Polyunsaturated fatty acids and inflammatory bowel disease

Intestinal anti-inflammatory activity of combined quercitrin and dietary olive oil supplemented with fish oil, rich in EPA and DHA (n-3) polyunsaturated fatty acids, in rats with DSS-induced colitis

BACKGROUND AND AIMS

Previous studies have described the intestinal anti-inflammatory effects exerted by the bioflavonoid quercitrin (QR) and by an n-3 polyunsaturated fatty acids (PUFA)-enriched diet in experimental models of rat colitis. The aim of the present study was to test if the combination of both treatments would result in an improvement in the intestinal anti-inflammatory effect achieved separately.

METHODS

Colitis was induced in female Wistar rats by incorporating dextran sodium sulfate (DSS) in drinking water at 5% (w/v) for 5 days and at 2% (w/v) for the following 10 days. Five groups of rats (n=10) were used: two of them received an olive-oil-based diet with fish oil, rich in n-3 PUFA (FO diet) for 2 weeks before colitis induction and until the end of the experiment, and one of those also was administered daily QR (1mg/kg, PO), starting when DSS concentration was changed. DSS colitis was induced in other two groups fed with standard rat diet, one of them being administered QR as before. A non-colitic group fed standard diet was also included. After that period, the rats were sacrificed and colonic damage was assessed both histologically and biochemically.

RESULTS

The concurrent administration of FO diet and QR exhibited an intestinal anti-inflammatory effect, as evidenced by a significant improvement of all biochemical parameters of colonic inflammation assayed in comparison with non-treated colitic rats. Thus, both colonic myeloperoxidase (MPO) and alkaline phosphatase (AP) activities were significantly reduced compared with untreated colitic rats. In addition, a complete restoration of colonic glutathione content, which was depleted as a consequence of the colonic insult, was obtained in rats treated with QR plus FO diet; this content was even higher than that obtained when colitic rats were treated with FO diet alone. When compared with the control colitic group, the combined treatment was also associated with a lower colonic nitric oxide synthase and cyclooxygenase-2 expression as well as with a significant reduction in different colonic proinflammatory mediators assayed, i.e. leukotriene B(4), tumor necrosis factor alpha and interleukin 1beta, showing a significantly greater inhibitory effect of the latter in comparison with rats receiving FO diet without the flavonoid.

CONCLUSIONS

These results support the potential synergism between the administration of the flavonoid and the incorporation of olive oil and n-3 PUFA to the diet for the treatment of these intestinal inflammatory disorders.

Is atrial fibrillation an inflammatory disorder?

There is mounting evidence to support the influence of inflammation in the pathogenesis of atrial fibrillation (AF). Indeed, AF is associated with increased levels of known inflammatory markers, even after adjustment for confounding factors. The renin-angiotensin-aldosterone system (RAAS) appears to play a key role in this process. Atrial biopsies from patients with AF have also confirmed the presence of inflammation. Furthermore, there is preliminary evidence to support a number of drug therapies that have the potential to reduce the clinical burden of AF. In this review, we present an overview of the evidence supporting a link between inflammation and AF, and some of the drug therapies, such as the angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, steroids, fish oils, and vitamin C, that might be efficacious in the prevention of AF by modulating inflammatory pathways.

Gestational age and birth weight in relation to n-3 fatty acids among Inuit (Canada)

Seafood consumption during pregnancy carries both benefits (high n-3 FA intake) and risks (exposure to environmental contaminants) for the developing fetus. We determined the impacts of marine n-3 FA and environmental contaminants on gestational age (GA) of Nunavik women and the anthropometric characteristics of their newborns. FA and contaminant (polychlorinated biphenyls and mercury) concentrations were measured in cord plasma of Nunavik newborns (n = 454) and compared with those of a group of newborns (n = 29) from southern Québec. Data were collected from hospital records and birth certificates. In Nunavik newborns, arachidonic acid (AA) was two times lower (P < 0.0001), whereas DHA concentration, the sigman-3 / sigman-6 ratio, and the percentage of n-3 highly unsaturated FA (HUFA) (of the total HUFA) were three times higher (P < 0.0001) compared with southern Québec newborns. After controlling for confounders, GA and birth weight were higher by 5.4 d [95% confidence interval (CI): 0.7-10.1] and 77 g (95% CI: -64 to 217) in the third tertile of percentage of n-3 HUFA (of the total HUFA) as compared with the first tertile. There was no evidence that contaminants had negative effects on GA or birth weight. In this seafood-eating population, an increase in the proportion of n-3 HUFA (of the total HUFA), measured in umbilical cord plasma phospholipids, was associated with a significantly longer GA.

Intestinal responsiveness to experimental colitis in young rats is altered by maternal diet

Increasing evidence suggests that fetal and neonatal nutrition impacts later health. Aims of the present study were to determine the effect of maternal dietary fat composition on intestinal phospholipid fatty acids and responsiveness to experimental colitis in suckling rat pups. Female rats were fed isocaloric diets varying only in fat composition throughout gestation and lactation. The oils used were high (8%) in n-3 [canola oil (18:3n-3)], n-6 (72%) [safflower oil (18:2n-6)], or n-9 (78%) [high oleic acid safflower oil (18:1n-9)] fatty acids, n = 6/group. Colitis was induced on postnatal day 15 by intrarectal 2,4-dinitrobenzene sulfonic acid (DNBS) administration with vehicle (50% ethanol) and procedure (0.9% saline) controls. Jejunal and colonic phospholipids and milk fatty acids were determined. The distal colon was assessed for macroscopic damage, histology, and MPO activity. The 18:2n-6 maternal diet increased n-6 fatty acids, whereas the 18:3n-3 diet increased n-3 fatty acids in milk and pup jejunal and colonic phospholipids. Maternal diet, milk, and pup intestinal n-6-to-n-3 fatty acid ratios increased significantly in order: high 18:3n-3 < high 18:1n-9 < high 18:2n-6. DNBS administration in pups in the high 18:2n-6 group led to severe colitis with higher colonic damage scores and MPO activity than in the 18:1n-9 and 18:3n-3 groups. High maternal dietary 18:3n-3 intake was associated with colonic damage scores and MPO activity, which were not significantly different from ethanol controls. We demonstrate that maternal dietary fat influences the composition of intestinal lipids and responsiveness to experimental colitis in nursing offspring.

Dietary olive oil supplemented with fish oil, rich in EPA and DHA (n-3) polyunsaturated fatty acids, attenuates colonic inflammation in rats with DSS-induced colitis

Previous studies proposed a protective role of the dietary intake of (n-3) PUFA in human inflammatory bowel disease (IBD), but almost no studies have been performed using olive oil. The aims of the present study were to test the beneficial effects of an olive oil-based diet with or without fish oil, rich in (n-3) PUFA, in the dextran sodium sulfate (DSS) model of rat colitis and to elucidate the mechanisms involved in their potential beneficial effects, with special attention to the production of some of the mediators involved in the intestinal inflammatory response, such as leukotriene B(4) (LTB(4)), tumor necrosis factor alpha (TNFalpha) and nitric oxide (NO). Rats were fed the different diets for 2 wk before colitis induction and thereafter until colonic evaluation 15 d later. Colitic rats fed the olive oil-based diet had a lower colonic inflammatory response than those fed the soybean oil diet, and this beneficial effect was increased by the dietary incorporation of (n-3) PUFA. A restoration of colonic glutathione levels and lower colonic NO synthase expression occurred in all colitic rats fed an olive oil diet compared with the control colitic group that consumed the soybean oil diet. However, (n-3) PUFA incorporation into an olive oil diet significantly decreased colonic TNFalpha and LTB(4) levels compared with colitic rats that were not supplemented with fish oil. These results affirm the benefits of an olive oil diet in the management of IBD, which are further enhanced by the addition of (n-3) PUFA.

Dietary n-3 polyunsaturated fatty acids reduce disease and colonic proinflammatory cytokines in a mouse model of colitis

BACKGROUND

n-3 polyunsaturated fatty acids (PUFAs) reduce the severity of chronic inflammatory bowel disease, probably by means of reduction of immune cell activation or enhancement of the epithelial barrier. Using the severe combined immunodeficient (SCID) mouse model of colitis, this study examined the effect of dietary n-3 PUFAs on development of colitis and on immunologic, epithelial, and matrix parameters in the intestines of control and colitic animals.

METHODS

SCID mice were fed n-3-enriched or control diet for 3 weeks before colitis induction by transplantation of CD45RB T cells and maintained on the same diet for 4 to 8 weeks. Phenotype of infiltrating cells, epithelial ZO-1 protein, and mucosal type I collagen were assessed by immunohistology and tissue cytokines by ELISA.

RESULTS

Transplanted n-3-fed animals had significantly reduced pathology scores, colonic tumor necrosis factor-alpha, interleukin-12, and interleukin-1beta compared with animals fed standard diet. Proinflammatory cytokines were reduced despite a similar level of immune cell infiltration by T cells, CD11c cells, and CD11b cells. Neutrophil infiltration was significantly reduced in n-3-fed control and colitic mice, and other myeloid populations were reduced in mice on the n-3 diet. Epithelial ZO-1 expression was increased, and myofibroblast activation significantly decreased in transplanted n-3-fed animals compared with standard diet mice. Submucosal collagen synthesis was enhanced in n-3-fed mice.

CONCLUSIONS

Dietary n-3 PUFAs reduced clinical colitis and colonic immunopathology in this model of colonic inflammation by decreasing proinflammatory cytokine synthesis, reducing myeloid cell recruitment and activation, and enhancing epithelial barrier function and mucosal wound healing mechanisms.

Food components and immune function

PURPOSE OF REVIEW

Enhancing immune function or alternatively dampening inflammatory processes by specific food components has received a lot of interest. The purpose of this review is to summarize recent findings with the emphasis on underlying mechanisms.

RECENT FINDINGS

Dietary beta-glucans are relatively new candidates in the field of immune modulation by diet. In-vitro and animal studies suggest that beta-glucans shift inflammatory profiles to a Th1 type, which may enhance resistance against bacterial and parasitic infections. Regarding polyunsaturated fatty acids, there is evidence that n-3 fatty acids from fish oils (eicosapentaenoic acid and docosahexaenoic acid) dampen inflammatory responses. Whether eicosapentaenoic acid or docosahexaenoic acid is responsible for this phenomenon remains controversial. It is also inconclusive whether the plant-derived n-3 fatty acid alpha-linolenic acid has the same antiinflammatory effects as observed for fish oils. Saturated fatty acids may activate toll-like receptors and consequently the inflammatory pathway. The effect of total fat intake is controversial, since high-fat diets have been found to suppress immune function, while also improving intestinal barrier function. Finally, Gingko biloba was found to lower nuclear factor kappaB and activator protein 1 activation, possibly due to its high content of polyphenols.

SUMMARY

In this review we discuss the nutritional components able to enhance immune function or show antiinflammatory effects. It can be concluded that diet certainly has the potential to direct immune responses. Apart from studies on fish oils, however, evidence from human studies is limited.

Polyunsaturated fatty acids block dendritic cell activation and function independently of NF-kappaB activation

Polyunsaturated fatty acids (PUFAs) modulate immune responses leading to clinically significant beneficial effects in a variety of inflammatory disorders. PUFA effects on T cells have been extensively studied, but their influence on human dendritic cells (DCs), which are the most potent antigen-presenting cells and play a key role in initiating immune responses, has not been elucidated so far. Here we show that PUFAs of the n-3 and n-6 series (arachidonic and eicosapentaenoic acid) affect human monocyte-derived DC differentiation and inhibit their activation by LPS, resulting in altered DC surface molecule expression and diminished cytokine secretion. Furthermore, the potency to stimulate T cells was markedly inhibited in PUFA-treated DCs. The PUFA-mediated block in LPS-induced DC activation is reflected by diminished TNF-alpha, IL-12p40, CD40, and COX-2 mRNA levels. Strikingly, typical LPS-induced signaling events such as degradation of IkappaB and activation of NF-kappaB were not affected by PUFAs, even though DC membrane lipid composition was markedly altered. Arachidonic and eicosapentaenoic acid both altered DC prostaglandin production, but inhibitors of cyclooxygenases and lipoxygenases did not abolish PUFA effects, indicating that the observed PUFA actions on DCs were independent of autoregulation via eicosanoids. These data demonstrate a unique interference with DC activation and function that could significantly contribute to the well known anti-inflammatory effects of PUFAs.

A new family of synthetic diterpenes that regulates cytokine synthesis by inhibiting IkappaBalpha phosphorylation

The synthesis and the biological evaluation of a new family diterpenes are presented. The synthetic studies were inspired by the structural framework of acanthoic acid (1) and yielded a family of compounds that were evaluated as anti-inflammatory agents. Among them, compounds 2, 10, 12, and 16 exhibited a very low nonspecific cytotoxicity and inhibited the synthesis of TNF-alpha with greater than 65 % efficacy at low micromolar concentrations. Cytokine-specificity studies revealed that these compounds also inhibited the synthesis of the proinflammatory cytokines IL-1beta and IL-6, while inhibition of IL-1ra and IL-8 synthesis was marginal and only occurred at high concentrations. Further studies, through EMSA and Western blot analyses, indicated that these compounds decreased the extent of phosphorylation of IkappaBalpha; this suggests that they exert their anti-inflammatory profile by inhibiting NF-kappaB-mediated cytokine synthesis. These findings imply that these diterpenes represent promising leads for the development of novel anti-inflammatory agents.

Polyunsaturated Fatty Acid Regulation of Gene Expression

Polyunsaturated fatty acids (PUFAs), specifically the n-3 series, have been implicated in the prevention of various human diseases, including obesity, diabetes, coronary heart disease and stroke, and inflammatory and neurologic diseases. PUFAs function mainly by altering membrane lipid composition, cellular metabolism, signal transduction, and regulation of gene expression. PUFAs regulate the expression of genes in various tissues, including the liver, heart, adipose tissue, and brain. The role of transcription factors such as SREBP1c and nuclear receptors such as PPAR-alpha, HNF-4alpha, and LXRalpha in mediating the nuclear effects of PUFAs are addressed.

Nutritional therapy in inflammatory bowel diseas

Nutritional intervention is an important adjunctive therapy for patients with inflammatory bowel disease (IBD). The correction and maintenance of nutritional status, achieved by careful nutritional monitoring and intervention, should be an integral part of the multidisciplinary management of IBD throughout all stages of the disease. In acute Crohn's disease, enteral nutrition (polymeric and elemental) is an effective and safe primary therapy for many patients. Enteral diets should be considered as primary therapy in pediatric Crohn's disease patients, especially in children with poor nutritional status or growth impairment and in patients with severe drug-induced side effects. Total parenteral nutrition does not have a primary therapeutic role in IBD.

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.

Inflammatory bowel diseases in pediatric and adolescent patients: clinical, therapeutic, and psychosocial considerations

Inflammatory bowel diseases (Crohn's disease and ulcerative colitis) primarily affect young adults, but in 15%-25% of cases, the initial disease starts in childhood. Many aspects of inflammatory bowel disease, including initial evaluation, nutritional support, medical and surgical intervention, and the direction of future research, are encountered in both adult and pediatric patients. However, it is important to delineate issues specific to pediatric patients, especially growth velocity impairment, derangements in and treatment of abnormal bone mineralization, and transitional care issues; the lack of extensive randomized, controlled pediatric therapeutic trials is also a concern. This article reviews the epidemiology of pediatric inflammatory bowel disease incidence and prevalence worldwide, clinical issues (including impairments of growth velocity and bone density), diagnostic and therapeutic interventions, and psychosocial issues unique to pediatric patients. Future research directions defined by the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and opportunities provided by existing pediatric research databases are highlighted.

Expression of acyl-CoA synthetase 5 reflects the state of villus architecture in human small intestine

Several disorders of the small intestine are associated with disturbances in villus architecture. Thus, an understanding of the molecular mechanisms associated with the differentiation of villi represents an important step in the improvement of the understanding of small intestinal pathology. Screening of antibodies from a hybridoma library led to the identification of an acyl-CoA synthetase 5-specific monoclonal antibody. Protein synthesis, mRNA expression, and the enzyme activity of acyl-CoA synthetase 5 were studied by several methods in human small intestinal tissues with Crohn's disease or coeliac disease, respectively. Acyl-CoA synthetase 5 mRNA and protein levels were substantially reduced in injured small intestinal mucosa. Moreover, impaired synthesis of the acyl-CoA synthetase 5 protein was reflected by a decrease in intramucosal enzyme activity. Subtle changes of the acyl-CoA synthetase 5 pattern correlate with conversion of intestinal epithelial cells to a gastric phenotype. These results suggest that deranged acyl-CoA synthetase 5 expression, synthesis, and activity are closely related to the state of villus architecture and epithelial homeostasis in human small intestine.

Eicosapentaenoic Acid Prevents LPS-Induced TNF-α Expression by Preventing NF-κB Activation

BACKGROUND

Many studies have shown that fish oil supplementation inhibits tumor necrosis factor-alpha (TNF-alpha) production in mice and human subjects; however, the mechanisms remain unclear. Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays an important role in controlling the expression of pro-inflammatory genes including TNF-alpha. Activation of NF-kappaB has been shown to mediate the maximal expression of TNF-alpha in human monocytes. NF-kappaB is kept in an inactive form in the cytoplasm by IkappaB, the inhibitory subunit of NF-kappaB complex. Phosphorylation and subsequent degradation of IkappaB lead to NF-kappaB activation.

OBJECTIVES

The effect of eicosapentaenoic acid (EPA), a major n-3 fatty acid in fish oil, on the lipopolysaccharide (LPS)-induced expression of TNF-alpha and activation of NF-kappaB were investigated. The mechanism underlying EPA modulation of NF-kappaB activation was also studied.

METHODS

Human monocytic THP-1 cells were pre-incubated with EPA and stimulated with LPS. The levels of secreted TNF-alpha were determined by ELISA. The DNA binding activity of NF-kappaB was analyzed by EMSA. The degradation and phosphorylation of IkappaB-alpha were examined by Western blot analysis.

RESULTS

TNF-alpha production and expression induced by LPS were significantly decreased in cells pre-incubated with EPA. LPS-induced NF-kappaB activation, translocation of p65 subunit to the nucleus, phosphorylation and degradation of IkappaB-alpha were partially prevented by EPA.

CONCLUSIONS

The results suggest that suppression of the TNF-alpha expression by EPA is partly attributed to its inhibitory effect on NF-kappaB activation. EPA appears to prevent NF-kappaB activation by preventing the phosphorylation of IkappaB-alpha.

Effects of highly purified eicosapentaenoic acid on erythrocyte fatty acid composition and leukocyte and colonic mucosa leukotriene B4 production in children with ulcerative colitis

BACKGROUND

n-3 Polyunsaturated fatty acids (PUFAs) have been suggested as a treatment for ulcerative colitis (UC). However, the efficacy of n-3 PUFAs against UC has not been examined in children. Therefore, the authors investigated the effects of eicosapentaenoic acid (EPA) on fatty acid composition and leukotriene (LT) production in children with UC.

METHODS

For 2 months the authors administered highly purified EPA ethyl ester (EPA-E) (1.8 g/d) to children with UC in remission. Colonic mucosal histology, fatty acid composition of erythrocyte membrane phospholipids, and LTB4 production by leukocytes and colonic mucosa were measured before and 2 months after the initiation of EPA-E treatment.

RESULTS

No patients relapsed during the study period, and no significant differences were detected in laboratory findings obtained before and 2 months after the initiation of EPA-E ingestion. There were no significant differences in mucosal histologic scores before and 2 months after EPA-E treatment. The EPA levels in erythrocyte membranes 2 months after the initiation of EPA-E treatment were significantly higher than before treatment, but the other fatty acids showed no significant changes. LTB4 production by leukocytes and rectal mucosa after 2 months of EPA-E treatment was significantly lower than before treatment.

CONCLUSION

EPA-E treatment increased the levels of EPA in erythrocytes and decreased LTB4 levels produced by leukocytes and colonic mucosa. To assess the concomitant clinical changes, we should examine the long-term effects of EPA-E ingestion on the maintenance of remission in children with UC.

Measuring dietary fatty acid intake:validation of a food-frequency questionnaire against 7 d weighed records

There are few validated methods of measuring dietary fatty acid intake that are suitable for epidemiological research. The purpose of the present study was to develop and validate a food-frequency questionnaire (FFQ) developed to measure individual dietary fatty acid intakes against 7 d weighed dietary records, in a sample of thirty-one healthy adult volunteers. The FFQ was based on a previously validated questionnaire (DIETQ; Tinuviel Software, Warrington, Ches., UK), adapted to include greater detail on those foods from which the majority of dietary fatty acids are obtained. The FFQ and weighed records were analysed using food nutrient data from McCance and Widdowson's Food Composition Tables, supplemented with a food fatty acid content database (Foodbase, London, UK). Results from the two dietary assessment methods were compared by correlation coefficients and limits of agreement. The mean intake of individual fatty acids tended to be lower when assessed by FFQ. Correlation coefficients comparing unadjusted individual fatty acid intakes assessed by FFQ and weighed records ranged from 0.29 for 18 : 1n-9 to 0.71 for 20 : 4n-6. Adjusting for energy intake tended to increase the correlation coefficients between saturated fatty acids and decrease those between unsaturated fatty acids. In conclusion, this food-frequency method provides reliable estimates of dietary intake of many individual fatty acids for use in epidemiological studies.

Marine lipid-based liposomes increase in vivo FA bioavailability

Liposomes made from an extract of natural marine lipids and containing a high n-3 PUFA lipid ratio were envisaged as oral route vectors for FA supplements in order to increase PUFA bioavailability. The absorption of FA in thoracic lymph duct-cannulated rats, after intragastric feeding of dietary fats in the form of liposomes or fish oil, was compared. Lipid and FA analyses were also performed on feces. Five mole percent alpha-tocopherol was added to fish oil and incorporated into the liposome membrane. The influence of alpha-tocopherol on FA lymph recovery was also investigated. In vivo, FA absorption in rats was favored by liposomes (98 +/- 1%) compared to fish oil (73 +/- 6%). In the same way, the DHA proportion in lymph was higher after liposome ingestion (78%) than after fish oil ingestion (47%). However, phospholipid (PL) concentration in lymph was not affected by the kind of dietary fat ingested, suggesting a PL regulation due to de novo TAG synthesis. The influence of the intramolecular distribution of n-3 PUFA in dietary lipids (TAG and PL) on the intramolecular FA distribution in TAG of chylomicrons was also investigated. The results obtained showed that the distribution of n-3 PUFA esterified on the sn-2 position of chylomicron TAG depended on the lipid source administered. All these results correlated, at least partly, with in vitro liposome behavior under conditions that mimic those of the gastrointestinal tract. As a whole, this study pointed out that marine PL may constitute an attractive material for the development of liposomes as oral PUFA supplements.

Dietary fish oil impairs primary host resistance against Listeria monocytogenes more than the immunological memory response

The primary objective of this study was to determine whether dietary (n-3) polyunsaturated fatty acids (PUFA) impair the ability of mice to generate an immunological memory response against the bacterial pathogen, Listeria monocytogenes. Weanling BALB/c female mice were fed for 28 d one of two semipurified high fat diets containing either lard or refined menhaden fish oil, rich in long-chain (n-3) PUFA. Mice were immunized with 10(4) or 10(3) colony forming units (cfu) bacteria. Thirty-five days later, these immune mice and age-matched naïve (i.e., unimmunized) mice were challenged with 10(5) cfu bacteria. Three days postchallenge, bacterial clearance was determined. Compared with lard-fed mice, naïve mice in the fish oil treatment group had higher bacterial loads in their liver and spleen (P < 0.001). When mice were immunized with 10(4) cfu bacteria before rechallenge with 10-fold more bacteria, both lard- and fish oil-fed mice had significantly lower bacterial loads in their liver and spleen (e.g., approximately 2 log(10); P < 0.001) compared with their naïve counterparts. However, when the immunization dose was reduced to 10(3) bacteria, a modest diet treatment effect was observed, such that compared with immune lard-fed mice, immune fish oil-fed mice had significantly greater bacterial loads in their liver and spleen (i.e., approximately 0.5 log(10); P < 0.01). These data demonstrate for the first time that although dietary (n-3) PUFA can significantly impair host resistance to a primary as well as a secondary L. monocytogenes infection, the impairment of the immunological memory response is much less severe.

The effect of dietary n-3 fatty acids on serum concentrations of C-reactive protein: a dose-response study

C-reactive protein (CRP) is a sensitive marker for low-grade inflammation. Long-chain n-3 polyunsaturated fatty acids (PUFA) have anti-inflammatory effects. The objective of the present study was to investigate the effect on serum levels of CRP of n-3 PUFA at two different doses. We also investigated correlations between CRP and the cellular contents of PUFA. Sixty healthy volunteers (twenty-five women and thirty-five men) were randomly assigned to three treatment groups in a double-blind design. The subjects received a supplement of either 6.6 g n-3 PUFA/d, 2.0 g n-3 PUFA/d or placebo (olive oil) for 12 weeks. CRP was measured using a highly sensitive assay. The median serum CRP concentration was 0.78 mg/l. No significant correlations were found between CRP and the content of n-3 PUFA in granulocytes or platelets. Subjects receiving n-3 PUFA had a significant (P<0.01) increase in the cellular contents of 20 : 5n-3, 22 : 5n-3 and 22 : 6n-3, with the largest increase occurring in the group receiving 6.6 g PUFA/d. A significant (P<0.01) decrease in cellular content of 18 : 2n-6 and 20 : 4n-6 was observed simultaneously. Serum CRP concentrations, however, were unaffected by the PUFA-containing supplements. The present study shows that dietary supplementation with PUFA-containing supplements has no effect on serum concentrations of CRP, measured with a highly sensitive assay, in healthy subjects.

Could n-3 polyunsaturated fatty acids reduce pathological pain by direct actions on the nervous system?

The intake of n-3 polyunsaturated fatty acids (PUFAs) in many industrialized countries is relatively low and its increased consumption has protective and modifying effects on such diverse conditions as atherosclerosis, ventricular arrhythmias, multiple sclerosis, major depression and inflammatory and autoimmune diseases. In addition, n-3 PUFAs have been shown to alleviate pain in patients with rheumatoid arthritis, inflammatory bowel disease and in a number of other painful conditions. This has been attributed to the inhibition of pro-inflammatory eicosanoid and cytokine production by peripheral tissues. n-3 PUFAs have also been shown to inhibit eicosanoid production in glial cells, block voltage-gated sodium channels (VGSCs), inhibit neuronal protein kinases and modulate gene expression. They also appear to have mood-stabilizing and sympatholytic effects. The present article explores the possibility that, based on what is known about their neural and non-neural effects, n-3 PUFAs directly attenuate the neuronal and glial processes that underlie neuropathic and inflammatory pain.

Etiopathogenesis of pediatric Crohn's disease. Biologic pathways based on interactions between genetic and environmental factors

The incidence and prevalence of Crohn's disease (CD) among children in developed countries is extremely high. Although, dietary factors have long been implicated, to date no single causative element has been identified. Risks or benefits for CD from dietary elements would depend on their appropriate metabolism within the gut by xenobiotic metabolising enzymes (XME). The metabolising capacity among individuals differs and is determined by the level and/or activity of the specific XME. As the latter is the function of the DNA variants that code them, we propose that certain individuals exposed to dietary elements are likely to be more or less susceptible for CD. We highlight this hypothesis by describing gene-environment interaction (GxE) mechanisms that could determine susceptibility for CD. We suggest that investigating these mechanisms will be paramount for the appropriate identification of susceptible populations, such that preventive and/or therapeutic interventions could be adequately targeted.

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.

Diet and gastrointestinal disease

Dietary manipulation can be an important part of therapy for several common gastrointestinal disorders. In Crohn disease, the provision of adequate protein and calories may not only improve symptoms but may be associated with acceleration of growth. In celiac disease, the dietary restriction of gluten is curative of the intestinal inflammation. In chronic nonspecific diarrhea and functional constipation, the provision of appropriate amounts of fiber and fluids may ameliorate symptoms. A thorough understanding of the role of diet is essential to the management of these disorders.

Polyunsaturated fatty acids and inflammatory diseases

Inflammation is overall a protective response, whose main goal is to liberate the human being of cellular lesions caused by micro-organisms, toxins, allergens, etc., as well as its consequences, and of death cells and necrotic tissues. Chronic inflammation, which is detrimental to tissues, is the basic pathogenic mechanism of hypersensitivity reactions against xenobiotics. Other frequent pathologies, for instance atherosclerosis, chronic hepatitis, inflammatory bowel disease (IBD), liver cirrhosis, lung fibrosis, psoriasis, and rheumatoid arthritis are also chronic inflammatory diseases. Chemical mediators of inflammation are derived from blood plasma or different cell-type activity. Biogenic amines, eicosanoids and cytokines are within the most important mediators of inflammatory processes. The different activities of eicosanoids derived from arachidonic acid (20:4 n-6) versus those derived from eicosapentaenoic acid (20:5 n-3) are one of the most important mechanisms to explain why n-3, or omega-3, polyunsaturated fatty acids (PUFA) exhibit anti-inflammatory properties in many inflammatory diseases. Dietary supplements ranging 1-8 g per day of n-3 PUFA have been reportedly beneficial in the treatment of IBD, eczema, psoriasis and rheumatoid arthritis. In addition, recent experimental studies in rats with experimental ulcerative colitis, induced by intrarectal injection of trinitrobenzene sulphonic acid, have documented that treatment with n-3 long-chain PUFA reduces mucosal damage as assessed by biochemical and histological markers of inflammation. Moreover, the defence antioxidant system in this model is enhanced in treated animals, provided that the n-3 PUFA supply is adequately preserved from oxidation.

Dietary polyunsaturated fatty acids improve histological and biochemical alterations in rats with experimental ulcerative colitis

The aim of the present study was to determine whether dietary intake of monounsaturated (MUFA) and/or polyunsaturated fatty acids (PUFA) of the (n- 3) and (n-6) series could improve intestinal damage and reduce inflammation in experimental ulcerative colitis (UC). Rats were treated with 80 mg/kg body of 2,4,6-trinitrobenzenesulfonic acid and fed for 1 or 2 wk diets enriched in olive oil (OO), fish oil (FO), or purified pig brain phospholipids (BPL), as sources of monounsaturated and PUFA of the (n-3) and (n-3) + (n-6) series. Evaluation of macroscopic and microscopic colonic damage was assessed. Ultrastructural and histologic changes were analyzed as well as plasma and colonic mucosa fatty acid profiles and some biochemical markers of injury and inflammation [alkaline phosphatase (AP), mieloperoxidase (MPO), prostaglandin E(2) (PGE(2)) and leukotriene B(4)]. Fatty acid profiles of both plasma and mucosa mostly reflected the dietary fatty acid composition. Plasma MUFA proportions were higher in UC animals fed the OO diet compared with FO or BPL groups 1 and 2 wk and (n-3) long chain PUFA (LC-PUFA) were higher in the FO than in the OO and BPL groups. At 1 wk, UC led to lower MUFA mucosa levels and (n-3)LC-PUFA were higher in the FO group compared with the OO and BPL groups. Rats with UC fed FO at 1 wk showed significantly less macroscopic and microscopic colonic damage. They also have lower AP and MPO activities and PGE(2) levels compared with the OO and BPL groups and showed enhanced histological repair, less necrotic areas within the mucosa, and more goblet cells with mature mucin granules. These results suggest that the use of balanced diets containing (n-3) LC-PUFA could ameliorate the inflammation and mucosal damage in UC.

Modification of enteral diets in inflammatory bowel disease

The provision of food is thought to promote the maintenance of gut integrity. Nutrients are able to elicit and affect both systemic and mucosal immune responses. Enteral diet therapy has long been known to be efficacious in inflammatory bowel disease (IBD), particularly in childhood Crohn's disease. However, the mechanisms of action of these diets are not clear. Nutritional repletion, direct effects on the gut mucosa or decreased intestinal permeability have all been postulated as being important in nutritional therapy. There is some evidence that the enteral diet has a direct effect on the gut mucosa by reducing cytokine production and the accompanying inflammation, thus leading to decreased intestinal permeability. Modifications of enteral diet composition have been evaluated in many studies. Such modifications include fat and/or protein content and the addition of bioactive peptides. The fatty acid composition of the enteral diet seems to have a much greater impact on its efficacy than modification of the N source. As specific fatty acids are precursors of inflammatory mediators derived from arachidonic acid, the reduction in these components may be beneficial in nutritional therapy for IBD. Addition of bioactive peptides to enteral diet formulas may also have a role; such peptides may have specific growth factor or anti-inflammatory actions. There is still much work to be done to define disease-specific enteral diet formulas that are effective as therapies for both Crohn's disease and ulcerative colitis.

Upregulation of lymphocyte apoptosis as a strategy for preventing and treating autoimmune disorders: a role for whole-food vegan diets, fish oil and dopamine agonists

Induced apoptosis of autoreactive T-lymphocyte precursors in the thymus is crucial for the prevention of autoimmune disorders. IGF-I and prolactin, which are lymphocyte growth factors, may have the potential to suppress apoptosis in thymocytes and thus encourage autoimmunity; conversely, dietary fish oil rich in omega-3 fats appears to upregulate apoptosis in lymphocytes. Since whole-food vegan diets may downregulate systemic IGF-I activity, it is proposed that such a diet, in conjunction with fish oil supplementation and treatment with dopamine agonists capable of suppressing prolactin secretion, may have utility for treating and preventing autoimmune disorders. This prediction is consistent with the extreme rarity of autoimmune disorders among sub-Saharan black Africans as long as they followed their traditional quasi-vegan lifestyles, and with recent ecologic studies correlating risks for IDDM and for multiple sclerosis mortality with animal product and/or saturated fat consumption. Moreover, there is evidence that vegan or quasi-vegan diets are useful in the management of rheumatoid arthritis, multiple sclerosis, and possibly SLE. The dopamine agonist bromocryptine exerts anti-inflammatory effects in rodent models of autoimmunity, and there is preliminary evidence that this drug may be clinically useful in several human autoimmune diseases; better tolerated D2-specific agonists such as cabergoline may prove to be more practical for use in therapy. The moderate clinical utility of supplemental fish oil in rheumatoid arthritis and certain other autoimmune disorders is documented. It is not unlikely that extra-thymic anti-inflammatory effects contribute importantly to the clinical utility of vegan diets, bromocryptine, and fish oil in autoimmunity. The favorable impact of low latitude or high altitude on autoimmune risk may be mediated by superior vitamin D status, which is associated with decreased secretion of parathyroid hormone; there are theoretical grounds for suspecting that parathyroid hormone may inhibit apoptosis in thymocytes. Androgens appear to up-regulate thymocyte apoptosis, may be largely responsible for the relative protection from autoimmunity enjoyed by men, and merit further evaluation for the management of autoimmunity in women. It will probably prove more practical to prevent autoimmune disorders than to reverse them once established; a whole-food vegan diet, coupled with fish oil and vitamin D supplementation, may represent a practical strategy for achieving this prevention, while concurrently lowering risk for many other life-threatening 'Western' diseases.

Non-herbal nutritional supplements-the next wave: a comprehensive review of risks and benefits for the C-L psychiatrist

The continuing popularity of complementary medicine has led to the frequent appearance of new products in the marketplace. Non-herbal supplements are now a popular choice for patients seeking relief from a variety of medical conditions. As with herbal medicines, there are concerns about the safety of these products in those with physical illness. Clearly, consultation-liaison psychiatrists will encounter patients using non-herbal products or inquiring about them. This article seeks to provide knowledge about the risks and benefits of non-herbal supplements that consultation-liaison psychiatrists are likely to encounter.

Nutrition in inflammatory bowel disease: impact on disease and therapy

Nutritional derangements are frequent in inflammatory bowel disease. In the last year, significant work was published examining the mechanisms of impaired food intake in animal models of inflammatory bowel disease, which allow a better understanding of these processes. These data have shed new light on the relative role of underfeeding and inflammation on the growth retardation associated with intestinal inflammation. Other studies have provided further information on the risk factors and predictive biomarkers of bone loss in patients with inflammatory bowel disease. The potential role of enteral nutrition as primary therapy for Crohn disease is particularly addressed in the present review. Recent contributions emphasized the special importance of this therapeutic modality in pediatric patients, but the possible mechanisms for such therapeutic effect are still not well understood. Other nutrients may have a therapeutic potential in inflammatory bowel disease. In particular, recent data on the in vivo antiinflammatory action of butyrate merit special mention. Finally, novel nutritional therapeutic strategies for inflammatory bowel disease, such as transforming growth factor-beta2-enriched enteral feeding or hydrothermally processed cereals, have recently been explored.

Nutritional Treatments in Inflammatory Bowel Disease

The role of nutritional intervention in inflammatory bowel disease (IBD) is twofold: first, as primary therapy for patients with acute Crohn's disease; second, as an invaluable adjunctive therapy for the correction and maintenance of nutritional status for both patients with Crohn's disease and those with ulcerative colitis. Careful nutritional monitoring and appropriate nutritional intervention throughout all stages of disease should be an integral part of the multidisciplinary management approach to IBD. In terms of primary therapy, polymeric and elemental enteral diets are an effective therapy for patients with acute Crohn's disease, offering an unrivaled safety profile and significant nutritional benefits. Enteral diets should be considered as primary therapy in children with Crohn's disease, especially in those with poor nutritional status or growth impairment, and in patients with severe drug-induced side effects. Total parenteral nutrition (TPN) does not have a primary therapeutic role in patients with IBD.

Enteral feeding and Crohn disease

Enteral nutrition is an established therapeutic option in the treatment of patients with Crohn disease. The mode of action for enteral nutrition remains unknown but research efforts have begun to elucidate the complex interaction between nutritional luminal contents, intestinal epithelium, and mucosal immune response. Trials of novel enteral diet formulations have been conducted to explore the antiinflammatory role of specific nutrients.

Nutrition in inflammatory bowel disease

Recent developments concerning nutritional complications of inflammatory bowel disease include a better understanding of disease-associated anorexia and increasing recognition of the interaction of nutrition and cytokines in the pathogenesis of growth impairment of children. Decreased bone mineral density is a multifactorial complication and an increased focus of research. Enteral nutrition continues to play an important role in the therapy of Crohn's disease. The mechanisms whereby specific nutrients, such as n-3 fatty acids, antioxidants, and butyrate, ameliorate inflammation are being elucidated in in-vitro studies, but beneficial effects have yet to be translated into the clinical sphere.