A case-control study of drinking water and dairy products in Crohn's Disease--further investigation of the possible role of Mycobacterium avium paratuberculosis

Dairy Consumption and Inflammatory Bowel Disease among Arab Adults: A Case-Control Study and Meta-Analysis

BACKGROUND

Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), is a complex disease with increasing global incidence and prevalence. Although dairy consumption has been linked to various chronic diseases, its relationship with IBD remains uncertain. Additionally, there is a lack of data on this topic from Arab countries. This study aimed to investigate the association between dairy consumption and IBD through a case-control study among Arab populations, followed by a meta-analysis of available studies.

METHOD

First, we used data from 158 UC patients, 244 CD patients, and 395 controls attending a polyclinic in Riyadh, Saudi Arabia. All participants were aged ≥ 18 years. Logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (95% CIs) of UC and CD for individuals who reported the highest versus the lowest frequencies of dairy consumption. Next, we conducted a meta-analysis, combining our results with those from other eligible studies after searching several databases. We used the I2 statistics to examine statistical heterogeneity across studies and the regression test for funnel plot asymmetry to assess publication bias.

RESULTS

The case-control study showed a negative association between frequent dairy consumption and UC (OR (95% CI) = 0.64 (0.41, 1.00)) but not CD (OR (95% CI) = 0.97 (0.65, 1.45)). In the meta-analysis, the highest frequencies of dairy consumption were negatively associated with both UC and CD: ORs (95% CIs) = 0.82 (0.68, 0.98) and 0.72 (0.59, 0.87), respectively. A moderate heterogeneity across studies was noticed in the UC meta-analysis (I2 = 59.58%) and the CD meta-analysis (I2 = 41.16%). No publication bias was detected.

CONCLUSIONS

Frequent dairy consumption could protect against the development of UC and CD, suggesting potential dietary recommendations in the context of IBD prevention.

Drinking water quality and inflammatory bowel disease: a prospective cohort study

Environmental factors, such as drinking water and diets, play an important role in the development of inflammatory bowel disease (IBD). This study aimed to investigate the associations of metal elements and disinfectants in drinking water with the risk of inflammatory bowel disease (IBD) and to assess whether diet influences these associations. We conducted a prospective cohort study including 22,824 participants free from IBD from the Yinzhou cohort study in the 2016-2022 period with an average follow-up of 5.24 years. The metal and disinfectant concentrations were measured in local pipeline terminal tap water samples. Cox regression models adjusted for multi-level covariates were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (95% CIs). During an average follow-up period of 5.24 years, 46 cases of IBD were identified. For every 1 standard deviation (SD) increase in the concentration of manganese, mercury, selenium, sulfur tetraoxide (SO₄)_, chlorine, and nitrate nitrogen (NO₃_N) were associated with a higher risk of IBD with the HRs of 1.45 (95% CI: 1.14 to 1.84), 1.51 (95% CI: 1.24-1.82), 1.29 (95% CI: 1.03-1.61), 1.52 (95% CI: 1.26-1.83), 1.26 (95% CI: 1.18-1.34), and 1.66 (95% CI: 1.32-2.09), whereas zinc and fluorine were inversely associated with IBD with the HRs of 0.42 (95% CI: 0.24 to 0.73) and 0.68 (95% CI: 0.54-0.84), respectively. Stronger associations were observed in females, higher income groups, low education groups, former drinkers, and participants who never drink tea. Diets have a moderating effect on the associations of metal and nonmetal elements with the risk of IBD. We found significant associations between exposure to metals and disinfectants and IBD. Diets regulated the associations to some extent.

IS DAIRY FOODS RESTRICTION MANDATORY FOR INFLAMMATORY BOWEL DISEASE PATIENTS: A MULTINATIONAL CROSS-SECTIONAL STUDY

BACKGROUND

The role of dairy foods in inflammatory bowel disease (IBD) has been controversial and it is debatable if patients with IBD should avoid milk and dairy products or not, as well as the relationship between these foods and symptoms among those population.

OBJECTIVE

This multi centric cross-sectional study designed to evaluate if it is really necessary to deprive IBD patients from consumption of dairy foods.

METHODS

A multicenter study with 12 gastroenterology referral centers in four countries was designed to evaluate gastrointestinal (GI) symptoms after consumption of dairy foods from all outpatients with IBD during 6 months and to compare patients treated at the same centers without IBD (non IBD cases).

RESULTS

Overall 1888 cases included (872 IBD patients and 1016 non IBD cases). 56.6% of participants were female with average age of 40.1 years. Racially 79.8% participants were Caucasians and originally they were citizens of 10 countries. Relative prevalence of IBD was higher in Africans and Indians and the most frequent prevalence of dairy foods intolerance was seen in Asians. Among IBD patients, 571 cases diagnosed as ulcerative colitis and 189 participants as Crohn's disease. Average duration of diagnosis as IBD was 6.8 years (from 2 months to 35 years). The most prevalent GI symptoms after consumption of all the dairy foods were bloating and abdominal pain. Totally, intolerance of dairy foods and lactase deficiency was more prevalent among IBD patients in comparison with non IBD cases (65.5% vs 46.1%, P=0.0001). But the rate of GI complains among IBD patients who had not any family history of lactase deficiency, history of food sensitivity or both were 59.91%, 52.87% & 50.33% respectively and similar to non IBD cases (P=0.68, 0.98 & 0.99 respectively).

CONCLUSION

The rate of dairy foods intolerance among IBD patients without family history of lactase deficiency or history of food sensitivity is similar to non IBD cases and probably there is no reason to deprive them from this important source of dietary calcium, vitamin D and other nutrients.

Safe Game: Hygienic Habits in Self-Consumption of Game Meat in Eastern Spain

We used anonymous questionnaires to assess the hygienic and sanitary aspects of game meat self-consumption in Eastern Spain as the first step towards a health risk assessment. The survey yielded 472 valid interviews from active hunters. The maximum possible score was 65 points (average 29 ± 8; range 1–52). Most participants were men (95%), but women achieved significantly better scores (p = 0.003). Hunters above 65 years old scored significantly lower results than younger groups (p = 0.007). The score increased with the educational level (p = 0.046). A 92% of the collaborators consumed game meat. Veterinary inspection and freezing were irregular among the participants. Most respondents declared carrying the animals in their personal vehicles. Of the dressing process, 61% of sites were outdoors, 68% of the participants declared using specific knives, 64% used the same clothes as in the field, and 42% used disposable gloves. The most usual way to dispose of the remains was garbage containers (41%); offal abandonment in the field was 33%, and 13% fed domestic animals using the remains. We conclude that public health authorities should increase their interest in the self-consumption of game meat. Clear guidelines about domestic dressing facilities and hygienic habits should be published, these being essential when looking for synergies with hunter associations.

Habitual Fish Oil Supplementation and Risk of Incident Inflammatory Bowel Diseases: A Prospective Population-Based Study

Background

Inflammatory Bowel Diseases (IBDs) have been emerging in recent years with the advance of global industrialization and diet pattern transformation. Marine n-3 polyunsaturated fatty acids (n-3 PUFAs), enriched in fish oils, have well-known human health promotion. Evidence on the association of fish oil supplementation with the risk of developing IBDs was scarce. This study aimed to examine the association between the use of fish oil supplements and the risk of developing inflammatory bowel diseases (IBDs) among the general population.

Methods

We conducted a prospective cohort study of 447,890 participants aged 40-69 years from the UK Biobank. A touch screen questionnaire was used to get the data about fish oil intake at baseline. Incident diagnoses of IBDs were ascertained by the International Classification of Diseases (ICD-9 and ICD-10) or self-report. Cox proportional hazards model was applied to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of developing IBDs and their subtypes.

Results

We documented 1,646 incident cases of IBDs, including 533 incident cases of Crohn's disease (CD) and 1,185 incident cases of ulcerative colitis (UC) during an average of 8 years of follow-up. After multivariate adjustment, the use of fish oil was associated with a 12% lower risk of IBDs (HR: 0.88, 95% CI: 0.78-0.99, p = 0.03) compared with non-consumers. For subtypes of IBDs, fish oil supplementation was inversely associated with a 15% lower risk of UC (HR: 0.85, 95% CI: 0.75-0.99, p = 0.02) but was not correlated with the risk of CD (p = 0.22). Besides, fish oil supplementation showed a significant inverse correlation with baseline CRP levels (β = -0.021, p < 0.001) and a positive association with baseline albumin levels (β = 0.135, p < 0.001) after adjustment for multiple variates.

Conclusion

Habitual intake of fish oil supplements was associated with a lower risk of IBDs and UC. Fish oil users tended to have lower baseline C-reactive protein levels and higher baseline albumin levels compared with non-users. It was concluded that fish oil supplement use may be recommended for the prevention and control of IBDs.

Lactose intolerance: An update on its pathogenesis, diagnosis, and treatment

Lactose intolerance has a high prevalence worldwide, ranging between 57% and 65%. It is caused by a reduction or loss of the activity of the intestinal enzyme lactase-phlorizin hydrolase, responsible for the digestion of lactose. This alteration determines an increased osmotic load in the small intestine and the fermentation of lactose by the bacterial flora, which leads to a high production of short-chain fatty acids and gas. This is followed by the onset of abdominal pain, diarrhea, and flatulence. In addition to these problems, it was found that subjects with lactose intolerance have an increased risk of developing various extra-intestinal diseases, including cancers. The diagnosis is essential to undertake an adequate treatment and, for this purpose, different methods have been tested. These include genetic test, hydrogen breath test (HBT), quick lactase test, and lactose tolerance test. HBT is the most used method because it is non-invasive, inexpensive, and highly sensitive and specific, as well as easy to perform. In clinical practice, the other methods are mainly used as HBT integration tests. There are also many therapeutic options. An appropriate intervention concerns the dietetic style, such as the consumption of lactose-free foods, but with nutritional characteristics comparable to dairy products. Other valid choices are represented by the use of exogenous enzymes, probiotics, prebiotics, the selection of milk containing specific types of beta-caseins. This review is intended to illustrate the diagnostic methods currently available and the possible therapeutic options for lactose intolerance.

Fish Oil for Inflammatory Bowel Disease: Panacea or Placebo?

Dietary supplements have increasingly gained popularity over the years not only to replete micronutrient deficiencies but for their use in treatment of disease. The popularity of dietary supplements for inflammatory bowel diseases (IBD) arises from their perceived ease of use, potential disease-modifying benefits, and perceived safety. Overall, randomized controlled trials have not consistently shown a benefit of fish oil for the maintenance of remission with Crohn's disease. The inconsistency of these findings highlights the need for more studies that are powered to clarify the context in which omega-3 fatty acids might have a role in the treatment algorithm of IBD.

A food pyramid, based on a review of the emerging literature, for subjects with inflammatory bowel disease

Emerging literature suggests that diet plays an important modulatory role in inflammatory bowel disease (IBD) through the management of inflammation and oxidative stress. The aim of this narrative review is to evaluate the evidence collected up till now regarding optimum diet therapy for IBD and to design a food pyramid for these patients. The pyramid shows that carbohydrates should be consumed every day (3 portions), together with tolerated fruits and vegetables (5 portions), yogurt (125ml), and extra virgin olive oil; weekly, fish (4 portions), white meat (3 portions), eggs (3 portions), pureed legumes (2 portions), seasoned cheeses (2 portions), and red or processed meats (once a week). At the top of the pyramid, there are two pennants: the red one means that subjects with IBD need some personalized supplementation and the black one means that there are some foods that are banned. The food pyramid makes it easier for patients to decide what they should eat.

Milk Exosomes Prevent Intestinal Inflammation in a Genetic Mouse Model of Ulcerative Colitis: A Pilot Experiment

Background

Milk is rich in nutrients and anabolic mediators rendering it essential for postnatal growth and metabolic programming. However, in adults, excessive consumption of milk is controversial as civilization disorders such as diabetes or prostate cancer may be promoted. A cytoprotective effect of milk could be utilized in inflammatory conditions, that is, chronic colitis.

Objective

To evaluate the effect of bovine milk exosomes on intestinal inflammation in a genetic mouse model of ulcerative colitis.

Methods

Intestinal-specific kindlin 2 knockout (KO) mice were exposed for 4 days to tamoxifen for induction of an ulcerative colitis phenotype. At the same time 4 other kindlin 2 KO mice were exposed to 33 μg/g cow milk derived exosomes in PBS by oral gavage. Both groups were compared to untreated wild-type controls.

Results

Milk exosomes prevented the appearance of a severe ulcerative phenotype. The macroscopic colitis score dropped from a mean of 3.33 in untreated mice to 0.75 index points (p < 0.01) in exosome-treated mice, which included significant improvement of the subscores of stool improvement and colon weight and length. Treated mice featured a noninflamed appearance of the intestinal mucosa.

Key Message

Milk exosomes have cytoprotective/anti-inflammatory activity in a genetic mouse model of ulcerative colitis. The mechanisms behind this need to be elucidated. This pilot study needs verification before a therapeutic strategy is developed.

Australian Veterinarians' Perceptions Regarding the Zoonotic Potential of Mycobacterium avium Subspecies Paratuberculosis

Public concerns over exposure to Mycobacterium avium subspecies paratuberculosis (MAP) or MAP components via foods of animal origin could have negative trade consequences, despite the absence of conclusive scientific evidence of a causal association between Mycobacterium avium subspecies paratuberculosis (MAP) and Crohn’s disease (CD). This study was conducted among Australian veterinarians to understand (a) their perceptions regarding the role of MAP in the causation of CD (an ordinal outcome), and (b) their consideration of the adoption of the precautionary principle against Johne’s disease (JD; a binary outcome). Ordinal and binary logistic regression analyses were performed to evaluate the association of explanatory variables with the above outcomes, respectively. Almost one-third of the respondents (32.2%) considered that MAP was likely to be involved in the causation of CD whereas more than two-thirds (69.8%) agreed with the adoption of the precautionary principle against JD. Veterinarians who were concerned about exposure to and/or getting infected with MAP were more likely to consider MAP as a causative agent of CD (odds ratio: 7.63; 95% CI: 1.55, 37.63) and favor the adoption of the precautionary principle against JD (odds ratio: 6.20; 95% CI: 1.90, 20.25). Those perceiving MAP as a causative agent of CD were also more likely to favor the adoption of the precautionary principle against JD (odds ratio: 13.2; 95% CI: 1.26, 138.90). The results suggest that Australian veterinarians, particularly those who consider MAP as a causative agent of CD are concerned about exposure to MAP and favor the adoption of the precautionary principle against JD. These findings can be useful for animal health authorities for designing JD control programs and policies.

Dietary intake of fish, n-3 polyunsaturated fatty acids, and risk of inflammatory bowel disease: a systematic review and meta-analysis of observational studies

PURPOSE

Fish consumption and dietary intake of n-3 polyunsaturated acids (PUFAs) may be associated with inflammatory bowel disease (IBD). We aimed to conduct a systematic review and summarize published articles on the association between fish consumption and dietary intake of n-3 PUFAs with the risk of IBD.

METHODS

PubMed, Scopus, and Web of Science databases were used to conduct a comprehensive search and identify eligible literature published prior to January 2019. Fixed-effects model or random-effects models (DerSimonian-Laird method) were applied to pool the effect sizes. Cochrane Q test was used to trace the potential source of heterogeneity across studies.

RESULTS

12 studies (5 prospective and 7 case-control) were included in the systematic review, which ten of them were eligible for inclusion in the meta-analysis. Studies were included a total sample size of 282610 participants which 2002 of them were cases of IBD [1061 Crohn's disease (CD) and 937 ulcerative colitis (UC)]. A negative association was found between fish consumption and the incidence of CD (pooled effect size: 0.54, 95%CI: 0.31-0.96, P = 0.03). There was no relationship between total dietary n-3 PUFAs intake and IBD (pooled effect size: 1.17, 95%CI: 0.80-1.72, P = 0.41). A significant inverse association was observed between dietary long-chain n-3 PUFAs and the risk of UC (pooled effect size: 0.75, 95%CI: 0.57-0.98, P = 0.03). Moreover, no association was found between α-Linolenic acid (ALA) and IBD (pooled effect size: 1.17, 95%CI: 0.63-2.17, P = 0.62).

CONCLUSIONS

Findings showed a negative association between fish consumption and the risk of CD. Moreover, there was a significant inverse association between dietary long-chain n-3 PUFAs and the risk of UC.

Lactose Intolerance, Dairy Avoidance, and Treatment Options

Lactose intolerance refers to symptoms related to the consumption of lactose-containing dairy foods, which are the most common source for this disaccharide. While four causes are described, the most common is the genetically-determined adult onset lactose maldigestion due to loss of intestinal lactase governed by control of the gene by a 14,000 kb promoter region on chromosome 2. Gastrointestinal symptoms from lactose have expanded to include systemic effects and have also been confounded by other food intolerances or functional gastrointestinal disorders. Partly because lactose maldigestion is often interpreted as lactose intolerance (symptoms), focus of therapy for these symptoms starts with lactose restriction. However, withholding of dairy foods completely is not appropriate due to a more favorable impact on health. Industrial efforts to substitute with plant-based products is not completely successful at this time. This narrative article reviews the complexities of the perception of lactose intolerance, its epidemiology, and pathogenesis. Treatments are discussed, including the inappropriateness of dairy avoidance. In conjunction, effects of dairy products on 19 common diseases are reviewed. Different methods of treatment, lactose-reduced products, plant-based dairy substitutes, adaptation, prebiotics, exogenous lactase, probiotics, and some other dietary interventions are further discussed.

Chronic regional intestinal inflammatory disease: A trans-species slow infection?

Crohn's disease and ulcerative colitis in humans and paratuberculosis in domestic and wild ruminants can be defined as chronic regional intestinal inflammatory diseases (CRIID). This review is a literature overview on these diseases in humans, non-human primates, dogs, cats, rabbits, equids and ruminants with a focus on pathological and microbiological features aimed identifying common characteristics that could lead to a unified pathological classification for a better understanding of their mechanisms and causes. The result is a framework of inflammatory forms throughout the different species indicative of common mechanisms of the slow infection type characterized by a time course varying from weeks to months or even years, and where the inflammatory component would be more prominent in the intestinal interphase between host and environment and be morphologically characterized by an infiltrate ranging from lymphoplasmacytic to histiocytic. This should provide new insights for causation demonstration and therapeutic approaches in human IBD.

Mycobacterium avium ssp. paratuberculosis detection in animals, food, water and other sources or vehicles of human exposure: A scoping review of the existing evidence

Mycobacterium avium ssp. paratuberculosis is the etiologic agent of Johne's disease in ruminants and is hypothesized to be an infectious cause of Crohn's disease, as well as some other human diseases. Due to key knowledge gaps, the potential public health impact of M. paratuberculosis is unknown. This scoping review aims to identify and characterised the evidence on potential sources and vehicles of M. paratuberculosis exposure for humans to better understand how exposure is likely to occur. Evidence from 255 primary research papers is summarized; most examined the prevalence or concentration of M. paratuberculosis in animals (farmed domestic, pets and wildlife) (n=148), food for human consumption (62) (milk, dairy, meat, infant formula) or water (drinking and recreational) and the environment (farm, pasture and areas affected by runoff water) (20). The majority of this research has been published since 2000 (Figure- abstract). Nine case-control studies examining risk factors for Crohn's disease highlighted significant associations with the consumption of processed meats and cheese, while direct contact with ruminants, high risk occupations (farmer, veterinarian), milk consumption and water source were factors not associated with the disease and/or M. paratuberculosis exposure status. Molecular epidemiology studies demonstrated strain-sharing between species. Produce and seafood were the only previously suggested sources of human exposure for which there was no supporting evidence identified in this scoping review. The results of this review indicate that ruminant populations from around the globe are infected with M. paratuberculosis and many non-ruminant species have also been found to carry or be infected with M. paratuberculosis. Several potential sources for human exposure to M. paratuberculosis were identified; however there remain important gaps in quantitative information on the prevalence and concentration of M. paratuberculosis in contaminated sources of exposure. This information is critical to understanding the risk of exposure, opportunities for risk mitigation interventions and modelling exposures to distill the importance of various sources of human exposure to M. paratuberculosis including direct contact with animals and the environment as well as consumption of contaminated foods and water. Results of this study may be used to prioritize future research and to support evidence-informed decision-making on the M. paratuberculosis issue.

Systematic review and meta-analysis of lactose digestion, its impact on intolerance and nutritional effects of dairy food restriction in inflammatory bowel diseases

BACKGROUND

Relationships between inflammatory bowel disease and lactose containing foods remain controversial and poorly defined regarding symptoms, nutritional outcomes, and epidemiologic associations for lactose maldigestion.

METHODS

A literature review was performed using Pub Med, Cochrane library and individual references, to extract data on lactose maldigestion prevalence in inflammatory bowel diseases. A meta-analysis was done using selected articles, to determine odds ratios of maldigestion. Information was collected about symptoms, impact on pattern of dairy food consumption, as well as the effects of dairy foods on the course of inflammatory bowel diseases.

RESULTS

A total of 1022 articles were evaluated, 35 articles were retained and 5 studies were added from review articles. Of these 17 were included in meta-analysis which showed overall increased lactose maldigestion in both diseases. However increased risk on sub analysis was only found in Crohn's in patients with small bowel involvement. Nine additional studies were reviewed for symptoms, with variable outcomes due to confounding between lactose intolerance and lactose maldigestion. Fourteen studies were evaluated for dairy food effects. There was a suggestion that dairy foods may protect against inflammatory bowel disease. Nutritional consequences of dairy restrictions might impact adversely on bone and colonic complications.

CONCLUSIONS

Lactose maldigestion in inflammatory bowel disease is dependent on ethnic makeup of the population and usually not disease. No bias of increased disease prevalence was noted between lactase genotypes. Intolerance symptoms depend on several parameters besides lactose maldigestion. Dairy foods may decrease risks of inflammatory bowel disease. Dairy restrictions may adversely affect disease outcome.

Dairy Products, Dietary Calcium, and Risk of Inflammatory Bowel Disease: Results From a European Prospective Cohort Investigation

BACKGROUND

Dairy products may be involved in the etiology of inflammatory bowel disease by modulating gut microbiota and immune responses, but data from epidemiological studies examining this relationship are limited. We investigated the association between prediagnostic intake of these foods and dietary calcium, and the subsequent development of Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

In total, 401,326 participants were enrolled in the European Prospective Investigation into Cancer and Nutrition cohort. At recruitment, consumption of total and specific dairy products (milk, yogurt, and cheese) and dietary calcium was measured using validated food frequency questionnaires. Cases developing incident CD (n = 110) or UC (n = 244) during follow-up were matched with 4 controls. Conditional logistic regression analyses were used to calculate odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for total energy intake and smoking.

RESULTS

Compared with the lowest quartile, the ORs for the highest quartile of total dairy products and dietary calcium intake were 0.61 (95% CI, 0.32-1.19, p trend = 0.19) and 0.63 (95% CI, 0.28-1.42, p trend = 0.23) for CD, and 0.80 (95% CI, 0.50-1.30, p trend = 0.40) and 0.81 (95% CI, 0.49-1.34, p trend = 0.60) for UC, respectively. Compared with nonconsumers, individuals consuming milk had significantly reduced odds of CD (OR 0.30, 95% CI, 0.13-0.65) and nonsignificantly reduced odds of UC (OR 0.85, 95% CI, 0.49-1.47).

CONCLUSIONS

Milk consumption may be associated with a decreased risk of developing CD, although a clear dose-response relationship was not established. Further studies are warranted to confirm this possible protective effect.

Adaptation to Lactose in Lactase Non Persistent People: Effects on Intolerance and the Relationship between Dairy Food Consumption and Evalution of Diseases

Dairy foods contain complex nutrients which interact with the host. Yet, evolution of lactase persistence has divided the human species into those that can or cannot digest lactose in adulthood. Such a ubiquitous trait has differential effects on humanity. The literature is reviewed to explore how the divide affects lactose handling by lactase non persistent persons. There are two basic differences in digesters. Firstly, maldigesters consume less dairy foods, and secondly, excess lactose is digested by colonic microflora. Lactose intolerance in maldigesters may occur with random lactose ingestion. However, lactose intolerance without maldigestion tends to detract from gaining a clear understanding of the mechanisms of symptoms formation and leads to confusion with regards to dairy food consumption. The main consequence of intolerance is withholding dairy foods. However, regular dairy food consumption by lactase non persistent people could lead to colonic adaptation by the microbiome. This process may mimic a prebiotic effect and allows lactase non persistent people to consume more dairy foods enhancing a favorable microbiome. This process then could lead to alterations in outcome of diseases in response to dairy foods in lactose maldigesters. The evidence that lactose is a selective human prebiotic is reviewed and current links between dairy foods and some diseases are discussed within this context. Colonic adaptation has not been adequately studied, especially with modern microbiological techniques.

Consumption of vegetables and fruit and the risk of inflammatory bowel disease: a meta-analysis

To date, associations between consumption of vegetables and fruit and the risk of inflammatory bowel disease have been a controversial subject. Therefore, we carried out a meta-analysis to evaluate the associations. A comprehensive search was performed in PubMed, Embase, Web of Science, and the China National Knowledge Infrastructure to identify all relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) from random-effects or fixed-effects models were calculated. Publication bias was estimated using Egger's test and the funnel plot. A total of 14 case-control studies were included in this meta-analysis. On the basis of the highest versus the lowest analysis, consumption of vegetables was associated inversely with the risk of ulcerative colitis (UC) (OR=0.71, 95% CI 0.58-0.88, n=9 studies), but not with Crohn's disease (CD) (OR=0.66, 95% CI 0.40-1.09, n=8 studies). Higher consumption of fruit was associated inversely with the risk of UC (OR=0.69, 95% CI 0.49-0.96, n=8 studies) and CD (OR=0.57, 95% CI 0.44-0.74, n=10 studies). For intake of vegetables and the risk of CD, subgroup analysis showed a significant association for studies carried out in Europe (OR=0.36, 95% CI 0.23-0.57), but not in Asia (OR=1.00, 95% CI 0.50-2.03). No significant publication bias was found for the analysis of intake of vegetables and the risk of UC, intake of fruit and the risk of UC, and intake of vegetables and the risk of CD. This meta-analysis indicates that consumption of vegetables and fruit might be associated inversely with the risk of UC and CD, and the results need to be further confirmed.

Adult lactose digestion status and effects on disease

BACKGROUND

Adult assimilation of lactose divides humans into dominant lactase-persistent and recessive nonpersistent phenotypes.

OBJECTIVES

To review three medical parameters of lactose digestion, namely: the changing concept of lactose intolerance; the possible impact on diseases of microbial adaptation in lactase-nonpersistent populations; and the possibility that the evolution of lactase has influenced some disease pattern distributions.

METHODS

A PubMed, Google Scholar and manual review of articles were used to provide a narrative review of the topic.

RESULTS

The concept of lactose intolerance is changing and merging with food intolerances. Microbial adaptation to regular lactose consumption in lactase-nonpersistent individuals is supported by limited evidence. There is evidence suggestive of a relationship among geographical distributions of latitude, sunhine exposure and lactase proportional distributions worldwide.

DISCUSSION

The definition of lactose intolerance has shifted away from association with lactose maldigestion. Lactose sensitivity is described equally in lactose digesters and maldigesters. The important medical consequence of withholding dairy foods could have a detrimental impact on several diseases; in addition, microbial adaptation in lactase-nonpersistent populations may alter risk for some diseases. There is suggestive evidence that the emergence of lactase persistence, together with human migrations before and after the emergence of lactase persistence, have impacted modern-day diseases.

CONCLUSIONS

Lactose maldigestion and lactose intolerance are not synonymous. Withholding dairy foods is a poor method to treat lactose intolerance. Further epidemiological work could shed light on the possible effects of microbial adaptation in lactose maldigesters. The evolutionary impact of lactase may be still ongoing.

Mycobacterium avium subspecies paratuberculosis in the etiology of Crohn’s disease, cause or epiphenomenon?

The origin of inflammatory bowel disease is unknown. Attempts have been made to isolate a microorganism that could explain the onset of inflammation, but no pathological agent has ever been identified. Johne’s disease is a granulomatous chronic enteritis of cattle and sheep caused by Mycobacterium avium subspecies paratuberculosis (MAP) and shows some analogies with Crohn’s disease (CD). Several studies have tried to clarify if MAP has a role in the etiology of CD. The present article provides an overview of the evidence in favor and against the “MAP-hypothesis”, analyzing the methods commonly adopted to detect MAP and the role of antimycobacterial therapy in patients with inflammatory bowel disease. Studies were identified through the electronic database, MEDLINE, and were selected based on their relevance to the objective of the review. The presence of MAP was investigated using multiple diagnostic methods for MAP detection and in different tissue samples from patients affected by CD or ulcerative colitis and in healthy controls. On the basis of their studies, several authors support a close relationship between MAP and CD. Although increasing evidence of MAP detection in CD patients is unquestionable, a clear etiological link still needs to be proven.

Mycobacterium avium subspecies paratuberculosis causes Crohn's disease in some inflammatory bowel disease patients

Crohn’s disease (CD) is a chronic inflammatory condition that plagues millions all over the world. This debilitating bowel disease can start in early childhood and continue into late adulthood. Signs and symptoms are usually many and multiple tests are often required for the diagnosis and confirmation of this disease. However, little is still understood about the cause(s) of CD. As a result, several theories have been proposed over the years. One theory in particular is that Mycobacterium avium subspecies paratuberculosis (MAP) is intimately linked to the etiology of CD. This fastidious bacterium also known to cause Johne’s disease in cattle has infected the intestines of animals for years. It is believed that due to the thick, waxy cell wall of MAP it is able to survive the process of pasteurization as well as chemical processes seen in irrigation purification systems. Subsequently meat, dairy products and water serve as key vehicles in the transmission of MAP infection to humans (from farm to fork) who have a genetic predisposition, thus leading to the development of CD. The challenges faced in culturing this bacterium from CD are many. Examples include its extreme slow growth, lack of cell wall, low abundance, and its mycobactin dependency. In this review article, data from 60 studies showing the detection and isolation of MAP by PCR and culture techniques have been reviewed. Although this review may not be 100% comprehensive of all studies, clearly the majority of the studies overwhelmingly and definitively support the role of MAP in at least 30%-50% of CD patients. It is very possible that lack of detection of MAP from some CD patients may be due to the absence of MAP role in these patients. The latter statement is conditional on utilization of methodology appropriate for detection of human MAP strains. Ultimately, stratification of CD and inflammatory bowel disease patients for the presence or absence of MAP is necessary for appropriate and effective treatment which may lead to a cure.

Latitude, sunshine, and human lactase phenotype distributions may contribute to geographic patterns of modern disease: the inflammatory bowel disease model

Countries with high lactase nonpersistence (LNP) or low lactase persistence (LP) populations have lower rates of some "western" diseases, mimicking the effects of sunshine and latitude. Inflammatory bowel disease (IBD), ie, Crohn's disease and ulcerative colitis, is putatively also influenced by sunshine. Recent availability of worldwide IBD rates and lactase distributions allows more extensive comparisons. The aim of this study was to evaluate the extent to which modern day lactase distributions interact with latitude, sunshine exposure, and IBD rates. National IBD rates, national distributions of LP/LNP, and population-weighted average national annual ultraviolet B exposure were obtained, estimated, or calculated from the literature. Negative binomial analysis was used to assess the relationship between the three parameters and IBD rates. Analyses for 55 countries were grouped in three geographic domains, ie, global, Europe, and non-Europe. In Europe, both latitude and ultraviolet B exposure correlate well with LP/LNP and IBD. In non-Europe, latitude and ultraviolet B exposure correlate weakly with LP/LNP, but the latter retains a more robust correlation with IBD. In univariate analysis, latitude, ultraviolet B exposure, and LP/LNP all had significant relationships with IBD. Multivariate analysis showed that lactase distributions provided the best model of fit for IBD. The model of IBD reveals the evolutionary effects of the human lactase divide, and suggests that latitude, ultraviolet B exposure, and LP/LNP mimic each other because LP/LNP follows latitudinal directions toward the equator. However, on a large scale, lactase patterns also follow lateral polarity. The effects of LP/LNP in disease are likely to involve complex interactions.

Role of the gut microbiota in inflammatory bowel disease pathogenesis: What have we learnt in the past 10 years?

Our understanding of the microbial involvement in inflammatory bowel disease (IBD) pathogenesis has increased exponentially over the past decade. The development of newer molecular tools for the global assessment of the gut microbiome and the identification of nucleotide-binding oligomerization domain-containing protein 2 in 2001 and other susceptibility genes for Crohn’s disease in particular has led to better understanding of the aetiopathogenesis of IBD. The microbial studies have elaborated the normal composition of the gut microbiome and its perturbations in the setting of IBD. This altered microbiome or “dysbiosis” is a key player in the protracted course of inflammation in IBD. Numerous genome-wide association studies have identified further genes involved in gastrointestinal innate immunity (including polymorphisms in genes involved in autophagy: ATG16L1 and IGRM), which have helped elucidate the relationship of the local innate immunity with the adjacent luminal bacteria. These developments have also spurred the search for specific pathogens which may have a role in the metamorphosis of the gut microbiome from a symbiotic entity to a putative pathogenic one. Here we review advances in our understanding of microbial involvement in IBD pathogenesis over the past 10 years and offer insight into how this will shape our therapeutic management of the disease in the coming years.

Fecal detection of Mycobacterium avium paratuberculosis using the IS900 DNA sequence in Crohn's disease and ulcerative colitis patients and healthy subjects

BACKGROUND AND AIM

Despite the increasing evidence of MAP/DNA isolation in Crohn's disease (CD), its potential pathogenetic role remains unclear. To further clarify the possible relationship between MAP and CD, we investigated the presence of IS900 DNA fragment in feces from Crohn's disease and ulcerative colitis (UC) patients and from healthy controls (HC).

METHODS

Stool samples were collected from 31 CD, 20 UC, and 23 HC and stored at -20°C in 200-mg aliquots. DNA was extracted. MAP presence was detected with a specific PCR amplifying a 409-bp fragment from IS900. The specificity of PCR for IS900 was confirmed sequencing three positive products. Statistical analysis was performed using the Chi-square test.

RESULTS

Twenty-one of 31 CD (68%), 13 of 20 UC (65%) and 11 of 23 HC (48%) were MAP-positive (CD vs. HC: p = ns; UC vs. HC: p = ns). With the limits of a small sample size, the IS900-positive percentage in CD and UC was higher than HC, although the difference was not statistically significant.

CONCLUSIONS

The possibility to track the MAP presence in human feces represents a new approach to the "MAP hypothesis". Detection of MAP DNA in feces is very common, reaching very high prevalence both in CD and in UC and even in HC. Our findings seem consistent with a high prevalence of MAP asymptomatic infection among the general population and so the possible involvement of MAP in CD pathogenesis could be linked to a specific immune defective response.

A 60-day probiotic protocol with Dietzia subsp. C79793-74 prevents development of Johne's disease parameters after in utero and/or neonatal MAP infection

The research reported herein was designed to assess whether the bacterium, Dietzia subspecies C79793-74, used as a probiotic, could prevent development of parameters indicative of bovine paratuberculosis after potential in utero, birthing and neonatal (colostrum) exposure to Mycobacterium avium subspecies paratuberculosis (MAP). Such exposure avenues are especially relevant for dairy farms practicing good management procedures since calves on these farms could be infected via dams that have yet to be identified as MAP-positive. Indeed, of 18 calves in the present study that became paratuberculosis parameter-positive, five had dams that were negative for all parameters pre-calving. Parameters used herein to define paratuberculosis status were serum ELISA, serum agar gel immunodiffusion, cultureable fecal MAP, histopathology at necropsy and clinical disease. Thirty-four newborn calves, whose dams were paratuberculosis-positive, were assigned to four different treatment groups. Ten were treated daily for 60 days with viable Dietzia added to their antibiotic-free milk feedings; none became positive for any parameter with age. In contrast, seven of eight calves that were not treated became positive for one or more paratuberculosis-associated parameter. Sixteen calves were treated with viable Dietzia for the first two days of life; eight were then not treated further, whereas the other eight were treated an additional 58 days with Dietzia added to tetracycline-fortified milk (Dietzia is sensitive to tetracycline). In these two groups, positivity developed in five of eight and six of eight, respectively. These results indicated that (a) a daily, 60-day treatment with viable Dietzia effectively prevented development of parameters indicative of paratuberculosis and (b) this treatment, in combination with good management practices, has the potential to eradicate MAP from animals/herds, which should curtail the spread of MAP. Such results should significantly reduce human exposure to MAP, which in turn, could have relevance for the controversial role of MAP in Crohn's disease, type-1 diabetes mellitus, sarcoidosis, Blau syndrome, ulcerative colitis, irritable bowel syndrome and multiple sclerosis.

Diet in inflammatory bowel disease

The past few years have seen a great expansion of our understanding of the pathophysiology of inflammatory bowel disease (IBD). Much of the progress has been on the genetic basis of disease as well as the role of microbiota. These findings have magnified the role of the environmental component of this rather complex process. Recent advances have emanated from more in-depth, comprehensive, and at times nontraditional inquiry into the potential role of diet through its anti-inflammatory properties and modulation of microbiota. This concise review focuses on the novel aspects of research related to the potential role of diet in IBD.

Mycobacterium avium subsp. Paratuberculosis and the expression of selected virulence and pathogenesis genes in response to 6°C, 65°c and ph 2.0

The aim of this work was to study the expression of selected Mycobacterium avium subsp. paratuberculosis (MAP) genes connected with MAP virulence, adhesion and stress response. The temperature of 6°C and 65°C were chosen with regard to the food industry, storage conditions (refrigerator) and low-temperature pasteurization. A pH of 2.0, using lactic acid, was selected to mimic the natural environment of the stomach. Expression of selected genes was studied using real time reverse transcription PCR on three different MAP isolates. MAP isolates were chosen according to the number of their preceding cultivations. While isolates 8672 and 8819 were previously cultivated only once, MAP isolate 12146 went through four passages. Different expression profiles were observed in each of the three MAP isolates. However, particular similar patterns were observed. SigE, sigF and ahpC were up-regulated, while sigL was down-regulated under temperature stress. Mmp gene was found to be down-regulated under acidic conditions. Low passage isolates (8672 and 8819) showed certain level of acid resistance.

Crohn's disease: evidence for involvement of unregulated transcytosis in disease etio-pathogenesis

Crohn's disease (CD) is a chronic inflammatory bowel disease. Research has identified genetic predisposition and environmental factors as key elements in the development of the disease. However, the precise mechanism that initiates immune activation remains undefined. One pathway for luminal antigenic molecules to enter the sterile lamina propria and activate an immune response is via transcytosis. Transcytosis, although tightly regulated by the cell, has the potential for transepithelial transport of bacteria and highly antigenic luminal molecules whose uncontrolled translocation into the lamina propria can be the source of immune activation. Viewed as a whole, the evidence suggests that unregulated intestinal epithelial transcytosis is involved in the inappropriate presentation of immunogenic luminal macromolecules to the intestinal lamina propria. Thus fulfilling the role of an early pre-morbid mechanism that can result in antigenic overload of the lamina propria and initiate an immune response culminating in chronic inflammation characteristic of this disease. It is the aim of this paper to present evidence implicating enterocyte transcytosis in the early etio-pathogenesis of CD.

Genetic adult lactase persistence is associated with risk of Crohn's Disease in a New Zealand population

Background

Mycobacterium avium subspecies paratuberculosis (MAP) is an infective agent found in ruminants and milk products, which has been suggested to increase the risk of gastrointestinal inflammation in genetically susceptible hosts. It is hypothesized that lactase persistence facilitates exposure to such milk products increasing the likelihood of adverse outcomes. Individuals either homozygous or heterozygous for the T allele of DNA variant, rs4988235, located 14kb upstream from the LCT locus, are associated with having lactase persistence.

The aim of this study was to determine whether lactase persistence as evident by the T allele of rs4988235 is associated with Crohn's Disease (CD) in a New Zealand population.

Findings

Individuals homozygous for the T allele (T/T genotype) showed a significantly increased risk of having CD as compared with those homozygous for the C allele (OR = 1.61, 95% CI = 1.03-2.51). Additionally, a significant increase in the frequency of the T allele was observed in CD patients (OR = 1.30, 95% CI = 1.05-1.61, p = 0.013), indicating that the T allele encoding lactase persistence was associated with an increased risk of CD.

Conclusions

Our findings indicate that lactase persistence as evident by the presence of the T allele of rs4988235 is associated with risk of CD in this New Zealand Caucasian population.

Mycobacterium avium paratuberculosis and the etiology of Crohn's disease: a review of the controversy from the clinician's perspective

Mycobacterium avium paratuberculosis (MAP) is an obligate intracellular organism that has frequently been associated with Crohn's disease (CD). Because CD is a chronic inflammatory condition, many researchers have speculated that an infectious agent must be the cause of CD. MAP has often been proposed to be one such agent; however, despite considerable research, the evidence remains inconclusive. Higher levels of MAP have been found in the tissues and blood of CD patients than in controls, forming the foundation for much of the research into the role of MAP in CD and the primary argument in support of a causative role for MAP in CD. MAP is a slow-growing and fastidious organism that is difficult to grow in culture and, therefore, challenging to detect in patients. As a result, there has been variability in the results of studies attempting to detect the presence of MAP in CD patients, and considerable controversy over whether this organism has a causative role in the etiology of CD. Two main hypotheses exist with respect to the role of MAP in CD. The first is that MAP is a principal cause of CD, while the second is that MAP is more prevalent because of the immune dysfunction seen in CD but does not play a causative role. Clinicians are often faced with questions regarding the role of this organism and the need to treat it. The present article attempts to provide an overview of the controversy including the nature of the mycobacterium, the difficulty in detecting it, the use of antimycobacterial agents to treat it and the effect of immunosuppressive agents - all from a clinician's perspective. Although the role of MAP in CD remains controversial and an area of considerable research, it is currently only of academic interest because there is no clinically useful test to identify the presence of the organism, and no evidence to support the use of antibiotics to eradicate it for the treatment of CD.

Animal protein intake and risk of inflammatory bowel disease: The E3N prospective study

OBJECTIVES

Diet composition has long been suspected to contribute to inflammatory bowel disease (IBD), but has not been thoroughly assessed, and has been assessed only in retrospective studies that are prone to recall bias. The aim of the present study was to evaluate the role of dietary macronutrients in the etiology of IBD in a large prospective cohort.

METHODS

The Etude Épidémiologique des femmes de la Mutuelle Générale de l'Education Nationale cohort consists of women living in France, aged 40-65 years, and free of major diseases at inclusion. A self-administered questionnaire was used to record dietary habits at baseline. Questionnaires on disease occurrence and lifestyle factors were completed every 24 months. IBDs were assessed in each questionnaire until June 2005, and subsequently validated using clinical and pathological criteria. We estimated the association between nutrients or foods and IBD using Cox proportional hazards models adjusted for energy intake.

RESULTS

Among 67,581 participants (705,445 person-years, mean follow-up since completion of the baseline dietary questionnaire 10.4 years), we validated 77 incident IBD cases. High total protein intake, specifically animal protein, was associated with a significantly increased risk of IBD, (hazards ratio for the third vs. first tertile and 95% confidence interval being 3.31 and 1.41-7.77 (P trend=0.007), and 3.03 and 1.45-6.34 (P trend=0.005) for total and animal protein, respectively). Among sources of animal protein, high consumption of meat or fish but not of eggs or dairy products was associated with IBD risk.

CONCLUSIONS

High protein intake is associated with an increased risk of incident IBD in French middle-aged women.

Lack of association between the occurrence of Crohn's disease and occupational exposure to dairy and beef cattle herds infected with Mycobacterium avium subspecies paratuberculosis

A cross-sectional survey was conducted to identify associations between Crohn's disease (CD) and Mycobacterium avium ssp. paratuberculosis (Map) exposure. A questionnaire was used to collect information on exposure to cattle infected with Map, and personal and family history of CD in dairy and beef cattle producers with and without Map-infected herds, and in veterinarians who did or did not have contact with Map-infected herds. Cases of CD were selected from respondents and matched 1:4 with controls on occupation, age, and sex. Multivariable conditional logistic regression was used to assess associations between Map exposure and CD. There were 3 cases of CD in 702 producers and 4 cases in 774 veterinarians, yielding a prevalence of 0.47%. No association was found between exposure to JD and CD in any phase of the analysis. However, the number of cases of CD is not large and limits the power to detect important differences.

Short communication: progression of Johne's disease curtailed by a probiotic

The naturally occurring inflammatory bowel disease Johne's, caused by Mycobacterium avium ssp. paratuberculosis (MAP), has many clinical manifestations in common with the human inflammatory bowel disease Crohn's disease. In addition, both lack preventive and curative therapies. Because a high percentage of Crohn's patients harbor MAP, it is not surprising that MAP is at the center of controversy as to its contribution. Special concern is being raised as to what role, if any, food animals play in transmission of MAP to humans. Because management practices, presently considered the best way to control the spread of MAP, have not and most likely will not eliminate MAP from food animals, other preventive or curative measures are needed. The results presented herein show that a unique bacterium, Dietzia ssp. C79793-74, used as a probiotic, was therapeutic for adult paratuberculosis animals, and resulted in a cure rate of 37.5%.

Commensal bacteria, traditional and opportunistic pathogens, dysbiosis and bacterial killing in inflammatory bowel diseases

PURPOSE OF REVIEW

The authors present evidence published during the past 2 years of the roles of commensal and pathogenic bacteria in the pathogenesis of the inflammatory bowel diseases.

RECENT FINDINGS

Rodent models conclusively implicate commensal enteric bacteria in chronic, immune-mediated, experimental colitis, and genetically determined defects in bacterial killing by innate immune cells are found in a subset of patients with Crohn's disease. There is no evidence that a single pathogen, including Mycobacterium avium subspecies paratuberculosis, causes Crohn's disease or ulcerative colitis. However, adherent/invasive Escherichia coli are associated with ileal Crohn's disease, with the mechanisms and genetics of adherent/invasive E. coli virulence being elucidated. Molecular characterization of the microbiota in patients with inflammatory bowel diseases reveals decreased biodiversity of commensal bacteria, most notably the phyla Bacteroidetes and Firmicutes, including the clinically relevant Faecalibacterium prausnitzii, and increased E. coli concentrations. VSL#3 is one probiotic preparation shown to be efficacious in certain clinical situations in small clinical trials.

SUMMARY

Further characterization of altered microbiota in patients with inflammatory bowel diseases and linking dysbiosis with host genetic alterations in immunoregulation, innate microbial killing and barrier function are critical, so that individualized treatments to increase beneficial commensals and their metabolic products (probiotic and prebiotic administration) and diminish deleterious species such as adherent/invasive E. coli can be tailored for defined patient subsets.

The association between water supply and inflammatory bowel disease based on a 1990-1993 cohort study in southeastern Norway

Inflammatory bowel disease refers to a group of chronic diseases of unknown etiology related to both genetic and environmental factors. In this 1990-1993 study, the authors investigated associations between the content and quality of drinking water and the incidence of inflammatory bowel disease. They used data from a population-based cohort recruited in southeastern Norway and a registry of water quality derived from Norwegian waterworks that contained measurements of iron, aluminum, acidity (pH), color, turbidity, and coliform bacteria. The authors found that risk of developing inflammatory bowel disease, including ulcerative colitis and Crohn's disease, was associated with high iron content. The relative risk of developing inflammatory bowel disease increased by 21% (95% confidence interval: 9, 34) when the iron content in the drinking water increased by 0.1 mg/L. They found no association between the diseases and aluminum in the water, color of the water, and turbidity of the water. The authors suggest that the observations can be explained by 2 mechanisms. First, high iron concentration works as a catalyst for oxidative stress, which will cause inflammation and/or increase the rate of cell mutations. Second, iron content stimulates the growth of bacteria and increases the likelihood of inappropriate immune responses in genetically predisposed individuals.

Interplay of commensal and pathogenic bacteria, genetic mutations, and immunoregulatory defects in the pathogenesis of inflammatory bowel diseases

Enteric microbiota can contribute to Crohn's disease and ulcerative colitis in several ways. Pathogenic or functionally altered commensal bacteria with increased mucosal adherence, invasion and intracellular persistence can activate pathogenic T cells and chronic intestinal inflammation. Compositional changes in intestinal microbiota can lead to decreased protective and increased aggressive species. Genetic polymorphisms resulting in increased mucosal permeability, decreased microbial killing, ineffective clearance of bacteria, biased TH1 and TH17 immune responses and loss of immunological tolerance are probably key contributors to IBD. Future therapies for these heterogeneous diseases should be individualized based on the patient-specific subset.

Microbial host interactions in IBD: implications for pathogenesis and therapy

Crohn's disease (CD), ulcerative colitis (UC), and pouchitis appear to be caused by pathogenic T-cell responses to discrete antigens from the complex luminal microbiota, with susceptibility conferred by genetic polymorphisms that regulate bacterial killing, mucosal barrier function, or immune responses. Environmental triggers initiate or reactivate inflammation and modulate genetic susceptibility. New pathogenesis concepts include defective bacterial killing by innate immune cells in CD, colonization of the ileum in CD with functionally abnormal Escherichia coli that adhere to and invade epithelial cells and resist bacterial killing, and alterations in enteric microbiota composition in CD, UC, and pouchitis detected by molecular probes. The considerable therapeutic potential of manipulating the enteric microbiota in inflammatory bowel disease patients has not been realized, probably due to failure to recognize heterogenic disease mechanisms that require individualized use of antibiotics, probiotics, prebiotics, combination therapies, and genetically engineered bacteria to restore mucosal homeostasis.

Microbial influences in inflammatory bowel diseases

The predominantly anaerobic microbiota of the distal ileum and colon contain an extraordinarily complex variety of metabolically active bacteria and fungi that intimately interact with the host's epithelial cells and mucosal immune system. Crohn's disease, ulcerative colitis, and pouchitis are the result of continuous microbial antigenic stimulation of pathogenic immune responses as a consequence of host genetic defects in mucosal barrier function, innate bacterial killing, or immunoregulation. Altered microbial composition and function in inflammatory bowel diseases result in increased immune stimulation, epithelial dysfunction, or enhanced mucosal permeability. Although traditional pathogens probably are not responsible for these disorders, increased virulence of commensal bacterial species, particularly Escherichia coli, enhance their mucosal attachment, invasion, and intracellular persistence, thereby stimulating pathogenic immune responses. Host genetic polymorphisms most likely interact with functional bacterial changes to stimulate aggressive immune responses that lead to chronic tissue injury. Identification of these host and microbial alterations in individual patients should lead to selective targeted interventions that correct underlying abnormalities and induce sustained and predictable therapeutic responses.