A solubilized cellulose fiber decreases peak postprandial cholecystokinin concentrations after a liquid mixed meal in hypercholesterolemic men and women

Viscous dietary fibers can modify the alimentary responses to a meal and improve glucose tolerance. There may be a relationship between the effect of these fibers in the gut and the ability of the hormone cholecystokinin (CCK) to slow gastric emptying and affect glucose homeostasis. We investigated the acute and long-term (adaptive) glucose and CCK responses to liquid mixed test meals, with or without 5 g of solubilized cellulose (SC), a novel viscous fiber, in 33 hypercholesterolemic men and women. In the acute study, there was a lower peak CCK concentration (P = 0.01) after a SC-containing test meal compared with a fiber-free test meal. The CCK area under the curve responses also tended to be lower after the fiber-containing meal (P = 0.08). After a 6-wk intervention with 2.5 g of SC or placebo twice daily, fasting plasma glucose concentration tended to decrease in the SC group, whereas it increased in the control group (for between-group difference in change, P = 0.13). There were no differences between the groups in the changes from baseline to the end of the study in any other variable. There were significant gender differences in several variables at baseline. These findings support the hypothesis that CCK may mediate the effect of viscous fibers on glucose metabolism. The gender differences in glucose and CCK may explain some of the discrepancies in the results of similar experiments reported to date.     

Alternation between foods within a meal. Influence on satiation and consumption in humans

Food habituation/dishabituation has been observed in non-human primates in neurophysiological investigations of feeding, and in humans, through salivation or hedonic responses to food. The objective of the study was to evaluate in humans the effect of disruption of habituation by alternation between foods in a meal. Sixteen volunteers (8 males, 8 females; age: 21 ± 1 yr; BMI: 21.5 ± 0.5 kg m⁻²) ate a two-course meal [meatballs (M) and fries (F), then vanilla cream (C) and brownies (B)] during three randomized sessions. Sessions differed by the alternation of these foods: No-Repetition session with M-F–C-B; Single-Repetition session with F-M-F–B-C-B; Multiple-Repetition session with M-F-M-F-M-F–C-B-C-B-C-B. Final intakes of F and B were ad libitum. Quantities consumed (g, kJ) and ratings of hunger, pleasantness and desire to eat each food were evaluated. Compared to the No-Repetition session, subjects ate 18% more fries and 16% more brownies in the Single-Repetition, and 13% more fries but 20% less brownies in the Multiple-Repetition session. Pleasantness for the food decreased from before to after intake for both fries and brownies with no significant difference between the sessions. It therefore appears that moderate alternation between foods at lunch increases intake, but multiple alternations of foods at the end of the meal may decrease consumption. These differences in intakes could result from differences in sensory-specific satiety via disruption of habituation.     

Plasma cholecystokinin and pancreatic polypeptide responses after ingestion of a liquid test meal rich in medium-chain fatty acids in patients with chronic pancreatitis

Plasma cholecystokinin (CCK) and human pancreatic polypeptide (hPP) responses after ingestion of a liquid test meal rich in medium-chain fatty acids (MCFA) were studied in patients with chronic pancreatitis with or without diabetes mellitus (DM). Integrated response of plasma CCK was significantly lower in patients with chronic pancreatitis and DM than in the two other groups. There was no statistically significant difference between the healthy control subjects and the patients with chronic pancreatitis without DM in the integrated responses of hPP and plasma CCK. These results indicate that diabetic patients with a greatly destroyed pancreas do not release as much CCK as do nondiabetic patients with a mildly impaired pancreas. An MCFA meal is therefore considered safe in patients with a mildly impaired pancreas. For diabetic patients, however, care should be taken not to exacerbate the DM.     

Metabolic effects of nicotine after consumption of a meal in smokers and nonsmokers

The thermogenic effect of nicotine intake after calorie consumption was investigated to determine if nicotine influences metabolic response to a calorie challenge. Smokers and nonsmokers (10 males in each group), matched for body weight, age, and physical fitness, each participated in four sessions that involved consuming a liquid calorie load (4.77 kcal/kg body wt) or water, followed by nicotine (15 micrograms/kg body wt) or placebo via nasal spray every 20 min for 2 h. Energy expenditure was significantly increased above baseline resting metabolic rate (RMR) over the 2 h by nicotine alone (6.5% of RMR, p less than 0.01). However, the combined effect of nicotine after calorie load (20.1% of RMR, p less than 0.001) was not significantly greater than the effect of calorie load alone (18.4% of RMR, p less than 0.001). Smokers and nonsmokers did not differ in baseline RMR or in response to nicotine or calorie load. These results confirm the thermogenic effect of nicotine but suggest that the effect of nicotine after calorie consumption is less than additive.     

A sulfur amino acid-free meal increases plasma lipids in humans

The content of sulfur amino acid (SAA) in a meal affects postprandial plasma cysteine concentrations and the redox potential of cysteine/cystine. Because such changes can affect enzyme, transporter, and receptor activities, meal content of SAA could have unrecognized effects on metabolism during the postprandial period. This pilot study used proton NMR ((1)H-NMR) spectroscopy of human plasma to test the hypothesis that dietary SAA content changes macronutrient metabolism. Healthy participants (18-36 y, 5 males and 3 females) were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (depletion), and then fed isoenergetic, isonitrogenous meals containing 56 mg·kg(-1)·d(-1) SAA for 4.5 d (repletion). On the first and last day of consuming the chemically defined meals, a morning meal containing 60% of the daily food intake was given and plasma samples were collected over an 8-h postprandial time course for characterization of metabolic changes by (1)H-NMR spectroscopy. SAA-free food increased peak intensity in the plasma (1)H-NMR spectra in the postprandial period. Orthogonal signal correction/partial least squares-discriminant analysis showed changes in signals associated with lipids, some amino acids, and lactate, with notable increases in plasma lipid signals (TG, unsaturated lipid, cholesterol). Conventional lipid analyses confirmed higher plasma TG and showed an increase in plasma concentration of the lipoprotein lipase inhibitor, apoC-III. The results show that plasma (1)H-NMR spectra can provide useful macronutrient profiling following a meal challenge protocol and that a single meal with imbalanced SAA content alters postprandial lipid metabolism.     

Carotenoid bioavailability in humans from tomatoes processed in different ways determined from the carotenoid response in the triglyceride-rich lipoprotein fraction of plasma after a single consumption and in plasma after four days of consumption

Tomatoes are the main dietary source of lycopene, and the bioavailability of lycopene from tomato paste is higher than that from fresh tomatoes. We investigated systematically the effect of mechanical homogenization and heating on the bioavailability of carotenoids from canned tomatoes. Further, we compared the carotenoid response in triglyceride-rich lipoproteins (TRL) after single consumption with the change in fasting plasma carotenoid concentrations after 4 d of daily consumption. In a split plot design, 17 men and women consumed tomatoes which had received minimal additional heating and 16 others consumed extensively additionally heated tomatoes (1 h at 100 degrees C). These tomatoes were not, mildly or severely homogenized. The tomato products were consumed daily (ca. 22 mg/d lycopene) for 4 d. Eleven participants provided postprandial blood samples on the d 1 and all gave fasting blood samples on d 1 and 4. Homogenization enhanced the lycopene response significantly (P<0.05) both in TRL [mean areas under the curves: 54.9, 72.0 and 88.7 nmol. h/L (SE 11.0) for not, mildly and severely homogenized tomatoes, respectively] and in plasma [mean changes: 0.19, 0.22 and 0.23 micromol/L (SE 0.009), respectively]. Additional heating also tended to enhance the lycopene responses in TRL (P = 0.14) and plasma (P = 0.17). Similar effects to those for lycopene were found for beta-carotene. We conclude that the intactness of the cellular matrix of tomatoes determines the bioavailability of carotenoids and that matrix disruption by mechanical homogenization and/or heat treatment enhances the bioavailability. The carotenoid response in plasma after 4 d intervention can be used to compare the bioavailability of carotenoids from different foods.     

Lithium chloride, cholecystokinin and meal patterns: Evidence that cholecystokinin suppresses meal size in rats without causing malaise

Gut hormones which are proposed as natural satiety factors may act through malaise to suppress short-term feeding instead of through a normal physiological process. Evaluation of the ability of candidate satiety hormones to serve as the unconditioned stimulus in the development of a conditioned taste aversion is not adequate evidence of malaise since agents which do not produce malaise in humans are also capable of conditioning aversions. Examination of the patterns of eating behavior when drugs are given during a meal in rats may serve as a better test of the potential of an agent to produce illness. To evaluate this approach, LiCl (a known aversive agent) was infused into five rats at the start of each free-feeding meal at a dose of 1.9 mg/meal/rat for four days and at 3.8 mg/meal/rat for an additional four days. Feeding patterns during drug infusion were compared with patterns for six days when no drugs were infused. LiCl infusion produced a significant dose-dependent reduction in feeding frequency while the size and duration of meals were not changed. At the higher dose of lithium, daily meal number was reduced from a normal 13.2 +/- 1.4 to 9.9 +/- 0.5 meals/day. This pattern of behavior is significantly different from the behavior exhibited when cholecystokinin octapeptide (CCK-8) was infused using the same paradigm. CCK-8 significantly reduced meal size while meal frequency increased to compensate for the smaller meals. These findings suggest that LiCl infusion during a meal will lead to an aversion to feeding while CCK-8 is not effective at producing an aversion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Food intake in dieters and nondieters after a liquid meal containing medium-chain triglycerides

Medium-chain triglycerides (MCT) may be of benefit in the control of body weight by reducing food intake but this has not been established in humans. The effect of three doses (100, 200, and 300 kcal) of preloads of two complete liquid diets containing either 30% long-chain triglycerides (LCT) or 24% MCT with 6% LCT on subsequent intake was tested in dieting and nondieting females. Thirty minutes after consuming these preloads, subjects were offered a varied self-selection lunch. The major finding was that in the nondieters MCT at all doses was followed by a significantly decreased caloric intake in the lunch. Dieters were unresponsive to the type of dietary fat and tended to eat the same number of calories regardless of the preload. Although MCT can reduce short-term food intake in some individuals, further experiments are required to establish the possible benefit of MCT in weight control.     

Peptide YY release in anorectic patients after liquid meal

Fasting and postprandial levels of human peptide YY (PYY) were recently found to be lower in obesity. To investigate whether PYY levels are correspondingly high in patients with anorexia nervosa, PYY concentrations were analyzed under basal conditions and in response to a liquid meal. We investigated PYY plasma levels in 16 female anorectic (BMI 15.2+/-0.3 kg/m2) and seven lean subjects (BMI 21.3+/-0.6 kg/m2) before and after ingestion of a liquid meal (250 kcal; 15% protein, 55% carbohydrates, and 30% fat). PYY levels were analyzed using PYY ELISA (DSL, USA). Values are given as mean+/-SEM. Basal PYY levels in anorectic patients (89.0+/-14.4 pg/mL) were not significantly different from lean subjects (64.1+/-12.1 pg/mL). Postprandial PYY levels in healthy volunteers increased significantly after 20 and 60 min (80.4+/-12.7 and 96.0+/-19.9 pg/mL, respectively). In anorectic women PYY was increased at 20 min (137.9+/-19.5 pg/mL) and at 60 min (151.3+/-19.2 pg/mL). No difference was found between both groups. We conclude that basal and postprandial PYY levels in normal weight women are not different from anorectic patients. We could not confirm the recently published blunted postprandial PYY response in anorexia, a finding that merits further study.     

Whey protein consumption after resistance exercise reduces energy intake at a post-exercise meal

Purpose

Protein consumption after resistance exercise potentiates muscle protein synthesis, but its effects on subsequent appetite in this context are unknown. This study examined appetite and energy intake following consumption of protein- and carbohydrate-containing drinks after resistance exercise.

Methods

After familiarisation, 15 resistance training males (age 21 ± 1 years, body mass 78.0 ± 11.9 kg, stature 1.78 ± 0.07 m) completed two randomised, double-blind trials, consisting of lower-body resistance exercise, followed by consumption of a whey protein (PRO 23.9 ± 3.6 g protein) or dextrose (CHO 26.5 ± 3.8 g carbohydrate) drink in the 5 min post-exercise. An ad libitum meal was served 60 min later, with subjective appetite measured throughout. Drinks were flavoured and matched for energy content and volume. The PRO drink provided 0.3 g/kg body mass protein.

Results

Ad libitum energy intake (PRO 3742 ± 994 kJ; CHO 4172 ± 1132 kJ; P = 0.007) and mean eating rate (PRO 339 ± 102 kJ/min; CHO 405 ± 154 kJ/min; P = 0.009) were lower during PRO. The change in eating rate was associated with the change in energy intake (R = 0.661, P = 0.007). No interaction effects were observed for subjective measures of appetite. The PRO drink was perceived as creamier and thicker, and less pleasant, sweet and refreshing (P < 0.05).

Conclusion

These results suggest whey protein consumption after resistance exercise reduces subsequent energy intake, and this might be partially mediated by a reduced eating rate. Whilst this reduced energy intake is unlikely to impair hypertrophy, it may be of value in supporting an energy deficit for weight loss.

     

A protein-rich beverage consumed as a breakfast meal leads to weaker appetitive and dietary responses v. a protein-rich solid breakfast meal in adolescents

The purpose of the present study was to determine whether a protein-rich beverage leads to a differential response in appetite, satiety and subsequent energy intake compared with an energy- and macronutrient-matched solid version in young people. A total of fifteen adolescents (eight girls and seven boys; age 14 (SEM 1) years, BMI percentile 79 (SEM 4) %) randomly completed two testing days that included protein-rich (PR) breakfast meals (38 % of energy as protein, 48 (SEM 2) g/meal) provided as a solid (S) or beverage (B). Breakfast was 24 % of estimated daily energy needs (2146 (SEM 96) kJ/meal). Perceived appetite and satiety responses were collected over 5 h followed by an ad libitum lunch buffet. The PR-S meal led to greater reductions in 4 h postprandial appetite (- 6221 (SEM 1171) mm × 240 min) v. the PR-B meal (- 3570 (SEM 957) mm × 240 min; P < 0·05). When examining the data according to hourly responses, the PR-S meal led to greater reductions in appetite during postprandial hours 2, 3 and 4 v. the PR-B meal (all comparisons, P < 0·05). No differences in postprandial hourly or total (4 h) fullness were observed following the PR-S v. PR-B meals. The PR-S meal led to approximately 480 kJ less energy consumed at the ad libitum lunch buffet (1418 (SEM 222) kJ) v. the PR-B meal (1900 (SEM 326) kJ; P < 0·05). These data indicate that, although the food form of the PR breakfast meals had little, if any, effect on satiety, the appetitive responses were diminished and the subsequent food intake was greater when protein was consumed as a beverage v. a solid meal.     

Relation between appetite ratings before and after a standard meal and estimates of daily energy intake in obese and reduced obese individuals

The aim of the present study was to relate appetite ratings before and after a standard breakfast to estimates of daily energy intake, before and after weight loss obese men and women. Nineteen obese subjects (9 men and 10 women) took part in a 15-week drug-based weight-loss program coupled to energy intake restriction. Body weight and body composition were significantly decreased in men and women. Both before and after the weight loss program, desire to eat, hunger, fullness and prospective food consumption (PFC) were measured after an overnight fast and at 10-min intervals in the hour following the ingestion of a standardized breakfast. Energy intakes were also measured and reported before and after weight loss.Fasting desire to eat and postprandial area under the curve (AUC) for hunger were significantly increased (p<0.05) after the intervention. No association was observed between measured or reported energy intakes and appetite ratings before weight loss in either men or women. Reported energy intake was not associated with appetite sensations after weight loss either. In contrast, measured energy intake was significantly associated with postprandial AUC for fullness (r=-0.90, p<0.01) and PFC (r=0.80, p<0.01) in men at the end of the program. In stepwise multiple regression analysis, only postprandial AUC for PFC contributed independently to the variance of measured energy intake after weight loss (r(2)=0.60, p=0.01).This study did not show consistent associations between averaged appetite ratings after a meal and daily energy intake, either before or after weight loss.     

Coffee stimulation of cholecystokinin release and gallbladder contraction in humans

We studied the effect of the ingestion of 400 mL regular coffee on plasma cholecystokinin (CCK) concentrations and of 165 mL regular and decaffeinated coffee on plasma CCK and gallbladder contraction in six healthy regular coffee drinkers. Plasma CCK concentrations rose 3.3 +/- 0.4 pmol/L after 400 mL and 2.8 +/- 0.9 pmol/L after 165 mL regular coffee compared with 1.8 +/- 0.6 pmol/L after 165 mL decaffeinated coffee. These plasma CCK increments were greater than those after 400 and 165 mL of an isosmotic and isothermic sodium chloride solution (0.6 +/- 0.2 and 0.4 +/- 0.1 pmol/L, respectively). An average gallbladder contraction of 33 +/- 7% was observed after 165 mL regular coffee and 29 +/- 10% after 165 mL decaffeinated coffee, whereas after 165 mL sodium chloride the contraction was only 10 +/- 12%. We conclude that both regular coffee and decaffeinated coffee give rise to increments in plasma CCK and contractions of the gallbladder.     

Nitrite plasma levels after an oral fat meal in normolipemic subjects

BACKGROUND: The authors, investigating the effects of an oral triglyceride-rich fatty load upon the endothelial function as regards the production of nitric oxide, performed the determination of plasma nitrites, which are stable, specific and irreversible end-products of nitric oxide. METHODS: The series consists of 13 metabolically normal female subjects (mean age 55 +/- 7 years); after an overnight fasting each subject undertook an oral fat load (butter 1 g/kg); a venous blood withdrawal was carried out before oral fat meal and after two and four hours. For each plasma sample total cholesterol, HDL-cholesterol and triglyceride plasma levels were determined by enzymatic methods; LDL-cholesterol was calculated by Friedwald's formula; the nitrite plasma levels were obtained by the Gutman and Hollywood colorimetric method. RESULTS: Total cholesterol, HDL-cholesterol, LDL-cholesterol did not show significant changes after the oral fat load; triglycerides rose significantly (p < 0.05) after 4 hours as compared to the basal value (226 +/- 12 vs 175 +/- 12 mg/dl, +30%). The nitrite plasma levels were almost unchanged before oral fat load and after 2 and 4 hours. CONCLUSIONS: The results suggest that the acute biochemical stress consisting of increased triglyceride-rich very low density lipoproteins was not able to stimulate the endothelial production of nitric oxide.     

Effects of blackcurrant-based juice on atherosclerosis-related biomarkers in cultured macrophages and in human subjects after consumption of a high-energy meal

Regular consumption of fruit and vegetables may be associated with decreased CVD risk. In the present study, we investigated the effects of blackcurrant (BC) juice, rich in polyphenols and ascorbic acid, on oxidative and inflammatory biomarkers in cultured macrophages in vitro and in human subjects with an atherosclerosis-prone phenotype (after consumption of a high-energy meal). In cultured macrophages (RAW264.7), BC treatment significantly inhibited lipopolysaccharide-induced inflammation as indicated by lower mRNA levels of TNF-α, IL-1β and inducible NO synthase (iNOS) and lower nuclear p65 levels indicating decreased NF-κB activity. iNOS protein levels were lower and haem oxygenase 1 levels higher in BC-treated cells when compared with untreated controls. Subjects given a high-energy meal had elevated serum glucose and insulin levels with no significant difference between the BC-based juice and placebo treatment groups. TAG following meal ingestion tended to be attenuated after the BC treatment. Plasma ascorbic acid and radical-scavenging capacity were decreased following placebo meal consumption; however, BC significantly elevated both parameters compared with baseline and placebo ingestion. Plasma oxidised LDL, α-tocopherol and paraoxonase activity were unchanged in both treatment groups. Furthermore, production of TNF-α and IL-1β was not significantly changed by BC meal consumption. The present results suggest potential antioxidative and anti-inflammatory properties of BC in vitro in cultured macrophages. Although the observations were not directly transferable to a postprandial in vivo situation, the present results show that BC juice consumption may improve postprandial antioxidant status as indicated by higher ascorbic acid levels and free radical-scavenging capacity in plasma.     

Determinants for urinary and plasma isoflavones in humans after soy intake

Consumption of soy foods leads to a biphasic appearance pattern of isoflavones (IFLs) in blood and urine, with peaks appearing at 1-2 h and 4-8 h after intake, but its causes are not understood. IFLs were measured repeatedly from plasma and/or urine after intake of soy foods, IFL glucosides, or aglycons without or with a mildly or radically reduced gut flora as a result of oral antibiotic (AB) treatment, or this combined with mechanical bowel preparation (AB+MBP). The typical biphasic IFL pattern in blood and/or urine was observed when a soy protein drink without (control) or with AB treatment or when IFL glucosides or aglycons were consumed. Soy intake combined with AB+MBP or consumption of puerarin led to a shift of the second peak to much later times. The first peak was absent after puerarin intake. Total urinary IFL recovery was more than 50% lower in the first 24 h, but overall 61% higher after AB+MBP vs. the control. When the area under the curves for corresponding time intervals were compared, individual or total urinary IFL excretion rates were highly correlated with individual or total plasma IFL levels (r=0.85-0.91; P <0.001). At the same urinary excretion rate three times more genistein than daidzein remained in the circulation. We conclude that urinary IFL excretion rates reflect circulating IFL levels, with daidzein appearing less in blood and more in urine than genistein. The first and second IFL peaks are due to uptake in the small and large intestine, respectively. The latter is the major locus of uptake (90%) at usual dietary IFL doses (0.15-1.5 mmol/kg body weight). A reduced gut flora delayed IFL uptake but led overall to increased urinary recovery because of less bacterial degradation in the intestine.     

A digestive tolerance study of maltitol after occasional and regular consumption in healthy humans

AIM: We aimed to evaluate the gastro-intestinal tolerance to an indigestible bulking sweetener containing sugar alcohol using a double-blind random cross-over study. METHOD: In order to simulate their usual pattern of consumption, 12 healthy volunteers ingested maltitol or sucrose throughout the day, either occasionally (once a week for each sugar, first period) or regularly (every day for two 9 day periods, second period). In both patterns of consumption, daily sugar doses were increased until diarrhea and/or a grade 3 (ie severe) digestive symptom occurred, at which the dose level was defined as the threshold dose (TD). RESULTS: In the first period (occasional consumption), the mean TD was 92+/-6 g with maltitol and 106+/-4 g with sucrose (P=0.059). The mean intensity of digestive symptoms was 1.1 and 1.3, respectively (P=NS). Diarrhea appeared in six and one subjects respectively (P=0.035). In the second period (regular consumption), the mean TD was 93+/-9 g with maltitol and 113+/-7 g with sucrose (P=0.008). The mean intensity of digestive symptoms was 1.7 and 1.2, respectively (P=NS). However, diarrhea appeared in eight and three subjects, respectively (P=0.04). Maltitol and sucrose TDs between the two periods were not different. CONCLUSIONS: Under our experimental conditions, in comparison to sucrose: (a) occasional or regular consumption of maltitol is not associated with severe digestive symptoms; (b) in both patterns of maltitol consumption, diarrhea frequency is higher, but it appeared only for very high doses of maltitol, much greater than those currently used; (c) maltitol does not lead to intestinal flora adaptation after a 9 day period of consumption.     

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.