Differences in cholecystokinin release and gallbladder contraction between emulsified and nonemulsified long-chain triglycerides

A comparison of the satiating properties of medium-chain triglycerides and conjugated linoleic acid in participants with healthy weight and overweight or obesity

PURPOSE

Inconsistent evidence exists for greater satiety after medium-chain triglycerides (MCT) or conjugated linoleic acid (CLA) compared to long-chain triglycerides (LCT). Furthermore, the mechanisms are poorly understood and effects in people with a healthy weight and those with overweight/obesity have not been compared. This study aimed to compare appetite responses in these groups and examine the mechanisms behind any differences.

METHODS

Fifteen participants with healthy weight (BMI: 22.7 ± 1.9 kg·m-2) and fourteen participants with overweight/obesity (BMI: 30.9 ± 3.9 kg·m-2) consumed a breakfast containing either 23.06 g vegetable oil (CON), 25.00 g MCT oil (MCT), or 6.25 g CLA and 16.80 g vegetable oil (CLA). Appetite, peptide YY (PYY), total ghrelin (TG), β-hydroxybutyrate, and gastric emptying (GE) were measured throughout. Energy intake was assessed at an ad libitum lunch and throughout the following ~ 36 h.

RESULTS

Neither MCT nor CLA decreased ad libitum intake; however MCT decreased day 1 energy intake (P = 0.031) and the 48-h period (P = 0.005) compared to CON. MCT delayed GE (P ≤ 0.01) compared to CON, whereas CLA did not. PYY and TG concentrations were not different (P = 0.743 and P = 0.188, respectively), but MCT increased β-hydroxybutyrate concentrations compared to CON (P = 0.005) and CLA (P < 0.001). β-hydroxybutyrate concentrations were higher in participants with overweight/obesity (P = 0.009).

CONCLUSION

Consumption of MCT reduces energy intake in the subsequent 48 h, whereas CLA does not. Delayed gastric emptying or increased β-hydroxybutyrate concentrations may mediate this.

Capsaicin-induced satiety is associated with gastrointestinal distress but not with the release of satiety hormones

BACKGROUND

Capsaicin, which is the major pungent principle in chili peppers, is able to induce satiety and reduce caloric intake. The exact mechanism behind this satiating effect is still unknown. We hypothesized that capsaicin induces satiety through the release of gastrointestinal peptides, such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), from enteroendocrine cells in the small intestine.

OBJECTIVE

We investigate the effects of an intraduodenal capsaicin infusion (1.5 mg pure capsaicin) in healthy volunteers on hunger, satiety, and gastrointestinal symptoms and the release of GLP-1 and PYY.

DESIGN

Thirteen participants (7 women) [mean ± SEM age: 21.5 ± 0.6 y; body mass index (in kg/m(2)): 22.8 ± 0.6] participated in this single-blind, randomized, placebo-controlled crossover study with 2 different treatments. During test days, an intraduodenal infusion of either capsaicin or a placebo (physiologic saline) was performed with the use of a nasoduodenal catheter over a period of 30 min. Visual analog scale scores were used to measure hunger, satiety, and gastrointestinal symptoms. Blood samples were drawn at regular intervals for GLP-1 and PYY. Gallbladder volumes were measured with the use of real-time ultrasonography.

RESULTS

The intraduodenal capsaicin infusion significantly increased satiety (P-treatment effect < 0.05) but also resulted in an increase in the gastrointestinal symptoms pain (P-treatment × time interaction < 0.0005), burning sensation (P-treatment × time interaction < 0.0001), nausea (P-treatment × time interaction < 0.05), and bloating (P-treatment × time interaction < 0.001) compared with the effects of the placebo infusion. Satiety scores had a positive correlation with all gastrointestinal symptoms. No differences in GLP-1 and PYY concentrations and gallbladder volumes were observed after the capsaicin infusion compared with after the placebo infusion.

CONCLUSIONS

An intraduodenal infusion of capsaicin significantly increases satiety but does not affect plasma concentrations of GLP-1 and PYY. Rather, the effect on satiety seems related to gastrointestinal stress as shown by the associations with pain, burning sensation, nausea, and bloating scores. This trial was registered at clinicaltrials.gov as NCT01667523.

Fat emulsion intragastric stability and droplet size modulate gastrointestinal responses and subsequent food intake in young adults

BACKGROUND

Intragastric creaming and droplet size of fat emulsions may affect intragastric behavior and gastrointestinal and satiety responses.

OBJECTIVES

We tested the hypotheses that gastrointestinal physiologic responses and satiety will be increased by an increase in intragastric stability and by a decrease in fat droplet size of a fat emulsion.

METHODS

This was a double-blind, randomized crossover study in 11 healthy persons [8 men and 3 women, aged 24 ± 1 y; body mass index (in kg/m(2)): 24.4 ± 0.9] who consumed meals containing 300-g 20% oil and water emulsion (2220 kJ) with 1) larger, 6-μm mean droplet size (Coarse treatment) expected to cream in the stomach; 2) larger, 6-μm mean droplet size with 0.5% locust bean gum (LBG; Coarse+LBG treatment) to prevent creaming; or 3) smaller, 0.4-μm mean droplet size with LBG (Fine+LBG treatment). The participants were imaged hourly by using MRI and food intake was assessed by using a meal that participants consumed ad libitum.

RESULTS

The Coarse+LBG treatment (preventing creaming in the stomach) slowed gastric emptying, resulting in 12% higher gastric volume over time (P < 0.001), increased small bowel water content (SBWC) by 11% (P < 0.01), slowed appearance of the (13)C label in the breath by 17% (P < 0.01), and reduced food intake by 9% (P < 0.05) compared with the Coarse treatment. The Fine+LBG treatment (smaller droplet size) slowed gastric emptying, resulting in 18% higher gastric volume (P < 0.001), increased SBWC content by 15% (P < 0.01), and significantly reduced food intake by 11% (P < 0.05, equivalent to an average of 411 kJ less energy consumed) compared with the Coarse+LBG treatment. These high-fat meals stimulated substantial increases in SBWC, which increased to a peak at 4 h at 568 mL (range: 150-854 mL; P < 0.01) for the Fine+LBG treatment.

CONCLUSION

Manipulating intragastric stability and fat emulsion droplet size can influence human gastrointestinal physiology and food intake.

Effects of various food ingredients on gall bladder emptying

Background/objectives:

The emptying of the gall bladder in response to feeding is pivotal for the digestion of fat, but the role of various food ingredients in contracting the gall bladder postprandially is not well understood. We hypothesized that different food ingredients, when consumed, will have a different effect on stimulating gall bladder emptying. To investigate this we designed two randomized, investigator-blind, cross-over studies in healthy subjects using magnetic resonance imaging (MRI) to measure gall bladder volumes serially and non-invasively.

Subjects/methods:

Study 1: exploratory study evaluating the effects of 10 different food ingredients on gall bladder emptying in eight healthy subjects. The choice of ingredients varied from common items like coffee, tea and milk to actives like curcumin and potato protease inhibitor. Study 2: mechanistic study investigating the cholecystokinin (CCK) dose response to the best performer ingredient from Study 1 in 21 healthy subjects four ways.

Results:

The largest gall bladder volume change in Study 1 was observed with fat, which therefore became the dose-response ingredient in Study 2, where the maximum % gall bladder volume change correlated well with CCK.

Conclusions:

These serial test-retest studies showed that the fasted gall bladder volume varied remarkably between individuals and that individual day-to-day variability had wide coefficients of variation. Improved knowledge of how to stimulate bile release using food ingredients will be useful to improve in vitro–in vivo correlation of bioavailability testing of hydrophobic drugs. It could improve performance of cholesterol-lowering plant stanol and sterol products and possibly aid understanding of some cholesterol gallstone disease.

Influence of emulsifier structure on lipid bioaccessibility in oil-water nanoemulsions

The influence of several nonionic surfactants (Tween-20, Tween-40, Tween-60, Span-20, Span-60, or Span-80) and anionic surfactants (sodium lauryl sulfate, sodium stearoyl lactylate, and sodium stearyl fumarate) showed drastic differences in the rank order of lipase activity/lipid bioaccessibility. The biophysical composition of the oil and water interface has a clear impact on the bioaccessibility of fatty acids (FA) by altering the interactions of lipase at the oil-water interface. It was found that the bioaccessibility was positively correlated with the hydrophilic/lipophilic balance (HLB) of the surfactant and inversely correlated to the surfactant aliphatic chain length. Furthermore, the induction time in the jejunum increased as the HLB value increased and decreased with increasing aliphatic chain length. The rate of lipolysis slowed in the jejunum with increasing HLB and with increasing aliphatic chain length.

Long-chain fatty acid sensing in the gastrointestinal tract

The gastrointestinal tract actively responds to the presence of nutrients in the lumen, and there is a high level of specificity to these responses. This specificity exists for different nutrient types and anatomical regions, with physiologically appropriate target end-organ responses. This review will journey from outlining the effects of dietary fat on digestive function and feeding behaviour to the evidence for lipid sensory cells, particularly the enteroendocrine system, in the epithelium. It will also outline potential molecular bases for these mechanisms. This will deal exclusively with issues specific to fatty acid sensing and not the emergent acid pH-sensing mechanisms that may also be activated in the presence of free fatty acids.

Enhancement of intragastric acid stability of a fat emulsion meal delays gastric emptying and increases cholecystokinin release and gallbladder contraction

Preprocessed fatty foods often contain calories added as a fat emulsion stabilized by emulsifiers. Emulsion stability in the acidic gastric environment can readily be manipulated by altering emulsifier chemistry. We tested the hypothesis that it would be possible to control gastric emptying, CCK release, and satiety by varying intragastric fat emulsion stability. Nine healthy volunteers received a test meal on two occasions, comprising a 500-ml 15% oil emulsion with 2.5% of one of two emulsifiers that produced emulsions that were either stable (meal A) or unstable (meal B) in the acid gastric environment. Gastric emptying and gallbladder volume changes were assessed by MRI. CCK plasma levels were measured and satiety scores were recorded. Meal B layered rapidly owing to fat emulsion breakdown. The gastric half-emptying time of the aqueous phase was faster for meal B (72 +/- 13 min) than for meal A (171 +/- 35 min, P < 0.008). Meal A released more CCK than meal B (integrated areas, respectively 1,095 +/- 244 and 531 +/- 111 pmol.min.l(-1), P < 0.02), induced a greater gallbladder contraction (P < 0.02), and decreased postprandial appetite (P < 0.05), although no significant differences were observed in fullness and hunger. We conclude that acid-stable emulsions delayed gastric emptying and increased postprandial CCK levels and gallbladder contraction, whereas acid-instability led to rapid layering of fat in the gastric lumen with accelerated gastric emptying, lower CCK levels, and reduced gallbladder contraction. Manipulation of the acid stability of fat emulsion added to preprocessed foods could maximize satiety signaling and, in turn, help to reduce overconsumption of calories.

Metabolically active functional food ingredients for weight control

The scale of the obesity epidemic creates a pressing consumer need as well as an enormous business opportunity for successful development and marketing of food products with added benefits for weight control. A number of proposed functional food ingredients have been shown to act post-absorptively to influence substrate utilization or thermogenesis. Characteristics and supporting data on conjugated linoleic acid, diglycerides, medium-chain triglycerides, green tea, ephedrine, caffeine, capsaicin and calcium, are reviewed here, giving examples of how these could act to alter energy expenditure or appetite control. Consideration is also given to other factors, in addition to efficacy, which must be satisfied to get such ingredients into foods. We conclude that, for each of the safe, putatively metabolically active agents, there remain gaps in clinical evidence or knowledge of mechanisms, which need to be addressed in order to specify the dietary conditions and food product compositions where these ingredients could be of most benefit for weight control.

Influence on gallbladder volume of early postoperative gastric supply of nutrients

BACKGROUND & AIM

The gallbladder volume is a predictor of biliary stasis and the formation of biliary sludge. Biliary stasis and sludge have been recently recognized as the precursors of acute acalculous cholecystitis, as well as 'idiopathic' postoperative pancreatitis, rare but very serious complications after surgery. The aim of the study was to establish how early postoperative gastric supply of nutrients affects the gallbladder volume in patients after noncardiac and cardiac surgery.

METHODS

In the two prospective, randomized studies 40 patients (study I-noncardiac surgery) treated at surgical ICU after major elective extrahepatobiliary and extragastrointestinal surgeries (7 thoracic, 19 vascular, 14 urological) and 40 patients (study II-cardiac surgery) treated at cardiosurgical ICU after CABG surgery were analyzed. In both studies the patients were divided into two groups: control group C (study I: 20 patients, age 45+/-18 yrs, male 65%; study II: 20 patients age 58+/-7 yrs, male 60%) and group E (group of early postoperative gastric supply of nutrients) (study I: 20 patients, age 52+/-17 yrs, male 50%; study II: 20 patients; age 59+/-8 yrs, male 65%). For the first 24 hours the patients in group C received only crystalloid solutions and the gallbladder volume was verified 24 hours after the surgery. In group E, postoperative gastric supply of nutrients began 18 hours after surgery (Osmolite, Ross; first 3 hours 30 ml/h and second 3 hours 50 ml/h; total 240 ml after 6 hours). In all patients sonographic measurement of gallbladder volume was performed immediately before surgery and 6 hours after the start of feeding (24 hours after surgery). The measurement was done with ultrasonographic scanner Hitachi 405 EUB (convex probe 3.5-5MHz) by the same specialist, and the volume was calculated using the ellipsoid method.

RESULTS

The gallbladder volume measured by ultrasonography 24 hours after surgery in study I (noncardiac surgery) in group E amounted to 43+/-25 ml while in control group C it was significantly higher, i.e. 67+/-30 ml (P<0.05). In study II (cardiac surgery) in group E gallbladder volume amounted to 59+/-15 ml while in control group C it was also significantly higher, i.e. 71+/-11 ml (P<0.05).

CONCLUSION

An early postoperative gastric supply of nutrients after both noncardiac and cardiac adult surgery diminishes the volume and probably stimulates the motility of the gallbladder, thus preventing biliary stasis and the formation of biliary sludge.