentrations, guar gum reduced by approximately 40% the urinary excretion of endogenous urea for the first 2-h period after the meal (P < 0.01), although endogenous urinary excretion was similar at later stages. CONCLUSIONS: Guar gum did not significantly affect the bioavailability or utilization of dietary protein. We showed an early effect of guar gum on endogenous urea kinetics, which most probably arose from very early, short-term stimulation of the intestinal disposal of endogenous urea, at the expense of its urinary excretion.     

Long-term effects of dietary fiber on glucose tolerance and gastric emptying in noninsulin-dependent diabetic patients

Effects of long-term (2 months) supplementation of diet with 20 g of guar gum and 10 g of wheat bran on metabolic control was studied in 12 obese, poorly controlled noninsulin-dependent diabetic patients. Addition of fiber reduced urinary excretion of glucose from 30.5 +/- 6 to 8.3 +/- 2 g/24 h, (p less than 0.025), fasting plasma glucose concentration from 301 +/- 24 to 184 +/- 15 mg/dl (p less than 0.025), and plasma cholesterol concentration from 277 +/- 24 to 193 +/- 9 mg/dl (p less than 0.025). No significant changes were observed in the patients weight and serum concentrations of triglycerides, high-density lipoproteins, free fatty acids, and insulin. Addition of fiber also delayed gastric emptying of liquids and solids. This effect became statistically significant 60 and 90 min after intake of a test meal for liquids and solids, respectively. We conclude that addition of guar and bran to the diet resulted in long-term improvement of metabolic control in these patients and that delayed gastric emptying may be one of the mechanisms responsible for this beneficial effect.