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.     

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.     

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.     

A comparison of the gastric emptying characteristics of selected sports drinks.

The purpose of this study was to determine the effects of repeated ingestion of drinks containing varying concentrations of carbohydrate on gastric emptying rate during steady-state exercise. On five separate occasions, 14 subjects cycled for 90 min at an average power output of 151 +/- 2 W. At 15-min intervals, subjects ingested 227 +/- 3 ml of either water, 4% carbohydrate (CHO), 6% CHO, or 8% CHO. Gastric volume was determined prior to each drink and at 90 min using the modified double-sampling technique. Gross gastric volumes were significantly greater and mean gastric emptying rates and the percentage of ingested beverage emptied from the stomach were significantly less for 8% CHO. These data indicate that repeated ingestion of an 8% CHO beverage during exercise significantly reduces gastric emptying rate, whereas lower concentrations of carbohydrate do not. In addition, beverage osmolality is not as important as beverage energy content in influencing gastric emptying rate at these carbohydrate concentrations.     

Dietary restriction delays gastric emptying in rats

In rats allowed to eat for only 2 h per day, gastric emptying of three different meals [poached egg white, glucose (0.5 kcal/ml) and physiological saline, each labelled with 60 MBq of technetium-99m tin colloid visualized using a gamma camera] was markedly slowed 8 h after the last meal. Mean body weight in rats on the restricted feeding schedule was 80% of the weight of free-feeding controls. Gastric emptying curves for all three meals in controls were best described using loge transformed counts. Other models used were linear and square root. For each of the three meals, the percentage remaining in the stomach at 120 min was estimated using linear regression of gastric contents, transformed if necessary to yield the best curve against time. At 120 min, % gastric contents (mean +/- SEM) were 19.5 +/- 5.6 (egg), 15.5 +/- 6.27 (glucose) and 27.1 +/- 7.48 (saline) in control rats. After 4 months restriction, the corresponding figures were 75.2 +/- 4.04, 81.5 +/- 4.75 and 70.3 +/- 5.83. After 3 months of free feeding, emptying rates of the three meals were not significantly different from control values. We conclude that dietary restriction causes profound changes in gastric emptying by unknown mechanisms which may be operating in patients with anorexia nervosa.     

Gastric emptying in infants with or without gastro-oesophageal reflux according to the type of milk

The present study was designed to determine the effects of milk composition and the influence of gastro-oesophageal reflux (GOR) on gastric emptying. Cineoesogastrocintigraphy (COGS) was performed in 201 infants between 0-1 year of age in order to detect GOR, and provided a means of estimation of the gastric emptying (GE). Ninety infants appeared free from GOR and constituted the control group; 111 had GOR. There infants were fed human milk or various standard formulae. In addition, 20 infants fed a whey-hydrolysate formula were tested. An appropriate volume of milk was marked with sulfur-colloid Tc (200 microcuries). Measurements of gastric radioactivity were made 30 min and 120 min after ingestion. For the whole population, the infants with GOR had slightly more rapid GE after 30 min (P less than 0.05), but, for the same type of milk, there was no significant difference between GOR and controls. GE did not differ with age or sex, but differed mainly according to the type of milk. In the control group, gastric residual content (GRC) at 120 min was 18 +/- 11 per cent with human milk (n = 7), 16 +/- 21 per cent with whey-hydrolysate formula (n = 8), 25 +/- 17 per cent with acidified formula (n = 13), 26 +/- 19 per cent with whey-predominant formula (n = 22), 39 +/- 17 per cent with casein-predominant formulae (n = 20), 47 +/- 19 per cent with follow-up formulae (n = 16) and 55 +/- 19 per cent with cow's milk (n = 12).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

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.     

Dietary protein precipitation properties have effects on gastric emptying in healthy volunteers

BACKGROUND & AIMS: Strategies that reduce the size of particles in the stomach accelerate gastric emptying. Partial dephosphorylation of casein reduces the size of protein precipitates (curds) in acid conditions and facilitates peptic digestion. We hypothesized that changing the precipitation properties of casein by partial dephosphorylation would accelerate gastric emptying. METHODS: Eight healthy male volunteers entered a prospective, double blind, randomized study with crossover design. Gastric emptying of milk based formula containing either unmodified or dephosphorylated casein was assessed by scintigraphy. Gastric pH measurements were acquired concurrently. RESULTS: A trend to faster gastric emptying was observed for the unmodified preparation, with lower median half time (unmodified 133; dephosphorylated 214 min, P = 0.09) and area under the curve (unmodified 8425 min%; dephosphorylated 9135 min%, P = 0.08). A positive correlation was found between half time for the dephosphorylated preparation and the treatment effect (r2 = 0.81, P < 0.02). Gastric pH was unaffected. CONCLUSIONS: The study hypothesis was rejected; indeed gastric emptying tended to be faster for the unmodified than the dephosphorylated protein. This effect was more pronounced in subjects with slow gastric emptying on the dephosphorylated preparation. Properties other than the size of protein precipitates determine the rate of gastric emptying for milk based formula.     

Comparison of gastric emptying of a solid and a liquid nutritional rehabilitation food

OBJECTIVE: To compare gastric emptying of a solid and a liquid nutritional rehabilitation food. DESIGN: Cross-over trial. Eight volunteers took, in random order at least 1 week apart, 2100 kJ of a solid and a liquid nutritional rehabilitation food with added labelled [13C] glycine. SETTING: Research ward for healthy volunteers. SUBJECTS: Eight healthy volunteers. METHODS: Appearance of 13CO2 was monitored in expired gas every 15 min for 240 min after meal intake and compared between solid and liquid meals. Parameters of gastric emptying were then calculated. RESULTS: Gastric half-emptying time was slightly longer for solid meal compared to liquid meal (101+/-6.0 vs 88+/-9.8 min, P=0.24). 13CO2 excretion peaked 138+/-5.3 min after the solid meal compared with 119+/-8.6 min with liquid meal (P=0.06). 13CO2 excretion was higher for the liquid food up to 110 min after the meal but then became higher for the solid food. Analysis of variance for repeated measures of 13CO2 excretion showed a significant interaction term between the type of food and time indicating a delayed elimination of 13CO2 for the solid food (P=0.018). CONCLUSIONS: Attempts to replace liquid nutritional rehabilitation foods by a solid food in malnourished patients should take into account a possible slower gastric emptying. SPONSORSHIP: Supported by a grant from Nutriset (Malaunay, France) and ANVAR (Agence Nationale de la Valorisation de la Recherche, contract no. A9703021P).     

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.     

Effect of carob bean on gastric emptying time in Thai infants

Thickening agents, such as carob bean gum or galactomannan, have been successfully administered for the treatment of gastroesophageal reflux in infants. To study the effect of carob bean gum on gastric emptying and to symptoms of regurgitation, we recruited 20 full term Thai infants (mean age=13.4+/-7 week; mean body weight=4943+/-1272gm) without pathological gastroesophageal reflux. Initially, we determined half time gastric emptying (T 1/2 GET) by Tc99m radioscintigraphy method (mean T 1/2 GET=116.1+/-72 min) in infants consuming standard infant cow's milk formula for 2 weeks. Afterwards, carob bean infant formula was given for 2-4 weeks and weight gain, vomiting symptoms, night cough, colic, flatus, defaecation character and T 1/2 GET were assessed. There were statistically significant improvements in symptoms of vomiting (a smaller quantity P<0.001 and frequency of vomiting P<0.0001) and improvements in weight gain per week (W1=121.2+106.9gm, W2=221.3+136.1gm; P=0.005) when infants consumed the carob bean formula. However, there was no significance difference in gastric emptying half time (GET1=116.1+72, GET2=148.5+130.9; P=0.154). In conclusion, carob bean gum, as a thickening agent, improves the clinical symptoms of regurgitating infants, but does not significantly alter the gastric emptying physiology.     

Ghrelin does not influence gastric emptying in obese subjects

OBJECTIVE: To evaluate the relationship between fasting plasma concentrations of ghrelin and gastric emptying in obese individuals compared with lean subjects. RESEARCH METHODS AND PROCEDURES: We included 20 obese patients (9 men and 11 women, BMI > 30 kg/m2) and 16 nonobese control subjects (7 men and 9 women, BMI < or = 25 kg/m2). Gastric emptying of solids (egg sandwich labeled with radionuclide) was measured at 120 minutes with (99m)Tc-single photon emission computed tomography imaging. Ghrelin and leptin were analyzed by radioimmunoassay and ELISA methods, respectively. RESULTS: The gastric half-emptying time was similar in obese men and women (67.8 +/- 14.79 vs. 66.6 +/- 13.56 minutes) but significantly shorter (p < 0.001) than in the control population (men: 88.09 +/- 11.72 minutes; women: 97.25 +/- 10.31 minutes). Ghrelin levels were significantly lower in obese subjects (131.37 +/- 47.67 vs. 306.3 +/- 45.52 pg/mL; p < 0.0001 in men and 162.13 +/- 32.95 vs. 272.8 +/- 47.77 pg/mL; p < 0.0001 in women). A negative correlation between gastric emptying and fasting ghrelin levels was observed only in lean subjects (y = -0.2391x + 157.9; R2 = 0.95). Also, in the lean group, ghrelin was the only significant independent determinant of gastric emptying, explaining 98% of the variance (adjusted R2) in a multiple regression analysis. DISCUSSION: This report shows that, in humans, gastric emptying is faster in obese subjects than in lean controls and that, whereas ghrelin is the best determinant of gastric kinetics in healthy controls, this action is lost in obesity.     

Effect of cereal-thickened formula and upright positioning on regurgitation, gastric emptying, and weight gain in infants with regurgitation

OBJECTIVE: We compared the effect of cereal-thickened formula or postural therapy on regurgitation and gastroesophageal reflux, weight gain, and gastric emptying in infants. METHODS: We performed a prospective trial in exclusively formula-fed infants 2 to 6 mo of age presenting with regurgitation or vomiting at least three times a day. Infants were randomized into two groups; group A received cereal-thickened formula versus group B who were placed in a postprandial upright position for 90 min and evaluated over an 8-wk period. A 90-min technetium 99m milk scintigraphy was performed before and at the end of the intervention period. RESULTS: Thirty-one infants were included in group A and 32 in group B; at inclusion, there were no anthropometric differences between groups (P = 0.813-0.955). After 4 and 8 wk, the difference in regurgitation frequency per day between groups A and B had become significant (at 4 wk, 2.39 +/- 0.86 for group A versus 2.84 +/- 0.81 for group B, P = 0.039; at 8 wk, 1.61 +/- 0.76 for group A versus 2.38 +/- 0.83 for group B, P < 0.001). The volume ingested per meal was not different between groups after 4 wk, although this parameter showed a larger intake in group A after 8 wk (156.8 +/- 23.5 mL for group A versus 143.4 +/- 25.1 mL for group B, P = 0.035), resulting in a significant difference in mean caloric intake. Gastric emptying after 8 wk showed no significant difference between groups A and B. Group A infants had significantly greater weight gain than did group B infants after 4 wk (636.2 +/- 103.4 g for group A versus 577.4 +/- 102.7 g for group B, P = 0.03) and 8 wk (1261.3 +/- 131.4 g for group A versus 1121.4 +/- 137.2 g for group B, P < 0.001). After 8 wk of intervention, the increase in length was significantly greater in group A than in group B (5.2 +/- 0.6 cm for group A versus 4.7 +/- 0.6 cm for group B, P = 0.032). CONCLUSION: Cereal-thickened formula is significantly more efficacious than postural therapy in decreasing the frequency of regurgitation in regurgitating infants. Treatment of regurgitation with cereal-thickened formula results in an increased caloric intake ( approximately 25%), related to increased gain in weight and length, in comparison with regular formula and positioning therapy.     

Measurements of gastric emptying during continuous nasogastric infusion of liquid feed: electric impedance tomography versus gamma scintigraphy

BACKGROUND & AIMS: Continuous nasogastric infusion is commonly used to deliver enteral feed but current methods used to assess tolerance based on aspiration and measurement of gastric residual volume have been criticised. Electric impedance tomography (EIT) measures gastric emptying by monitoring changes in epigastric impedance when a meal progressively empties from the stomach. Aims: (1) to establish whether EIT was a valid method for measuring gastric emptying during continuous nasogastric infusion by comparing it with gamma scintigraphy (GS) and (2) to provide data on gastric emptying patterns during continuous nasogastric infusion. METHODS: Gastric emptying of 400 ml of enteral feed given over 200 min was measured simultaneously using EIT and GS in 10 healthy volunteers (five male and five female). RESULTS: Gastric emptying curves were obtained in 10 subjects by EIT but only eight by GS. Visual examination of the curves showed reasonable agreement. Patterns of emptying and filling during continuous nasogastric infusion were variable between individuals; the prevailing pattern was a trend towards a steady-state volume of approximately 50-125 ml. CONCLUSIONS: While EIT does not provide an accurate estimate of gastric volume during continuous infusion, it does show patterns of gastric emptying over time. With further development this could make it a useful tool for monitoring gastric emptying in patients at risk of gastroparesis.     

Gastric emptying of fluids during variable-intensity running in the heat

This study examined gastric emptying, core temperature, and sprint performance during prolonged intermittent shuttle running in 30 degrees C when ingesting a carbohydrate-electrolyte solution (CES) or flavored water (FW). Nine male soccer players performed 60 min of shuttle running, ingesting fluid before exercise and every 15 min during exercise. Gastric emptying was measured using a double-sampling aspiration technique, and intestinal temperature was monitored via ingested capsules. There were no differences between trials in the total fluid volume emptied from the stomach during each exercise period (P = 0.054). The volume emptied every 15 min was 244 +/- 67 mL in the CES trial and 273 +/- 66 mL in the FW trial. Intestinal temperature was higher during exercise in the CES trial (P = 0.004), and cumulative sprint time was shorter (P = 0.037). Sprint performance was enhanced by the ingestion of a CES, which resulted in elevated core temperatures, and the rate of gastric emptying remained similar between solutions.     

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.     

Effects of dietary proteins on absorption and gastrointestinal movement of p-aminobenzoic acid in conscious rats.

We monitored the absorption and movement of dietary soluble components along the gastrointestinal tract of rats by using p-aminobenzoic acid (PABA) as a marker after feeding 8 and 16% casein or soybean protein isolate (SPI) diets containing 1% PABA. The portal concentration of PABA, as an index of absorption, increased rapidly and reached the same high level 10 min after the feeding of all four diets, and the increased level of portal PABA was maintained for 30-80 min in each group. The increased levels of the SPI-fed groups continued longer than those of the casein-fed groups. In contrast, the gastric emptying rate slowed after 20 min in all the groups, and the gastric emptying of PABA for the initial 60 min in the 8% casein group was significantly faster than that in the 8% SPI group. The PABA content of the first small intestinal segment, which may be influenced by small intestinal transit, was higher in the casein group. These results indicate that the absorptive rate of PABA is determined not only by gastric emptying but also by small intestinal transit. The gastric emptying and the content of PABA in the first segment of the small intestine was not correlated in 8% protein groups. This suggests that the effect of SPI on gastrointestinal movement is different from that of casein.     

Calcium bioavailability of calcium carbonate fortified soymilk is equivalent to cow's milk in young women

Calcium (Ca)-fortified soymilk has gained popularity in the United States. Tricalcium phosphate (TCP)-fortified soymilk was shown to have a lower Ca bioavailability than cow's milk in men. However, the most popular soymilk in the U.S. is fortified with Ca carbonate (CC) and has not been evaluated. Ca bioavailability from CC-fortified soymilk (CCSM) and TCP-fortified soymilk (TCPSM) was compared with cow's milk in young healthy women using the dual stable isotope technique. In a 3-way crossover design, 20 volunteers (23 +/- 2 y old) consumed 250 mg Ca in cow's milk, CCSM, or TCPSM along with 10 mg 44Ca after an overnight fast. Cow's milk was extrinsically labeled, whereas each fortified soymilk was intrinsically labeled with each chemical salt of 44Ca at the manufacturing facility. Another stable isotope, 43Ca, was injected i.v. 1 h after the complete consumption of cow's milk or soymilk. Fractional Ca absorption was determined from the ratios of 43Ca:42Ca and 44Ca:42Ca by inductively coupled plasma (ICP)-MS in the 24-h urine samples. A mixed linear model (SAS proc mixed) was used to compare the fractional Ca absorption among groups. Fractional Ca absorption in CCSM (0.211 +/- 0.057) did not differ from that of cow's milk (0.217 +/- 0.040), but both were higher (P < 0.05) than that of TCPSM (0.181 +/- 0.039). Our result suggests that calcium absorption is equivalent for CCSM and cow's milk at similar calcium loads.     

Gastric digestion of bovine lactoferrin in vivo in adults

Lactoferrin (LF), an iron-binding glycoprotein present in milk and other endocrine and exocrine secretions, may exert a number of physiologic effects in the intestines. To study the effects of oral LF supplementation in vivo in the gastrointestinal tract, information about the gastric survival of LF in vivo is important. We tested 12 healthy volunteers (age 21 +/- 0.3 y) on 3 separate d according to a randomized, cross-over design. A test drink containing 4.5 g of bovine LF (20% iron-saturated LF; apoLF) in the presence of a gastric pH buffer (0.1 mol/L sodium citrate/citric acid; apoLFbuf), apoLF without the buffer (apoLF) or iron-saturated LF (holoLF) was administered into the stomach using nasogastric intubation. Gastric emptying rate, determined by a marker dilution technique, did not differ among any of these drinks. Gastric survival of LF, analyzed by gel permeation chromatography under denaturing conditions, was 64%, 62% and 79% after consumption of the apoLFbuf, apoLF and holoLF test drinks, respectively. Addition of the gastric pH buffer initially lowered intragastric pH because of its hydroxide buffering effect. However, it did not elevate intragastric pH over a prolonged period and thereby inhibit intragastric LF breakdown. We conclude that after oral administration, substantial amounts of apoLF and holoLF survive gastric transit.