Effects of medium-chain and long-chain triglycerides on antroduodenal motility and small bowel transit time in man

Importance of the enteric nervous system in the control of the migrating motility complex

The migrating motility complex (MMC), a cyclical phenomenon, represents rudimentary motility pattern in the gastrointestinal tract. The MMC is observed mostly in the stomach and gut of man and numerous animal species. It contains three or four phases, while its phase III is the most characteristic. The mechanisms controlling the pattern are unclear in part, although the neural control of the MMC seems crucial. The main goal of this article was to discuss the importance of intrinsic innervation of the gastrointestinal tract in MMC initiation, migration, and cessation to emphasize that various MMC-controlling mechanisms act through the enteric nervous system. Two main neural regions, central and peripheral, are able to initiate the MMC. However, central regulation of the MMC may require cooperation with the enteric nervous system. When central mechanisms are not active, the MMC can be initiated peripherally in any region of the small bowel. The enteric nervous system affects the MMC in response to the luminal stimuli which can contribute to the initiation and cessation of the cycle, and it may evoke irregular phasic contractions within the pattern. The hormonal regulators released from the endocrine cells may exert a modulatory effect upon the MMC mostly through the enteric nervous system. Their central action could also be considered. It can be concluded that the enteric nervous system is involved in the great majority of the MMC-controlling mechanisms.

Medium chain triglycerides (MCT) formulas in paediatric and allergological practice

Fats constitute the most significant nutritional source of energy. Their proper use by the body conditions a number of complex mechanisms of digestion, absorption, distribution, and metabolism. These mechanisms are facilitated by fats made of medium chain fatty acids; therefore, they are an easy and quick source of energy. Thus, an increased supply of medium chain triglycerides (MCT) is particularly important in patients with disturbances of digestion and absorption such as disturbed bile secretion, classic coeliac disease, short bowel syndrome, inflammatory diseases of the intestines, disturbed outflow of lymph, some metabolic disease, and severe food allergies, as well as in prematurely born neonates. Use of preparations containing an additive of MCT is limited, especially if they are to be used for a longer period of time. With a large quantity of MCT in a diet, there is a risk of deficiency of necessary unsaturated fatty acids and some fat-soluble vitamins. The caloricity of MTC compared to long-chain triglycerides is lower, and formulas with MCT are characterised by higher osmolality. Medium chain triglycerides is not recommended as an additive to standard formulas for healthy children. The use of MCT should be limited to strictly specified medical indications.

Impact of formulation excipients on human intestinal transit

The accelerating effect of polyethylene glycol 400 on small intestinal transit has been previously reported. The aim of this study was to investigate the influence of other solubility-enhancing excipient, propylene glycol, D-α-tocopheryl-polyethylene glycol-1000 succinate (VitE-TPGS) and Capmul MCM, on human intestinal transit. A 5-g dose of each excipient was administered to seven healthy male subjects. Propylene glycol and VitE-TPGS were administered dissolved in 150 mL water. Capmul MCM was administered in the form of four 000 hard gelatin capsules to mask its taste and then given with 150 mL water. On a separate occasion, 150 mL water was administered as the control. Each formulation was radiolabelled with technetium-99 m to follow its transit using a gamma camera. The mean small intestinal transit times were 234, 207, 241 and 209 min for the control, propylene glycol, VitE-TPGS and Capmul MCM treatments, respectively. Although there were differences in the small intestinal transit times for the excipients investigated compared with the control, none of the results were statistically significant. Unlike polyethylene glycol 400 at the same dose of 5g, the excipients tested (propylene glycol, VitE-TPGS and Capmul MCM) had little or no impact on small intestinal transit.

Effect of triglycerides with different fatty acid chain length on superior mesenteric artery blood flow

Fat stimulates superior mesenteric artery (SMA) blood flow. Little is known, however, about the influence of fatty acid chain length on SMA flow. The present study was performed to compare the effect of long chain triglycerides (LCT, corn oil), very long chain triglycerides (VLCT, fish oil) and medium chain triglycerides (MCT) on SMA flow. A total of seven healthy volunteers (four men, three women; aged 26 +/- 4 years) participated in three experiments, performed in random order during 60 min continuous intra-duodenal infusion of either LCT (30 mL h(-1); 240 kcal h-1), equicaloric VLCT (30 mL h(-1); 240 kcal h(-1)) or MCT in equimolar (15 mL h(-1); 113 kcal h(-1)) and equicaloric amount (30 mL h(-1); 225 kcal h(-1)). Basal and stimulated SMA blood flow were measured by Doppler ultrasonography. At regular intervals blood samples were taken for measurement of plasma cholecystokinin (CCK) and plasma peptide YY (PYY). Basal SMA blood flow volumes were not significantly different among the LCT, VLCT and MCT experiments (426 +/- 135, 460 +/- 114 and 503 +/- 177 mL min(-1), respectively). The SMA flow increased significantly (P < 0.05) during fat infusion but was significantly higher during LCT (1460 +/- 692 mL min-1) compared with VLCT (1061 +/- 384 mL min-1), MCT 15 mL h(-1) (870 +/- 286 mL min(-1)) and MCT 30 mL h-1 (904 +/- 223 mL min(-1)). Plasma CCK levels increased significantly (P < 0.05) during LCT and VLCT but not during MCT infusion. No correlation was found between SMA flow and plasma CCK levels (r = 0.27; P = 0.2) The SMA blood flow in response to triglycerides is dependent on fatty acid chain length. This chain length-dependent blood flow response is, however, not linear and is not related to plasma CCK levels.

The fatty acid pattern of dietary fat influences the oral bioavailability of the flavonol quercetin in pigs

We have shown recently that dietary fat content influences the bioavailability of the flavonol quercetin. In the present study, the influence of the fatty acid pattern of dietary fats on the oral bioavailability of quercetin was investigated. Quercetin (30 micromol/kg body weight) was administered to growing pigs (n 6) in test meals consisting either of 200 g of a standard pig diet (2% crude fat) or of the same diet supplemented with 15 g fat/100 g diet using either medium-chain (MCT) or long-chain fatty acid triacylglycerols (LCT). Blood samples were drawn repeatedly over a period of 24 h and analysed by HPLC. In addition, the influence of the different diets on gastric emptying was investigated in rats. In pigs, the bioavailability of quercetin was measured by quantifying its plasma metabolites with an intact flavonol structure. Bioavailability was enhanced by 38% (P<0.05) and 12% (P>0.05) after intake with the MCT and LCT diets, respectively, compared to the standard diet. Maximum plasma concentrations of quercetin were reached significantly later with the MCT diet than with the LCT or the standard diet (P<0.05). No differences in dry matter of the gastric content were observed 60 min after intake of the experimental diets in rats. Thus, administration of quercetin together with a diet containing MCT fat enhances the bioavailability of the flavonol. Absorption of quercetin was delayed significantly with this diet. However, this was probably not due to slower gastric emptying of the MCT diet.

Effects of miglyol 812 on rats after 4 weeks of gavage as compared with methylcellulose/tween 80

Miglyol 812 is a medium-chain triglyceride used in toxicology studies as an excipient to improve test compound solubility/absorption. As part of a larger toxicology study, 15 Wistar Han IGS rats/sex/group were dosed by oral gavage for 4 weeks with 10 mL kg(-1) day(-1) of 100% Miglyol 812 or 0.5% methylcellulose/0.1% Tween 80 in water (MC-T) followed by 4 weeks without treatment to evaluate the potential effects of this excipient in long-term toxicology studies relative to a traditional excipient such as MC-T. Clinical signs evident during the dosing phase included soft and/or mucoid stool in 12/15 males and 11/15 females treated with Miglyol 812 but in no animals treated with MC-T. Animals treated with Miglyol 812 had a 6-7% statistically significant reduction in body weight gain as compared to MC-T-treated animals. Statistically significant changes in clinical chemistry parameters as compared to MC-T included decreased blood urea nitrogen (50% and 29% in males and females, respectively), increased cholesterol (1.6-fold and 1.5-fold in males and females, respectively), decreased total protein (6% and 8% in males and females, respectively), decreased globulins (15% and 11% in males and females, respectively), and increased triglycerides (2.8-fold and 1.7-fold in males and females, respectively). Absolute and relative thymic weights decreased 28% and 24%, respectively, in males, and 18% and 17%, respectively, in females without histological alterations. Histopathology revealed increased alveolar histiocytosis with focal interstitial inflammation in lungs in 5/10 males and 7/10 females treated with Miglyol 812 compared to only 1/10 males and 1/10 females treated with MC-T. All effects were reversible during the recovery period. Results of this study indicate that 100% miglyol 812 produces reversible gastrointestinal effects and decreases in body weight gains along with changes in several serum chemistry parameters. Therefore, it should not be considered innocuous when delivered by oral gavage in long-term rodent toxicology studies.

Rate of gastric emptying influences dietary cholesterol absorption efficiency in selected inbred strains of mice

This study compared the physiological process of cholesterol absorption in different strains of inbred mice with the goal of identifying novel mechanism(s) by which cholesterol absorption can be controlled. The rate and amount of cholesterol absorption were evaluated based on [14C]cholesterol appearance in plasma after feeding a meal containing [14C]cholesterol and by the percentage of [14C]-cholesterol absorbed over a 24 h period. Results showed that the rate of [14C]cholesterol appearance in plasma was slower in 129P3/J mice than in SJL/J mice. However, more dietary cholesterol was absorbed over a 24 h period by 129P3/J mice than by SJL/J mice. In both strains of mice, cholesterol delivered with medium-chain triglyceride was absorbed less efficiently than cholesterol delivered with olive oil. The strain- and vehicle-dependent differences in cholesterol absorption efficiency correlated negatively with stomach-emptying rates. Furthermore, inhibition of gastric emptying with nitric oxide synthase inhibitor increased cholesterol absorption efficiency in SJL/J mice. These results document that stomach-emptying rate contributes directly to the rate of dietary cholesterol absorption, which is inversely correlated with the total amount of cholesterol absorbed from a single meal. Additionally, genetic factor(s) that influence gastric emptying may be an important determinant of cholesterol absorption efficiency.

Effects of intraduodenal application of peppermint oil (WS(R) 1340) and caraway oil (WS(R) 1520) on gastroduodenal motility in healthy volunteers

Enteric-coated preparations containing a fixed peppermint oil/caraway oil combination (e.g. Enteroplant(R)) are widely used in patients with functional dyspepsia. The effect of a separate intraduodenal application of the active ingredients of Enteroplant(R) (90 mg peppermint oil (WS(R) 1340), 50 mg caraway oil (WS(R) 1520) per capsule) and of a hydrophobic phase galenic auxiliary material contained in the Enteroplant(R) formulation (dose as contained per capsule) on gastroduodenal motility were studied with stationary manometry in healthy volunteers. The carrier demanded by the experimental setup also served as a control. The results showed that: (1) during phase III of the migrating motor complex (MMC) the frequency and duration of contractions showed a significant decrease in the duodenum for WS(R) 1340; (2) WS(R) 1520 significantly reduced the contraction amplitudes in the duodenum during phase I and II of the MMC; (3) trends for decreased values were seen for WS(R) 1340 in the gastric corpus and duodenum and for WS(R) 1520 in the gastric antrum; (4) in the gastric corpus the duration of contractions was significantly reduced after application of WS(R) 1340 during phases I and II of the MMC; (5) WS(R) 1520 significantly reduced the contraction amplitudes and the duration of contractions in the gastric corpus during phase III of the MMC; (6) for the hydrophobic phase a moderate but significant decrease of duration of contractions in the duodenum and of frequency of contractions in the gastric corpus was seen. No adverse events were observed during the study. In conclusion, it could be shown that both WS(R) 1340 and WS(R) 1520 contribute to the efficacy of Enteroplant(R). They act locally in the stomach and duodenum to produce smooth-muscle relaxation. The effects of the active ingredients WS(R) 1340 and WS(R) 1520 substantially exceed the effects observed with the galenic auxiliary material and the carrier, respectively.

The effect of equicaloric medium-chain and long-chain triglycerides on pancreas enzyme secretion

It has been shown previously that medium chain triglycerides (MCT) do not affect gallbladder emptying and cholecystokinin (CCK) release. The effect of MCT on exocrine pancreas secretion in humans is unknown. We have compared the effect of enteral administration of MCT versus long chain triglycerides (LCT) on exocrine pancreatic secretion. Eight healthy subjects (three female, five male; mean age 22 +/- 1.9 years) participated in two experiments, performed in random order. Duodenal contents, obtained by aspiration, were used to calculated the output of pancreatic enzymes and bilirubin. An equicaloric amount of either MCT or LCT (2 kcal min-1) oil was continuously administered in the proximal jejunum for 2 h. Gallbladder volume was measured by ultrasonography and blood samples were drawn for determination of CCK. The experiments consisted of 1 h basal secretion, 2 h of continuous oil administration and 1 h poststimulation. During the LCT feeding the pancreatic enzyme secretion, bilirubin output, gallbladder emptying and CCK release increased significantly (P < 0.05) over basal levels. MCT had no effect on pancreatic enzyme secretion nor gallbladder emptying or CCK release. We conclude that enteral administration of MCT in the proximal jejunum does not stimulate exocrine pancreatic secretion nor gallbladder contraction or CCK release, in contrast to an equicaloric amount of LCT.

Effect of medium- and long-chain triglycerides on lower esophageal sphincter pressure: role of CCK

Fat meals are known to decrease lower esophageal sphincter (LES) pressure, possibly through postprandial CCK release. Dietary fat consists mainly of long-chain triglycerides (LCT), which potently stimulate CCK secretion. This effect contrasts with that of medium-chain triglycerides (MCT), which do not induce CCK release. We recorded LES pressure and gallbladder volume in six healthy subjects on five separate occasions during intraduodenal administration of 1) saline control, 2) LCT, 3) MCT, 4) LCT during intravenous infusion of the CCK receptor antagonist loxiglumide, and 5) MCT together with loxiglumide. LES pressure decreased significantly during administration of both LCT and MCT. Loxiglumide completely prevented the reduction in LES pressure during intraduodenal LCT, but not during intraduodenal MCT. Gallbladder volume decreased during LCT, but not during MCT. It is concluded that intraduodenal administration of equimolar amounts of both LCT and MCT significantly reduces LES pressure. The effect of LCT on LES pressure is mediated by CCK. The effect of MCT is not dependent on CCK, since MCT does not release CCK and loxiglumide does not prevent the MCT-induced reduction in LES pressure.