Gut bacteria convert glucocorticoids into progestins in the presence of hydrogen gas.

Recent studies suggest that human-associated bacteria interact with host-produced steroids, but the mechanisms and physiological impact of such interactions remain unclear. Here, we show that the human gut bacteria Gordonibacter pamelaeae and Eggerthella lenta convert abundant biliary corticoids into progestins through 21-dehydroxylation, thereby transforming a class of immuno- and metabo-regulatory steroids into a class of sex hormones and neurosteroids. Using comparative genomics, homologous expression, and heterologous expression, we identify a bacterial gene cluster that performs 21-dehydroxylation. We also uncover an unexpected role for hydrogen gas production by gut commensals in promoting 21-dehydroxylation, suggesting that hydrogen modulates secondary metabolism in the gut. Levels of certain bacterial progestins, including allopregnanolone, better known as brexanolone, an FDA-approved drug for postpartum depression, are substantially increased in feces from pregnant humans. Thus, bacterial conversion of corticoids into progestins may affect host physiology, particularly in the context of pregnancy and women's health.

Identification of environmental factors that promote intestinal inflammation.

Genome-wide association studies have identified risk loci linked to inflammatory bowel disease (IBD)1-a complex chronic inflammatory disorder of the gastrointestinal tract. The increasing prevalence of IBD in industrialized countries and the augmented disease risk observed in migrants who move into areas of higher disease prevalence suggest that environmental factors are also important determinants of IBD susceptibility and severity2. However, the identification of environmental factors relevant to IBD and the mechanisms by which they influence disease has been hampered by the lack of platforms for their systematic investigation. Here we describe an integrated systems approach, combining publicly available databases, zebrafish chemical screens, machine learning and mouse preclinical models to identify environmental factors that control intestinal inflammation. This approach established that the herbicide propyzamide increases inflammation in the small and large intestine. Moreover, we show that an AHR-NF-κB-C/EBPß signalling axis operates in T cells and dendritic cells to promote intestinal inflammation, and is targeted by propyzamide. In conclusion, we developed a pipeline for the identification of environmental factors and mechanisms of pathogenesis in IBD and, potentially, other inflammatory diseases.

The Burden of Work Productivity and Activity Impairment in Patients with Psoriasis, Psoriatic Arthritis, Ulcerative Colitis, and Crohn's Disease.

BACKGROUND: Comparisons among autoimmune diseases enable understanding of the burden and factors associated with work productivity loss and impairment. AIMS: The objective was to compare work productivity and activity and associated factors among patients with inflammatory bowel diseases and other autoimmune conditions. METHODS: This cross-sectional study included employed, adult patients (age 20-64 years) in the CorEvitas Inflammatory Bowel Disease, Psoriasis, and Psoriatic Arthritis/Spondyloarthritis Registries between 5/2017 and 6/2020. Any patient-reported impairment on four domains of the Work Productivity and Activity Index (WPAI) was collected across registries. Prevalence for each autoimmune disease was reported and stratified by disease activity using direct age-sex-standardization. Factors associated with the presence of any WPAI were identified in logistic regression models. RESULTS: A total of 7,169 patients with psoriasis (n = 4,768, 67%), psoriatic arthritis (n = 1,208, 17%), Crohn's disease (CD, n = 621, 9%), and ulcerative colitis (UC, n = 572, 8%) met inclusion criteria. Among patients not in remission across all disease cohorts, the age-sex-standardized prevalence of any presenteeism, work productivity loss, and activity impairment ranged from 54 to 97%. Patients with CD in remission had higher standardized prevalence of presenteeism (53% [48-57%]) and work productivity loss (54% [49-59%]), compared to those from other cohorts (presenteeism [range: 33-39%] and work productivity loss [range: 37-41%]). For all WPAI domains, the strongest adjusted associations were for moderate to severe disease activity and psychosocial symptoms. CONCLUSIONS: Patients with moderate to severe disease activity reported the highest WPAI burden. However, patients in remission or mild disease activity also report some WPAI burden, emphasizing a multidisciplinary treatment approach to improve work productivity loss and impairment.

An Expert Consensus to Standardize Assessment of Bowel Cleansing for Clinical Trials of Bowel Preparations for Crohn's Disease.

BACKGROUND: Despite regular need for colonoscopy in patients with Crohn's disease (CD), the efficacy and tolerability of bowel preparation (BP) agents is rarely assessed in this population. Assessing BP quality with existing scales may be challenging in CD due to presence of inflammation, bowel resection, and strictures. AIMS: To provide recommendations for assessing BP quality in clinical trials for CD using a modified Research and Development/University of California, Los Angeles appropriateness process. METHODS: Based on systematic reviews and a literature search, 110 statements relating to BP quality assessment in CD were developed. A panel of 15 gastroenterologists rated the statements as appropriate, uncertain, or inappropriate using a 9-point Likert scale. RESULTS: Panelists considered it appropriate that central readers, either alone or with local assessment, score BP quality in clinical trials. Central readers should be trained on scoring BP quality and local endoscopists on performing high-quality video recording. Both endoscope insertion and withdrawal phases should be reviewed to score BP quality in each colonic segment and segments should align with endoscopic disease activity indices. The Harefield Cleansing Scale and the Boston Bowel Preparation Scale were considered appropriate. The final score should be calculated as the average of all visualized segments. Both total and worst segment scores should also be assessed. CONCLUSIONS: We developed a framework for assessing BP quality in patients with CD based on expert feedback. This framework could support the development or refinement of BP quality scales and the integration of BP quality assessment in future CD studies.

Creation of a Case-Finding Definition for Identifying Patients With Acute Pouchitis in Administrative Claims Data.

Acute pouchitis is the most common complication after a restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis, affecting 40% of patients within the first year after surgery.1 Although up to 80% of patients can develop pouchitis symptoms,2,3 substantial gaps remain in our understanding of the epidemiology and burden of pouchitis. Administrative claims have been used to advance the knowledge of other areas of inflammatory bowel disease4-6; however, a prerequisite to conducting such studies in pouchitis is a valid, reliable case-finding algorithm. Given concerns that the International Classification of Diseases (ICD) code for pouchitis may not be reliably used by clinicians (resulting in a low sensitivity), the objectives of the study were to (1) develop a series of case-finding definitions for acute pouchitis and (2) compare the performance of these case-finding definitions to that of a single ICD code for pouchitis.

Fecal Microbiota Transplantation in Patients With Primary Sclerosing Cholangitis: A Pilot Clinical Trial.

BACKGROUND: Primary sclerosing cholangitis (PSC) is a cholestatic liver disease with no effective medical therapies. A perturbation of the gut microbiota has been described in association with PSC, and fecal microbiota transplantation (FMT) has been reported to restore the microbiome in other disease states. Accordingly, we aimed at evaluating the safety, change in liver enzymes, microbiota, and metabolomic profiles in patients with PSC after FMT. METHODS: An open-label pilot study of patients with PSC with concurrent inflammatory bowel disease and alkaline phosphatase (ALP) > 1.5× the upper limit of normal was conducted. The patients underwent a single FMT by colonoscopy. Liver enzyme profiles and stool microbiome and metabolomic analysis were conducted at baseline and weeks 1, 4, 8, 12, and 24 post-FMT. The primary outcome was safety, and the secondary outcome was a decrease in ALP levels ≥50% from baseline by week 24 post-FMT; stool microbiota (by 16S rRNA gene profiling) and metabonomic dynamics were assessed. RESULTS: Ten patients underwent FMT. Nine patients had ulcerative colitis, and 1 had Crohn's colitis. The mean baseline ALP level was 489 U/L. There were no related adverse events. Overall, 30% (3/10) experienced a ≥50% decrease in ALP levels. The diversity increased in all patients post-FMT, as early as week 1 (P < 0.01). Importantly, abundance of engrafter operational taxonomic units in patients post-FMT correlated with decreased ALP levels (P = 0.02). DISCUSSION: To our knowledge, this is the first study to demonstrate that FMT in PSC is safe. In addition, increases in bacterial diversity and engraftment may correlate with an improvement in ALP among patients with PSC.

A probabilistic pathway score (PROPS) for classification with applications to inflammatory bowel disease.

Summary: Gene-based supervised machine learning classification models have been widely used to differentiate disease states, predict disease progression and determine effective treatment options. However, many of these classifiers are sensitive to noise and frequently do not replicate in external validation sets. For complex, heterogeneous diseases, these classifiers are further limited by being unable to capture varying combinations of genes that lead to the same phenotype. Pathway-based classification can overcome these challenges by using robust, aggregate features to represent biological mechanisms. In this work, we developed a novel pathway-based approach, PRObabilistic Pathway Score, which uses genes to calculate individualized pathway scores for classification. Unlike previous individualized pathway-based classification methods that use gene sets, we incorporate gene interactions using probabilistic graphical models to more accurately represent the underlying biology and achieve better performance. We apply our method to differentiate two similar complex diseases, ulcerative colitis (UC) and Crohn's disease (CD), which are the two main types of inflammatory bowel disease (IBD). Using five IBD datasets, we compare our method against four gene-based and four alternative pathway-based classifiers in distinguishing CD from UC. We demonstrate superior classification performance and provide biological insight into the top pathways separating CD from UC. Availability and Implementation: PROPS is available as a R package, which can be downloaded at http://simtk.org/home/props or on Bioconductor. Contact: rbaltman@stanford.edu. Supplementary information: Supplementary data are available at Bioinformatics online.

A crossover-crossback prospective study of dibutyl-phthalate exposure from mesalamine medications and serum reproductive hormones in men.

BACKGROUND: Phthalates, such as dibutyl phthalate (DBP), are endocrine disruptors used in some medication coatings e.g., mesalamine to treat inflammatory bowel disease (IBD). OBJECTIVES: Taking advantage of different mesalamine formulations with/without DBP, we assessed whether DBP from mesalamine (>1000x background) altered serum hormones. METHODS: Men (N=73) with IBD participated in a crossover-crossback prospective study and provided up to 6 serum samples (2:baseline, 2:crossover, 2:crossback). Men on non-DBP mesalamine (background) at baseline crossed-over for 4 months to DBP-mesalamine (high) and then crossed-back for 4 months to non-DBP mesalamine (B1HB2-arm) and vice versa for men on DBP-mesalamine at baseline (H1BH2-arm). We divided H1BH2-arm at the median (H1<3yrs or H1≥3yrs). We estimated crossover and crossback % changes in serum reproductive hormones using multivariable linear mixed effect models. RESULTS: When B1HB2-arm (26 men,134 samples) crossed-over, luteinizing hormone decreased 13.9% (95% confidence interval(CI): -23.6,-3.0) and testosterone, inhibin-B, and follicle-stimulating hormone (FSH) marginally decreased; after crossback all increased 8-14%. H1BH2-arm, H1≥3yrs (25 men,107samples) had no changes at crossover or crossback whereas in H1BH2-arm,H1<3yrs (22 men,100 samples) after crossover, inhibin-B increased 13.2% (CI: 4.2,22.9), FSH decreased 9.9% (CI: -17.9,-1.1) and after crossback, inhibin-B further increased 11.3%, and FSH marginally increased. CONCLUSIONS: High-DBP exposure may disrupt pituitary-gonadal hormones that largely reversed after exposure removal, but only in men with no or short previous high-exposure history. Paradoxically, men with longer duration of high-DBP exposure, exposure removal did not change hormone levels, suggesting that long-term high-DBP exposure may alter the pituitary-gonadal axis and make it insensitive to exposure changes.

High Dietary Intake of Specific Fatty Acids Increases Risk of Flares in Patients With Ulcerative Colitis in Remission During Treatment With Aminosalicylates.

BACKGROUND & AIMS: Dietary factors may have a significant role in relapse of disease among patients with ulcerative colitis (UC). However, the relationship between diet and UC is inadequately understood. We analyzed data from the diet's role in exacerbations of mesalamine maintenance study to determine whether dietary factors affect the risk of disease flares in patients with UC. METHODS: We performed a prospective, multicenter, observational study of 412 patients, from 25 sites, with UC in remission during monotherapy with an aminosalicylate. Patients completed a validated food frequency questionnaire at enrollment and were followed for 12 months. We analyzed the relationship between diet and disease remission or flare for groups of macronutrients and micronutrients, and food groups previously associated with an increased risk of flare. RESULTS: Forty-five patients (11%) had a UC relapse within 1 year of study enrollment. When analyzed in tertiles, increasing intake of multiple fatty acids was associated with increasing odds of relapse. In multivariable logistic regression analysis, only myristic acid (odds ratio, 3.01; 95% confidence interval, 1.17-7.74) maintained this dose-response relationship. Other foods previously implicated in flares of UC, such as processed meat, alcohol, and foods high in sulfur, were not associated with an increased risk of flare. CONCLUSIONS: In a prospective study of more than 400 patients with UC undergoing treatment with aminosalicylates, we associated high dietary intake of specific fatty acids, including myristic acid (commonly found in palm oil, coconut oil, and dairy fats) with an increased risk of flare. These findings can help design interventional studies to evaluate dietary factors in UC.

The Burden of Hospital Readmissions among Pediatric Patients with Inflammatory Bowel Disease.

OBJECTIVE: To evaluate the burden and predictors of hospital readmissions among pediatric patients with inflammatory bowel disease using the Nationwide Readmissions Database. STUDY DESIGN: We performed a retrospective cohort study using 2013 Nationwide Readmissions Database. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify patients <18 years with diagnoses of ulcerative colitis (UC) or Crohn's disease (CD). Demographic factors and details of hospitalizations were evaluated using survey procedures in SAS v 9.4 (SAS Institute, Cary, North Carolina). Multivariable logistic regression was used to estimate ORs and 95% CIs of readmission. RESULTS: Among 2733 hospitalizations (63% CD, 37% UC), 611 (22%) patients were readmitted within 90 days of the index hospitalization. Readmission resulted in weighted estimates of 11 440 excess days of hospitalization and total charges of over $107 million. For CD, male sex (aOR 1.36, 95% CI 1.03-1.81) and co-existing anxiety or depression (aOR 1.89, 95% CI 1.06-3.40) were associated with increased readmissions, while patients who underwent surgery had decreased readmissions (aOR 0.40, 95% CI 0.24-0.65). In patients with UC, an index admission of >7 days was associated with increased readmissions (aOR 1.69, 95% CI 1.09-2.62). CONCLUSIONS: Readmission occurs frequently in children with inflammatory bowel disease and is associated with significant cost and resource burdens. Among patients with CD, psychiatric comorbidities such as anxiety and depression are apparent drivers of readmission.

Clinical patient registry recruitment and retention: a survey of patients in two chronic disease registries.

BACKGROUND: The collection of routine clinical data in the setting of research registries can serve an important role in understanding real world care. However, relatively little is known about the patient experience in registries, motivating us to survey patients enrolled in two chronic disease registries. METHODS: We conducted similar surveys in two disease-based registries based at one academic medical center in the US. One group of patients with rheumatoid arthritis (RA) had been enrolled in a registry, and we focused on retention factors. In a second group of patients with inflammatory bowel disease (IBD) recently enrolled or considering enrollment, we examined factors that would influence their enrollment and willingness to answer frequent questionnaires and give biospecimens. The surveys were analyzed using descriptive statistics and the two cohorts were compared using nonparametric and chi-square tests. RESULTS: We received 150 (50%) completed surveys from RA and 169 (63%) from IBD patients. Mean age of subjects was 62 years in RA and 43 in IBD with more women respondents with RA (83%) than IBD (62%). The two groups described very similar factors as the top three motivations for participation: desire to help others, desire to improve care of own disease, and ease of volunteering. Preferred methods of surveying included mail, e-mail, but telephone was not favored; age was an important correlate of this preference. Respondents preferred surveys either every 1-3 months (28.7% RA and 55.0% IBD) or every 4-6 months (50.7% RA and 29.0% IBD). They differed in the preference for payment for answering surveys with 68.0% with RA answering that no payment was necessary but only 36.1% with IBD felt similarly. CONCLUSIONS: Patients engaged in clinical registries demonstrate a high level of commitment to improve care and many report a willingness to answer questions relatively frequently.

Predictors of Clinical Response and Remission at 1 Year Among a Multicenter Cohort of Patients with Inflammatory Bowel Disease Treated with Vedolizumab.

BACKGROUND: Vedolizumab (VDZ) has demonstrated long-term efficacy in Crohn's disease (CD) and ulcerative colitis (UC) in phase III trials. AIMS: Our aim was to evaluate the efficacy of VDZ at week 54 in inflammatory bowel disease (IBD) in a multicenter cohort of patients. METHODS: Adult patients completing induction therapy with VDZ were eligible for this study. Clinical response and remission was assessed using the Harvey-Bradshaw Index (HBI) for CD, the Simple Clinical Colitis Activity Index for UC and physician assessment. RESULTS: Among 136 total patients (96 CD and 40 UC), 76 (56%) demonstrated clinical response or remission at week 54. In univariate analysis, for patients with CD concomitant initiation of immunomodulator therapy (2.71, 95% CI 1.11-6.57), the addition of an immunomodulator (OR 11.49, 3.16-41.75) and CRP < 3 (4.92, 95% CI 1.99-12.15) was associated with increased odds of clinical response or remission at week 54. For UC patients, hospitalization after VDZ induction was associated with decreased odds of response or remission at week 54 (OR 0.22, 95% CI 0.05-0.88). On multivariate analysis in CD, addition of an immunomodulator (OR 8.33, 95% CI 2.15-32.26) remained significant predictors of clinical response or remission at week 54. CONCLUSIONS: Among a multicenter cohort of patients with IBD demonstrating primary response to VDZ, the addition of combination therapy with an immunomodulator is a significant predictor of clinical response or remission at week 54 in patients with CD.

Colorectal cancer in Crohn's colitis is comparable to sporadic colorectal cancer.

PURPOSE: It is now recognized that Crohn's disease (CD), similar to ulcerative colitis (UC), carries an up to 20-fold higher cancer risk, and the development of colorectal carcinoma (CRC) is a major long-term complication. Once CRC is present, molecular profiling is one of the components in selecting appropriate treatment strategies; however, in contrast to UC, genetic alterations in Crohn's colitis-associated CRC are poorly understood. METHODS: In a series of 227 patients with Crohn's colitis, we identified 33 cases of CRC (~14 %) and performed targeted mutational analysis of BRAF/KRAS/NRAS and determined microsatellite status as well as immunophenotype of the tumors. RESULTS: In the CRC cohort, the median age at time of cancer diagnosis was 58 (range 34-77 vs. 59.5 in sporadic; P = 0.81) and the median CD duration was 29 years (range 6-45). As a group, CRC complicating Crohn's colitis is BRAF (97 %) and NRAS (100 %) wild type and the vast majority is microsatellite stable (94 %); KRAS-mutations were found in six cases (18 %). Stage grouping, anatomic distribution, and overall survival were similar to sporadic CRC; however, long-standing CD (≥25 years) as well as gastric-immunophenotype (MUC5AC+) was associated with significantly shorter overall survival (P = 0.0029; P = 0.036, respectively). CONCLUSION: In summary, the clinicopathological and molecular profile of CD-associated CRC is similar to that observed in sporadic CRC.

Functionally defective germline variants of sialic acid acetylesterase in autoimmunity.

Sialic acid acetylesterase (SIAE) is an enzyme that negatively regulates B lymphocyte antigen receptor signalling and is required for the maintenance of immunological tolerance in mice. Heterozygous loss-of-function germline rare variants and a homozygous defective polymorphic variant of SIAE were identified in 24/923 subjects of European origin with relatively common autoimmune disorders and in 2/648 controls of European origin. All heterozygous loss-of-function SIAE mutations tested were capable of functioning in a dominant negative manner. A homozygous secretion-defective polymorphic variant of SIAE was catalytically active, lacked the ability to function in a dominant negative manner, and was seen in eight autoimmune subjects but in no control subjects. The odds ratio for inheriting defective SIAE alleles was 8.6 in all autoimmune subjects, 8.3 in subjects with rheumatoid arthritis, and 7.9 in subjects with type I diabetes. Functionally defective SIAE rare and polymorphic variants represent a strong genetic link to susceptibility in relatively common human autoimmune disorders.

Inflammatory Bowel Disease Provoked by Etanercept: Report of 443 Possible Cases Combined from an IBD Referral Center and the FDA.

BACKGROUND: Anti-TNF therapies have revolutionized the treatment of autoimmune inflammatory conditions. Paradoxical treatment with these agents is associated with the development of de novo autoimmune diseases. Less well recognized is the provocation of de novo IBD by these agents. Etanercept is not effective for the treatment of inflammatory bowel disease and may be more often reported with the development of Crohn's disease or ulcerative colitis. AIM: This study assessed the association of new onset IBD in patients with receiving etanercept. METHODS: The Brigham and Women's (BWH) patient database and the FDA Adverse Event Reporting System were searched for cases of IBD reported with etanercept. RESULTS: A total of 443 cases were identified: 5 pts at BWH (3 CD, 2 UC) and 438 (294 CD, 144 UC) reported to the FDA. Data which were most complete were pooled from 49 patients. NSAID use was reported in 43 % and combination with methotrexate in 29 %. Etanercept was discontinued in 34 pts and 19 required treatment with a different anti-TNF agent. Eight patients had resolution of GI symptoms on discontinuation of etanercept. Therapy was continued in three patients in response to 5-ASA therapy. CONCLUSION: Development of IBD should be suspected in patients receiving etanercept who develop GI symptoms. This phenomenon appears more commonly associated with initiation of CD. The clinical phenotype appears indistinguishable from usual patterns of IBD. Unlike other autoimmune phenomenon associated with anti-TNF therapy, IBD often does not resolve when the agent is discontinued. This tentative association requires further investigation.

Sequential Combination Therapy Versus Monotherapy: A Lack of Benefit in Time to Inflammatory Bowel Disease-Related Surgery.

BACKGROUND: The benefits of combination therapy with infliximab and azathioprine have been demonstrated in clinical trials of patients with ulcerative colitis (UC) and Crohn's disease (CD). Concerns remain regarding the ideal duration and benefits of adding therapies in a sequential manner. AIMS: We aim to compare long-term outcomes among patients with inflammatory bowel disease (IBD) treated with sequentially added combination therapy or monotherapy strategies . METHODS: We performed a retrospective cohort study involving adult patients with UC and CD. One cohort included patients treated with infliximab, adalimumab, or a thiopurine as monotherapy. A second cohort included patients treated with sequentially added combination therapy including infliximab or adalimumab and a thiopurine. The primary outcome was the rate of IBD-related surgery. RESULTS: Among 462 patients, 181 (39 %) were treated with combination therapy. 12 % of patients treated with combination therapy underwent an IBD-related surgery compared to 18 % of patients treated with monotherapy (p = 0.091), with no overall difference in time to IBD-related surgery demonstrated (log-rank test, p = 0.063). When evaluating the subtypes of IBD, there was a significant benefit in time to IBD-related surgery among patients with CD treated with sequentially added combination therapy (HR 0.46, 95 % CI 0.25-0.85) but not UC (HR 0.82, 95 % CI 0.30-2.22). CONCLUSIONS: The benefits of sequentially added combination therapy seem blunted when evaluating long-term clinical outcomes. This may be due to a decreased effectiveness of sequential combination therapy, a loss of benefit over time, or a differential effect between subtypes of IBD.

Chemical and cytokine features of innate immunity characterize serum and tissue profiles in inflammatory bowel disease.

Inflammatory bowel disease (IBD) arises from inappropriate activation of the mucosal immune system resulting in a state of chronic inflammation with causal links to colon cancer. Helicobacter hepaticus-infected Rag2(-/-) mice emulate many aspects of human IBD, and our recent work using this experimental model highlights the importance of neutrophils in the pathology of colitis. To define molecular mechanisms linking colitis to the identity of disease biomarkers, we performed a translational comparison of protein expression and protein damage products in tissues of mice and human IBD patients. Analysis in inflamed mouse colons identified the neutrophil- and macrophage-derived damage products 3-chlorotyrosine (Cl-Tyr) and 3-nitrotyrosine, both of which increased with disease duration. Analysis also revealed higher Cl-Tyr levels in colon relative to serum in patients with ulcerative colitis and Crohn disease. The DNA chlorination damage product, 5-chloro-2'-deoxycytidine, was quantified in diseased human colon samples and found to be present at levels similar to those in inflamed mouse colons. Multivariate analysis of these markers, together with serum proteins and cytokines, revealed a general signature of activated innate immunity in human IBD. Signatures in ulcerative colitis sera were strongly suggestive of neutrophil activity, and those in Crohn disease and mouse sera were suggestive of both macrophage and neutrophil activity. These data point to innate immunity as a major determinant of serum and tissue profiles and provide insight into IBD disease processes.

A prospective study of long-term intake of dietary fiber and risk of Crohn's disease and ulcerative colitis.

BACKGROUND & AIMS: Increased intake of dietary fiber has been proposed to reduce the risk of inflammatory bowel disease (Crohn's disease [CD] and ulcerative colitis [UC]). However, few prospective studies have examined associations between long-term intake of dietary fiber and risk of incident CD or UC. METHODS: We collected and analyzed data from 170,776 women, followed up over 26 years, who participated in the Nurses' Health Study, followed up for 3,317,425 person-years. Dietary information was prospectively ascertained via administration of a validated semiquantitative food frequency questionnaire every 4 years. Self-reported CD and UC were confirmed through review of medical records. Cox proportional hazards models, adjusting for potential confounders, were used to calculate hazard ratios (HRs). RESULTS: We confirmed 269 incident cases of CD (incidence, 8/100,000 person-years) and 338 cases of UC (incidence, 10/100,000 person-years). Compared with the lowest quintile of energy-adjusted cumulative average intake of dietary fiber, intake of the highest quintile (median of 24.3 g/day) was associated with a 40% reduction in risk of CD (multivariate HR for CD, 0.59; 95% confidence interval, 0.39-0.90). This apparent reduction appeared to be greatest for fiber derived from fruits; fiber from cereals, whole grains, or legumes did not modify risk. In contrast, neither total intake of dietary fiber (multivariate HR, 0.82; 95% confidence interval, 0.58-1.17) nor intake of fiber from specific sources appeared to be significantly associated with risk of UC. CONCLUSIONS: Based on data from the Nurses' Health Study, long-term intake of dietary fiber, particularly from fruit, is associated with lower risk of CD but not UC. Further studies are needed to determine the mechanisms that mediate this association.