Editorial: One step closer to personalised nutrition therapy for irritable bowel syndrome

This article is linked to Wilson et al paper. To view this article, visit https://doi.org/10.1111/apt.17609

Review article: Mechanisms underlying the effectiveness of exclusive enteral nutrition in Crohn's disease

BACKGROUND

Exclusive enteral nutrition (EEN) induces remission and mucosal healing in patients with Crohn's disease, but the mechanism of action remains unknown.

AIM

To outline current understanding of the mechanisms of action of EEN.

METHODS

From a comprehensive literature search, published data were critically examined in a narrative review.

RESULTS

Multiple potential mechanisms of action have been identified. EEN optimises nutritional status. Differences in gut microbiota in terms of overall diversity and taxonomic community structure are observed between responders and non-responders to EEN. Therapy with EEN alters microbial metabolites (including faecal short-chain fatty acids, amino acids, branched-chain amino acids and sulphide) and faecal pH. Epithelial effects and restoration of barrier function, as well as changes in mucosal cytokine profiles and T-cell subsets are observed in responders to EEN. The impact of inclusion or exclusion of specific dietary components may be of importance, but putative detrimental components are found in many formulas. A major challenge in interpreting these findings is that they often contradict or change in opposite directions to what is considered 'beneficial'. It is difficult to differentiate between the observations following EEN being driven by EEN per se and those associated with resolving inflammation.

CONCLUSIONS

The mechanisms of action of EEN are likely to involve a complex interplay between host mucosal immune response and luminal environment, but the identity of key factors remains poorly understood. A better definition of pathogenic factors may aid in developing more targeted dietary treatment and provide insights into the pathogenesis of Crohn's disease.

Dietary management of adults with IBD - the emerging role of dietary therapy

Historically, dietitians played a minor part in the management of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis. Patients were commonly referred for consequences of uncontrolled disease, such as malnutrition and bowel obstruction risk. Today, dietitians are fundamental members of the multidisciplinary IBD team, from educating on the role of diet at diagnosis and throughout the lifespan of a patient with IBD to guiding primary induction therapy. This aspect is reflected in published guidelines for IBD management, which previously placed diet as only a minor factor, but now have diet-specific publications. This Review describes a four-step approach in a dietitian's assessment and management of diet in patients with IBD: (1) identifying and correcting nutritional gaps and dietary imbalances; (2) considering diet to treat active disease with the use of exclusive enteral nutrition (EEN) or emerging diets that could replace EEN; (3) using therapeutic diets to control existing complications of IBD, such as reduced fibre to prevent bowel obstruction in stricturing disease or a fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet to manage co-existing functional gut symptoms; and (4) considering the role of diet in preventing IBD development in high-risk populations.

Lessons from an audit of exclusive enteral nutrition in adult inpatients and outpatients with active Crohn's disease: a single-centre experience

OBJECTIVE

To evaluate clinical outcomes, patterns of use, tolerance and nutritional outcomes of exclusive enteral nutrition (EEN) in adults with Crohn's disease and to compare initiation in the inpatient compared with ambulatory care setting.

DESIGN/METHOD

Adults with Crohn's disease who received EEN at a single centre over 2.5 years were identified and outcomes assessed via examination of patient records.

RESULTS

EEN was initiated in 60 patients (23 as an outpatient) who had objective evidence of active disease. Of 49 in whom the goal was induction of remission, 28 completed EEN and 24 achieved clinical remission/response. Twenty-one withdrew prematurely, due to intolerance in 15 and disease factors in 6. Of 11 with a planned intervention, 6 fulfilled the goal of downstaging disease while two were intolerant. Completion of the prescribed therapy was associated with self-reported adherence to EEN and with improvements in disease activity scores and biochemical markers. Malnutrition halved (40% to 20%) and intentional weight loss (median 5.1 kg) was achieved in six obese patients. The major reason for intolerance was the inability to accept total avoidance of non-formula food. There were no differences in any outcomes according to the location of initiation of therapy.

CONCLUSION

Positive outcomes occur in 70% of adult patients with Crohn's disease tolerating EEN and 81% in those who are able to completely adhere to EEN, without compromise of nutritional status. Similar success occurs when initiated as an inpatient or outpatient. Failure to tolerate EEN is the major hurdle to its use.

Feeding encapsulated ground full-fat soybeans to increase polyunsaturated fat concentrations and effects on flavor volatiles in fresh lamb

This research assessed the potential of increasing PUFA concentrations and the effect on flavor volatiles in red meat by feeding ground, full-fat soybean supplemented in casein complex. Supplements consisted of untreated ground, full-fat soybean (CO) or ground, full-fat soybeans treated with acetaldehyde (AC) or diacetyl (DA) to form gels. On a DM basis, the control (CO), AC, and DA supplements contained 48.6, 50.0, and 49.1% CP and 17.3, 17.3, and 17.4% fat, respectively. Weaned feeder lambs (n = 18) were divided into three treatment groups with two pens of three lambs per group. One of three supplements (200 g of DM) plus 1 kg DM of a ground corn basal diet and 0.36 kg DM of grass hay was fed daily to each of six lambs in a group for 9 wk. Samples of the intramuscular (LM), intermuscular, subcutaneous, and kidney fat were obtained from each lamb carcass for determination of total lipid contents and fatty acid profiles. Flavor volatiles of broiled LM were also analyzed. Total fat content of the LM was 3.7, 4.6, and 2.6% for lambs consuming diets supplemented with CO, AC, and DA, respectively. Compared with lambs fed the untreated supplement (CO), lambs supplemented with AC or DA had 1) higher (P < 0.05) concentrations of linoleic (4.80 vs. 6.37 or 6.80%) and linolenic (0.28 vs. 0.43 or 0.45%) acids in the LM nonpolar lipids; 2) a higher (P < 0.05) concentration of linoleic acid (22.1 vs. 27.1 or 25.6%), but a lower (P < 0.05) concentration of oleic acid (17.2 vs. 13.0 or 13.1%), in the LM polar lipids; 3) a higher (P < 0.05) concentration of linoleic acid (3.77 vs. 6.13 or 6.06%) in subcutaneous fat; and 4) higher (P < 0.05) concentrations of linoleic (4.46 vs. 7.65 or 7.13%), linolenic (0.50 vs. 0.85 or 0.80%), and stearic (24.9 vs. 27.2 or 26.9%) acids, but a lower (P < 0.05) concentration of oleic acid (39.1 vs. 35.4 or 36.3%), in kidney fat. In broiled LM chops, 21 volatiles were identified, including seven alkanals, seven 2-alkenals, two 2,4-alkadienals, and five other compounds, but most differences in the volatile concentrations among lambs fed the different supplements did not correspond to concentration differences in their precursor fatty acids. Results indicated that compared with the untreated supplement (CO), AC and DA supplements protected linoleic (C 18:2n6) and linolenic (C18:3n3) acids in soybean oil from degradation in the rumen of the lambs, resulting in increased deposition in the muscle and adipose tissues of lamb.

Ultrasound evaluation of the magnitude of pneumothorax: a new concept

Pneumothorax is commonly seen in trauma patients; the diagnosis is confirmed by radiography. The use of ultrasound where radiographic capabilities are absent, is being investigated by the National Aeronautics and Space Administration. We investigated the ability of ultrasound to assess the magnitude of pneumothorax in a porcine model. Sonography was performed on anesthetized pigs in both ground-based laboratory (n = 5) and microgravity conditions (0 x g) aboard the KC-135 aircraft during parabolic flight (n = 4). Aliquots of air (50-100 cm3) were introduced into the chest to simulate pneumothorax. Results were videorecorded and digitized for later interpretation. Several distinct sonographic patterns of partial lung sliding were noted including the combination of a sliding zone with a still zone and a "segmented" sliding zone. These "partial lung sliding" patterns exclude massive pneumothorax manifested by a complete separation of the lung from the parietal pleura. In 0 x g, the sonographic picture is more diverse; one x g differences between posterior and anterior aspects are diminished. Modest pneumothorax can be inferred by the ultrasound sign of "partial lung sliding." This finding, which increases the negative predictive value of thoracic ultrasound, may be attributed to intermittent pleural contact, small air spaces, or alterations in pleural lubricant. Further studies of these phenomena are warranted.

The effects of n-3 fatty acid supplementation on bleeding time, plasma fatty acid composition, and in vitro platelet aggregation in cats

Dietary supplementation with fish and fish oils rich in the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been shown to alter eicosanoid metabolism and impair platelet function in several species. As an initial step in evaluating the antithrombotic effect of these n-3 fatty acids in cats, purified EPA and DHA were administered daily to 8 clinically normal cats for 2 months. Platelet function was evaluated biweekly by determining mucosal bleeding time and in vitro platelet aggregation parameters. Plasma fatty acid profiles were obtained before fish oil supplementation and at the termination of the study. In spite of significant increases (P < .0001) in the plasma concentrations of EPA and DHA after n-3 fatty acid supplementation, there were no significant changes in platelet aggregation or bleeding times. Although it is tempting, based on extrapolation of data from other species, to recommend dietary supplementation with fish oil for cats prone to arterial thromboembolism, these results indicate that administration of large doses of purified EPA and DHA once daily does not inhibit platelet function in normal cats and is unlikely to prevent thrombosis in cats with cardiovascular disease. Additional studies are recommended to ascertain whether more frequent administration of these purified n-3 fatty acids or continual feeding of diets high in n-3 fatty acid content will impair platelet function.

Effects of feeds on flavor of red meat: a review

The effects of diet ingredients on red meat flavor are dependent on the type of diet, and, to a large extent, on the species: pork, mutton or lamb and beef. Sensory analysis of meat flavor has been used in most of the studies on the effects of feeds on meat flavor. In general, high-energy grain diets produced a more acceptable or a more intense flavor in red meats than low-energy forage or grass diets. Feeding pigs unsaturated fats increases the unsaturation in pork fat but results in only minor changes in pork flavor. Sheep must be fed protected, unsaturated fats in order to increase the unsaturation in their fat to be similar to pork fat. This increased unsaturation results in a greater flavor change in lamb or beef than in pork. Several dietary ingredients such as fish products, raw soybeans, canola oil and meal, and pasture grasses cause undesirable flavors in red meat. Analyses of lamb and beef produced on different diets have shown that type of feed affects the concentration of many flavor volatile compounds. However, only a few studies have quantified the volatiles of beef and lamb produced on different diets, and no reports of studies were found in which the volatiles of pork produced on different diets had been investigated. Hence, the importance of these changes in volatile concentration to meat flavor has not been determined.