Red blood cell folate is associated with the development of dysplasia and cancer in ulcerative colitis

Folic Acid Supplementation Promotes Hypomethylation in Both the Inflamed Colonic Mucosa and Colitis-Associated Dysplasia

PURPOSE

The purpose of this study was to assess the effect of folic acid (FA) supplementation on colitis-associated colorectal cancer (CRC) using the azoxymethane/dextran sulfate sodium (AOM/DSS) model.

METHODS

Mice were fed a chow containing 2 mg/kg FA at baseline and randomized after the first DSS treatment to receive 0, 2, or 8 mg/kg FA chow for 16 weeks. Colon tissue was collected for histopathological evaluation, genome-wide methylation analyses (Digital Restriction Enzyme Assay of Methylation), and gene expression profiling (RNA-Seq).

RESULTS

A dose-dependent increase in the multiplicity of colonic dysplasias was observed, with the multiplicity of total and polypoid dysplasias higher (64% and 225%, respectively) in the 8 mg FA vs. the 0 mg FA group (p < 0.001). Polypoid dysplasias were hypomethylated, as compared to the non-neoplastic colonic mucosa (p < 0.05), irrespective of FA treatment. The colonic mucosa of the 8 mg FA group was markedly hypomethylated as compared to the 0 mg FA group. Differential methylation of genes involved in Wnt/β-catenin and MAPK signaling resulted in corresponding alterations in gene expression within the colonic mucosa.

CONCLUSIONS

High-dose FA created an altered epigenetic field effect within the non-neoplastic colonic mucosa. The observed decrease in site-specific DNA methylation altered oncogenic pathways and promoted colitis-associated CRC.

Possible role of nutrition in the prevention of inflammatory bowel disease-related colorectal cancer: A focus on human studies

Patients with inflammatory bowel disease (IBD) are at substantially high risk for colorectal cancer (CRC). IBD-associated CRC accounts for roughly 10% to 15% of the annual mortality in patients with IBD. IBD-related CRC also affects younger patients compared with sporadic CRC, with a 5-y survival rate of 50%. Regardless of medical therapies, the persistent inflammatory state characterizing IBD raises the risk for precancerous changes and CRC, with additional input from several elements, including genetic and environmental risk factors, IBD-associated comorbidities, intestinal barrier dysfunction, and gut microbiota modifications. It is well known that nutritional habits and dietary bioactive compounds can influence IBD-associated inflammation, microbiome abundance and composition, oxidative stress balance, and gut permeability. Additionally, in recent years, results from broad epidemiologic and experimental studies have associated certain foods or nutritional patterns with the risk for colorectal neoplasia. The present study aimed to review the possible role of nutrition in preventing IBD-related CRC, focusing specifically on human studies. It emerges that nutritional interventions based on healthy, nutrient-dense dietary patterns characterized by a high intake of fiber, vegetables, fruit, ω-3 polyunsaturated fatty acids, and a low amount of animal proteins, processed foods, and alcohol, combined with probiotic supplementation have the potential of reducing IBD-activity and preventing the risk of IBD-related CRC through different mechanisms, suggesting that targeted nutritional interventions may represent a novel promising approach for the prevention and management of IBD-associated CRC.

A Systematic Review and Meta-Analysis on the Association between Inflammatory Bowel Disease Family History and Colorectal Cancer

Background

Colorectal cancer (CRC) and inflammatory bowel disease (IBD) are closely interrelated. However, the effect of having a family history of one disease on the risk of another remains undetermined.

Aim

The purpose of this meta-analysis was to estimate the prevalence of a family history of CRC among patients with IBD, as well as the prevalence of a family history of IBD among patients with CRC.

Methods

PubMed, Scopus, Embase, Web of Science, and Google Scholar were searched to identify studies reporting the prevalence of family history of IBD among patients with CRC, in addition to the prevalence of family history of CRC among IBD patients. Criteria for study inclusion consisted of the following: (1) studies that evaluated either IBD or CRC and dysplasia, (2) included all age groups, and (3) evaluated the family history effects for IBD or CRC. The total number of IBD patients and IBD patients with a family history of CRC and the total number of CRC patients and CRC patients with a family history of IBD were reviewed. The pooled prevalence of diseases was also estimated according to degree of relatives and geographical area. Random-effects models were used for estimating pooled prevalence.

Results

A total of 27 studies were included with 26,576 IBD and 9,181 CRC or dysplasia patients. Eligible studies included 13 case-control, 10 cohort, and 4 cross-sectional types. The pooled prevalence of a family history of CRC among patients with IBD was 6% (95% CI: 4-9%). The pooled prevalence for first- and second-degree relatives (11%, 95% CI: 0-37%) was more than that for the other relative subgroups of relatedness degree. The prevalence in the American regions (8% (95% CI: 5-13%)) was higher than that in the others. The pooled prevalence for a family history of IBD among CRC or dysplasia patients was 11% (95% CI: 6-16%). The pooled prevalence for first-degree relatives (13% (95% CI: 3-28%) was higher than that for the other relative subgroups of relatedness degree; it was also greater in American countries (15%, 95% CI: 8-23%).

Conclusion

This study emphasizes the relationship between a family history of IBD and CRC development. Additionally, there was notable prevalence for a family history of CRC among IBD patients. American countries and first-degree relatives were identified to have a higher prevalence for both disease processes.

Folate Intake Alters Mutation Frequency and Profiles in a Tissue- and Dose-Specific Manner in MutaMouse Male Mice

BACKGROUND

While cancer is common, its incidence varies widely by tissue. These differences are attributable to variable risk factors, such as environmental exposure, genetic inheritance, and lifetime number of stem cell divisions in a tissue. Folate deficiency is generally associated with increased risk for colorectal cancer (CRC) and acute lymphocytic leukemia (ALL). Conversely, high folic acid (FA) intake has also been associated with higher CRC risk.

OBJECTIVE

Our objective was to compare the effect of folate intake on mutant frequency (MF) and types of mutations in the colon and bone marrow of mice.

METHODS

Five-week-old MutaMouse male mice were fed a deficient (0 mg FA/kg), control (2 mg FA/kg), or supplemented (8 mg FA/kg) diet for 20 wk. Tissue MF was assessed using the lacZ mutant assay and comparisons made by 2-factor ANOVA. LacZ mutant plaques were sequenced using next-generation sequencing, and diet-specific mutation profiles within each tissue were compared by Fisher's exact test.

RESULTS

In the colon, the MF was 1.5-fold and 1.3-fold higher in mice fed the supplemented diet compared with mice fed the control (P = 0.001) and deficient (P = 0.008) diets, respectively. This contrasted with the bone marrow MF in the same mice where the MF was 1.7-fold and 1.6-fold higher in mice fed the deficient diet compared with mice fed the control (P = 0.02) and supplemented (P = 0.03) diets, respectively. Mutation profiles and signatures (mutation context) were tissue-specific.

CONCLUSIONS

Our data indicate that dietary folate intake affects mutagenesis in a tissue- and dose-specific manner in mice. Mutation profiles were generally tissue- but not dose-specific, suggesting that altered cellular folate status appears to interact with endogenous mutagenic mechanisms in each tissue to create a permissive context in which specific mutation types accumulate. These data illuminate potential mechanisms underpinning differences in observed associations between folate intake/status and cancer.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

Diet, Nutrition, and Cancer Epigenetics

The search for a connection between diet and human cancer has a long history in cancer research, as has interest in the mechanisms by which dietary factors might increase or decrease cancer risk. The realization that altering diet can alter the epigenetic state of genes and that these epigenetic alterations might increase or decrease cancer risk is a more modern notion, driven largely by studies in animal models. The connections between diet and epigenetic alterations, on the one hand, and between epigenetic alterations and cancer, on the other, are supported by both observational studies in humans as well as animal models. However, the conclusion that diet is linked directly to epigenetic alterations and that these epigenetic alterations directly increase or decrease the risk of human cancer is much less certain. We suggest that true and measurable effects of diet or dietary supplements on epigenotype and cancer risk are most likely to be observed in longitudinal studies and at the extremes of the intersection of dietary risk factors and human population variability. Careful analysis of such outlier populations is most likely to shed light on the molecular mechanisms by which suspected environmental risk factors drive the process of carcinogenesis.

Hyperhomocysteinemia as a potential contributor of colorectal cancer development in inflammatory bowel diseases: A review

Homocysteine is an amino acid generated metabolically by the S-adenosylmethionine-dependent transmethylation pathway. In addition to being a well-known independent risk factor for coronary heart disease, is also a risk factor for cancer. Patients suffering from inflammatory bowel diseases (IBD) including ulcerative colitis and Crohn’s disease are at increased risk of developing colorectal cancer in comparison to healthy individuals. Furthermore, the risk of hyperhomocysteinaemia is significantly higher in IBD patients when compared with controls. In the present article, we review the mechanisms in which hyperhomocysteinemia may contribute to increased risk of colorectal cancer in IBD patients.

Colorectal Cancer in Inflammatory Bowel Disease: Epidemiology, Pathogenesis and Surveillance

BACKGROUND

Inflammatory bowel disease (IBD; including ulcerative colitis and Crohn's disease) is associated with an increased risk for colorectal cancer (CRC). Chronic mucosal inflammation is a key factor in the onset of carcinogenesis in IBD patients. Although most gene alterations that cause sporadic CRCs also occur in patients with IBD-associated CRC, some gene sequences and mutation frequencies differ between sporadic CRCs and IBD-associated CRCs.

SUMMARY

This review explores the incidence of CRC in IBD patients, with the goal of identifying the risk and protective factors for CRC in order to facilitate dysplasia management via individualized surveillance strategies.

KEY MESSAGE

The incidence of CRC is higher among IBD patients. Identifying the risk and protective factors for CRC will facilitate dysplasia management via individualized surveillance strategies.

PRACTICAL IMPLICATIONS

Several risk factors, including active inflammation, the coexistence of primary sclerosing cholangitis, a family history of sporadic CRC and the extent and duration of colonic disease, can lead to the development of CRC in patients with IBD. These risk factors should be utilized in individualized surveillance strategies to lower CRC incidence among IBD patients. Use of 5-aminosalicylic acid may play an important role in CRC prevention. Until newer, more reliable markers of IBD-associated CRC risk are found, dysplasia will continue to be the best marker of CRC risk in IBD. Dysplasia management continues to play a key role in preventing the progression of carcinogenesis.

Micronutrient deficiencies in inflammatory bowel disease: from A to zinc

Inflammatory bowel disease (IBD) has classically been associated with malnutrition and weight loss, although this has become less common with advances in treatment and greater proportions of patients attaining clinical remission. However, micronutrient deficiencies are still relatively common, particularly in CD patients with active small bowel disease and/or multiple resections. This is an updated literature review of the prevalence of major micronutrient deficiencies in IBD patients, focusing on those associated with important extraintestinal complications, including anemia (iron, folate, vitamin B12) bone disease (calcium, vitamin D, and possibly vitamin K), hypercoagulability (folate, vitamins B6, and B12), wound healing (zinc, vitamins A and C), and colorectal cancer risk (folate and possibly vitamin D and calcium).

Dietary folate does not significantly affect the intestinal microbiome, inflammation or tumorigenesis in azoxymethane-dextran sodium sulphate-treated mice

Inflammatory bowel disease (IBD) is a risk factor for the development of colon cancer. Environmental factors including diet and the microflora influence disease outcome. Folate and homocysteine have been associated with IBD-mediated colon cancer but their roles remain unclear. We used a model of chemically induced ulcerative colitis (dextran sodium sulphate (DSS)) with or without the colon carcinogen azoxymethane (AOM) to determine the impact of dietary folic acid (FA) on colonic microflora and the development of colon tumours. Male mice (n 15 per group) were fed a FA-deficient (0 mg/kg), control (2 mg/kg) or FA-supplemented (8 mg/kg) diet for 12 weeks. Folate status was dependent on the diet (P< 0·001) and colitis-induced treatment (P= 0·04) such that mice with colitis had lower circulating folate. FA had a minimal effect on tumour initiation, growth and progression, although FA-containing diets tended to be associated with a higher tumour prevalence in DSS-treated mice (7-20 v. 0%, P= 0·08) and the development of more tumours in the distal colon of AOM-treated mice (13-83% increase, P= 0·09). Folate deficiency was associated with hyperhomocysteinaemia (P< 0·001) but homocysteine negatively correlated with tumour number (r - 0·58, P= 0·02) and load (r - 0·57, P= 0·02). FA had no effect on the intestinal microflora. The present data indicate that FA intake has no or little effect on IBD or IBD-mediated colon cancer in this model and that hyperhomocysteinaemia is a biomarker of dietary status and malabsorption rather than a cause of IBD-mediated colon cancer.

Cancer surveillance strategies in ulcerative colitis: the need for modernization

The risk of colorectal cancer is increased in patients with long-standing ulcerative colitis. Traditional surveillance has centered around regular standard white-light colonoscopy, with multiple biopsies aimed at detecting dysplasia or the identification of early cancer. This has resulted in only a modest reduction in cancer incidence and mortality. A better understanding of disease risk factors may allow endoscopic resources to be more focused on patients at higher risk. In addition, advanced endoscopic techniques have the potential to improve dysplasia detection, minimize the need for routine biopsies, and allow for the removal of dysplastic lesions, avoiding the need for surgery. Techniques such as magnification colonoscopy, chromoendoscopy, narrow band imaging, autofluorescence, and confocal endomicroscopy may all have a role to play in improving the benefits of endoscopic surveillance. Revised endoscopic surveillance strategies are proposed, incorporating aspects of risk stratification, a well-established practice in noncolitis-related colorectal cancer screening, and some of these new technologies.

Colon cancer in inflammatory bowel disease: recent trends, questions and answers

Patients with chronic colitis (ulcerative colitis or colonic Crohn's disease) have an increased risk of colorectal cancer (CRC). Although most of the molecular alterations reported in sporadic CRC have also been observed in colitis-associated CRC, they do not occur at the same timing and frequency, indicating a different pathophysiology. In particular, recent work highlighted the importance of chronic mucosal inflammation as a key factor favouring colorectal carcinogenesis in these patients. This may also be one of the reasons explaining the role of 5-aminosalicylates as chemopreventive agents for CRC in inflammatory bowel disease (IBD) patients with colonic involvement. Beside chemoprevention, colonoscopic screening and surveillance have been shown to be the cornerstone for CRC prevention and early detection in this particular patients' population. Periodic surveillance colonoscopy to detect dysplasia has been shown to decrease the mortality attributed to CRC. More recently, progress in imaging techniques increased our ability to identify dysplasia, and should probably now be considered to be an integral part of surveillance colonoscopy. In the future, further improvement of our knowledge of CRC biology, refinement of imaging techniques, as well as molecular discovery (e.g. identification of specific mutations in stool DNA extracts), might lead to develop more accurate diagnostic strategies to reduce the morbidity and mortality related to CRC in patients with ulcerative colitis or colonic Crohn's disease.

Increased serum levels of L-arginine in ulcerative colitis and correlation with disease severity

BACKGROUND

L-arginine (L-Arg) is a semi-essential amino acid that is the substrate for both nitric oxide and polyamine synthesis. Cellular uptake of L-Arg is an active transport process that is subject to competitive inhibition by L-ornithine (L-Orn) and L-lysine (L-Lys). We investigated L-Arg utilization in patients with ulcerative colitis (UC).

METHODS

Serum was collected from 14 normal controls and 22 UC patients with pancolitis of moderate or severe activity by histopathology score. The Mayo Disease Activity Index (DAI) and endoscopy subscore were assessed. Serum amino acid levels were measured by high-performance liquid chromatography. Arginine availability index (AAI) was defined as [L-Arg]/([L-Orn] + [L-Lys]).

RESULTS

Serum L-Arg levels were significantly associated with histopathologic grade (P = 0.001). L-Arg levels were increased in subjects with severe colitis when compared to those with moderate colitis or normal mucosa. L-Orn + L-Lys levels were also increased in severe colitis, so that AAI was not significantly increased. L-Arg levels were also strongly associated with the endoscopy subscore (P < 0.001). There was a strong correlation between DAI and L-Arg levels (r = 0.656, P < 0.001).

CONCLUSIONS

Serum L-Arg levels correlate with UC disease severity but availability is not increased due to competitive inhibition by L-Orn and L-Lys. Our findings suggest that L-Arg uptake by cells in the inflamed colon is defective, which may contribute to the pathogenesis of UC. Studies delineating the mechanism of uptake inhibition could enhance our understanding of UC or lead to novel treatment options.

Importance of nutrition in inflammatory bowel disease

Inflammatory bowel disease (IBD) results from the interaction between an individual's immune response and precipitant environmental factors, which generate an anomalous chronic inflammatory response in those who are genetically predisposed. Various feeding practices have been implicated in the origin of IBD based on epidemiological observations in developed countries, but we do not have solid evidence for the etiological role played by specific food types. IBD is associated with frequent nutritional deficiencies, the pattern and severity of which depends on the extent, duration and activity of the inflammation. Nutritional support allows these deficiencies in calories, macro- and micro-nutrients to be rectified. Enteral nutrition is also a primary therapy for IBD, especially for Crohn's disease, as it allows the inflammatory activity to be controlled, kept in remission, and prevents or delays the need for surgery. Nutritional support is especially important in childhood IBD as an alternative to pharmacological treatment. This report discusses the complex relationship between diet and IBD.

Importance of nutrition in inflammatory bowel disease

Inflammatory bowel disease (IBD) results from the interaction between an individual’s immune response and precipitant environmental factors, which generate an anomalous chronic inflammatory response in those who are genetically predisposed. Various feeding practices have been implicated in the origin of IBD based on epidemiological observations in developed countries, but we do not have solid evidence for the etiological role played by specific food types. IBD is associated with frequent nutritional deficiencies, the pattern and severity of which depends on the extent, duration and activity of the inflammation. Nutritional support allows these deficiencies in calories, macro- and micro-nutrients to be rectified. Enteral nutrition is also a primary therapy for IBD, especially for Crohn’s disease, as it allows the inflammatory activity to be controlled, kept in remission, and prevents or delays the need for surgery. Nutritional support is especially important in childhood IBD as an alternative to pharmacological treatment. This report discusses the complex relationship between diet and IBD.

Folic acid supplementation inhibits recurrence of colorectal adenomas: A randomized chemoprevention trial

AIM: To determine whether folic acid supplementation will reduce the recurrence of colorectal adenomas, the precursors of colorectal cancer, we performed a double-blind placebo-controlled trial in patients with adenomatous polyps.

METHODS: In the current double-blind, placebo-controlled trial at this VA Medical Center, patients with colorectal adenomas were randomly assigned to receive either a daily 5 mg dose of folic acid or a matched identical placebo for 3 years. All polyps were removed at baseline colonoscopy and each patient had a follow up colonoscopy at 3 years. The primary endpoint was a reduction in the number of recurrent adenomas at 3 years.

RESULTS: Of 137 subjects, who were eligible after confirmation of polyp histology and run-in period to conform compliance, 94 completed the study; 49 in folic acid group and 45 in placebo group. Recurrence of adenomas at 3-year was compared between the two groups. The mean number of recurrent polyps at 3-year was 0.36 (SD, 0.69) for folic acid treated patients compared to 0.82 (SD, 1.17) for placebo treated subjects, resulting in a 3-fold increase in polyp recurrence in the placebo group. Patients below 70 years of age and those with left-sided colonic adenomas or advanced adenomas responded better to folic acid supplementation.

CONCLUSION: High dose folic acid supplementation is associated with a significant reduction in the recurrence of colonic adenomas suggesting that folic acid may be an effective chemopreventive agent for colorectal neoplasia.

Association of hyperhomocysteinemia and folate deficiency with colon tumors in patients with inflammatory bowel disease

BACKGROUND

Folate deficiency associated with hyperhomocysteinemia might increase the risk of developing colorectal cancer. The aim of this study was to evaluate factors associated with colonic carcinogenesis, in particular, folate and homocysteinemia levels, in a cross-sectional study of patients with inflammatory bowel disease (IBD).

METHODS

IBD patients with carcinogenic lesions discovered during colonoscopy [dysplasia-associated lesion or masses (DALM), colorectal cancer] were included and compared with the whole population of IBD patients with a normal colonoscopy performed during the same period. The following parameters were collected at the time of colonoscopy: age, sex, type, duration, activity, and extent of the disease, treatment, smoking status, and vitamin B12, folate, and homocysteinemia levels. Univariate and multivariate analyses were performed after adjusting for the main parameters.

RESULTS

One hundred and fourteen patients [41 with ulcerative colitis (UC), 73 with Crohn's disease (CD)] were included. Twenty-six carcinogenic lesions were isolated: 18 DALM (7 high-grade and 11 low-grade dysplasia) and 8 colorectal cancers. In univariate analysis, the factors associated with carcinogenesis were: active smoking (P = 0.03), folate level < 145 pmol/L (P = 0.02), hyperhomocysteinemia > 15 micromol/L (P = 0.003), duration of disease > 10 years (P = 0.006), and UC (P = 0.02). In multivariate analysis, patients with hyperhomocysteinemia associated with folate deficiency had 17 times as many carcinogenic lesions as patients with normal homocysteinemia whatever the folate status and duration of the disease (P = 0.01). Patients with hyperhomocysteinemia without folate deficiency had 2.5 times as many carcinogenic lesions as patients with normal homocysteinemia (P = 0.08).

CONCLUSIONS

Our data suggest that in IBD patients with normal homocysteinemia, the increase in carcinogenic risk is negligible. Conversely, in patients with hyperhomocysteinemia, folate deficiency may be associated with increased colorectal carcinogenesis in IBD patients.

Gender-specific modulation of tumorigenesis by folic acid supply in the Apc mouse during early neonatal life

Epidemiological studies suggest an inverse association between folic acid intake and colorectal cancer risk. Conversely, conventional treatment of existing tumours includes the use of folate antagonists. This suggests that the level of exposure to folate and its timing in relation to stage of tumorigenesis may be critical in determining outcomes. We hypothesised that folic acid depletion in utero and during early neonatal life may affect tumorigenesis in offspring. To investigate this hypothesis, female C57Bl6/J mice were randomised to a folic acid adequate (2 mg folic acid/kg diet) or folic acid depleted diet (0.4 mg folic acid/kg) from mating with Apc+/Min sires and throughout pregnancy and lactation. At weaning the Apc+/Min offspring were randomised to a folic acid adequate (2 mg folic acid/kg diet) or depleted (0.26 mg folic acid/kg diet) diet, creating four in utero/post-weaning dietary regimens. At 10 weeks post-weaning, mice were killed and the intestinal tumour number and size were recorded. Folic acid depletion during pregnancy and post-weaning reduced erythrocyte folate concentrations in offspring significantly. Folic acid depletion during pregnancy and lactation did not affect tumour multiplicity or size. However, female mice fed normal folic acid diets post-weaning had more, and larger, tumours when compared with depleted females and both depleted and adequate folic acid fed males. These data suggest that folate depletion post-weaning was protective against neoplasia in female Apc+/Min mice and highlights the need for further investigation of the optimal timing and dose of folic acid supplementation with regard to colorectal cancer risk.

Increased risk of colorectal cancer in ulcerative colitis patients diagnosed after 40 years of age

BACKGROUND

The association between ulcerative colitis (UC) and colorectal cancer (CRC) is well established. Retrospective data show a 5.4% CRC incidence rate among patients with pancolitis and suggest that cancer surveillance should be provided to patients following eight to 10 years of extensive UC.

AIM

To identify premalignant risk factors for UC patients and to determine whether current recommendations for cancer surveillance need reviewing.

PATIENTS AND METHODS

A retrospective audit was conducted of adult patients with UC who were diagnosed with CRC between 1991 and 2002 in five hospitals in Edmonton, Alberta.

RESULTS

Thirty-one cases of CRC (68% male) were identified. In this group, the mean ages at diagnosis were 44.4 years for UC patients and 60.1 years for CRC patients. For patients in whom the initial data of diagnosis of UC could be determined (n=29), the median duration of UC at the time of CRC diagnosis was 16 years. Patients diagnosed with UC after 40 years of age (n=15, mean age 64 years) progressed more rapidly to CRC than patients diagnosed before 40 years of age (n=14, mean age 23 years). The median durations of UC before development of CRC were 22 years and 10 years, respectively, for patients with a diagnosis of UC before and after 40 years of age (OR 11.5, 95% CI 2.41 to 20.16; P=0.00029). Only four patients (13%) were enrolled in an appropriate cancer-screening program. Nine of these UC patients (29%) who were older than 40 years of age developed CRC before the 10-year point.

CONCLUSIONS

In the present study, patients diagnosed with UC after 40 years of age developed CRC more rapidly than those diagnosed before 40 years of age. This finding suggests that patients who are diagnosed with UC after 40 years of age should undergo CRC surveillance earlier than current recommendations.

Endoscopy/surveillance in inflammatory bowel disease

Patients with chronic colitis from inflammatory bowel disease (IBD) have an increased risk of colorectal cancer (CRC). Previously, to ameliorate this, prophylactic total colectomy was offered to patients who had chronic ulcerative colitis (UC); however, research has identified less invasive management options through better understanding of the pathogenesis of cancer in chronic inflammation, a more uniform histologic diagnosis by pathologists, and proper surveillance colonoscopy techniques. This article reviews the pathogenesis of neoplasia in IBD, and then reviews the risk factors for CRC in IBD, surveillance guidelines and their limitations, surveillance techniques, ileal pouch dysplasia, and chemoprevention. Although data for CRC risk in Crohn's disease (CD) are not as extensive, it has been suggested that the risks are comparable to UC.

Folate and colorectal cancer: an evidence-based critical review

Currently available evidence from epidemiologic, animal, and intervention studies does not unequivocally support the role of folate, a water-soluble B vitamin and important cofactor in one-carbon transfer, in the development and progression of colorectal cancer (CRC). However, when the portfolio of evidence from these studies is analyzed critically, the overall conclusion supports the inverse association between folate status and CRC risk. It is becoming increasingly evident that folate possesses dual modulatory effects on colorectal carcinogenesis depending on the timing and dose of folate intervention. Folate deficiency has an inhibitory effect whereas folate supplementation has a promoting effect on the progression of established colorectal neoplasms. In contrast, folate deficiency in normal colorectal mucosa appears to predispose it to neoplastic transformation, and modest levels of folic acid supplementation suppress, whereas supraphysiologic supplemental doses enhance, the development of cancer in normal colorectal mucosa. Several potential mechanisms relating to the disruption of one-carbon transfer reactions exist to support the dual modulatory role of folate in colorectal carcinogenesis. Based on the lack of compelling supportive evidence and on the potential tumor-promoting effect, routine folic acid supplementation should not be recommended as a chemopreventive measure against CRC at present.

Vascular and cellular stress in inflammatory bowel disease: revisiting the role of homocysteine

Moderate hyperhomocysteinemia is a complex trait commonly associated with inflammatory bowel disease (IBD). Nutritional deficiencies and genetic determinants have been identified as risk factors for moderate hyperhomocysteinemia, such as folate and vitamin B(12) deprivation and polymorphisms in the 5,10 methylenetetrahydrofolate reductase (MTHFR) encoding gene, respectively. Homocysteine has a crucial role in cellular stress, epigenetic events, inflammatory processes, and host-microbial interactions. Hyperhomocysteinemia might therefore influence the clinical history of IBD, including disease severity, susceptibility to particular enteric infections, and the risk for the development of colorectal cancer. In contrast, homocysteine metabolism does not seem to contribute to the greater risk of thrombosis in IBD subjects. Herein, we review the evidence linking homocysteine metabolism to the pathophysiology of IBD. Furthermore, we discuss the relevance of screening and treating folate and vitamin B(12) deficiencies in IBD subjects. Given the peculiar frequency of such deficiencies in IBD, normalizing vitamin levels should be an integral part of the management of these patients, especially those with active disease, history of intestinal resection, and/or treated with methotrexate.

Risk factors for colorectal neoplasia in inflammatory bowel disease: a nested case-control study from Copenhagen county, Denmark and Olmsted county, Minnesota

OBJECTIVES

Population-based data on risk factors and protective factors for colorectal dysplasia and cancer in patients with inflammatory bowel disease (IBD) are sparse. We conducted a nested case-control study of such factors in two well-described IBD cohorts from Copenhagen County, Denmark and Olmsted County, Minnesota.

METHODS

Forty-three neoplasia cases were matched on six criteria to 1-3 controls (N = 102). Medical records were scrutinized for demographic and clinical data. For each variable, the odds of neoplasia were estimated using conditional logistic regression.

RESULTS

Primary sclerosing cholangitis (PSC) (odds ratio [OR] 6.9, 95% confidence interval [CI] 1.2-40), percentage of disease course with clinically active disease (OR [per 5% increase] 1.2, 95% CI 0.996-1.4), and >or=1 yr of continuous symptoms (OR 3.2, 95% CI 1.2-8.6) were associated with neoplasia, whereas a borderline association with median number of small-bowel x-rays (OR 1.3, 95% CI 0.96-1.6) was observed. We did not observe a protective effect of frequency of physician visits (OR 1.4, 95% CI 0.96-2.0), number of colonoscopies (OR 1.4, 95% CI 1.0-2.1), cumulative dose of sulfasalazine (OR [per 1,000 g] 1.1, 95% CI 1.0-1.3) and mesalamine (OR [per 1,000 g] 1.3, 95% CI 0.9-1.9), or partial intestinal resections (OR 1.5, 95% CI 0.3-7.1).

CONCLUSIONS

Subgroups of IBD patients-those with PSC, severe long-standing disease, and exposure to x-ray-were at greater risk of colorectal neoplasia. The protective effect of close follow-up, colonoscopy, and treatment with 5-aminosalicylates was questionable.

Herbs or Natural Products That Protect Against Cancer Growth: Part Three of a Four-Part Series

PURPOSE/OBJECTIVES

To provide evidence-based research information about 47 herbs and natural products that have the potential to protect against the development of cancer.

DATA SOURCES

Natural Medicines Comprehensive Database and Lawrence Review of Natural Products-Monograph System. Information about these herbs has been found in evidence-based studies cited in the references.

DATA SYNTHESIS

Early research shows that some herbs and natural products appear to have the potential to prevent cancer growth.

CONCLUSIONS

This preliminary evidence may be useful to healthcare professionals or patients who are concerned about cancer.

IMPLICATIONS FOR NURSING

Oncology nurses who receive this information can become resources for patients or other healthcare professionals.

Cytogenetic damage in blood lymphocytes and exfoliated epithelial cells of children with inflammatory bowel disease

This longitudinal, prospective study sought to establish whether pediatric Crohn's disease (CD) and ulcerative colitis (UC) are associated with increased levels of cytogenetic damage and whether folate supplementation in combination with other treatments mitigates cytogenetic damage in children with inflammatory bowel disease (IBD). After a 1-mo treatment and folate supplementation, all clinical tests in CD (n = 24) and UC (n = 17) patients improved. Patients with CD were comparable in the cytogenetic response with controls (n = 28) assessed by micronucleus (MN) assay, but both groups differed from the UC group. While the MN frequency in epithelial cells slightly decreased from first to second observations in CD patients (p = 0.05) and controls (p = 0.11), an increase was observed in UC patients (p = 0.001). Similar changes were observed in blood lymphocytes resulting in significantly higher levels of the MNs and chromosome bridges in UC patients. These preliminary findings of a difference in chromosome damage between pediatric UC patients compared with CD patients and healthy controls warrant confirmation and expansion to determine (1) the role of cytogenetic damage in the pathogenesis of these diseases, (2) relative contribution of treatment and folate supplementation, and (3) potential links to the eventual development of cancer in some patients.

Chemoprevention: risk reduction with medical therapy of inflammatory bowel disease

The ideal chemopreventative agent, in addition to being efficacious in the prevention of cancer, must be easily administered, affordable, safe, and well tolerated, with minimal side effects. In the past decade, a growing body of literature has emerged on the prevention of CRC in patients with long-standing CD and UC. The data are not definitive and consist almost exclusively of retrospective case-control and cohort studies rather than the more rigorous prospective RCTs. 5-ASA compounds have been most thoroughly studied, and most of the existing data support the use of 5-ASA in the prevention of CRC. Although the precise dose and duration are unclear, studies suggest that chronic systemic administration of 5-ASA at a dose of at least 1.2 g/d is most likely to be effective. A beneficial effect of folate, albeit not statistically significant, has been consistently shown in every study performed for this purpose. Folate supplementation, which is safe and affordable, should also be recommended for all patients with IBD, especially those taking sulfasalazine. UDCA has been shown to exert a protective effect in most studies on patients with UC and concomitant PSC. Because this patient population is at particularly high risk for CRC, it is advisable to consider UDCA in all patients with colitis complicated by PSC. For patients without PSC, sufficient data do not exist to recommend it for the purpose of cancer prevention. Five of the six corticosteroid studies have found a beneficial effect of systemic steroids, although most did not reach statistical significance. Regardless, given the frequent and serious adverse effects associated with chronic steroid use, systemic corticosteroids should not be prescribed for this indication. Budesonide, an oral corticosteroid with minimal systemic absorption, is a potential alternative, although it has not yet been studied as a chemopreventative agent. Similarly, until the long-term safety of chronic NSAID use can be demonstrated in patients with IBD, the role of NSAIDs in chemoprevention remains undefined. Although the data are conflicting, immune-modulating medications, such as AZA, do not seem to confer any reduction in the risk of dysplasia or CRC. The data on calcium supplementation and statin use are still too limited to endorse their use for the prevention of colitis-related CRC. Chemoprevention is an area that holds great promise in the reduction of morbidity and mortality associated with IBD. Further studies, including prospective trials when possible and cost-effectiveness analyses, need to be performed to develop an optimal strategy for the reduction of cancer risk in patients with IBD.

Oral mesalamine and clinical remission are associated with a decrease in the extent of long-standing ulcerative colitis

OBJECTIVE

To compare colonoscopy alone with surveillance biopsy for the determination of anatomic extent in long-standing ulcerative colitis (UC). To assess the influences of mesalamine use and clinical disease activity on the change of histologic extent with time.

MATERIALS AND METHODS

Disease extent (proctosigmoiditis, left-sided colitis, or pancolitis) measured by colonoscopy and surveillance biopsy was compared among 212 consecutive patients with long-standing UC. Among the 102 patients who had 2 consecutive colonoscopies with surveillance biopsies, the following influences on change in histologic extent were determined: disease activity, mesalamine use, age at disease onset, folic acid, corticosteroid and azathioprine/6-mercaptopurine use, and time between colonoscopies.

RESULTS

Agreement between gross and microscopic findings was poor (kappa = 0.39). Colonoscopy underestimated and overestimated extent in 25.9% and 8.5%, respectively. Microscopic distribution between consecutive colonoscopies remained the same in 60.8%. Where distribution changed, an increase was twice as common as a decrease in extent. There was no difference in age at onset, time between colonoscopies, or disease duration among those with an increase, decrease, or no change in extent. Clinical remission and oral mesalamine were independently associated with 10.7 and 5.8 times the odds of a decrease in disease extent, respectively. Folic acid, topical mesalamine, corticosteroids, and immunomodulators did not influence change in extent.

CONCLUSIONS

UC extent is best determined by surveillance biopsy. Among patients with long-standing UC, histologic extent fluctuates with time. Disease remission and oral mesalamine were independently associated with decreases in disease extent.

Sensitivity of markers of DNA stability and DNA repair activity to folate supplementation in healthy volunteers

We have previously reported that supplementation with folic acid (1.2 mg day⁻¹ for 12 week) elicited a significant improvement in the folate status of 61 healthy volunteers. We have examined effects of this supplement on markers of genomic stability. Little is known about the effect of folate supplementation on DNA stability in a cohort, which is not folate deficient. Preintervention, there was a significant inverse association between uracil misincorporation in lymphocyte DNA and red cell folate (P<0.05). In contrast, there were no associations between folate status and DNA strand breakage, global DNA methylation or DNA base excision repair (measured as the capacity of the lymphocyte extract to repair 8-oxoGua ex vivo). Folate supplementation elicited a significant reduction in uracil misincorporation (P<0.05), while DNA strand breakage and global DNA methylation remained unchanged. Increasing folate status significantly decreased the base excision repair capacity in those volunteers with the lowest preintervention folate status (P<0.05). Uracil misincorporation was more sensitive to changes in folate status than other measures of DNA stability and therefore could be considered a specific and functional marker of folate status, which may also be relevant to cancer risk in healthy people.

ESPEN Guidelines on Enteral Nutrition: Gastroenterology

Undernutrition as well as specific nutrient deficiencies have been described in patients with Crohn's disease (CD), ulcerative colitis (UC) and short bowel syndrome (SBS). The present guideline gives evidence-based recommendations for the indication, application and type of formula of enteral nutrition (EN) (oral nutritional supplements (ONS) or tube feeding (TF)) in these patients. It was developed in an interdisciplinary consensus-based process in accordance with officially accepted standards and is based on all relevant publications since 1985. ONS and/or TF in addition to normal food is indicated in undernourished patients with CD or CU to improve nutritional status. In active CD EN is the first line therapy in children and should be used as sole therapy in adults mainly when treatment with corticosteroids is not feasible. No significant differences have been shown in the effects of free amino acid, peptide-based and whole protein formulae for TF. In remission ONS is recommended only in steroid dependent patients in CD. In patients with SBS TF should be introduced in the adaptation phase and should be changed with progressing adaptation to ONS in addition to normal food.

Folate and prevention of colorectal cancer in ulcerative colitis

Patients with ulcerative colitis are at greater risk of developing colorectal cancer than the general population. Prophylactic colectomy is the only certain method of avoiding this risk. To avoid indiscriminate surgery, efforts have focused on colonoscopic surveillance in order to select for prophylactic surgery only patients at ultra-high risk. However this policy has not always been proven to reduce mortality for colorectal cancer in these patients. Recently, there has been growing interest in chemoprevention using folate. Folate maintains the normal DNA methylation process and steady-state levels of DNA precursors. These properties indicate that folate has potential as chemopreventive agent.

Folate and its preventive potential in colorectal carcinogenesis

Based on a 15-year old hypothesis, it is believed that an adequate ingestion of folate vitamins decreases, whereas a nutritional depletion of folate increases the risk of colorectal cancer. The present article reviews the efforts to provide biochemical and epidemiological evidence for folate as a chemopreventive agent against colorectal carcinogenesis. BIOLOGICAL EVIDENCE: Tetrahydrofolates govern the intracellular one-carbon metabolism and account for proper DNA biosynthesis and macromolecular modification. Numerous experimental studies traced different molecular pathways and tried to link folate depletion with DNA instability and/or mutagenesis. However, none of the proposed underlying molecular mechanisms appear clearly defined. EPIDEMIOLOGICAL EVIDENCE: Numerous case-control and prospective studies have been conducted on folate and colorectal cancer, which all together miss a clinical bottom line. The recommendation of folate intake to prevent colorectal cancer is therefore not evidence-based.

Influence of folate status on genomic DNA methylation in colonic mucosa of subjects without colorectal adenoma or cancer

DNA hypomethylation may increase the risk of colorectal cancer. The main aim of this study was to assess the influence of folate status (serum and erythrocyte folate and plasma homocysteine concentrations) on DNA methylation. Methylenetetrahydrofolate reductase (MTHFR 677C --> T and 1298A --> C), methionine synthase (MS 2756A --> G) and cystathionine synthase (CBS 844ins68) polymorphisms were measured to account for potential confounding effects on folate status and DNA methylation. A total of 68 subjects (33 men and 35 women, 36-78 years) free from colorectal polyps or cancer were recruited in a cross-sectional study. Tissue biopsies were obtained at colonoscopy for the determination of DNA methylation in colonic mucosa using an in vitro radiolabelled methyl acceptance assay. Serum and erythrocyte folate were inversely correlated with plasma homocysteine (r=-0.573, P<0.001 and r=-0.307, P=0.01 respectively) and DNA hypomethylation in colonic mucosa (r=-0.311, P=0.01 and r=-0.356, P=0.03). After adjusting for gender, age, body mass index, smoking and genotype, there were weak negative associations between serum and erythrocyte folate and colonic DNA hypomethylation (P=0.07 and P=0.08, respectively).

Interactions between folate and aging for carcinogenesis

Inadequate folate intake and aging are each strongly implicated as important risk factors for certain cancers. Since both folate depletion and aging are strongly associated with hyperhomocysteinemia, genomic DNA hypomethylation, and increased uracil misincorporation into DNA, it appears that each of them enhances carcinogenesis by inducing a derangement of one-carbon metabolism that supplies one-carbons to biological methylation reactions and nucleotide synthesis. Recent studies have demonstrated that inadequate dietary folate and aging may interact and synergistically disturb the normal homeostasis of one-carbon metabolism, thereby provoking subsequent biochemical and molecular aberrations, including alterations in critical gene expression related to carcinogenesis. These studies have further indicated that modest folate supplementation may reverse or partially ameliorate those adverse effects induced by folate depletion and aging.

Effect of Folic Acid Supplementation on the Folate Status of Buccal Mucosa and Lymphocytes

Folate deficiency may be associated with an increased risk of cancer at certain sites. There is a need to measure folate status and putative biomarkers of cancer risk in the same target tissue, or in surrogate tissues. A study was carried out to develop a method for the rapid measurement of folate in human buccal mucosa and lymphocytes and to evaluate the responsiveness of this measurement in both tissues to folic acid supplementation in healthy subjects, relative to conventional markers of folate status. Three hundred and twenty-three adults, ages between 20 and 60 years, were screened for RBC folate concentrations. Sixty-five subjects with red cell folate between 200 and 650 nmol/L participated in a randomized, double blind, placebo-controlled, folic acid (1.2 mg) intervention trial, lasting 12 weeks. As anticipated, a significant baseline correlation (r = 0.36, P &lt; 0.01) was observed between red cell folate and plasma 5-methyltetrahydrofolate (5-MeTHF). Lymphocyte total folate was significantly associated with plasma 5-MeTHF (r = 0.28, P &lt; 0.05) and plasma total homocysteine concentration (r = −0.34, P &lt; 0.05). Buccal mucosa total folate showed no correlation with either red cell folate or 5-MeTHF, but was significantly associated with lymphocyte total folate (r = 0.35, P &lt; 0.01). Supplementation elicited a significant increase in lymphocyte total folate (P &lt; 0.01), and this was strongly associated with the increase in RBC total folate (P &lt; 0.01) and plasma 5-MeTHF (P &lt; 0.01). Buccal mucosa total folate was not influenced by folate supplementation. Methods have been developed for the rapid measurement of lymphocyte and buccal mucosal total folate. Lymphocyte folate is sensitive to folate intake and is reflected by plasma 5-MeTHF.

Left-sided ulcerative colitis

Left-sided ulcerative colitis is not a distinct entity, but a less extensive form of pancolitis. The epidemiologic and genetic characteristics are thought to be analogous. The rate of colorectal cancer, however, seems to be proportional to the extent of disease. Primary treatment for left-sided disease is topical 5-aminosalicyclic acid (5ASA) agents. In patients who do not respond to topical therapy, oral 5ASA agents of differing delivery methods to the distal bowel can be used. There is much debate pertaining to the clinical superiority of the oral 5ASA agents.

Colorectal cancer chemoprevention--an overview of the science

The development and dissemination of sophisticated detection technologies have recently exposed the high prevalence of preinvasive colorectal neoplasia in the adult U.S. population. Although cancer screening and surveillance provide opportunities for risk stratification, they achieve risk reduction only when coupled with effective interventions. This review surveys the lead compounds for colorectal cancer prevention and the measures by which they may be prioritized for clinical testing. Clinical trials remain the rate-limiting step in agent development, and novel trial designs are needed to hasten agent identification and testing for cancer prevention. Innovative research models include the nesting of prevention end points within cancer treatment trials and within trials testing promising preventive compounds intended for nononcologic indications.

Folate, colorectal carcinogenesis, and DNA methylation: lessons from animal studies

Folate, a water-soluble B vitamin and cofactor in one-carbon transfer, is an important nutritional factor that may modulate the development of colorectal cancer (CRC). Epidemiologic and clinical studies indicate that dietary folate intake and blood folate levels are inversely associated with CRC risk. Collectively, these studies suggest an approximately 40% reduction in the risk of CRC in individuals with the highest dietary folate intake compared with those with the lowest intake. Animal studies using chemical and genetically predisposed rodent models have provided considerable support for a causal relationship between folate depletion and colorectal carcinogenesis as well as a dose-dependent protective effect of folate supplementation. However, animal studies also have shown that the dose and timing of folate intervention are critical in providing safe and effective chemoprevention; exceptionally high supplemental folate levels and folate intervention after microscopic neoplastic foci are established in the colorectal mucosa promote, rather than suppress, colorectal carcinogenesis. These animal studies, in conjunction with clinical observations, suggest that folate possesses dual modulatory effects on carcinogenesis depending on the timing and dose of folate intervention. Folate deficiency has an inhibitory effect, whereas folate supplementation has a promoting effect on the progression of established neoplasms. In contrast, folate deficiency in normal epithelial tissues appears to predispose them to neoplastic transformation, and modest levels of folate supplementation suppress the development of tumors in normal tissues. Notwithstanding the limitations associated with animal models, these studies suggest that the optimal timing and dose of folate intervention must be established for safe and effective chemoprevention in humans. Folate is an important factor in DNA synthesis, stability, and integrity, the repair aberrations of which have been implicated in colorectal carcinogenesis. Folate may also modulate DNA methylation, which is an important epigenetic determinant in gene expression (an inverse relationship), in the maintenance of DNA integrity and stability, in chromosomal modifications, and in the development of mutations. A mechanistic understanding of how folate status modulates colorectal carcinogenesis further strengthens the case for a causal relationship and provides insight into a possible chemopreventive role of folate.

Role of Folate in Colon Cancer Development and Progression

Folate, a water-soluble B vitamin and important cofactor in 1-carbon transfer, is an important nutritional factor that may modulate the development of colorectal cancer. Epidemiologic and clinical studies indicate that dietary folate intake and blood folate levels are inversely associated with colorectal cancer risk. Collectively, these studies suggest an approximately 40% reduction in the risk of colorectal cancer in individuals with the highest dietary folate intake compared with those with the lowest intake. Animal studies using chemical and genetically predisposed rodent models have provided considerable support for a causal relationship between folate depletion and colorectal carcinogenesis as well as a dose-dependent protective effect of folate supplementation. However, animal studies have also shown that the dose and timing of folate intervention are critical in providing safe and effective chemoprevention; exceptionally high supplemental folate levels and folate intervention after microscopic neoplastic foci are established in the colorectal mucosa promote rather than suppress colorectal carcinogenesis. These animal studies in conjunction with clinical observations suggest that folate possesses the dual modulatory effects on carcinogenesis depending on the timing and dose of folate intervention. Folate deficiency has an inhibitory effect whereas folate supplementation has a promoting effect on progression of established neoplasms. In contrast, folate deficiency in normal epithelial tissues appears to predispose them to neoplastic transformation, and modest levels of folate supplementation suppress the development of tumors in normal tissues. Notwithstanding the limitations associated with animal models, these animal studies suggest that the optimal timing and dose of folate intervention need to be established for safe and effective chemoprevention in humans.

Aminosalicylates and colorectal cancer in IBD: a not-so bitter pill to swallow

Inflammatory bowel disease (IBD) is associated with an increased risk of developing intestinal cancer at sites of chronic inflammation. Aminosalicylates, including both sulfasalazine and mesalamine, are the most commonly prescribed anti-inflammatory agents prescribed in IBD. On balance, the body of literature to date suggests that aminosalicylates confer some protection against the development of colonic neoplasia in patients with IBD and in a variety of models, including in the noninflamed gut. This latter observation implies that aminosalicylates may be of chemopreventive value in normal as well as IBD individuals. The current review examines and gives an overview of the evidence from a variety of sources, including epidemiological, in vivo and in vitro studies that have investigated the potential anticancer effects of aminosalicylates.

Epidemiologic considerations to assess altered DNA methylation from environmental exposures in cancer

Epidemiologic studies in human populations have identified a broad spectrum of risk factors for cancer. Gene-damaging agents have been a primary focus of cancer epidemiology; however, all xenobiotics do not interact with DNA directly. Some exogenous agents induce epigenetic changes. In view of this, markers that measure changes to the epigenome must also be incorporated into molecular epidemiologic studies. We review the current understanding of the impact of exogenous agents including: micronutrients, chemotherapeutic agents, metals, and others, on DNA methylation. Two categories of genes are described: (1) genes that can alter susceptibility to aberrant DNA methylation and (2) genes that increase susceptibility to cancer when they are silenced through DNA methylation. Methods for incorporating markers of DNA methylation status into etiologic investigations of the impact of environmental exposures on disease (e.g., cancer) are discussed.

Nutrition in Crohn disease

Nutrition plays an important role in the pathogenesis, treatment, and morbidity of Crohn disease. Approximately two thirds to three fourths of hospitalized patients with active disease and one fourth of outpatients with Crohn disease are malnourished. Malnutrition, which can be present even when Crohn disease is in remission, can affect growth, cellular and humoral immunity, bone density, and wound healing. Decreased nutrient intake, malabsorption, drug-nutrient interactions, anorexia, and protein-losing enteropathy can all contribute to the protein-calorie malnutrition and other specific nutrient deficiencies seen in Crohn disease. Therefore, by preventing and correcting nutrient deficiencies, nutritional therapy is an important component in the overall management of patients with Crohn disease.

Review article: nutrition and adult inflammatory bowel disease

Major advances in the understanding of the aetio-pathogenesis and genetics of inflammatory bowel disease have been accompanied by an escalation in the sophistication of immunomodulatory inflammatory bowel disease therapeutics. However, the basic 'triple' therapy (5-aminosalicylates, corticosteroids, azathioprine) and nutrition have maintained their central role in the management of patients with inflammatory bowel disease over recent decades. This review provides an overview of the supportive and therapeutic perspectives of nutrition in adult inflammatory bowel disease. The objective of supportive nutrition is to correct malnutrition in terms of calorie intake or specific macro- or micronutrients. Of particular clinical relevance is deficiency in calcium, vitamin D, folate, vitamin B12 and zinc. There is justifiably a growing sense of unease amongst clinicians and patients with regard to the long-term use of corticosteroids in inflammatory bowel disease. This, rather than arguments about efficacy, should be the catalyst for revisiting the use of enteral nutrition as primary treatment in Crohn's disease. Treatment failure is usually related to a failure to comply with enteral nutrition. Potential factors that militate against successful completion of enteral nutrition are feed palatability, inability to stay on a solid-free diet for weeks, social inconvenience and transient feed-related adverse reactions. Actions that can be taken to improve treatment outcome include the provision of good support from dietitians and clinicians for the duration of treatment and the subsequent 'weaning' period. There is evidence to support a gradual return to a normal diet through exclusion-re-introduction or other dietary regimen following the completion of enteral nutrition to increase remission rates. We also review the evidence for emerging therapies, such as glutamine, growth factors and short-chain fatty acids. The future may see the evolution of enteral nutrition into an important therapeutic strategy, and the design of a 'Crohn's disease-specific formulation' that is individually tailored, acceptable to patients, cost-effective, free from adverse side-effects and combines enteral nutrition with novel pre- and pro-biotics and other factors.

Colonic dysplasia and cancer in inflammatory bowel disease

Extracolonic malignancies are a relatively rare complication of inflammatory bowel disease. In contrast, colorectal cancer remains a major concern for patients with long-standing UC. The best available evidence suggests that patients with long-standing Crohn's colitis are at similar risk for colorectal cancer as those patients with long-standing UC. In patients with UC, the magnitude of this increased risk appears to be greater in patients with more extensive colonic involvement. It appears that the magnitude of this risk increases with increasing duration of disease, at least in UC. Whether this reflects the increased risk of cancer that occurs with the aging process or a separate phenomena distinct to UC is unclear. To date, the methods available to reduce the risk of cancer are less than optimal. Although surgical procedures eliminate the risk, the mental and physical sequelae of these procedures can be substantial. Surveillance with colonoscopic biopsies is likely effective in reducing although not eliminating the risk of colorectal cancer. Efforts to develop chemopreventative agents and improved surveillance methods remain areas of active investigation.