Iron supplementation increases disease activity and vitamin E ameliorates the effect in rats with dextran sulfate sodium-induced colitis

Anemia and inflammatory bowel diseases

Too often anemia is considered a rare or unimportant manifestation in inflammatory bowel disease (IBD). However, over the last 10 years a number of studies have been conducted and the most relevant conclusions obtained are: (1) anemia is quite common in IBD; (2) although in many cases anemia parallels the clinical activity of the disease, many patients in remission have anemia, and iron, vitamin B12 and/or folic acid deficiency; (3) anemia, and also iron deficiency without anemia, have important consequences in the clinical status and quality of life of the patient; (4) oral iron can lead to gastrointestinal intolerance and failure of treatment; (5) intravenous iron is an effective and safe way to treat iron deficiency; (6) erythropoietin is needed in a significant number of cases to achieve normal hemoglobin levels. Thus, the clinician caring for IBD patients should have a comprehensive knowledge of anemia, and apply recently published guidelines in clinical practice.

Oral and intravenous iron treatment in inflammatory bowel disease: hematological response and quality of life improvement

BACKGROUND

The aim was to evaluate the efficacy and tolerance of oral and intravenous iron treatment in anemic inflammatory bowel disease (IBD) patients, considering both hematological and quality-of-life outcomes.

METHODS

We performed a prospective multicenter study in IBD patients with iron deficiency anemia. Patients having hemoglobin >10 g/dL were prescribed oral ferrous sulfate. If hemoglobin <10 g/dL, intravenous (sucrose) iron was administered. Oral iron-intolerant patients were changed to intravenous treatment. Clinical (Truelove/Harvey-Bradshaw), hematological (response defined as hemoglobin normalization), and quality-of-life (shortened CCVEII-9 questionnaire) evaluations were performed at baseline and at 3 and 6 months.

RESULTS

100 IBD patients (59 Crohn's disease, 41 ulcerative colitis) were included. Mean basal hemoglobin levels were 10.8 +/- 1.3 g/dL (range, 6.6-12.9). Seventy-eight patients received oral treatment and 22 intravenous iron. Hemoglobin normalization was achieved in 86% of patients: 89% with oral, and 77% with intravenous iron. An IBD activity increase was not demonstrated in any patient. Four patients (5.1%) showed oral iron intolerance leading to discontinuation of treatment. No adverse events were reported for intravenous iron. Hemoglobin correlated with CCVEII-9 (P < 0.001). The CCVEII-9 score increased in patients who normalized hemoglobin levels in 3 months (from 58 +/- 9 to 73 +/- 10) or 6 months (54 +/- 9, 68 +/- 12, and 74 +/- 10) (P < 0.001).

CONCLUSIONS

Oral iron treatment is effective and well tolerated in most IBD patients, and does not exacerbate the symptoms of the underlying IBD. Intravenous iron, on the other hand, is an effective and safe alternative treatment for iron deficiency anemia in more severely anemic or intolerant patients. Anemia correction with iron treatment is associated with a relevant improvement in the patients' quality of life.

Common misconceptions in the diagnosis and management of anemia in inflammatory bowel disease

Anemia is the most common systemic complication of inflammatory bowel disease (IBD); so common that it is almost invariably not investigated and rarely treated. Several misconceptions are the reason for these clinical errors, and our goal will be to review them. The most common misconceptions are: anemia is uncommon in IBD; iron deficiency is also uncommon; just by treating the intestinal disease, anemia will be corrected; iron deficiency is the only cause for anemia in IBD; ferritin is an accurate parameter for the diagnosis of iron deficiency in IBD; the impact of anemia on the quality of life of IBD patients is limited; iron supplementation is rarely needed in IBD; high-dose oral iron solves the problem of iron malabsorption in IBD; intravenous (IV) iron is dangerous and of no proven benefit in IBD; IV iron is useful only for severe anemia; and erythropoietin has no role in the treatment of IBD anemia. These misconceptions are not evidence-based. On the contrary, there is enough evidence to support the following statements: (a) anemia is very common in IBD, (b) anemia should be investigated with care because many factors can be responsible, (c) treatment of anemia results in clear improvement in the objective parameters of well-being, especially in the quality of life, (d) IV iron is safe and effective in the treatment of iron deficiency anemia in IBD patients, and (e) erythropoietin is useful in a subset of patients with refractory anemia. Anemia diagnosis and treatment must not be neglected in IBD patients, and several misconceptions should be promptly abandoned.

Dextran sulfate sodium-induced colitis-associated neoplasia: a promising model for the development of chemopreventive interventions

Individuals diagnosed with ulcerative colitis face a significantly increased risk of developing colorectal dysplasia and cancer during their lifetime. To date, little attention has been given to the development of a chemopreventive intervention for this high-risk population. The mouse model of dextran sulfate sodium (DSS) - induced colitis represents an excellent preclinical system in which to both characterize the molecular events required for tumor formation in the presence of inflammation and assess the ability of select agents to inhibit this process. Cyclic administration of DSS in drinking water results in the establishment of chronic colitis and the development of colorectal dysplasias and cancers with pathological features that resemble those of human colitis-associated neoplasia. The incidence and multiplicity of lesions observed varies depending on the mouse strain used (ie, Swiss Webster, C57BL/6J, CBA, ICR) and the dose (0.7%-5.0%) and schedule (1-15 cycles with or without a subsequent recovery period) of DSS. The incidence of neoplasia can be increased and its progression to invasive cancer accelerated significantly by administering DSS in combination with a known colon carcinogen (azoxymethane (AOM), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-1- methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)) or iron. More recent induction of colitis-associated neoplasia in genetically defined mouse strains has provided new insight into the role of specific genes (ie, adenomatous polyposis coli (Apc), p53, inducible nitric oxide synthase (iNOS), Msh2) in the development of colitis-associated neoplasias. Emerging data from chemopreventive intervention studies document the efficacy of several agents in inhibiting DSS-induced neoplasia and provide great promise that colitis-associated colorectal neoplasia is a preventable disease.

Redox-active labile iron in fortified flours from the Brazilian market

OBJECTIVE: To quantify the fraction of redox-active labile iron in iron-fortified flours acquired on the Brazilian market. METHODS: Samples of wheat flour, maize flour and breadcrumbs were extracted with buffers that mimic gastric juice, saliva and intestinal juice. Redox-active labile iron levels were assessed through the reaction of autoxidation of ascorbic acid catalyzed by iron in the presence of a fluorescence probe. RESULTS: Redox-active labile iron represents 1% to 9% of the total iron in the flour and breadcrumb samples, with the lowest values found under gastric juice conditions and the highest in the more alkaline media. Redox-active labile iron possibly arises from the decomposition of an iron-phytic acid complex. A positive correlation between redox-active labile iron and total iron was found in saline biomimetic fluids. CONCLUSION: Redox-active labile iron may be a risk factor for people with impaired antioxidant defenses, such as those who are atransferrinemic or iron overloaded (e.g. thalassemic). Total iron can be used to predict redox-active labile iron absorption at each stage of the gastrointestinal tract after ingestion of iron-fortified flours.

Colitis and colitis-associated cancer are exacerbated in mice deficient for tumor protein 53-induced nuclear protein 1

Tumor protein 53-induced nuclear protein 1 (TP53INP1) is an antiproliferative and proapoptotic protein involved in cell stress response. To address its physiological roles in colorectal cancer and colitis, we generated and tested the susceptibility of Trp53inp1-deficient mice to the development of colorectal tumors induced by injection of the carcinogen azoxymethane followed by dextran sulfate sodium (DSS)-induced chronic colitis. Trp53inp1-deficient mice showed an increased incidence and multiplicity of tumors compared to those of wild-type (WT) mice. Furthermore, acute colitis induced by DSS treatment was more severe in Trp53inp1-deficient mice than in WT mice. Treatment with the antioxidant N-acetylcysteine prevented colitis and colitis-associated tumorigenesis more efficiently in WT mice than in Trp53inp1-deficient mice, suggesting a higher oxidative load in the latter. Consistently, we demonstrated by electron spin resonance and spin trapping that colons derived from deficient mice produced more free radicals than those of the WT during colitis and that the basal blood level of the antioxidant ascorbate was decreased in Trp53inp1-deficient mice. Collectively, these results indicate that the oxidative load is higher in Trp53inp1-deficient mice than in WT mice, generating a more-severe DSS-induced colitis, which favors development of colorectal tumors in Trp53inp1-deficient mice. Therefore, TP53INP1 is a potential target for the prevention of colorectal cancer in patients with inflammatory bowel disease.

Systematic review: managing anaemia in Crohn's disease

BACKGROUND

Anaemia is a serious complication of Crohn's disease that triggers hospitalization and, if not interfered with, may lead to death.

AIMS

To systematically summarize and compare the literature on anaemia in Crohn's disease.

METHODS

For this systematic review the literature was searched for English-language articles using anaemia, Crohn* and IBD as key words. 144 articles were identified and sorted according to the following topics: prevalence, aetiology, diagnostic tests and therapy.

RESULTS

The reported prevalence of anaemia varied between 6.2% and 73.7%, with higher reported frequencies in older studies and in in-patients. Iron deficiency is the most common underlying condition. Vitamin B12 deficiency is related to the extent of ileal resection but has rarely impact on anaemia. Diagnostic criteria are not established and treatment guidelines are missing. Oral iron supplementation seems effective for short periods but intolerance leads to discontinuation in up to 21%. Eleven of 11 studies show that oral iron enhances intestinal inflammation and colon carcinogenesis in animal models of colitis. Intravenous iron supplementation with iron sucrose has been tested in over 250 Crohn's disease patients, is safe, effective and does not carry such hazards.

CONCLUSIONS

As disease activity is determining the degree of anaemia in Crohn's disease, implementation of more effective therapy for Crohn's disease will lower its incidence. However, further studies regarding the safety and effectiveness of iron supplementation are needed.

High-iron diet: foe or feat in ulcerative colitis and ulcerative colitis-associated carcinogenesis

Anemia associated with long-standing chronic inflammation and iron deficiency, and the increased risk for the development of dysplasia and carcinoma, are two of the most common complications in patients with ulcerative colitis (UC). Because of iron and nutrition deficiency, UC patients are encouraged to consume a high-protein and high-iron diet. The crucial clinical question is the effect of a high-iron diet on inflammation activity and inflammation-driven carcinogenesis. Is a high-iron diet a foe or a feat in UC and UC-associated carcinogenesis? This review updates the progress and information on (1) iron nutrition and iron-deficiency anemia in patients with UC, (2) experimental evidence of the exacerbating effect of a high-iron diet on UC and its associated carcinogenesis and the difference between a high-iron diet and parental iron supplementation, (3) the clinical efficacy of, and concerns about, oral and intravenous iron supplements in patients with inflammatory bowel disease and iron deficiency anemia, and (4) the clinical implications of long-term iron supplements and management of UC. These experimental findings from animal models provide evidence to warrant further consideration and clinical studies of iron nutrition, inflammation activity, and cancer development.

Exacerbation of dextran sulfate sodium-induced colitis by dietary iron supplementation: role of NF-kappaB

BACKGROUND

In colitis, iron therapy may be given to treat anemia, but it may also be detrimental based on our previous studies using a rat model with colitis where iron supplementation increased disease activity and oxidative stress. This effect was partially reduced by an antioxidant.

AIMS

The aim of this study was to further evaluate, in rats with dextran sulfate sodium (DSS)-induced colitis, the effect of iron on neutrophilic infiltration, cytokines and nuclear factor kappa-B (NF-kappaB)-associated inflammation and to determine whether the addition of vitamin E would be beneficial.

METHODS

Colitis was induced with DSS at 50 g/l in drinking water for 7 days. DSS rats were randomized to the following: DSS, receiving a control, non-purified diet (iron, 270 mg and DL-alpha-tocopherol acetate, 49 mg/kg); DSS+iron (diet+iron, 3,000 mg/kg); DSS+vitamin E (diet+DL-alpha-tocopherol acetate, 2,000 mg/kg); or the DSS+iron+vitamin E. Colonic inflammation, myeloperoxidase activity (MPO), lipid peroxides (LPO), proinflammatory cytokines [tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6] and NF-kappaB binding activity were measured.

RESULTS

The DSS+iron group showed a significant increase in inflammatory scores, MPO, TNF-alpha, IL-1, LPO and NF-kappaB activity compared to DSS or DSS+vitamin E. The addition of vitamin E to iron (DSS+iron+vitamin E group) significantly reduced the inflammatory scores, TNF-alpha and IL-6. None of the other parameters were affected.

CONCLUSION

Iron increases disease activity in colitis, and this is associated with oxidative stress, neutrophilic infiltration, increased cytokines and activation of NF-kappaB. This detrimental effect was partially reduced by vitamin E.

Effects of changes in hemoglobin level on quality of life and cognitive function in inflammatory bowel disease patients

BACKGROUND

Anemia commonly complicates inflammatory bowel disease (IBD). In patients with chronic renal failure, the treatment of anemia with iron+/-erythropoietin improves both quality of life (QOL) and cognitive function (CF). The same drugs are effective in treating severe anemia in IBD, but there is no evidence to direct the treatment of mild anemia. Concern exists that the use of iron may exacerbate inflammation in patients with IBD. The present study examined the association between changes in hemoglobin (Hb) in a population of IBD patients and changes in QOL and CF independent of change in disease activity (DA). Subsidiary aims were to assess whether the use of iron was associated with worsening DA.

METHODS

A cohort of 50 patients with IBD (29 Crohn's disease and 21 ulcerative colitis) took part. Iron replacement was given to 21 patients with low Hb. Measures of QOL, CF, DA, and Hb were recorded at baseline and at 6 months.

RESULTS

The iron-treated group had lower Hb and higher DA scores compared with the non-iron-treated group at baseline. In a hierarchical regression model, changes in DA accounted for 13% (P=0.17) and changes in Hb accounted for 18% (P=0.005) of the variance in change in SF-36 and 12% (P=0.23) and 17% (P=0.009) in the Inflammatory Bowel Disease Questionnaire. In this pilot study, although no associations were identified between changes in Hb or DA and CF, increases in Hb improved QOL scores in IBD patients independent of changes in DA. We found no similar effect with CF, but again, the sample size was small. We found no evidence that iron therapy causes worsening of DA.

CONCLUSIONS

Treatment of IBD-associated anemia with iron may lead to improvement in patients' QOL.

Novel synthesized aminosteroidal heterocycles intervention for inhibiting iron-induced oxidative stress

The objective of this study was to elucidate the potential role of novel synthesized aminosteroidal heterocyclic compounds 2, 5, 9b and 10c against iron-induced oxidative stress with particular insight on erythrocyte ghosts in male rats. Chronic iron supplementation (3000 mg kg(-1) diet) for 6 weeks significantly increased plasma iron and ferritin levels. It also produced significant increase in plasma TNF-alpha and NO levels. Lipid metabolism was also affected by excess iron, so that plasma and erythrocyte membrane total cholesterol, triglycerides, phospholipids and total lipid levels were significantly elevated. In consequence, a significant increase in plasma leptin level was detected. Iron overload clearly induces oxidative stress as indicated by the significant increase in both plasma and erythrocyte membrane lipid peroxidation levels. Noteworthy, excess iron not only decreased the mean value of erythrocyte membrane protein but also caused marked alterations in the membrane protein fractions with concomitant inhibition in erythrocyte membrane ATPases activity. On the other hand, treatment with the aminosteriodal heterocyclic compounds especially compounds 5, 2, and 10c in an oral dose of 5 mg kg(-1) B.W. per day could ameliorate almost all of the changes in plasma and erythrocyte ghosts components induced by iron overload. The efficacious role of these novel synthesized aminosteriods in preventing iron-induced oxidative stress may be mediated through their iron chelating properties, anti-lipid peroxidation activities and membrane stabilizing actions. The encouraging results obtained in the present study lend credence to substantial investigation to assess the use of these compounds as a potent line of therapy to retard the pathogenesis of iron overload diseases.

Efficacy and tolerability of oral iron therapy in inflammatory bowel disease: a prospective, comparative trial

BACKGROUND

In patients with inflammatory bowel disease, oral iron is anecdotally reported to be less effective and less well tolerated than in those without inflammatory bowel disease, and to increase disease activity.

AIM

To study prospectively the effects of oral iron in patients with and without inflammatory bowel disease.

METHODS

Patients with ulcerative colitis, Crohn's disease and non-inflammatory bowel disease controls, all with iron deficiency anaemia, were assessed with symptom diaries, a quality of life questionnaire (Inflammatory Bowel Disease Questionnaire; inflammatory bowel disease patients only) and blood tests to measure iron repletion, disease activity and antioxidant capacity before and after starting 4 weeks of oral iron. In patients with ulcerative colitis, sigmoidoscopic scoring and rectal biopsies for reactive oxygen metabolite production were performed before and after iron therapy.

RESULTS

All groups showed increases in haemoglobin and ferritin. Iron intolerance occurred in about a quarter of patients in each group. Two of 33 (6%) of inflammatory bowel disease patients had a relapse during treatment. Symptoms worsened in ulcerative colitis, but not in Crohn's disease or non-inflammatory bowel disease patients; Inflammatory Bowel Disease Questionnaire scores improved in ulcerative colitis. Laboratory markers of disease activity, sigmoidoscopic scores, histological scores, antioxidant capacity levels and reactive oxygen metabolite production did not change.

CONCLUSIONS

Oral iron is equally efficacious and well tolerated in inflammatory bowel disease and non-inflammatory bowel disease patients. A tiny minority of inflammatory bowel disease patients relapse in association with use of oral iron therapy.

Effects of ferrous sulphate and non-ionic iron-polymaltose complex on markers of oxidative tissue damage in patients with inflammatory bowel disease

BACKGROUND

Iron deficiency is a common complication of inflammatory bowel disease. Oral iron therapy may reinforce intestinal tissue injury by catalyzing production of reactive oxygen species.

AIM

To compare the effects of ferrous sulphate and non-ionic iron-polymaltose complex on markers of oxidative tissue damage and clinical disease activity in patients with inflammatory bowel disease.

METHODS

Forty-one patients with inflammatory bowel disease and iron deficiency were randomized to treatment with ferrous sulphate 100 mg twice a day or iron-polymaltose complex 200 mg once a day for 14 days.

RESULTS

Following ferrous sulphate, plasma malondialdehyde increased (P = 0.02), while urine 8-isoprostaglandin F(2alpha) and plasma antioxidants did not change significantly. Iron-polymaltose complex did not change plasma malondialdehyde, urine 8-isoprostaglandin F(2alpha) or plasma antioxidants. Comparing the two treatments, changes in plasma malondialdehyde tended to differ (P = 0.08), while urine 8-isoprostaglandin F(2alpha) and plasma antioxidants did not differ. Neither ferrous sulphate nor iron-polymaltose complex altered clinical disease activity indices.

CONCLUSIONS

Ferrous sulphate increased plasma malondialdehyde, a marker of lipid peroxidation. Comparing treatment with ferrous sulphate and iron-polymaltose complex, changes in plasma malondialdehyde tended to differ. Clinical disease activity was unchanged after both treatments.

Low-dose oral ferrous fumarate aggravated intestinal inflammation in rats with DSS-induced colitis

BACKGROUND

Oral ferrous iron therapy may reinforce intestinal inflammation. One possible mechanism is by catalyzing the production of reactive oxygen species. We studied the effects of low-dose oral ferrous fumarate on intestinal inflammation and plasma redox status in dextran sulfate sodium (DSS)-induced colitis in rats.

METHODS

Forty male Wistar rats were divided into 5 groups: no intervention, sham gavage (distilled water), ferrous fumarate, DSS, and ferrous fumarate + DSS. Ferrous fumarate was dissolved in distilled water (0.60 mg Fe/kg per day) and administered by gavage on days 1 to 14. All rats were fed a standard diet. Colitis was induced by 5% DSS in drinking water on days 8 to 14. Rats were killed on day 16. Histologic colitis scores, fecal granulocyte marker protein, plasma malondialdehyde, plasma antioxidant vitamins, and plasma aminothiols were measured.

RESULTS

DSS significantly increased histologic colitis scores (P < 0.001) and fecal granulocyte marker protein (P < 0.01). Ferrous fumarate further increased histologic colitis scores (P < 0.01) in DSS-induced colitis. DSS + ferrous fumarate decreased plasma vitamin A compared with controls (P < 0.01). Otherwise, no changes were seen in plasma malondialdehyde, plasma antioxidant vitamins, or plasma aminothiols.

CONCLUSION

Low-dose oral ferrous iron enhanced intestinal inflammation in DSS-induced colitis in rats.

Dietary iron affects inflammatory status in a rat model of colitis

Iron deficiency anemia is a common feature in inflammatory bowel disease, and oral supplementation is one of the mainstay therapies. However, there is some concern that oral iron supplementation may lead to oxidative stress and exacerbation of inflammation. Our objective was to study the effect of severely deficient, moderately deficient, normal and high iron status on oxidative stress and the course of inflammation in a rat model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). The rats were randomly assigned to receive the low-iron diet for 3 (moderately iron-deficient group, n = 16) or 5 (severely iron-deficient group, n = 16) wk, the normal iron diet for 2 wk (normal iron group, n = 16) or the high-iron diet for 2 wk (high-iron group, n = 16). Malondialdehyde concentration, electroparamagnetic resonance measurement, myeloperoxidase activity, and histological analysis were used to evaluate oxidative stress. Noncolitic rats in the high-iron group had higher oxidative stress parameters than those in the other groups. The induction of colitis resulted in severe inflammatory changes in the high-iron and severely iron-deficient groups, and produced higher histological scores in the colon of the normal and high-iron groups. Iron overload, oxidative stress, and inflammation were lower in the moderately iron-deficient group compared with the other 3 groups. In conclusion, we suggest that low rather than normal or high iron supplementation should be considered for the treatment of iron deficiency in inflammatory bowel disease.

Effects of iron deprivation or chelation on DNA damage in experimental colitis

BACKGROUND AND AIMS

In inflammatory bowel diseases iron contributes to the formation of DNA adducts through the production of hydroxyl radicals. The aim of our study was to evaluate the effects of dietary or pharmacological iron deprivation in an experimental model of colitis in the rat and its potential protective effect against DNA damage.

METHODS

Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulphonic acid. Rats were assigned to an iron-deprived diet or to desferrioxamine preceding the induction of colitis. The severity of colitis was assessed by the presence of bloody diarrhea, colonic macroscopic damage score, body-weight variations and the amount of DNA colonic adducts. Hepatic and colonic iron concentrations were measured.

RESULTS

Treated rats experienced less diarrhea and did not lose weight in comparison to untreated animals. The macroscopic damage score was significantly reduced in the iron-deprived diet for the 5-week group (P=0.03). Liver and colonic iron levels were significantly more reduced in the iron-deprived groups than in the standard diet group (P<0.03 and P<0.01 after a 3- and 5-week iron-deprived diet, respectively). DNA adduct formation was significantly reduced in the groups deprived of iron for 5 weeks (P<0.001) or treated with desferrioxamine (P<0.01).

CONCLUSIONS

The degree of colitis caused by DNBS is macroscopically improved by dietary iron deprivation and to a lesser extent by pharmacological chelation; genomic damage is reduced by dietary iron deprivation or chelation, and this may have clinical implications on cancer prevention.

Iron supplements: the quick fix with long-term consequences

Co-supplementation of ferrous salts with vitamin C exacerbates oxidative stress in the gastrointestinal tract leading to ulceration in healthy individuals, exacerbation of chronic gastrointestinal inflammatory diseases and can lead to cancer. Reactive oxygen and nitrogen species (RONS) have been ascribed an important role in oxidative stress. Redox-active metal ions such as Fe(II) and Cu(I) further activate RONS and thus perpetuate their damaging effects. Ascorbic acid can exert a pro-oxidant effect by its interaction with metal ions via a number of established RONS generating systems which are reviewed here. Further studies are required to examine the detrimental effects of nutraceuticals especially in chronic inflammatory conditions which co-present with anaemia.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.