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

Impact of fatty acid composition on markers of exocrine pancreatic stimulation in dogs

Chronic pancreatitis in dogs is typically managed with a low-fat diet. Human research suggests that consumption of medium-chain triglycerides (MCT) may lessen pancreatic enzyme release compared to consumption of long-chain fatty acids (LCFA). Twelve healthy adult colony dogs were fed a meal of cod and rice with either 3% metabolizable energy (ME) fat (control), high MCT (25% ME MCT oil, 25% ME butter), high saturated LCFA (50% ME butter), or high unsaturated LCFA (50% ME canola oil) in a 4-period by 4-treatment crossover design. Serum concentrations of canine pancreatic lipase immunoreactivity, gastrin, cholesterol, triglycerides, and serum activities of amylase and DGGR lipase (1,2-o-dilauryl-rac-glycero-3-glutaric acid-(69-methylresorufin) ester lipase) were measured at times 0 (fasted), 30, 120 and 180 minutes post-prandially. Following a 3-or 4-day wash-out period, each dog was assigned a new diet and the process was repeated for all treatments. Data were analyzed as a repeated-measures mixed model ANOVA. Post-hoc pairwise comparisons were run using Tukey-Kramer adjusted p-values. Shapiro-Wilk tests were used to evaluate residual normality. All statistical assumptions were sufficiently met. Statistical significance was defined as P<0.05. Of the markers tested, only serum triglyceride concentrations were affected by treatment, with consumption of high MCT resulting in lower triglycerides than both LCFA groups at times 120 and 180 minutes (P<0.0001). As expected, the high MCT group had higher triglycerides compared to the control group (P<0.0001). The type of dietary fat consumed had little acute impact on most markers of exocrine pancreatic stimulation in healthy dogs.

Risk factors and assessment considerations for essential fatty acid deficiency in nonparenterally fed patients using a case example

Essential fatty acid deficiency (EFAD) has most commonly been reported in parenterally fed individuals but may also present in patients receiving fat-restricted diets and in patients with fat-malabsorption disorders. This article reviews the physical and biochemical assessment for EFAD in clinical practice and disorders of fat malabsorption as potential risk factors for EFAD. A case report is included to describe the fatty acid profile of a patient with exocrine pancreatic insufficiency receiving low-dose pancreatic enzyme replacement therapy after a self-imposed fat-restricted diet. The current challenges with laboratory interpretation of essential fatty acid status are also discussed.

Gastrointestinal Toxicity of Pelvic Radiotherapy: Are We Letting Women Down?

For all cancers there are four areas of importance: prevention, early diagnosis, optimising therapy and living with and beyond. For women diagnosed with gynaecological cancers, progress in these first three areas has been immense. However, living with and beyond has largely been ignored as a significant issue. As a group, patients treated for gynaecological cancer are more often young and more often suffer the most difficult long-term issues. Despite the growing number of long-term survivors, little has been done to ensure appropriate assessment and treatment of side-effects of cancer therapies, especially when radiotherapy has been used. For many affected patients their symptoms become part of everyday life, 'normality' is adjusted and these changes are tolerated even when severely limiting activities. Data show that even expert clinicians frequently do not appreciate the true impact of these problems and the focus of treatment and of follow-up remains fixed on 5-year survival and cancer recurrence, respectively. Many clinicians are unaware of what experts can do for toxicity and do not know where to refer their patients. However, rapid identification of patients with significant symptoms can lead to earlier diagnosis of treatable pathologies and improvement in patients' quality of life. In addition, the underlying pathophysiology of radiation-induced damage is potentially amenable to disease-modifying therapies. This review focuses on the factors that contribute to patients developing pelvic radiation disease, what can be done to mitigate the toxicity of treatment and highlights the challenges that must be addressed to reduce the gastrointestinal toxicity of pelvic radiotherapy.

Intestinal sensing and handling of dietary lipids in gastric bypass-operated patients and matched controls

BACKGROUND

Altered meal-related gut hormone secretion seems important for weight loss and diabetes remission after Roux-en-Y gastric bypass (RYGB). Elucidating the responsible meal components and receptors could aid discovery of new treatments of obesity and diabetes. Enteroendocrine cells respond to digestion products of dietary triacylglycerol, especially long-chain fatty acids (LCFAs) and 2-oleoyl-glycerol (2-OG), but not medium-chain fatty acids (MCFAs).

OBJECTIVE

We examined the impact of olive oil (20 mL) and its derivates, LCFAs and 2-OG, on enteroendocrine secretions [glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), cholecystokinin (CCK), peptide YY (PYY), and neurotensin (NT)] and on glucose, lipid, and bile acid metabolism in RYGB-operated and unoperated individuals.

METHODS

In an exploratory randomized crossover design, 10 RYGB-operated patients and 10 matched controls ingested 3 equimolar triacylglycerol formulations on separate days: olive oil (digested to 2-OG + LCFAs), C8-dietary oil (2-OG + MCFAs), and tricaprylin (MCFAs; negative control). Hormone responses were calculated as area under the curve (AUC).

RESULTS

Independent of group status, olive oil had greater effects than C8-dietary oil on AUCs of plasma GLP-1 (+32%; 95% CI: 23%, 43%; P < 0.01), CCK (+53%, P < 0.01), and NT (+71%, P < 0.01), whereas the effect on GIP differed between groups (+90% in controls, P < 0.01; +24% in RYGB, P = 0.10). Independent of group status, C8-dietary oil had greater effects than tricaprylin on AUCs of plasma CCK (+40%, P < 0.01) and NT (+32%, P < 0.01), but not GLP-1 (+5%; 95% CI: -2.9%, 13%; P = 0.22), whereas the effect on GIP again differed between groups (+78% in controls, P < 0.01; +39% in RYGB, P = 0.01). Distal (GLP-1/PYY/NT), but not proximal (CCK/GIP), enteroendocrine responses were generally greater in RYGB patients than in controls.

CONCLUSIONS

The combination of LCFAs plus 2-OG was substantially more effective than 2-OG plus MCFAs in stimulating enteroendocrine secretion in RYGB-operated and matched control individuals. Distal lipid-induced gut hormone release was greater after RYGB.This trial was registered at clinicaltrials.gov as NCT03223389.

Nutritional strategies to prevent gastrointestinal toxicity during pelvic radiotherapy

Radiotherapy-induced damage to non-cancerous gastrointestinal mucosa has effects on secretory and absorptive functions and can interfere with normal gastrointestinal physiology. Nutrient absorption and digestion may be compromised. Dietary manipulation is an attractive option with sound rationale for intervention. The aim of this review was to synthesise published evidence for the use of elemental formulae, low or modified fat diets, fibre, lactose restriction and probiotics, prebiotics and synbiotics to protect the bowel from gastrointestinal side effects during long-course, radical pelvic radiotherapy. Thirty original studies (recruiting n 3197 patients) were identified comprising twenty-four randomised controlled trials, four cohort studies and two comparator trials. Endpoints varied and included symptom scales (Inflammatory Bowel Disease Questionnaire, Common Technology Criteria for Adverse Events, Radiation Therapy Oncology Group) and Bristol Stool Scale. Dietary and supplement interventions were employed with many studies using a combination of interventions. Evidence from RCT was weak for elemental, low or modified fat and low-lactose interventions and modestly positive for the manipulation of fibre during radiotherapy. Evidence for probiotics as prophylactic interventional agents was more promising with a number of trials reporting positive results but strength and strains of interventions vary, as do methodologies and endpoints making it difficult to arrive at firm conclusions with several studies lacking statistical power. This consolidated review concludes that there is insufficient high-grade evidence to recommend nutritional intervention during pelvic radiotherapy. Total replacement of diet with elemental formula could be effective in severe toxicity but this is unproven. Probiotics offer promise but cannot be introduced into clinical practice without rigorous safety analysis, not least in immunocompromised patients.

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.

Randomised clinical study: Aspergillus niger-derived enzyme digests gluten in the stomach of healthy volunteers

BACKGROUND

Aspergillus niger prolyl endoprotease (AN-PEP) efficiently degrades gluten molecules into non-immunogenic peptides in vitro.

AIM

To assess the efficacy of AN-PEP on gluten degradation in a low and high calorie meal in healthy subjects.

METHODS

In this randomised, double-blind, placebo-controlled, cross-over study 12 healthy volunteers attended to four test days. A liquid low or high calorie meal (4 g gluten) with AN-PEP or placebo was administered into the stomach. Via a triple-lumen catheter gastric and duodenal aspirates were sampled, and polyethylene glycol (PEG)-3350 was continuously infused. Acetaminophen in the meals tracked gastric emptying time. Gastric and duodenal samples were used to calculate 240-min area under the curve (AUC0-240 min ) of ?-gliadin concentrations. Absolute ?-gliadin AUC0-240 min was calculated using duodenal PEG-3350 concentrations.

RESULTS

AN-PEP lowered α-gliadin concentration AUC0-240 min, compared to placebo, from low and high calorie meals in stomach (low: 35 vs. 389 μg × min/mL; high: 53 vs. 386 μg × min/mL; P < 0.001) and duodenum (low: 7 vs. 168 μg × min/mL; high: 4 vs. 32 μg × min/mL; P < 0.001) and absolute α-gliadin AUC0-240 min in the duodenum from low (2813 vs. 31 952 μg × min; P < 0.001) and high (2553 vs. 13 095 μg × min; P = 0.013) calorie meals. In the placebo group, the high compared to low calorie meal slowed gastric emptying and lowered the duodenal α-gliadin concentration AUC0-240 min (32 vs. 168 μg × min/mL; P = 0.001).

CONCLUSIONS

AN-PEP significantly enhanced gluten digestion in the stomach of healthy volunteers. Increasing caloric density prolonged gastric residence time of the meal. Since AN-PEP already degraded most gluten from low calorie meals, no incremental effect was observed by increasing meal caloric density. ClinicalTrials.gov, Number: NCT01335503; www.trialregister.nl, Number: NTR2780.

Systematic review: the efficacy of nutritional interventions to counteract acute gastrointestinal toxicity during therapeutic pelvic radiotherapy

BACKGROUND

Radiotherapy-induced damage to noncancerous gastrointestinal mucosa has effects on secretory and absorptive functions and can interfere with normal gastrointestinal physiology. Nutrient absorption and digestion may be compromised. Dietary manipulation is an attractive option for the prevention and management of symptoms.

AIM

To synthesise the evidence for the use of elemental formula low- or modified-fat diets, fibre, lactose restriction and probiotics, prebiotics and synbiotics to protect the gastrointestinal tract during pelvic radiotherapy.

METHODS

Four electronic databases were searched. Randomised controlled trials (RCT), controlled trials (CT) and case series in adult patients receiving radiotherapy for pelvic cancers employing nutritional interventions to reduce gastrointestinal toxicity were included. Methodological quality was assessed using a bespoke tool.

RESULTS

Twenty-two original studies (2446 patients) were identified. Study quality was highly variable with only 37% scoring ≥10 points (maximum 17: bespoke scale). Few studies assessed compliance with the intervention. End-points varied and included symptom scales (IBDQ, CTC, Bristol Stool and RTOG). Evidence from RCTs was weak for elemental, low- or modified-fat, fibre and low-lactose interventions with 1/4, 3/4, 1/2, 0/1 trials respectively reporting favourable outcomes. Evidence for probiotics as prophylactic interventions was more promising (4/5 favourable), but dose, strains and methodologies varied.

CONCLUSIONS

There is insufficient high-grade evidence to recommend nutritional intervention during pelvic radiotherapy. Total replacement of diet with elemental formula may be appropriate in severe toxicity. Probiotics offer promise, but cannot be introduced into clinical practice without rigorous safety analysis, not least in immunocompromised patients. The methodological quality of nutritional intervention studies needs to be improved.

Clinical trial: Efficacy of a low or modified fat diet for the prevention of gastrointestinal toxicity in patients receiving radiotherapy treatment for pelvic malignancies

BACKGROUND

Inflammatory responses to pelvic radiotherapy can result in severe changes to normal gastrointestinal function with potentially severe long-term effects. Reduced or modified fat diets may confer benefit.

METHODS

This randomised controlled trial recruited patients with gynaecological, urological or lower gastrointestinal malignancy due to receive radical radiotherapy. Patients were randomised to a low fat (20% total energy from long chain triglycerides), modified fat (20% from long chain triglycerides and 20% from medium chain triglycerides) or normal fat diet (40% total energy from long chain triglycerides). The primary outcome was a difference in change in Inflammatory Bowel Disease Questionnaire--Bowel (IBDQ-B) score, from the start to end of radiotherapy.

RESULTS

A total of 117 patients with pelvic tumours (48% urological; 32% gastrointestinal; 20% gynaecological), with mean (SD) age: 65 (11.0) years, male:female ratio: 79:38, were randomised. The mean (SE) fall in paired IBDQ-B score was -7.3 (0.9) points, indicating a worsening toxicity. Differences between groups were not significant: P = 0.914 (low versus modified fat), P = 0.793 (low versus normal fat) and P = 0.890 (modified versus normal fat). The difference in fat intake between low and normal fat groups was 29.5 g [1109 kJ (265 kcal)] amounting to 11% (of total energy intake) compared to the planned 20% differential. Full compliance with fat prescription was only 9% in the normal fat group compared to 93% in the low fat group.

CONCLUSIONS

A low or modified fat diet during pelvic radiotherapy did not improve gastrointestinal symptom scores compared to a normal fat intake. An inadequate differential in fat intake between the groups may have confounded the results.

Nutritional and physiological role of medium-chain triglycerides and medium-chain fatty acids in piglets

Medium-chain fatty acids (MCFAs) are found at higher levels in milk lipids of many animal species and in the oil fraction of several plants, including coconuts, palm kernels and certainCupheaspecies. Medium-chain triglycerides (MCTs) and fatty acids are efficiently absorbed and metabolized and are therefore used for piglet nutrition. They may provide instant energy and also have physiological benefits beyond their energetic value contributing to several findings of improved performance in piglet-feeding trials. MCTs are effectively hydrolyzed by gastric and pancreatic lipases in the newborn and suckling young, allowing rapid provision of energy for both enterocytes and intermediary hepatic metabolism. MCFAs affect the composition of the intestinal microbiota and have inhibitory effects on bacterial concentrations in the digesta, mainly onSalmonellaand coliforms. However, most studies have been performedin vitroup to now andin vivodata in pigs are still scarce. Effects on the gut-associated and general immune function have been described in several animal species, but they have been less studied in pigs. The addition of up to 8% of a non-esterified MCFA mixture in feed has been described, but due to the sensory properties this can have a negative impact on feed intake. This may be overcome by using MCTs, allowing dietary inclusion rates up to 15%. Feeding sows with diets containing 15% MCTs resulted in a lower mortality of newborns and better development, particularly of underweight piglets. In conclusion, MCFAs and MCTs offer advantages for the improvement of energy supply and performance of piglets and may stabilize the intestinal microbiota, expanding the spectrum of feed additives supporting piglet health in the post-weaning period.

Enteral nutrition improves clinical outcome and shortens hospital stay after cancer surgery

BACKGROUND AND AIMS

The aim of our study was to investigate whether medium-chain triglyceride (MCT) and protein-enriched enteral nutrition (EN) could improve protein level and clinical outcomes in postoperative patients with gastrointestinal cancer.

MATERIAL AND METHODS

A randomized clinical trial was performed. A population of 229 patients with gastrointestinal cancer was enrolled and allocated to two groups: (a) 114 patients received MCT and protein-enriched EN (Group I) and (b) 115 patients received an isocaloric EN (Group II). The total calorie was 25 kcal/kg/day and the time period of full dose of EN must be at least five days.

RESULTS

The three plasma proteins were improved after the EN support in both groups (p < .05). But, the increase of prealbumin in Group I was higher than that in Group II (p < .05). Episodes of diarrhea rate were equal and the postoperative infectious complications were not different between both groups. The length of hospital stay was shorter in Group I (18.4 ± 12 vs. 24.5 ± 15 d; p < .05).

CONCLUSIONS

MCT and protein-enriched EN improves the prealbumin level and shortens the length of hospital stay in patients with gastrointestinal cancer without a high rate of adverse reaction, which may be due to high content of MCT and protein in EN.

Nutrition treatment of deficiency and malnutrition in chronic pancreatitis: a review

Chronic pancreatitis results in exocrine and endocrine dysfunction, affecting normal digestion and absorption of nutrients. In individuals with chronic pancreatitis, nutrition status may be further affected by poor dietary intake, often related to alcoholism. However, some deficiencies may be overlooked, potentially leading to nutrition-related problems with bone health and fatigue. The aim of this article is to describe the deficiencies that occur and to propose an evidence-based algorithm for the nutrition assessment and treatment of patients with chronic pancreatitis.

Control of pancreatic secretion in humans

Studies on the control of pancreatic secretion in humans of all ages have been a difficult task over the years because of patients' availability and ethic committee rules. Nevertheless, studies were performed and the objectives of this review are to summarize our knowledge on the development of secretory process in newborns, on the different phases of the pancreatic responses to a meal, on the pancreatic responses to the different components of the diet, on the mechanisms involved in the control of the pancreatic responses, and finally on the receptors involved in these controls.

The combined use of triacylglycerols containing medium-chain fatty acids and exogenous lipolytic enzymes as an alternative to in-feed antibiotics in piglets: concept, possibilities and limitations. An overview

In the search for alternatives to banned in-feed antibiotics, a concept was developed based on studies with medium-chain fatty acid-containing triacylglycerols (MCTAG) and selected lipases for in situ generation of diacylglycerols, monoacylglycerols and medium-chain fatty acids (MCFA) in the stomach and proximal gut of piglets. MCFA are known to have strong antibacterial properties but can hardly be used as such because of their repellent odour and taste. Those problems could be overcome by the generation of MCFA in situ. The concept was tested in vitro and validated in vivo with gastric-cannulated piglets and under field conditions, including effects on zootechnical performance, with classical antibacterial growth promoters or organic acids acting as positive controls. Furthermore, the metabolic and dietary constraints on the nutritional and nutritive use of MCTAG and/or MCFA (for example, the effects on digestive physiology, gut flora, feed intake, performance, carcass composition) are reviewed. The role of natural preduodenal lipase activity, the presence of endogenous plant lipase activity in raw materials and the feasibility for exogenous lipase addition to the feed are discussed, in order to optimize the concept. The present review illustrates the similarity of the action of MCFA and commonly used antimicrobials on the flora (total flora, Gram-positive flora, Gram-negative flora, potential pathogens) and epithelial morphology and histology in the foregut. These observations are believed to be the basis for obtaining optimal growth performances. In addition, these naturally occurring antimicrobial agents have little or no human or animal toxicity and induce no problems of residues and cross-resistance induction. They are proposed as a valuable alternative to in-feed antibiotics, used for growth promotion, and even for the preventive and curative treatment of gastrointestinal diseases.

Effect of fat saturation on satiety, hormone release, and food intake

BACKGROUND

Ileal delivery of fat reduces hunger and food intake through activation of the ileal brake. Physicochemical properties of fat have been shown to affect satiety and food intake.

OBJECTIVE

The objective of this study was to assess the effect of ileal fat emulsions with differing degrees of fatty acid saturation on satiety, food intake, and gut peptides (cholecystokinin and peptide YY). We hypothesized that long-chain triacylglycerols with diunsaturated fatty acids would increase satiety and reduce energy intake compared with long-chain triacylglycerols with monounsaturated or saturated fatty acids.

DESIGN

We performed a double-blind, randomized, crossover study in which 15 healthy subjects [mean age: 24 y; mean body mass index (in kg/m(2)): 22] were intubated with a naso-ileal catheter and participated in 4 experiments performed in random order on 4 consecutive days. After consumption of a liquid meal, subjects received a fat or control infusion in the ileum. Fat emulsions consisted of 6 g of 18:0 (shea oil; mainly 18:0), 18:1 (canola oil; mainly 18:1), or 18:2 (safflower oil; mainly 18:2) oils. Food intake was measured during an ad libitum lunch. Satiety questionnaires (visual analog scale) and blood samples were collected at regular intervals.

RESULTS

Compared with the control, only 18:2 and 18:1 significantly increased fullness and reduced hunger. No effect on food intake was observed. 18:1 and 18:2 increased cholecystokinin secretion significantly compared with the control. Fatty acid saturation did not affect peptide YY secretion.

CONCLUSIONS

When infused into the ileum, triacylglycerols with unsaturated fatty acids increase satiety, whereas triacylglycerols with saturated fatty acids does not. This trial was registered with the Dutch Trial Register as: ISRCTN51742545.

Effect of ileal fat perfusion on satiety and hormone release in healthy volunteers

OBJECTIVE

The ileal brake is a feedback mechanism activated by nutrients, especially fat, with marked effects on satiety. The effects of low doses of ileal fat on satiety are largely unknown. We therefore studied the effect of ileal vs oral delivery of low doses of fat on satiety and gut peptide secretion.

DESIGN

Randomized, single-blind crossover design.

SUBJECTS

Sixteen healthy, normal-weight volunteers (6 male; mean age 26 years, mean body mass index 22.4).

INTERVENTION

Participants were intubated with a 290-cm-long nasoileal tube and consumed, on 3 consecutive days, either a liquid breakfast with 3 g fat followed by an ileal placebo infusion at t=105-150 min (treatment C) or a fat-free liquid breakfast followed by an ileal infusion of either an emulsion of 3 g (treatment 13 g) or 9 g (treatment 19 g) fat (safflower oil).

MEASUREMENTS

Satiety parameters by visual analog scales and plasma concentrations of CCK and PYY.

RESULTS

C significantly increased satiety and CCK secretion compared with the fat-free breakfast. Ileal fat perfusion of both 3 and 9 g 13 g and 19 g) significantly increased satiety during and after fat perfusion, without differences in satiety between 13 g and 19 g. During ileal fat infusion, CCK increased dose dependently, whereas PYY concentrations increased significantly only after 9 g of fat. Secretion of CCK but not of PYY correlated to satiety levels.

CONCLUSION

Postprandial satiety following a liquid breakfast can be effectively and significantly increased by small amounts (as little as 3 g) of fat perfused into the ileum. Ileal fat dose-dependently increased CCK but not PYY secretion. The satiating effect of ileal fat may be partly mediated by CCK.

Dietary counseling versus dietary supplements for malnutrition in chronic pancreatitis: a randomized controlled trial

BACKGROUND & AIMS

Up to 50% of patients with chronic pancreatitis (CP) are malnourished. There are limited data on the role of dietary intervention in improving the nutritional status of such patients. The aim was to compare the efficacy of medium chain triglyceride (MCT)-enriched commercial dietary supplements with dietary counseling for homemade food in the management of malnutrition in patients with CP.

METHODS

In a randomized controlled trial, consecutive undernourished patients with CP (body mass index [BMI] <18.5 kg/m(2)) at a tertiary care hospital were randomized to receive either dietary counseling for regular homemade food or commercial MCT-enriched dietary supplements for a period of 3 months to compensate for the dietary calorie deficit. All patients received standard management for CP including pancreatic enzyme supplements. Primary outcome measure was improvement in BMI.

RESULTS

Sixty malnourished patients with CP were randomized to counseling group (n = 29; mean age, 32 +/- 10 years; male, 83%) and supplementation group (n = 31; mean age, 28 +/- 10 years; male, 84%). BMI increased in both the counseling group and supplementation group (17.2 +/- 1.7 vs 18.1 +/- 1.8 kg/m(2), P = .001; 16.7 +/- 1.6 vs 18.2 +/- 1.6 kg/m(2), P = .001). There were similar improvements in triceps skinfold thickness, dietary intake, fecal fat, and pain score during a period of 3 months in both groups. There was, however, no significant difference between the counseling and supplementation groups with regard to any of the outcome measures.

CONCLUSIONS

Dietary counseling for a balanced homemade diet is as good as commercial food supplements in improving malnutrition in patients with CP.

Acute pancreatitis

PURPOSE OF REVIEW

This review presents advances in our understanding of the pathobiologic responses that mediate acute pancreatitis with an emphasis on the interrelationship between the events occurring in the pancreatic acinar cell and the vascular, neural, and immune systems; information on recent reports describing clinical diagnostic and therapeutic aspects of autoimmune pancreatitis; and information on feeding strategies during acute pancreatitis.

RECENT FINDINGS

The reports during the past year provide important and clinically relevant findings about roles of intracellular events as well as vascular and neural regulatory pathways involved in the mechanism of pancreatitis. Reports during the past year also add to our rapidly growing portfolio describing the characteristics, course, and therapeutic responses in autoimmune pancreatitis. Finally, a provocative report demonstrates that a low-fat elemental-like diet administered by nasogastric tube during severe pancreatitis does not worsen outcome compared with administration of the diet by nasojejunal tube. This report provides rationale for early feeding in these patients by a simpler route than previously recommended and also raises the question about the types of nutrients that should be used in this situation that have the least effect on neurohumoral stimulation of the pancreas.

SUMMARY

Our understanding of the mechanistic processes that mediate the pathobiologic responses of pancreatitis is rapidly evolving. The continuing challenge is to translate these findings into treatment strategies for pancreatitis.

Effect of peptide YY on pancreatico-biliary secretion in humans

OBJECTIVE

The negative feedback on pancreatico-biliary secretion induced by ileal nutrients has been well documented but the role of the distal gut peptide YY (PYY) as mediator is less well defined. We determined the effect of PYY on basal, sham feeding and feeding-stimulated pancreatico-biliary secretion in humans.

MATERIAL AND METHODS

Eight healthy volunteers participated in a placebo-controlled, double-blind, randomized study with intravenous infusion of a physiological dose of PYY. Subjects were intubated with a naso-jejunal tube. Duodenal samples were aspirated continuously while a recovery marker perfused the duodenum. Outputs were measured in the basal state, in response to modified sham feeding (MSF) and during jejunal perfusion with a liquid meal. Blood samples were drawn for plasma cholecystokinin (CCK) and PYY measurements.

RESULTS

PYY infusion significantly (p<0.01) increased plasma PYY, from 16+/-2 to 55+/-6 pM. Basal outputs of amylase, lipase, trypsin and bilirubin were not affected by PYY. In the placebo experiment, MSF significantly increased amylase, lipase, trypsin and bilirubin outputs. However, during PYY infusion lipase, trypsin and bilirubin outputs did not significantly increase in response to MSF. Jejunal feeding, however, significantly (p<0.01) increased the outputs of bilirubin and enzymes equally during both the placebo and PYY infusions.

CONCLUSIONS

Infusion of PYY to physiological plasma levels exerts an inhibitory effect on pancreatico-biliary secretion during the cephalic phase of digestion, but not in the basal state or during the intestinal phase. PYY suppresses pancreatico-biliary secretion during the cephalic phase but not during the intestinal phase of nutrient digestion.

Neurohumoral control of exocrine pancreatic secretion

Reports over the past year provide significant advances in our knowledge of the neurohumoral control of exocrine pancreatic secretion, especially related to human physiology. Major findings include those demonstrating that human pancreatic acinar cells do not respond to cholecystokinin stimulation and that a major circulating form of cholecystokinin is CCK-58. These findings establish that in humans, cholecystokinin causes pancreatic secretion via a neural circuit after interacting with neural sensory receptors in the mucosa of the intestine and that CCK-58 is the likely form of cholecystokinin that stimulates the neural pathways. Other findings demonstrate significant differences in the pancreatic secretory response in humans as a function of the type of nutrient delivered to the gut, especially the fact the elemental diets and medium-chain triglycerides cause much less stimulation of pancreatic secretion than do complex diets. Finally, convincing evidence demonstrating that pancreatic proteases cause inhibition of pancreatic secretion in humans has been presented. In addition to new insights into the neurohumoral control of pancreatic secretion, these findings provide information relevant to both the pathogenesis of pancreatic disorders and their treatment.