The Importance of Dietary Fiber for Metabolic Health

Dietary fiber are non-digestible carbohydrates that are diverse, have varied functions, and are acquired by consuming plant-based foods. Some forms of fiber are digested by the gut microbiota and produce bioactive metabolites called short chain fatty acids-butyrate, acetate, and propionate. Dietary fiber is able to alter human physiology through multiple mechanisms that can result in health benefits. Unfortunately, nearly 19 out of 20 Americans do not consume the minimum recommended amount of fiber each day. This bears profound relevance to public health because at least six of the ten leading causes of death are potentially preventable or clinically improved through dietary means. Additionally, these same conditions share a common underlying pathophysiology-metabolic dysfunction. This can manifest as abdominal obesity, high blood pressure, insulin resistance, dyslipidemia, or collectively as metabolic syndrome. In this review, we will assess the evidence that consumption of dietary fiber undermines these forms of metabolic dysfunction, examine the mechanism of action for these physiologic effects, and consider the potential for dietary fiber to improve human health on a public health level by simply encouraging our patients to consume more plant-based foods in abundance and diversity.

The secondary bile acid isoursodeoxycholate correlates with post-prandial lipemia, inflammation, and appetite and changes post-bariatric surgery

Primary and secondary bile acids (BAs) influence metabolism and inflammation, and the gut microbiome modulates levels of BAs. We systematically explore the host genetic, gut microbial, and habitual dietary contribution to a panel of 19 serum and 15 stool BAs in two population-based cohorts (TwinsUK, n = 2,382; ZOE PREDICT-1, n = 327) and assess changes post-bariatric surgery and after nutritional interventions. We report that BAs have a moderately heritable genetic component, and the gut microbiome accurately predicts their levels in serum and stool. The secondary BA isoursodeoxycholate (isoUDCA) can be explained mostly by gut microbes (area under the receiver operating characteristic curve [AUC] = ∼80%) and associates with post-prandial lipemia and inflammation (GlycA). Furthermore, circulating isoUDCA decreases significantly 1 year after bariatric surgery (β = -0.72, p = 1 × 10-5) and in response to fiber supplementation (β = -0.37, p < 0.03) but not omega-3 supplementation. In healthy individuals, isoUDCA fasting levels correlate with pre-meal appetite (p < 1 × 10-4). Our findings indicate an important role for isoUDCA in lipid metabolism, appetite, and, potentially, cardiometabolic risk.

Genetic and gut microbiome determinants of SCFA circulating and fecal levels, postprandial responses and links to chronic and acute inflammation

Short-chain fatty acids (SCFA) are involved in immune system and inflammatory responses. We comprehensively assessed the host genetic and gut microbial contribution to a panel of eight serum and stool SCFAs in two cohorts (TwinsUK, n = 2507; ZOE PREDICT-1, n = 328), examined their postprandial changes and explored their links with chronic and acute inflammatory responses in healthy individuals and trauma patients. We report low concordance between circulating and fecal SCFAs, significant postprandial changes in most circulating SCFAs, and a heritable genetic component (average h2: serum = 14%(SD = 14%); stool = 12%(SD = 6%)). Furthermore, we find that gut microbiome can accurately predict their fecal levels (AUC>0.71) while presenting weaker associations with serum. Finally, we report different correlation patterns with inflammatory markers depending on the type of inflammatory response (chronic or acute trauma). Our results illustrate the breadth of the physiological relevance of SCFAs on human inflammatory and metabolic responses highlighting the need for a deeper understanding of this important class of molecules.

The anti-inflammatory effect of bacterial short chain fatty acids is partially mediated by endocannabinoids

The endocannabinoid (EC) system has pleiotropic functions in the body. It plays a key role in energy homeostasis and the development of metabolic disorders being a mediator in the relationship between the gut microbiota and host metabolism. In the current study we explore the functional interactions between the endocannabinoid system and the gut microbiome in modulating inflammatory markers. Using data from a 6 week exercise intervention (treatment n = 38 control n = 40) and a cross sectional validation cohort (n = 35), we measured the associations of 2-arachidonoylglycerol (2-AG), anandamide (AEA), N-oleoylethanolamine (OEA) and N-palmitoylethanolamine (PEA) with gut microbiome composition, gut derived metabolites (SCFAs) and inflammatory markers both cross-sectionally and longitudinally. At baseline AEA and OEA were positively associated with alpha diversity (β(SE) = .32 (.06), P = .002; .44 (.04), P < .001) and with SCFA producing bacteria such as Bifidobacterium (2-AG β(SE) = .21 (.10), P < .01; PEA β(SE) = .23 (.08), P < .01), Coprococcus 3 and Faecalibacterium (PEA β(SE) = .29 (.11), P = .01; .25 (.09), P < .01) and negatively associated with Collinsella (AEA β(SE) = -.31 (.12), P = .004). Additionally, we found AEA to be positively associated with SCFA Butyrate (β(SE) = .34 (.15), P = .01). AEA, OEA and PEA all increased significantly with the exercise intervention but remained constant in the control group. Changes in AEA correlated with SCFA butyrate and increases in AEA and PEA correlated with decreases in TNF-ɑ and IL-6 statistically mediating one third of the effect of SCFAs on these cytokines. Our data show that the anti-inflammatory effects of SCFAs are partly mediated by the EC system suggesting that there may be other pathways involved in the modulation of the immune system via the gut microbiome.

Effects of the Learning Curve on Efficacy of Radiofrequency Ablation for Barrett's Esophagus

BACKGROUND & AIMS

Complete eradication of Barrett's esophagus (BE) often requires multiple sessions of radiofrequency ablation (RFA). Little is known about the effects of case volume on the safety and efficacy of RFA or about the presence or contour of learning curves for this procedure.

METHODS

We collected data from the US RFA Patient Registry (from 148 institutions) for patients who underwent RFA for BE from July 2007 to July 2011. We analyzed the effects of the number of patients treated by individual endoscopists and individual centers on safety and efficacy outcomes of RFA. Outcomes, including stricture, bleeding, hospitalization, and complete eradication of intestinal metaplasia (CEIM), were assessed using logistic regression. The effects of center and investigator experience on numbers of treatment sessions to achieve CEIM were examined using linear regression.

RESULTS

After we controlled for potential confounders, we found that as the experience of endoscopists and centers increased with cases, the numbers of treatment sessions required to achieve CEIM decreased. This relationship persisted after adjusting for patient age, sex, race, length of BE, and presence of pretreatment dysplasia (P < .01). Center experience was not significantly associated with overall rates of CEIM or complete eradication of dysplasia. We did not observe any learning curve with regard to risks of stricture, gastrointestinal bleeding, perforation, or hospitalization (P > .05).

CONCLUSIONS

Based on analysis of a large multicenter registry, efficiency of the treatment, as measured by number of sessions needed to achieve CEIM, increased with case volume, indicating a learning curve effect. This trend began to disappear after treatment of approximately 30 patients by the center or individual endoscopist. However, there was no significant association between safety or efficacy outcomes and previous case volume.

Sex and race and/or ethnicity differences in patients undergoing radiofrequency ablation for Barrett's esophagus: results from the U.S. RFA Registry

BACKGROUND

Little is known about differences in Barrett's esophagus (BE) characteristics by sex and race and/or ethnicity or these differences in response to radiofrequency ablation (RFA).

OBJECTIVE

We compared disease-specific characteristics, treatment efficacy, and safety outcomes by sex and race and/or ethnicity in patients treated with RFA for BE.

DESIGN

The U.S. RFA patient registry is a multicenter collaboration reporting processes and outcomes of care for patients treated with RFA for BE.

PATIENTS

Patients enrolled with BE.

INTERVENTIONS

RFA.

MAIN OUTCOME MEASUREMENTS

We assessed safety (stricture, bleeding, perforation, hospitalization), efficacy (complete eradication of intestinal metaplasia [CEIM]), complete eradication of dysplasia, and number of treatments to CEIM by sex and race and/or ethnicity.

RESULTS

Among 5521 patients (4052 men; 5126 white, 137 Hispanic, 82 African American, 40 Asian, 136 heritage not identified), women were younger (60.0 vs 62.1 years) and had shorter BE segments (3.2 vs 4.4 cm) and less dysplasia (37% vs 57%) than did men. Women were almost twice as likely to stricture (odds ratio 1.7; 95% confidence interval, 1.2-2.3). Although white patients were predominantly male, about half of African Americans and Asians with BE were female. African Americans and Asians had less dysplasia than white patients. Asians and African Americans had more strictures than did white patients. There were no sex or race differences in efficacy.

LIMITATIONS

Observational study with non-mandated paradigms, no central laboratory for reinterpretation of pathology.

CONCLUSION

In the U.S. RFA patient registry, women had shorter BE segments and less-aggressive histology. The usual tendency toward BE in men was absent in African Americans and Asians. Posttreatment stricture was more common among women and Asians. RFA efficacy did not differ by sex or race.

Administrative coding is specific, but not sensitive, for identifying eosinophilic esophagitis

The use of administrative databases to conduct population-based studies of eosinophilic esophagitis (EoE) in the United States is limited because it is unknown whether the International Classification of Diseases, Ninth Revision (ICD-9) code for EoE, 530.13, accurately identifies those who truly have the disease. The aim of this retrospective study was to validate the ICD-9 code for identifying cases of EoE in administrative data. Confirmed cases of EoE as per consensus guidelines (symptoms of esophageal dysfunction and ≥15 eosinophils per high-power field on biopsy after 8 weeks of twice daily proton pump inhibitor therapy) were identified in the University of North Carolina (UNC) EoE Clinicopathologic Database from 2008 to 2010; 2008 was the first year in which the 530.13 code was approved. Using the Carolina Data Warehouse, the administrative database for patients seen in the UNC system, all diagnostic and procedure codes were obtained for these cases. Then, with the EoE cases as the reference standard, we re-queried the Carolina Data Warehouse over the same time frame for all patients seen in the system (n=308,372) and calculated the sensitivity and specificity of the ICD-9 code 530.13 as a case definition of EoE. To attempt to refine the case definition, we added procedural codes in an iterative fashion to optimize sensitivity and specificity, and restricted our analysis to privately insured patients. We also conducted a sensitivity analysis with 2011 data to identify trends in the operating parameters of the code. We identified 226 cases of EoE at UNC to serve as the reference standard. The ICD-9 code 530.13 yielded a sensitivity of 37% (83/226; 95% confidence interval: 31-43%) and specificity of 99% (308,111/308,146; 95% confidence interval: 98-100%). These operating parameters were not substantially altered if the case definition required a procedure code for endoscopy or if cases were limited to those with commercial insurance. However, in 2011, the sensitivity of the code had increased to 61%, while the specificity remained at 99%. The ICD-9 code for EoE, 530.13, had excellent specificity for identifying cases of EoE in administrative data, although this high specificity was achieved at an academic center. Additionally, the sensitivity of the code appears to be increasing over time, and the threshold at which it will stabilize is not known. While use of this administrative code will still miss a number of cases, those identified in this manner are highly likely to have the disease.

Durability and predictors of successful radiofrequency ablation for Barrett's esophagus

BACKGROUND & AIMS

After radiofrequency ablation (RFA), patients may experience recurrence of Barrett's esophagus (BE) after complete eradication of intestinal metaplasia (CEIM). Rates and predictors of recurrence after successful eradication have been poorly described.

METHODS

We used the US RFA Registry, a nationwide registry of BE patients receiving RFA, to determine rates and factors that predicted recurrence of intestinal metaplasia (IM). We assessed recurrence by Kaplan-Meier analysis for the overall cohort and by worst pretreatment histology. Characteristics associated with recurrence were included in a logistic regression model to identify independent predictors.

RESULTS

Among 5521 patients, 3728 had biopsies 12 months or more after initiation of RFA. Of these, 3169 (85%) achieved CEIM, and 1634 (30%) met inclusion criteria. The average follow-up period was 2.4 years after CEIM. IM recurred in 334 (20%) and was nondysplastic or indefinite for dysplasia in 86% (287 of 334); the average length of recurrent BE was 0.6 cm. In Kaplan-Meier analysis, more advanced pretreatment histology was associated with an increased yearly recurrence rate. Compared with patients without recurrence, patients with recurrence were more likely, based on bivariate analysis, to be older, have longer BE segments, be non-Caucasian, have dysplastic BE before treatment, and require more treatment sessions. In multivariate analysis, the likelihood for recurrence was associated with increasing age and BE length, and non-Caucasian race.

CONCLUSIONS

BE recurred in 20% of patients followed up for an average of 2.4 years after CEIM. Most recurrences were short segments and were nondysplastic or indefinite for dysplasia. Older age, non-Caucasian race, and increasing length of BE length were all risk factors. These risk factors should be considered when planning post-RFA surveillance intervals.

The impact of endoscopic ultrasound findings on clinical decision making in Barrett's esophagus with high-grade dysplasia or early esophageal adenocarcinoma

The clinical utility of endoscopic ultrasound (EUS) for staging patients with Barrett's esophagus and high-grade dysplasia (HGD) or intramucosal carcinoma (IMC) prior to endoscopic therapy is unclear. We performed a retrospective analysis of patients with HGD or IMC referred to an American medical center for endoscopic treatment between 2004 and 2010. All patients had pretreatment staging by EUS. We examined the frequency that EUS findings consistent with advanced disease (tumor invasion into the submucosa, lymph node involvement, or regional metastasis) led to a change in management. The analysis was stratified by nodularity and pre-EUS histology. We identified one hundred thirty-five patients with HGD (n = 106, 79%) or IMC (n = 29, 21%) had staging by EUS (79 non-nodular, 56 nodular). Pathologic lymph nodes or metastases were not found by EUS. There were no endosonographic abnormalities noted in any patient with non-nodular mucosa (0/79). Abnormal EUS findings were present in 8/56 patients (14%) with nodular neoplasia (five IMC, three HGD). Endoscopic mucosal resection was performed in 44 patients with a nodule, with 13% (6/44) having invasive cancer. In nodular neoplasia, the EUS and endoscopic mucosal resection were abnormal in 24% (5/21) and 40% (6/15) of those with IMC and 9% (3/35) and 0% (0/29) of those with HGD, respectively. In this study we found that EUS did not alter management in patients with non-nodular HGD or IMC. Because the diagnostic utility of EUS in subjects with non-nodular Barrett's esophagus is low, the value of performing endoscopic mucosal resection in this setting is questionable. For patients with nodular neoplasia, resection of the nodule with histological examination had greater utility than staging by EUS.

Safety and efficacy of endoscopic mucosal therapy with radiofrequency ablation for patients with neoplastic Barrett's esophagus

BACKGROUND & AIMS

The goal of radiofrequency ablation (RFA) for patients with Barrett's esophagus (BE) is to eliminate dysplasia and metaplasia. The efficacy and safety of RFA for patients with BE and neoplasia are characterized incompletely.

METHODS

We performed a retrospective study of 244 patients treated with RFA for BE with dysplasia or intramucosal carcinoma. Efficacy outcomes were complete eradication of intestinal metaplasia (CEIM), complete eradication of dysplasia, total treatments, and RFA sessions. Safety outcomes included death, perforation, stricture, bleeding, and hospitalization. We identified factors associated with incomplete EIM and stricture formation.

RESULTS

CEIM was achieved in 80% of patients, and complete eradication of dysplasia was achieved in 87%; disease progressed in 4 patients. A higher percentage of patients with incomplete EIM were female (40%) than those with CEIM (20%; P = .045); patients with incomplete EIM also had a longer segment of BE (5.5 vs 4.0 cm; P = .03), had incomplete healing between treatment sessions (45% vs 15%; P = 0.004), and underwent more treatment sessions (4 vs 3; P = .007). Incomplete healing was associated independently with incomplete EIM. Twenty-three patients (9.4%) had a treatment-related complication during 777 treatment sessions (3.0%), including strictures (8.2%), postprocedural hemorrhages (1.6%), and hospitalizations (1.6%). Patients who developed strictures were more likely to use nonsteroidal anti-inflammatory drugs than those without strictures (70% vs 45%; P = .04), have undergone antireflux surgery (15% vs 3%; P = .04), or had erosive esophagitis (35% vs 12%; P = .01).

CONCLUSIONS

RFA is highly effective and safe for treatment of BE with dysplasia or early stage cancer. Strictures were the most common complications. Incomplete healing between treatment sessions was associated with incomplete EIM. Nonsteroidal anti-inflammatory drug use, prior antireflux surgery, and a history of erosive esophagitis predicted stricture formation.

Prior fundoplication does not improve safety or efficacy outcomes of radiofrequency ablation: results from the U.S. RFA Registry

BACKGROUND

Ongoing gastroesophageal reflux may impair healing and re-epithelialization after radiofrequency ablation (RFA) of Barrett's esophagus (BE). Because prior fundoplication may improve reflux control, our aim was to assess the relationship between prior fundoplication and the safety/efficacy of RFA.

METHODS

We assessed the U.S. RFA Registry, a nationwide registry of BE patients receiving RFA at 148 institutions, to compare the safety and efficacy of ablation between those with prior fundoplication and those with medical management (proton pump inhibition).

RESULTS

Among 5,537 patients receiving RFA, 301 (5.4 %) had prior fundoplication. Of fundoplication subjects, 1.0 % developed stricture and 1.0 % were hospitalized after RFA. Rates of stricture, bleeding, and hospitalization were not statistically different (p = ns) between patients with and without prior fundoplication. Complete eradication of intestinal metaplasia and complete eradication of dysplasia were achieved in 71 % and 87 % of fundoplication patients, and 73 % and 87 % of patients without fundoplication, respectively (p = ns for both). Patients with prior fundoplication needed similar numbers of RFA sessions for eradication compared with those without fundoplication.

CONCLUSIONS

Radiofrequency ablation, with or without prior fundoplication, is safe and effective in eradicating BE. Prior fundoplication was associated with similar adverse event and efficacy rates when compared with medical management.

Burden of gastrointestinal disease in the United States: 2012 update

BACKGROUND & AIMS

Gastrointestinal (GI) diseases account for substantial morbidity, mortality, and cost. Statistical analyses of the most recent data are necessary to guide GI research, education, and clinical practice. We estimate the burden of GI disease in the United States.

METHODS

We collected information on the epidemiology of GI diseases (including cancers) and symptoms, along with data on resource utilization, quality of life, impairments to work and activity, morbidity, and mortality. These data were obtained from the National Ambulatory Medical Care Survey; National Health and Wellness Survey; Nationwide Inpatient Sample; Surveillance, Epidemiology, and End Results Program; National Vital Statistics System; Thompson Reuters MarketScan; Medicare; Medicaid; and the Clinical Outcomes Research Initiative's National Endoscopic Database. We estimated endoscopic use and costs and examined trends in endoscopic procedure.

RESULTS

Abdominal pain was the most common GI symptom that prompted a clinic visit (15.9 million visits). Gastroesophageal reflux was the most common GI diagnosis (8.9 million visits). Hospitalizations and mortality from Clostridium difficile infection have doubled in the last 10 years. Acute pancreatitis was the most common reason for hospitalization (274,119 discharges). Colorectal cancer accounted for more than half of all GI cancers and was the leading cause of GI-related mortality (52,394 deaths). There were 6.9 million upper, 11.5 million lower, and 228,000 biliary endoscopies performed in 2009. The total cost for outpatient GI endoscopy examinations was $32.4 billion.

CONCLUSIONS

GI diseases are a source of substantial morbidity, mortality, and cost in the United States.

Focal endoscopic mucosal resection before radiofrequency ablation is equally effective and safe compared with radiofrequency ablation alone for the eradication of Barrett's esophagus with advanced neoplasia

BACKGROUND

EMR is commonly performed before radiofrequency ablation (RFA) for nodular dysplastic Barrett's esophagus (BE).

OBJECTIVE

To determine the efficacy and safety of EMR before RFA for nodular BE with advanced neoplasia (high-grade dysplasia [HGD] or intramucosal carcinoma [IMC]).

DESIGN

Retrospective study.

SETTING

University of North Carolina Hospitals, from 2006 to 2011.

PATIENTS

169 patients with BE with advanced neoplasia: 65 patients treated with EMR and RFA for nodular disease and 104 patients treated with RFA alone for nonnodular disease.

INTERVENTIONS

EMR, RFA.

MAIN OUTCOME MEASUREMENTS

Efficacy (complete eradication of dysplasia, complete eradication of intestinal metaplasia, total treatment sessions, RFA treatment sessions), safety (stricture formation, bleeding, and hospitalization).

RESULTS

EMR followed by RFA achieved complete eradication of dysplasia and complete eradication of intestinal metaplasia in 94.0% and 88.0% of patients, respectively, compared with 82.7% and 77.6% of patients, respectively, in the RFA-only group (P = .06 and P = .13, respectively). The complication rates between the 2 groups were similar (7.7% vs 9.6%, P = .79). Strictures occurred in 4.6% of patients in the EMR-before-RFA group. compared with 7.7% of patients in the RFA-only group (P = .53).

LIMITATIONS

Retrospective study at a tertiary-care referral center.

CONCLUSION

In patients treated with EMR before RFA for nodular BE with HGD or IMC, no differences in efficacy and safety outcomes were observed compared with RFA alone for nonnodular BE with HGD or IMC. EMR followed by RFA is safe and effective for patients with nodular BE and advanced neoplasia.

Eosinophilic infiltration of the esophagus following endoscopic ablation of Barrett's neoplasia

To assess the incidence of esophageal intra-epithelial eosinophilic infiltration following endoscopic ablation of Barrett's esophagus (BE), a retrospective study of consecutive cases of endoscopic ablation of BE with dysplasia or cancer using radiofrequency ablation (RFA) and spray cryotherapy at two centers in the United States was performed. Post-ablation eosinophilia was defined as ≥ 5 eosinophils per high power field during post-treatment surveillance. Twenty of 122 patients (16%) undergoing ablation developed esophageal eosinophilia after ablation, including 8/77 (10%) treated with RFA and 12/44 (27%) treated with cryotherapy. No patient had clinical or endoscopic findings of or risk factors for eosinophilic esophagitis. Esophageal eosinophilia persisted in 30% over a median of 20.2 months. On multivariate analysis, post-ablation eosinophilia was independently associated with increasing BE segment length (adjusted odds ratio 1.46 for every 2-cm increase, 95% confidence interval 1.24-1.71) and cryotherapy as the ablation modality (adjusted odds ratio 5.23, 95% confidence interval 1.67-16.39). Esophageal eosinophilic infiltration after endoscopic ablation with RFA and cryotherapy is common and is associated with the BE segment length and treatment modality. The clinical significance of post-ablation eosinophilia is unclear.

The role of radiofrequency ablation in the management of Barrett's esophagus

Studies in the last several years have consistently shown radiofrequency ablation (RFA) to be effective, safe, and well tolerated in the treatment of nondysplastic and dysplastic Barrett's esophagus (BE). The results found at academic medical centers have been reproduced in the community setting. RFA provides a safe and cost-effective alternative to surgery or surveillance in the management of high-grade dysplasia (HGD). RFA should be given serious consideration as first-line therapy for HGD. This article reviews the evidence behind RFA to differentiate it from other management strategies in terms of efficacy, durability, safety, tolerability, and cost-effectiveness. The role of RFA in the management of BE is described, including endoscopic resection. Future directions are identified for research that will help to better define the role of RFA in the management of BE.

Evaluation of esophageal motor disorders in the era of high-resolution manometry and intraluminal impedance

The past few years were an exciting time in the study of esophageal motor disorders because new technologies emerged to study esophageal motor function and bolus transit. Although conventional manometry was long considered the "gold standard" for defining esophageal motor disorders, many technologic improvements occurred due to advances in transducer technology, computerization, and graphic data presentation. In addition, a relatively new technology, intraluminal impedance, was incorporated into manometric modalities. The most sophisticated systems now include combined high-resolution manometry with high-resolution impedance. Although these techniques provide more detailed information about esophageal function, whether they improve our ability to diagnose and treat patients more effectively is debatable. However, more recent data support that these advances actually improve our ability to diagnose and treat esophageal motor disorders. This article provides an update on these technologies in clinical practice and how they may be helpful in the future.