Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancer

Transition from traditional high-fiber to Western diets in urbanizing communities of Sub-Saharan Africa is associated with increased risk of non-communicable diseases (NCD), exemplified by colorectal cancer (CRC) risk. To investigate how urbanization gives rise to microbial patterns that may be amenable by dietary intervention, we analyzed diet intake, fecal 16 S bacteriome, virome, and metabolome in a cross-sectional study in healthy rural and urban Xhosa people (South Africa). Urban Xhosa individuals had higher intakes of energy (urban: 3,578 ± 455; rural: 2,185 ± 179 kcal/d), fat and animal protein. This was associated with lower fecal bacteriome diversity and a shift from genera favoring degradation of complex carbohydrates (e.g., Prevotella) to taxa previously shown to be associated with bile acid metabolism and CRC. Urban Xhosa individuals had higher fecal levels of deoxycholic acid, shown to be associated with higher CRC risk, but similar short-chain fatty acid concentrations compared with rural individuals. Fecal virome composition was associated with distinct gut bacterial communities across urbanization, characterized by different dominant host bacteria (urban: Bacteriodota; rural: unassigned taxa) and variable correlation with fecal metabolites and dietary nutrients. Food and skin microbiota samples showed compositional differences along the urbanization gradient. Rural-urban dietary transition in South Africa is linked to major changes in the gut microbiome and metabolome. Further studies are needed to prove cause and identify whether restoration of specific components of the traditional diet will arrest the accelerating rise in NCDs in Sub-Saharan Africa.

Fibre-rich Foods to Treat Obesity and Prevent Colon Cancer trial study protocol: a randomised clinical trial of fibre-rich legumes targeting the gut microbiome, metabolome and gut transit time of overweight and obese patients with a history of noncancerous adenomatous polyps

INTRODUCTION

Recently published studies support the beneficial effects of consuming fibre-rich legumes, such as cooked dry beans, to improve metabolic health and reduce cancer risk. In participants with overweight/obesity and a history of colorectal polyps, the Fibre-rich Foods to Treat Obesity and Prevent Colon Cancer randomised clinical trial will test whether a high-fibre diet featuring legumes will simultaneously facilitate weight reduction and suppress colonic mucosal biomarkers of colorectal cancer (CRC).

METHODS/DESIGN

This study is designed to characterise changes in (1) body weight; (2) biomarkers of insulin resistance and systemic inflammation; (3) compositional and functional profiles of the faecal microbiome and metabolome; (4) mucosal biomarkers of CRC risk and (5) gut transit. Approximately 60 overweight or obese adults with a history of noncancerous adenomatous polyps within the previous 3 years will be recruited and randomised to one of two weight-loss diets. Following a 1-week run-in, participants in the intervention arm will receive preportioned high-fibre legume-rich entrées for two meals/day in months 1-3 and one meal/day in months 4-6. In the control arm, entrées will replace legumes with lean protein sources (eg, chicken). Both groups will receive in-person and written guidance to include nutritionally balanced sides with energy intake to lose 1-2 pounds per week.

ETHICS AND DISSEMINATION

The National Institutes of Health fund this ongoing 5-year study through a National Cancer Institute grant (5R01CA245063) awarded to Emory University with a subaward to the University of Pittsburgh. The study protocol was approved by the Emory Institutional Review Board (IRB approval number: 00000563).

TRIAL REGISTRATION NUMBER

NCT04780477.

Is Salt at Fault? Dietary Salt Consumption and Inflammatory Bowel Disease

Epidemiological trends have led to a growing consensus that diet plays a central role in the etiopathogenesis of inflammatory bowel diseases (IBD). A Western diet high in ultra-processed foods has been associated with an increased prevalence of IBD worldwide. Much attention has focused on components of the Western diet, including the high fat content, lack of fiber, added sugars, and use of additives, such as carrageenan and other emulsifiers. Less attention has been paid to the impact of high salt intake, an integral component of ultra-processed foods, which has increased dramatically in the US diet over the past 50 years. We review a growing body of literature linking the rise in dietary salt intake with the epidemiology of IBD, increased consumption of salt as a component of ultra-processed foods, high salt intake and imbalances in immune homeostasis, the effects of a high-salt diet on other inflammatory disorders, salt's impact on animal colitis models, salt as an underrecognized component in diet modification-induced remission of IBD, and directions for future investigation.

Interactions between the environmental and human microbiota in the preservation of health and genesis of disease: symposium report

PURPOSE OF REVIEW

The purpose of this symposium was to bring thought leaders in the microbiome from the west to Africa to share their unique experiences with African investigators in order to build the foundations for scientifically rigorous explorations into the African human and environmental microbiome that may explain why disease patterns are different in Africa where the chief killers are infectious diseases, whereas noncommunicable diseases (NCDs) are the major threat to healthcare resources in the developed world.

RECENT FINDINGS

The application of new high throughput technologies to the investigation of the microbiome and its metabolome has revealed mechanisms whereby a traditional African high fiber diet can suppress NCDs which include colon cancer, inflammatory bowel diseases, obesity, type 2 diabetes and atherosclosis. There is concern that with migration and westernization, NCDs are becoming more common in Africa and that food security is becoming impaired by unbalanced obesogenic foods rather than inadequate food intake.

SUMMARY

There is an urgent need for the formation of combined African-Western research programs to identify what is good and bad in the African diet-microbiome axis to develop strategies to prevent the incidence of NCDs rising to western levels in Africa, at the same time offering novel prevention strategies against the #1 healthcare threat in the developed world.

Dietary fibre to reduce colon cancer risk in Alaska Native people: the Alaska FIRST randomised clinical trial protocol

INTRODUCTION

Diet, shown to impact colorectal cancer (CRC) risk, is a modifiable environmental factor. Fibre foods fermented by gut microbiota produce metabolites that not only provide food for the colonic epithelium but also exert regulatory effects on colonic mucosal inflammation and proliferation. We describe methods used in a double-blinded, randomised, controlled trial with Alaska Native (AN) people to determine if dietary fibre supplementation can substantially reduce CRC risk among people with the highest reported CRC incidence worldwide.

METHODS AND ANALYSES

Eligible patients undergoing routine screening colonoscopy consent to baseline assessments and specimen/data collection (blood, urine, stool, saliva, breath and colon mucosal biopsies) at the time of colonoscopy. Following an 8-week stabilisation period to re-establish normal gut microbiota post colonoscopy, study personnel randomise participants to either a high fibre supplement (resistant starch, n=30) or placebo (digestible starch, n=30) condition, repeating stool sample collection. During the 28-day supplement trial, each participant consumes their usual diet plus their supplement under direct observation. On day 29, participants undergo a flexible sigmoidoscopy to obtain mucosal biopsy samples to measure the effect of the supplement on inflammatory and proliferative biomarkers of cancer risk, with follow-up assessments and data/specimen collection similar to baseline. Secondary outcome measures include the impact of a high fibre supplement on the oral and colonic microbiome and biofluid metabolome.

ETHICS AND DISSEMINATION

Approvals were obtained from the Alaska Area and University of Pittsburgh Institutional Review Boards and Alaska Native Tribal Health Consortium and Southcentral Foundation research review bodies. A data safety monitoring board, material transfer agreements and weekly study team meetings provide regular oversight throughout the study. Study findings will first be shared with AN tribal leaders, health administrators, providers and community members. Peer-reviewed journal articles and conference presentations will be forthcoming once approved by tribal review bodies.

TRIAL REGISTRATION NUMBER

NCT03028831.

Dietary fat, bile acid metabolism and colorectal cancer

Colorectal cancer (CRC) risk is predominantly driven by environmental factors, in particular diet. A high intake of dietary fat has been implicated as a risk factor inducing the formation of pre-neoplastic lesions (e.g., adenomatous polyps) and/or exacerbating colonic tumorigenesis. Recent data attributed the tumor-promoting activity of high-fat diets to their effects on gut microbiota composition and metabolism, in particular with regard to bile acids. Bile acids are synthesized in the liver in response to dietary fat and facilitate lipid absorption in the small intestine. The majority of bile acids is re-absorbed during small intestinal transit and subjected to enterohepatic circulation. Bile acids entering the colon undergo complex biotransformation performed by gut bacteria, resulting in secondary bile acids that show tumor-promoting activity. Excessive dietary fat leads to high levels of secondary bile acids in feces and primes the gut microbiota to bile acid metabolism. This promotes an altered overall bile acid pool, which activates or restricts intestinal and hepatic cross-signaling of the bile acid receptor, farnesoid X receptor (FXR). Recent studies provided evidence that FXR is a main regulator of bile acid-mediated effects on intestinal tumorigenesis integrating dietary, microbial and genetic risk factors for CRC. Selective FXR agonist or antagonist activity by specific bile acids depends on additional factors (e.g., bile acid concentration, composition of bile acid pool, genetic instability of cells) and, thus, may differ in healthy and tumorigenic conditions in the intestine. In conclusion, fat-mediated alterations of the gut microbiota link bile acid metabolism to CRC risk and colonic tumorigenesis, exemplifying how gut microbial co-metabolism affects colon health.

A prospective cohort analysis of gut microbial co-metabolism in Alaska Native and rural African people at high and low risk of colorectal cancer

BACKGROUND

Alaska Native (AN) people have the world's highest recorded incidence of sporadic colorectal cancer (CRC) (∼91:100,000), whereas rural African (RA) people have the lowest risk (<5:100,000). Previous data supported the hypothesis that diet affected CRC risk through its effects on the colonic microbiota that produce tumor-suppressive or -promoting metabolites.

OBJECTIVES

We investigated whether differences in these metabolites may contribute to the high risk of CRC in AN people.

METHODS

A cross-sectional observational study assessed dietary intake from 32 AN and 21 RA healthy middle-aged volunteers before screening colonoscopy. Analysis of fecal microbiota composition by 16S ribosomal RNA gene sequencing and fecal/urinary metabolites by 1H-NMR spectroscopy was complemented with targeted quantification of fecal SCFAs, bile acids, and functional microbial genes.

RESULTS

Adenomatous polyps were detected in 16 of 32 AN participants, but not found in RA participants. The AN diet contained higher proportions of fat and animal protein and less fiber. AN fecal microbiota showed a compositional predominance of Blautia and Lachnoclostridium, higher microbial capacity for bile acid conversion, and low abundance of some species involved in saccharolytic fermentation (e.g., Prevotellaceae, Ruminococcaceae), but no significant lack of butyrogenic bacteria. Significantly lower concentrations of tumor-suppressive butyrate (22.5 ± 3.1 compared with 47.2 ± 7.3 SEM µmol/g) coincided with significantly higher concentrations of tumor-promoting deoxycholic acid (26.7 ± 4.2 compared with 11 ± 1.9 µmol/g) in AN fecal samples. AN participants had lower quantities of fecal/urinary metabolites than RA participants and metabolite profiles correlated with the abundance of distinct microbial genera in feces. The main microbial and metabolic CRC-associated markers were not significantly altered in AN participants with adenomatous polyps.

CONCLUSIONS

The low-fiber, high-fat diet of AN people and exposure to carcinogens derived from diet or environment are associated with a tumor-promoting colonic milieu as reflected by the high rates of adenomatous polyps in AN participants.

Fiber, Fat, and Colorectal Cancer: New Insight into Modifiable Dietary Risk Factors

PURPOSE OF REVIEW

To review recent data on the role and interactions of fiber and fat as dietary risk factors associated with colorectal cancer (CRC) risk in humans.

RECENT FINDINGS

Fiber intake shows convincing and linear dose-response negative correlation with CRC risk. Dietary fiber stimulates butyrogenic activity of the gut microbiota, providing high amounts of butyrate that shows extensive anti-neoplastic effects. A high-fat diet promotes CRC risk through stimulated bile acid metabolism, facilitating bile acid conversion by the gut microbiota to tumor-promoting deoxycholic acid. Comprehensive interactions of these microbial metabolites are likely to underlie mechanisms driving diet-dependent CRC risk in different populations, but require further experimental investigation. Dietary fiber and fat shape the composition and metabolic function of the gut microbiota, resulting in altered amounts of butyrate and deoxycholic acid in the colon. Fiber supplementation and restriction of fat intake represent promising strategies to reduce CRC risk in healthy individuals.

Association of Dietary Habits with Severity of Acute Pancreatitis

BACKGROUND

The effect of diet on risk of acute pancreatitis (AP) has been suggested by prior studies, but the association of dietary habits with severity of AP has not been previously evaluated.

OBJECTIVE

The objective of the study was to assess differences in reported dietary habits in patients with severe AP compared with those with mild or moderate AP.

METHODS

A prospectively maintained cohort of patients with AP was utilized. A brief questionnaire on dietary habits was implemented. Dietary habits were categorized based on the overall type of diet, fruit/vegetable servings, fat content, dairy consumption, dessert/sweets consumption, and fluid intake. Patients were grouped into mild/moderate and severe AP. Multivariate analysis was used to determine whether dietary habits have an independent association with AP severity.

RESULTS

407 patients with AP were studied. Mean patient age was 51 y, and 202 (50%) were men. 29% of patients were smokers and 46% actively consumed alcohol. 225 patients had mild AP, 103 moderate AP, and 79 developed severe AP. The 3 groups were comparable in race, body mass index, etiology of AP, and comorbidities. Dietary factors were overall comparable between the groups except for diet type: subjects with severe AP had a higher percentage of consuming a meat-rich diet (84%) than patients with mild AP (72%) and moderate AP (67%) (P = 0.04). Based on multivariable logistic regression, the OR of developing severe AP was 2.5 (95% CI: 1.24-5.32, P = 0.01) between patients who eat a meat-rich diet and those who consume a vegetable-based diet.

CONCLUSIONS

A meat-rich diet is independently associated with the development of persistent organ failure (severe disease) in patients with AP. These findings require further evaluation and could be useful for patient counseling, risk stratification, and disease prevention. This study is registered at clinicaltrials.gov as NCT03075605.

Abstract SY17-03: Can a change in diet change your cancer risk

There is a remarkable variation in gastrointestinal cancer risks around the world, best illustrated by colon cancer, where the incidence varies 20-fold between Westernized and less-developed countries. Overwhelming experimental and human study evidence shows that the variation can be accounted for by environmental factors rather than genetic constitution. For example, studies have shown that migration from a low-incidence country to a high-incidence country results in a change in risk to that of the host country within one generation. This is insufficient time for genetic mutation to account for the change. Less than 10% of cancers are due to inherited genetic aberrations, and GWAS studies have struggled to identify mutations that strongly influence risk for developing sporadic colon cancer. On the other hand, there is convincing evidence, based on observational and intervention studies, that risk of colon cancer is increased by consumption of meat and processed meats but suppressed by the consumption of fiber-rich foods, suggesting that the primary environmental factor that drives risk is what we eat. Recent studies of ours in African Americans, who suffer the highest rates of colon cancer incidence and death in the U.S., showed that a change to a traditional "African" high-fiber (55 gm/day), low-meat diet suppressed mucosal biomarkers of colon cancer risk in their colons within 2 weeks (1). Furthermore, these biomarkers were increased when rural Africans were given a "Western" diet for only 2 weeks. We obtained evidence that these benefits were mediated by the colonic microbiota, which break down undigested food into metabolites that either support mucosal health and are antineoplastic, for example short-chain fatty acids such as butyrate, or are inflammatory and carcinogenic, such as conjugated bile acids (which increase in a high-fat diet) and nitroso-compounds (which increase with a high-meat diet). Butyrate has a remarkable array of colonic health-promoting and antineoplastic properties: It is the preferred energy source for colonocytes, it maintains mucosal integrity, and it suppresses inflammation and carcinogenesis through effects on immunity, gene expression, and epigenetic modulation (2). There is experimental and epidemiologic evidence that the current recommended fiber intakes proposed by the U.S. Department of Agriculture of 22 gm/day for women and 38 gm/day for men, which were formulated to support cardiovascular health, are insufficient to prevent colon cancer. Our results suggest that the quantity should be closer to 50 gm/day, which is what is contained in the rural African diet; rural Africans rarely get colon cancer. This talk will discuss the mechanisms behind these diet-microbial-metabolite effects, which could be modified by diet change, to achieve the objective of preventing colorectal cancer in Western societies.

References

1. Nat Comm 2015.

2. Nature Reviews 2016.

Citation Format: Stephen J D O'Keefe. Can a change in diet change your cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr SY17-03. doi:10.1158/1538-7445.AM2017-SY17-03

Severe Acute Pancreatitis: Nutritional Management in the ICU

Patients with acute pancreatitis have elevated nutritional needs due to increased energy expenditure and catabolism. It is a clinical challenge to provide adequate nutrition to these patients while maintaining gut function, preventing pancreatic stimulation, and minimizing the risk of septic and metabolic complications associated with nutritional support. We present the case of a patient who had severe acute pancreatitis and was initially given total parenteral nutrition. After a period of initial improvement, he developed hyperglycemia, bacteremia, and sepsis. Parenteral nutrition was discontinued and infection was treated with antibiotics. Subsequent nutritional support consisted of enteral feeding with an elemental diet infused via a nasojejunal feeding tube. His condition improved gradually and he made a full recovery. This case illustrates the difficulties encountered while managing a case of severe acute pancreatitis and provides an evidence based approach to the nutritional management of severe acute pancreatitis in the intensive care unit setting.

Long-Term Teduglutide for the Treatment of Patients With Intestinal Failure Associated With Short Bowel Syndrome

OBJECTIVES:

In the pivotal 24-week, phase III, placebo-controlled trial, teduglutide significantly reduced parenteral support (PS) requirements in patients with short bowel syndrome (SBS). STEPS-2 was a 2-year, open-label extension of that study designed to evaluate long-term safety and efficacy of teduglutide.

METHODS:

Enrolled patients had completed 24 weeks of either teduglutide (TED/TED) or placebo (PBO/TED) in the initial placebo-controlled study or qualified for that study, but were not treated (NT/TED) because of full enrollment. Patients received subcutaneous teduglutide 0.05 mg/kg/day for up to 24 months (NT/TED and PBO/TED) or up to 30 months (TED/TED). Clinical response was defined as 20–100% reduction from baseline in weekly PS volume; baseline was considered the beginning of teduglutide treatment in the initial placebo-controlled study (TED/TED) or STEPS-2 (NT/TED and PBO/TED). Descriptive statistics summarized changes in efficacy and safety variables.

RESULTS:

Of 88 enrolled patients, 65 (74%) completed STEPS-2. The most common treatment-emergent adverse events were abdominal pain (34%), catheter sepsis (28%), and decreased weight (25%). Mean weight, body mass index, and serum albumin remained stable. In patients who completed the study, clinical response was achieved in 28/30 (93%) TED/TED, 16/29 (55%) PBO/TED, and 4/6 (67%) NT/TED patients. Mean PS volume reductions from baseline were 7.6 (66%), 3.1 (28%), and 4.0 (39%) l/week in the TED/TED, PBO/TED, and NT/TED groups, respectively. Thirteen patients achieved full enteral autonomy.

CONCLUSIONS:

In patients with SBS, long-term teduglutide treatment resulted in sustained, continued reductions in PS requirements. Overall health and nutritional status was maintained despite PS reductions.

Nutritional Issues in the Short Bowel Syndrome - Total Parenteral Nutrition, Enteral Nutrition and the Role of Transplantation

In this review, I focus on the extreme of the short bowel syndrome where the loss of intestine is so great that patients cannot survive without intravenous feeding. This condition is termed short bowel intestinal failure. The review outlines the principles behind diagnosis, assessing prognosis and management. The advent of intravenous feeding (parenteral nutrition) in the 1970s enabled patients with massive (>90%) bowel resection to survive for the first time and to be rehabilitated back into normal life. To achieve this, central venous catheters were inserted preferably into the superior vena cava and intravenous infusions were given overnight so that the catheter could be sealed by day in order to maximize ambulation and social integration. However, quality of life has suffered by the association of serious complications related to permanent catheterization - mostly in the form of septicemias, thrombosis, metabolic intolerance and liver failure - from the unphysiological route of nutrient delivery. This has led to intense research into restoring gut function. In addition to dietary modifications and therapeutic suppression of motility, novel approaches have been aimed at enhancing the natural adaptation process, first with recombinant growth hormone and more recently with gut-specific glucagon-like peptide-2 analogues, e.g. teduglutide. These approaches have met with some success, reducing the intravenous caloric needs by approximately 500 kcal/day. In controlled clinical trials, teduglutide has been shown to permit >20% reductions in intravenous requirements in over 60% of patients after 6 months of treatment. Some patients have been weaned, but more have been able to drop infusion days. The only approach that predictably can get patients with massive intestinal loss completely off parenteral nutrition is small bowel transplantation, which, if successful (1-year survival for graft and host >90%) is accompanied by dramatic improvements in quality of life.

Fat, fibre and cancer risk in African Americans and rural Africans

Rates of colon cancer are much higher in African Americans (65:100,000) than in rural South Africans (<5:100,000). The higher rates are associated with higher animal protein and fat, and lower fibre consumption, higher colonic secondary bile acids, lower colonic short-chain fatty acid quantities and higher mucosal proliferative biomarkers of cancer risk in otherwise healthy middle-aged volunteers. Here we investigate further the role of fat and fibre in this association. We performed 2-week food exchanges in subjects from the same populations, where African Americans were fed a high-fibre, low-fat African-style diet and rural Africans a high-fat, low-fibre western-style diet, under close supervision. In comparison with their usual diets, the food changes resulted in remarkable reciprocal changes in mucosal biomarkers of cancer risk and in aspects of the microbiota and metabolome known to affect cancer risk, best illustrated by increased saccharolytic fermentation and butyrogenesis, and suppressed secondary bile acid synthesis in the African Americans.

Diet, microbiota, and microbial metabolites in colon cancer risk in rural Africans and African Americans

BACKGROUND

Epidemiologic studies have suggested that most cases of sporadic colon cancer can be attributed to diet. The recognition that colonic microbiota have a major influence on colonic health suggests that they might mediate colonic carcinogenesis.

OBJECTIVE

To examine the hypothesis that the influence of diet on colon cancer risk is mediated by the microbiota through their metabolites, we measured differences in colonic microbes and their metabolites in African Americans with a high risk and in rural native Africans with a low risk of colon cancer.

DESIGN

Fresh fecal samples were collected from 12 healthy African Americans aged 50-65 y and from 12 age- and sex-matched native Africans. Microbiomes were analyzed with 16S ribosomal RNA gene pyrosequencing together with quantitative polymerase chain reaction of the major fermentative, butyrate-producing, and bile acid-deconjugating bacteria. Fecal short-chain fatty acids were measured by gas chromatography and bile acids by liquid chromatography-mass spectrometry.

RESULTS

Microbial composition was fundamentally different, with a predominance of Prevotella in native Africans (enterotype 2) and of Bacteroides in African Americans (enterotype 1). Total bacteria and major butyrate-producing groups were significantly more abundant in fecal samples from native Africans. Microbial genes encoding for secondary bile acid production were more abundant in African Americans, whereas those encoding for methanogenesis and hydrogen sulfide production were higher in native Africans. Fecal secondary bile acid concentrations were higher in African Americans, whereas short-chain fatty acids were higher in native Africans.

CONCLUSION

Our results support the hypothesis that colon cancer risk is influenced by the balance between microbial production of health-promoting metabolites such as butyrate and potentially carcinogenic metabolites such as secondary bile acids.

Safety and efficacy of teduglutide after 52 weeks of treatment in patients with short bowel intestinal failure

BACKGROUND & AIMS

Although home parenteral nutrition (PN) can save the lives of patients with massive bowel loss that results in short-bowel syndrome and intestinal failure, quality of life is impaired by PN and its complications. We examined the 12-month tolerability and efficacy of teduglutide to reduce PN dependency.

METHODS

Patients who received teduglutide (0.05 or 0.10 mg/kg/d) for 24 weeks in a randomized controlled trial were eligible for a 28-week double-blind extension study; 52 patients were given 52 weeks of the same doses of teduglutide. We investigated the safety, tolerability, and clinical efficacy (defined as a clinically meaningful ≥20% reduction in weekly PN volume from baseline) at week 52.

RESULTS

The most common adverse events reported included headache (35%), nausea (31%), and abdominal pain (25%); 7 patients withdrew because of adverse events (gastrointestinal disorders in 4). Both groups had progressive reduction in PN. At week 52, 68% of the 0.05-mg/kg/d and 52% of the 0.10-mg/kg/d dose group had a ≥20% reduction in PN, with a reduction of 1 or more days of PN dependency in 68% and 37%, respectively. Four patients achieved complete independence from PN.

CONCLUSIONS

For patients with short-bowel syndrome intestinal failure, the efficacy of teduglutide was maintained over 52 weeks and the safety profile was sufficient for it to be considered for long-term use. Further studies are needed to determine whether these effects will translate into improved quality of life and reduced PN complications. ClinicalTrials.gov number, NCT00172185.

Association between low colonic short-chain fatty acids and high bile acids in high colon cancer risk populations

We propose that the influence of diet on colon cancer risk is mediated by the microbiota. To investigate how dietary fat influences risk, we compared the colonic contents of 12 adult high-risk African Americans (AAs) and 10 Caucasian Americans (CAs) who consumed a high-fat diet (123 ± 11 g/d and 129 ± 17 g/d, respectively) to 13 native Africans (NAs) who subsisted on a low-fat (38 ± 3.0 g/d) diet, all aged 50-60 yr. The colonic bile acids were measured by LC-MS and the short-chain fatty acids (SCFAs) by GC. The chief secondary colonic bile acids, deoxycholic acid and lithocholic acid, were correlated with fat intake and similar between AAs and CAs, but 3-4 times higher than in AAs (p < 0.05). The major SCFAs were lower in AAs (p < 0.001) and CAs (p < 0.001) compared to AAs, but conversely, the branched chain fatty acids (BFCA) were higher. Our results suggest that the higher risk of colon cancer in Americans may be partly explained by their high-fat and high-protein, low complex carbohydrate diet, which produces colonic residues that promote microbes to produce potentially carcinogenic secondary bile acids and less antineoplastic SCFAs. The role of BCFA in colonic carcinogenesis deserves further study.

Association between low colonic short-chain fatty acids and high bile acids in high colon cancer risk populations

We propose that the influence of diet on colon cancer risk is mediated by the microbiota. To investigate how dietary fat influences risk, we compared the colonic contents of 12 adult high-risk African Americans (AAs) and 10 Caucasian Americans (CAs) who consumed a high-fat diet (123 ± 11 g/d and 129 ± 17 g/d, respectively) to 13 native Africans (NAs) who subsisted on a low-fat (38 ± 3.0 g/d) diet, all aged 50-60 yr. The colonic bile acids were measured by LC-MS and the short-chain fatty acids (SCFAs) by GC. The chief secondary colonic bile acids, deoxycholic acid and lithocholic acid, were correlated with fat intake and similar between AAs and CAs, but 3-4 times higher than in AAs (p < 0.05). The major SCFAs were lower in AAs (p < 0.001) and CAs (p < 0.001) compared to AAs, but conversely, the branched chain fatty acids (BFCA) were higher. Our results suggest that the higher risk of colon cancer in Americans may be partly explained by their high-fat and high-protein, low complex carbohydrate diet, which produces colonic residues that promote microbes to produce potentially carcinogenic secondary bile acids and less antineoplastic SCFAs. The role of BCFA in colonic carcinogenesis deserves further study.

Products of the colonic microbiota mediate the effects of diet on colon cancer risk

It is estimated that most colon cancers can be attributed to dietary causes. We have hypothesized that diet influences the health of the colonic mucosa through interaction with the microbiota and that it is the milieu interior that regulates mucosal proliferation and therefore cancer risk. To validate this further, we compared colonic contents from healthy 50- to 65-y-old people from populations with high and low risk, specifically low risk Native Africans (cancer incidence <1:100,000; n = 17), high risk African Americans (risk 65:100,000; n = 17), and Caucasian Americans (risk 50:100,000; n = 18). Americans typically consume a high-animal protein and -fat diet, whereas Africans consume a staple diet of maize meal, rich in resistant starch and low in animal products. Following overnight fasting, rapid colonic evacuation was performed with 2 L polyethylene glycol. Total colonic evacuants were analyzed for SCFA, vitamins, nitrogen, and minerals. Total SCFA and butyrate were significantly higher in Native Africans than in both American groups. Colonic folate and biotin content, measured by Lactobacillus rhamnoses and Lactobacillus plantarum ATCC 8014 bioassay, respectively, exceeded normal daily dietary intakes. Compared with Africans, calcium and iron contents were significantly higher in Caucasian Americans and zinc content was significantly higher in African Americans, but nitrogen content did not differ among the 3 groups. In conclusion, the results support our hypothesis that the microbiota mediates the effect diet has on colon cancer risk by their generation of butyrate, folate, and biotin, molecules known to play a key role in the regulation of epithelial proliferation.

Therapeutic efficacy of intestinal and multivisceral transplantation: survival and nutrition outcome

The clinical introduction of intestinal transplantation has added a new dimension and offered a valid therapeutic option for patients with irreversible intestinal failure. In the year 2000, the Center for Medicare & Medicaid Services (CMS) recognized intestinal, combined liver-intestinal, and multivisceral transplantation as the standard of care for patients with irreversible intestinal and parenteral nutrition (PN) failure. Accordingly, the indications for the procedure are currently limited to those who develop life-threatening PN complications. However, a recent improvement in survival similar to other solid organ transplant recipients should justify lifting the current restricted criteria, and the procedure should be considered before the development of PN failure. Equally important is the awareness of the recent evolution in nutrition management and outcome after transplantation. Early and progressive enteral feeding using a complex polymeric formula is safe and effective after successful transplantation. Full nutrition autonomy is universally achievable among most intestinal and multivisceral recipients, with enjoyment of unrestricted oral diet. Such a therapeutic benefit is commonly maintained among long-term survivors, with full rehabilitation and restoration of quality of life.

Environmental influences on the high mortality from colorectal cancer in African Americans

Colon cancer is the second leading cause of cancer related death in American adults. The incidence and mortality are highest in African Americans (AAs) (incidence: 52 per 100,000) and lowest in American Hispanics (37 per 100,000). Comparative studies with Native Africans (<5 per 100,000) suggest that genetic susceptibility is an unlikely explanation and that environmental influences are to blame. Studies have suggested that risk is high because of excessive intakes of animal meat and fat products and differences in colonic bacterial metabolism, and that preventative and therapeutic management of colon cancer is compromised by the development of greater tumour virulence possibly resulting from disparities in educational and insurance status, screening behaviour, treatment patterns, social support, and access to and use of health care facilities. It should be possible to reduce the unacceptably higher rates of morbidity and mortality from colon cancer in AAs by dietary and lifestyle changes aimed at suppressing excessive intakes of animal meat and fat products, increasing the consumption of fresh fruit and vegetables, controlling energy balance, and by developing strategies to improve the availability, use and accessibility to health care resources.

Physiological evaluation of the severity of pancreatic exocrine dysfunction during endoscopy

OBJECTIVES

Despite the advances in pancreatic imaging, there continues to be a need to measure exocrine function to determine which patient requires enzyme supplementation. To evaluate the potential use of a rapid endoscopic test that can be conducted by nonacademic centers, we investigated whether concentration of trypsin in food-stimulated secretion is related to trypsin synthesis and secretion.

METHODS

Subjects include 22 chronic pancreatitis patients (10 mild, 5 moderate, and 7 severe radiological disease) and 11 healthy controls. During upper gastrointestinal endoscopy, pancreatic secretion was stimulated by a single 30-mL duodenal injection of an enteral diet, followed 5 minutes later by periampullary juice aspiration (endoscopic pancreatic function test [ePFT]). This was followed by a conventional 2-hour marker-perfusion diet-stimulated pancreatic trypsin secretion and synthesis study (2-hour PFT [2hPFT]).

RESULTS

Severity of radiological disease was associated with a progressive loss of enzyme secretion measured by the 2hPFT. The endoscopic PFT correlated positively with 2hPFT (r2 = 0.48; P < 0.0001) and an activity of less than 5% of the average normal had a 96% specificity and 75% sensitivity for the detection of pancreatic insufficiency as defined by a loss of greater than 90% of pancreatic secretion.

CONCLUSIONS

The diagnostic power of endoscopy may be enhanced by the collection of a pancreatic juice sample after enteral feed stimulation because measurement of the trypsin content will identify chronic pancreatitis patients who will be benefited by enzyme supplementation.

Nutritional immunomodulation of acute pancreatitis

Despite the great advances in our understanding of the pathophysiology of acute pancreatitis, no specific therapy has emerged, and treatment remains supportive. In patients with the severe form of the disease, in which mortality remains high at 20% to 30%, the function of the upper gastrointestinal tract is disturbed due to extrinsic compression by the inflamed and swollen pancreas, and normal eating is impossible. Such patients often develop multiple organ failure, necessitating intensive-care management and artificial ventilation for weeks on end. In this setting, protein catabolism will rapidly result in protein deficiency and further complications unless nutritional support is commenced. Recent studies have shown that, despite the risk of disease exacerbation through pancreatic stimulation, enteral feeding is more effective than parenteral feeding in improving outcome. Experimental studies suggest that this can be attributed to its content of specific immunomodulating nutrients, such as glutamine, arginine, and n-3 fatty acids, and by its stabilizing effect on the gut flora through the provision of prebiotics. Further studies are indicated to examine whether dietary enrichment with these substrates, along with regulation of the gut bacteria with probiotics, can improve outcome further.

Nutrition support in severe acute pancreatitis

Nutritional support can improve the outcome from severe acute pancreatitis in two ways: first by providing the building blocks for tissue repair and recovery, and second, by modulating the inflammatory response and preventing organ failure, both of which are responsible for most of the morbidity and mortality associated with the disease. This review discusses the evidence on which these statements are based.

Nutrition and quality of life following small intestinal transplantation

BACKGROUND

The outcome from small bowel transplantation (SBTx) has improved progressively over the past decade raising questions as to whether indications should be broadened from those currently followed based on "TPN (total parenteral nutrition) failure."

OBJECTIVE AND METHODS

To assess current outcome, we studied the effect of transplantation on nutritional autonomy, organ function, and quality of life (QoL) measured by a validated self-administered questionnaire containing 26 domains and 130 questions, for a minimum of 12 months in a cohort of 46 consecutively transplanted patients between June 2003 and July 2004. The majority of transplanted patients (76%) had intestinal failure because of extreme short bowel, the remainder having either chronic pseudo-obstruction or porto-mesenteric vein thrombosis (PMVT). All but the PMVT patients were dependent on home TPN (HPN) (median 2, range 0-25 yr) and had developed serious recurrent infective complications with (25%) or without central vein thrombosis and liver failure. Sixty-one percent received a liver in addition to a small intestine.

RESULTS

Follow-up was for a mean of 21 (range 12-36) months. Five patients died, two with chronic graft rejection. All the remaining patients have graft survival with an average of 1.2 (range 0-5) episodes of acute rejection. All patients were weaned from TPN by a median of 18 days (range 1-117 days) and from tube feeding by day 69 (range 22-272 days). There was a significant improvement in overall assessment of QoL and in 13 of 26 of the specific domains examined.

CONCLUSION

Our results confirm the claim that a new era has dawned for SBTx, such that, with continued progress, it can potentially become an alternative to HPN for the management of permanent intestinal failure, rather than a last-chance treatment for "TPN failure."

Why do African Americans get more colon cancer than Native Africans?

The incidence of colorectal cancer (CRC) is dramatically higher in African Americans (AAs) than in Native Africans (NAs) (60:100,000 vs. <1:100,000) and slightly higher than in Caucasian Americans (CAs). To explore whether the difference could be explained by interactions between diet and colonic bacterial flora, we compared randomly selected samples of healthy 50- to 65-y-old AAs (n = 17) with NAs (n = 18) and CAs (n = 17). Diet was measured by 3-d recall, and colonic metabolism by breath hydrogen and methane responses to oral lactulose. Fecal samples were cultured for 7-alpha dehydroxylating bacteria and Lactobacillus plantarum. Colonoscopic mucosal biopsies were taken to measure proliferation rates. In comparison with NAs, AAs consumed more (P < 0.01) protein (94 +/- 9.3 vs. 58 +/- 4.1 g/d) and fat (114 +/- 11.2 vs. 38 +/- 3.0 g/d), meat, saturated fat, and cholesterol. However, they also consumed more (P < 0.05) calcium, vitamin A, and vitamin C, and fiber intake was the same. Breath hydrogen was higher (P < 0.0001) and methane lower in AAs, and fecal colony counts of 7-alpha dehydroxylating bacteria were higher and of Lactobacilli were lower. Colonic crypt cell proliferation rates were dramatically higher in AAs (21.8 +/- 1.1% vs. 3.2 +/- 0.8% labeling, P < 0.0001). In conclusion, the higher CRC risk and mucosal proliferation rates in AAs than in NAs were associated with higher dietary intakes of animal products and higher colonic populations of potentially toxic hydrogen and secondary bile-salt-producing bacteria. This supports our hypothesis that CRC risk is determined by interactions between the external (dietary) and internal (bacterial) environments.

Small bowel transplantation

Until very recently, outcomes from small bowel transplantation (SBTx) lagged behind those in liver, heart, and kidney transplantation because of the magnitude of the immunologic burden; the strong expression of histocompatibility antigens; and the contamination in grafts by bacterial organisms. With novel techniques of immune-induction therapies, such as recipient "preconditioning" with lymphocyte reduction, followed by the more subtle use of immunosuppression-based single-agent tacrolimus, graft and host 1-year survival is now over 90% in the most active US centers, a finding that parallels the outcomes in liver and kidney transplantation. In contrast to the alternative therapy for permanent intestinal failure, home total parenteral nutrition (TPN), SBTx improves quality of life and restores digestive and absorptive function, making patients nutritionally autonomous. With survival beyond 1 to 3 years, the procedure is cost-effective. Current results support expansion of the indications for SBTx from use as salvage therapy for patients with TPN failure to preemptive therapy for patients at risk of developing TPN failure.

Treatment of intestinal failure: home parenteral nutrition

Intestinal failure can result from surgical resection, obstruction, dysmotility, congenital deficiencies or disease-associated loss of absorption. Before the development of intravenous feeding in the late 1960s, the condition was fatal, but by the 1990s approximately 40,000 patients were being successfully managed on long-term home parenteral nutrition (HPN) annually in the US. Survival on HPN depends on the nature of the underlying medical condition: over 80% of Crohn's disease patients survive for 5 years, but only 20% of cancer patients survive for 1 year. Although a patient's nutritional status is easy to maintain, there are serious long-term complications that arise from bypassing the gut and infusing nutrients directly into the systemic circulation. Catheter sepsis occurs about once per year (range 0-12 times). Abnormalities in liver function tests are common, but end-stage liver disease is rare. Central venous thrombosis develops in nearly all patients after 5 years. Although approximately 80% of patients on HPN are completely rehabilitated at home, their quality of life is impaired by the perpetual dependence on nocturnal intravenous infusions (every 8-12 h). In conclusion, HPN has allowed patients with previously fatal intestinal failure to survive and lead relatively normal lives at home, but their quality of life remains impaired by the dependence on intravenous infusions and complications that progress with time.

Candidacy for intestinal transplantation

A recent report from the American Small Bowel Transplant Registry (2003) has highlighted the significant progressive increase in graft and host survival to over 80% at 1 yr, suggesting that a new era has dawned, and that soon transplantation may offer an attractive alternative to any patient with permanent intestinal failure. In order to investigate the potential candidacy for small bowel transplantation in Western Europe, 854 home long-term parenteral nutrition (TPN) patients and their physicians were surveyed in nine countries. Their results demonstrated that only a small proportion of patients were considered candidates, but that candidacy was higher in the pediatric population (34% vs 16%, respectively). Despite the general acceptance in the United States that the development of the complication of liver failure in home TPN patients is an indication for urgent transplantation, "immediate candidacy" was only made by physicians in 36% of such adults and 43% of such children. This study reveals that there remains reluctance in Europe to refer patients for transplantation, even when life-threatening complications have developed. Further investigations need to be performed to determine whether this was because of inaccessibility to a transplant center or unfamiliarity with the procedure and its outcomes.

Short bowel syndrome and intestinal failure: consensus definitions and overview

Short bowel syndrome (SBS)-associated intestinal failure is a highly disabling condition that impairs quality of life and social integration. Although the condition is not uniformly fatal, it might lead to serious, life-threatening complications. The basic goals of medical treatment are to maintain fluid, electrolyte, and nutrient balances and to make appropriate modifications in disease management to avoid side effects. Various definitions have been proposed for SBS and intestinal failure within the medical literature, but many focus on different aspects of the conditions, leading to confusion. In the past, identifying the cause of intestinal failure was of little consequence, because all patients were managed on total parenteral nutrition at home. However, with the recent development of medical therapies such as recombinant growth hormone, octreotide, and glucagon-like peptide-2 analogues and with improvements in small bowel transplantation, many patients can be made nutritionally autonomous. To evaluate the relative efficacy of these therapies, there is now a need to develop consensus definitions so that patients can be properly categorized before therapy. To this end, a group of experts on the subject was convened to develop the following new definitions: "Intestinal failure results from obstruction, dysmotility, surgical resection, congenital defect, or disease-associated loss of absorption and is characterized by the inability to maintain protein-energy, fluid, electrolyte, or micronutrient balance." "Short-bowel syndrome results from surgical resection, congenital defect, or disease-associated loss of absorption and is characterized by the inability to maintain protein-energy, fluid, electrolyte, or micronutrient balances when on a conventionally accepted, normal diet."

Enteral feeding without pancreatic stimulation

OBJECTIVE

All forms of commonly practiced enteral feeding techniques stimulate pancreatic secretion, and only intravenous feeding avoids it. In this study, we explored the possibility of more distal enteral infusions of tube feeds to see whether activation of the ileal brake mechanism can result in enteral feeding without pancreatic stimulation, with particular reference to trypsin, because the avoidance of trypsin stimulation may optimize enteral feeding in acute pancreatitis.

METHODS

The pancreatic secretory responses to feeding were studied in 36 healthy volunteers by standard double-lumen duodenal perfusion/aspiration techniques over 6 hours. Subjects were assigned to no feeding (n = 7), duodenal feeding with a polymeric diet (n = 7) or low-fat elemental diet (n = 6), mid-distal jejunal feeding (n = 11), or intravenous feeding (n = 5). All diets provided 40 kcal/kg ideal body weight/d and 1.5 g protein/kg ideal body weight/d. Plasma gut peptide responses were monitored in 15 subjects.

RESULTS

In comparison with basal fasting trypsin secretion rates (mean = 134 [standard error = 22] U/h), duodenal feeding with the polymeric and elemental formulae stimulated trypsin secretion (mean = 408 [standard error = 51] U/h; P < 0.001), whereas intravenous feeding (mean = 171 [standard error = 34] U/h) and mid-distal jejunal (mean = 119 [standard error = 16] U/h) did not. Stimulation was associated with an increase in plasma cholecystokinin, whereas distal jejunal feeding resulted in an increase in plasma glucagon-like peptide-1 and peptide YY concentrations.

CONCLUSIONS

Our results suggest that enteral feeding can be given without stimulating pancreatic trypsin secretion provided it is delivered into the mid-distal jejunum. The mechanism may involve activation of the ileal brake mechanism.

Trypsin secretion and turnover in patients with acute pancreatitis

Studies in humans have shown that pancreatic enzyme secretion is reduced during acute pancreatitis. It is not known, however, whether the reduction is due to impaired synthesis or disruption of the secretory pathway. The rate of secretion and turnover of trypsin was measured in 12 patients with acute pancreatitis of variable etiology and severity (median Ranson's score 2.5, range 0-5, 4 with severe necrotizing disease) and eight healthy volunteers by 4-h primed/continuous intravenous infusions of 1-(13)C-labeled l-leucine, and collection of pancreatic secretions by duodenal perfusion and sampling. Trypsin secretion was reduced from 476 +/- 73 to 153 +/- 60 U/h (means +/- SE, P = 0.005) in acute pancreatitis, with the greatest reductions being observed in patients with necrotizing disease (32 +/- 7 U/h, P = 0.003). The time for newly labeled trypsin to first appear in digestive juice was not, however, delayed in pancreatitis patients (87.2 +/- 11.1 vs. 94.7 +/- 4.9 min); on the contrary, there was an early appearance of newly labeled trypsin at 30 min in patients with severe necrotizing pancreatitis (P < 0.05). Calculated zymogen pool turnover was unchanged, but pool size was decreased (P = 0.01). Despite low rates of luminal secretion, trypsin continues to be synthesized in patients with acute pancreatitis. Our findings could be explained by post-Golgi leakage of enzymes from acinar cells or by loss of synthetic function in some cells with preservation in others.

Nutritional support in acute pancreatitis

Acute pancreatitis is one of the most catabolic of critical illnesses, and its clinical course is often prolonged. Consequently, the need for interventional nutritional support is great. Because of fears that feeding might exacerbate the tryptic autodigestion and disease process, total parenteral nutrition was used exclusively until recent years, when it was recognized that the complications of hyperglycemia and sepsis outweighed nutritional benefits. In clinical practice, enteral feeding has proven superior because it avoids these complications and maintains gut function, but enteral feeding needs to be given in a form that minimizes pancreatic stimulation. This review discusses the advances in our understanding of the pathophysiology of the disease, the results of recent clinical trials of nutritional support, and the challenges that remain in optimizing nutritional management.

Differential effect of saturated and polyunsaturated fatty acids on hepatic glucose metabolism in humans

Prolonged infusions of lipid and heparin that achieve high physiological free fatty acid (FFA) concentrations inhibit hepatic (and peripheral) insulin sensitivity in humans. These infusions are composed largely of polyunsaturated fatty acids (PUFA; linoleic and linolenic). It is not known whether fatty acid composition per se affects hepatic glucose metabolism in humans. To address this issue, we examined the impact of enteral infusions of either palm oil (48% palmitic, 35% oleic, and 8% linoleic acids) or safflower oil (6% palmitic, 12% oleic, 74% linoleic acids) in 14 obese nondiabetic subjects. (2)H(2)O was administered to determine the contribution of gluconeogenesis to endogenous glucose production (EGP), and a primed continuous infusion of [6,6-(2)H]glucose was administered to assess glucose appearance. As a result of the lipid infusions, plasma FFA concentrations increased significantly in both the palm oil (507.5 +/- 47.4 to 939.3 +/- 61.3 micromol/l, P < 0.01) and safflower oil (588.2.0 +/- 43.0 to 857.8 +/- 68.7 micromol/l, P < 0.01) groups after 4 h. EGP was similar at baseline (12.4 +/- 1.8 vs. 11.2 +/- 1.0 micromol x kg FFM(-1) x min(-1)). During a somatostatin-insulin clamp, the glucose infusion rate was significantly lower (AUC glucose infusion rate 195.8 +/- 50.7 vs. 377.8 +/- 38.0 micromol/kg FFM, P < 0.01), and rates of EGP were significantly higher (10.7 +/- 1.4 vs. 6.5 +/- 1.5 micromol x kg FFM(-1) x min(-1), P < 0.01) after palm oil compared with safflower oil, respectively. Baseline rates of gluconeogenesis and glycogenolysis were also similar. However, after lipid infusion, rates of glycogenolysis were suppressed by safflower oil but not by palm oil. Thus these studies demonstrate, for the first time in humans, a differential effect of saturated fatty acids and PUFA on hepatic glucose metabolism.

Transnasal endoscopic placement of feeding tubes in the intensive care unit

BACKGROUND

There is an increasing demand for enteral feeding in intensive care unit (ICU) patients. However, gastroparesis is common, and jejunal placement with gastric decompression leads to delays in feeding. In an attempt to minimize delays, we describe our technique and results with transnasal endoscopic placement of double-lumen gastric aspiration, jejunal feeding tubes (DLFT).

METHODS

Fifty-one consecutive ICU patients referred for nutrition support were studied; 29% had respiratory failure, 28% acute head injury, and 33% acute pancreatitis. A 5.8-mm ultraslim video endoscope was used to place a guidewire through the nose terminating beyond the Ligament of Treitz. After withdrawal of the endoscope, a DLFT was passed over the wire. Final position of the tube was checked and adjusted under direct vision by reendoscopy though the opposite nasal passage.

RESULTS

Initial placement of the guidewire and DLFT was successful in 46 of 51 patients. Massive gastric dilatation and acute pancreatitis complicated by duodenal compression impeded full duodenoscopy in 5 patients, necessitating fluoroscopy for correct guidewire deployment. In confirming correct tube placement, there was near perfect concordance between reendoscopy and x-ray (45/46). Previously unrecognized upper gastrointestinal tract pathology was detected in most patients, with acute gastritis in 47, superficial gastric ulceration in 24, and erosive esophagitis in 5.

CONCLUSIONS

Transnasal endoscopic placement of feeding tubes in the ICU is quick, effective, and minimally disruptive of intensive therapy. In addition, it can reveal unrecognized pathology, which potentially could lead to improvements in overall medical care.

Nutrition in the management of necrotizing pancreatitis

Comparative trials have shown that enteral feeding (EN) is better than total parenteral nutrition (TPN) in acute pancreatitis. However, the following case report of a 64-year-old man with necrotizing pancreatitis suggests that EN may cause complications in patients with ductular damage. In the second week, this patient with acute pancreatitis developed >50% pancreatic necrosis, resulting in gastroduodenal obstruction and pain, leading to the use of TPN. A trial of EN delivered past the obstruction was associated with increased abdominal pain, leukocytosis, and pancreatic fluid accumulation. Measurement of the pancreatic response to feeding showed a 90% reduction in enzyme secretion compared to healthy volunteers, but no change in the uptake of stable isotope labeled amino acids into secreted trypsin. This suggests that enzymes were being synthesized by the remaining pancreatic tissue, but that some of the secretions were leaking into the inflammatory mass. Symptoms resolved after reinstitution of TPN and bowel rest. A further trial of EN was successful when the tube was advanced to the distal jejunum to avoid pancreatic stimulation. After 3 weeks of home EN, he was readmitted for surgical evacuation of an infected fluid collection. Although enteral feeding is generally better than TPN in the nutritional management of acute pancreatitis, there may be a subgroup of patients with ductular damage due to necrotizing disease in whom TPN and pancreatic rest may be safer.

Physiological effects of enteral and parenteral feeding on pancreaticobiliary secretion in humans

In the nutritional management of digestive disorders, it is important to know the relative secretory and metabolic responses to enteral and parenteral feeding. Twenty-seven healthy volunteers were studied while receiving either oral drinks or duodenal infusions of a complex formula diet, duodenal or intravenous infusions of elemental (protein as free amino acids, low fat) formulae, or saline. Pancreaticobiliary secretory responses were measured by nasoduodenal polyethylene glycol perfusion and aspiration, while monitoring blood hormone and nutrient levels. Diets were matched for protein (1.5 g x kg(-1) x d(-1)) and energy (40 kcal x kg(-1) x d(-1)). Compared with placebo, all oroenteral diets stimulated amylase, lipase, trypsin, and bile acid secretion and increased plasma concentrations of gastrin and cholecystokinin, whereas intravenous feeding did not. The complex formula produced a similar response whether given as drinks or duodenal infusions. Changing the duodenal formula to elemental reduced enzyme secretion by 50%, independently of CCK. Higher increases in plasma insulin, glucose, and amino acids were noted with intravenous feeding. Delivering food directly to the intestine by a feeding tube does not reduce pancreaticobiliary secretion. Enteral "elemental" formulae diminish, but only intravenous feeding avoids pancreatic stimulation. Intravenous administration impairs metabolic clearance.

Nutrition support during acute pancreatitis

Studies have shown that protein catabolism increases by 80% and energy expenditure by 20% in acute pancreatitis, indicating that nutritional requirements are elevated. Other studies have associated the resolution of negative nitrogen balance by nutrition support with improved outcome. Consequently, the need for effective nutrition is one cornerstone of management of acute pancreatitis. Concerns that feeding may exacerbate the disease process by stimulating the synthesis of proteolytic enzymes in the acinar cell and perpetuating autolysis has led to the widespread use of total parenteral nutrition (TPN) and bowel rest. Unfortunately, the use of TPN in clinical practice has been associated with major metabolic and infective complications, possibly because 1). patients with acute pancreatitis are intolerant of glucose due to coexistent pancreatic endocrine dysfunction and 2). the disease causes immune suppression. This has led to the search for alternatives. Based on physiologic studies, infusion of nutrients into the distal jejunum bypasses the stimulatory effect of feeding on pancreatic secretion. Many controlled trials have compared TPN with jejunal feeding. No study has shown that jejunal feeding exacerbates the disease. Further, jejunal feeding is associated with fewer infectious and metabolic complications. These observations and the fact that enteral feeding is one-tenth the cost of TPN has resulted in the general acceptance of jejunal feeding as the preferred mode for maintaining nutrition in patients with acute pancreatitis.

Hypocaloric jejunal feeding is better than total parenteral nutrition in acute pancreatitis: results of a randomized comparative study

OBJECTIVES

The aims of this study were to define the indications for, and to evaluate the cost-effectiveness of, nutritional support in patients with acute pancreatitis.

METHODS

All admissions during the 12-month period from January through December 2000, were entered into a common management protocol consisting of an initial 48-h fast with i.v. fluids and analgesics. After 48 h, those patients who were improving were restarted on oral feeding (group O). The remaining patients were randomized to receive nasojejunal (group EN) or parenteral feeding (group TPN). The randomization study was continued until 50 patients had been accrued. Outcomes in the three groups were compared with respect to length of hospital stay, duration of feeding, complications, and hospital costs.

RESULTS

A total of 156 admissions were evaluated in the first 12 months. Of these, 87% patients had mild disease, 10% moderate, and 3% severe; 62% were related to alcohol abuse, 18% gallstones, and 8% idiosyncratic drug reactions. Of the patients, 75% improved on 48 h bowel rest and i.v. fluids, and were discharged within 4 days. The remainder were randomized to jejunal elemental (n = 26) or parenteral (n = 27) feeding. Duration of feeding was shorter with EN (6.7 vs 10.8 days, p < 0.05) and nutrition costs were lower, representing an average cost saving of $2362.00 per patient fed. EN was less effective in meeting estimated nutritional requirements (54 vs 88%, p < 0.0001), but metabolic (p < 0.003) and septic complications (p = 0.01) were lower. Subgroup analysis of patients with severe disease showed similar findings.

CONCLUSION

Despite concerns that metabolic expenditure is increased and that food-stimulated pancreatic secretion might exacerbate the disease process, hypocaloric enteral feeding seems to be safer and less expensive than parenteral feeding and bowel rest in patients with acute pancreatitis.