Omega-3 fatty acids improve the diagnosis-related clinical outcome*

Lipid emulsions - Guidelines on Parenteral Nutrition, Chapter 6

The infusion of lipid emulsions allows a high energy supply, facilitates the prevention of high glucose infusion rates and is indispensable for the supply with essential fatty acids. The administration of lipid emulsions is recommended within ≤7 days after starting PN (parenteral nutrition) to avoid deficiency of essential fatty acids. Low-fat PN with a high glucose intake increases the risk of hyperglycaemia. In parenterally fed patients with a tendency to hyperglycaemia, an increase in the lipid-glucose ratio should be considered. In critically ill patients the glucose infusion should not exceed 50% of energy intake. The use of lipid emulsions with a low phospholipid/triglyceride ratio is recommended and should be provided with the usual PN to prevent depletion of essential fatty acids, lower the risk of hyperglycaemia, and prevent hepatic steatosis. Biologically active vitamin E (α-tocopherol) should continuously be administered along with lipid emulsions to reduce lipid peroxidation. Parenteral lipids should provide about 25–40% of the parenteral non-protein energy supply. In certain situations (i.e. critically ill, respiratory insufficiency) a lipid intake of up to 50 or 60% of non-protein energy may be reasonable. The recommended daily dose for parenteral lipids in adults is 0.7–1.3 g triglycerides/kg body weight. Serum triglyceride concentrations should be monitored regularly with dosage reduction at levels >400 mg/dl (>4.6 mmol/l) and interruption of lipid infusion at levels >1000 mg/dl (>11.4 mmol/l). There is little evidence at this time that the choice of different available lipid emulsions affects clinical endpoints.

Therapeutic potential of n-3 polyunsaturated fatty acids in disease

PURPOSE

The potential therapeutic benefits of supplementation with n-3 polyunsaturated fatty acids (PUFAs) in various diseases are reviewed, and the antiinflammatory actions, activity, and potential drug interactions and adverse effects of n-3 PUFAs are discussed.

SUMMARY

Fish oils are an excellent source of long-chain n-3 PUFAs, such as eicosapentaenoic acid and docosahexaenoic acid. After consumption, n-3 PUFAs can be incorporated into cell membranes and reduce the amount of arachidonic acid available for the synthesis of proinflammatory eicosanoids (e.g., prostaglandins, leukotrienes). Likewise, n-3 PUFAs can also reduce the production of inflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1, and interleukin-6. Considerable research has been conducted to evaluate the potential therapeutic effects of fish oils in numerous conditions, including arthritis, coronary artery disease, inflammatory bowel disease, asthma, and sepsis, all of which have inflammation as a key component of their pathology. Additional investigations into the use of supplementation with fish oils in patients with neural injury, cancer, ocular diseases, and critical illness have recently been conducted. The most commonly reported adverse effects of fish oil supplements are a fishy aftertaste and gastrointestinal upset. When recommending an n-3 PUFA, clinicians should be aware of any possible adverse effect or drug interaction that, although not necessarily clinically significant, may occur, especially for patients who may be susceptible to increased bleeding (e.g., patients taking warfarin).

CONCLUSION

The n-3 PUFAs have been shown to be efficacious in treating and preventing various diseases. The wide variation in dosages and formulations used in studies makes it difficult to recommend dosages for specific treatment goals.

Omega-3 fatty acids and dementia

More than a dozen epidemiological studies have reported that reduced levels or intake of omega-3 fatty acids or fish consumption is associated with increased risk for age-related cognitive decline or dementia such as Alzheimer's disease (AD). Increased dietary consumption or blood levels of docosahexaenoic acid (DHA) appear protective for AD and other dementia in multiple epidemiological studies; however, three studies suggest that the ApoE4 genotype limits protection. DHA is broadly neuroprotective via multiple mechanisms that include neuroprotective DHA metabolites, reduced arachidonic acid metabolites, and increased trophic factors or downstream trophic signal transduction. DHA is also protective against several risk factors for dementia including head trauma, diabetes, and cardiovascular disease. DHA is specifically protective against AD via additional mechanisms: It limits the production and accumulation of the amyloid beta peptide toxin that is widely believed to drive the disease; and it also suppresses several signal transduction pathways induced by Abeta, including two major kinases that phosphorylate the microtubule-associated protein tau and promote neurofibrillary tangle pathology. Based on the epidemiological and basic research data, expert panels have recommended the need for clinical trials with omega-3 fatty acids, notably DHA, for the prevention or treatment of age-related cognitive decline--with a focus on the most prevalent cause, AD. Clinical trials are underway to prevent and treat AD. Results to-date suggest that DHA may be more effective if it is begun early or used in conjunction with antioxidants.

ESPEN Guidelines on Parenteral Nutrition: intensive care

Nutritional support in the intensive care setting represents a challenge but it is fortunate that its delivery and monitoring can be followed closely. Enteral feeding guidelines have shown the evidence in favor of early delivery and the efficacy of use of the gastrointestinal tract. Parenteral nutrition (PN) represents an alternative or additional approach when other routes are not succeeding (not necessarily having failed completely) or when it is not possible or would be unsafe to use other routes. The main goal of PN is to deliver a nutrient mixture closely related to requirements safely and to avoid complications. This nutritional approach has been a subject of debate over the past decades. PN carries the considerable risk of overfeeding which can be as deleterious as underfeeding. Therefore the authors will present not only the evidence available regarding the indications for PN, its implementation, the energy required, its possible complementary use with enteral nutrition, but also the relative importance of the macro- and micronutrients in the formula proposed for the critically ill patient. Data on long-term survival (expressed as 6 month survival) will also be considered a relevant outcome measure. Since there is a wide range of interpretations regarding the content of PN and great diversity in its practice, our guidance will necessarily reflect these different views. The papers available are very heterogeneous in quality and methodology (amount of calories, nutrients, proportion of nutrients, patients, etc.) and the different meta-analyses have not always taken this into account. Use of exclusive PN or complementary PN can lead to confusion, calorie targets are rarely achieved, and different nutrients continue to be used in different proportions. The present guidelines are the result of the analysis of the available literature, and acknowledging these limitations, our recommendations are intentionally largely expressed as expert opinions.

The effect of omega-3 FAs on tumour angiogenesis and their therapeutic potential

Omega-3 fatty acid (omega-3 FA) consumption has long been associated with a lower incidence of colon, breast and prostate cancers in many human populations. Human trials have demonstrated omega-3 FA to have profound anti-inflammatory effects in those with cancer. In vitro and small animal studies have yielded a strong body of evidence establishing omega-3 FA as having anti-inflammatory, anti-apoptotic, anti-proliferative and anti-angiogenic effects. This review explores the evidence and the mechanisms by which omega-3 FA may act as angiogenesis inhibitors and identifies opportunities for original research trialling omega-3 FAs as anti-cancer agents in humans. The conclusions drawn from this review suggest that omega-3 FAs in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found principally in oily fish have potent anti-angiogenic effects inhibiting production of many important angiogenic mediators namely; Vascular Endothelial Growth Factor (VEGF), Platelet-Derived Growth Factor (PDGF), Platelet-Derived Endothelial Cell Growth Factor (PDECGF), cyclo-oxygenase 2 (COX-2), prostaglandin-E2 (PGE2), nitric oxide, Nuclear Factor Kappa Beta (NFKB), matrix metalloproteinases and beta-catenin.

ESPEN Guidelines on Parenteral Nutrition: surgery

In modern surgical practice it is advisable to manage patients within an enhanced recovery protocol and thereby have them eating normal food within 1-3 days. Consequently, there is little room for routine perioperative artificial nutrition. Only a minority of patients may benefit from such therapy. These are predominantly patients who are at risk of developing complications after surgery. The main goals of perioperative nutritional support are to minimize negative protein balance by avoiding starvation, with the purpose of maintaining muscle, immune, and cognitive function and to enhance postoperative recovery. Several studies have demonstrated that 7-10 days of preoperative parenteral nutrition improves postoperative outcome in patients with severe undernutrition who cannot be adequately orally or enterally fed. Conversely, its use in well-nourished or mildly undernourished patients is associated with either no benefit or with increased morbidity. Postoperative parenteral nutrition is recommended in patients who cannot meet their caloric requirements within 7-10 days orally or enterally. In patients who require postoperative artificial nutrition, enteral feeding or a combination of enteral and supplementary parenteral feeding is the first choice. The main consideration when administering fat and carbohydrates in parenteral nutrition is not to overfeed the patient. The commonly used formula of 25 kcal/kg ideal body weight furnishes an approximate estimate of daily energy expenditure and requirements. Under conditions of severe stress requirements may approach 30 kcal/kg ideal body weights. In those patients who are unable to be fed via the enteral route after surgery, and in whom total or near total parenteral nutrition is required, a full range of vitamins and trace elements should be supplemented on a daily basis.

Rationale for using new lipid emulsions in parenteral nutrition and a review of the trials performed in adults

Lipids traditionally used in parenteral nutrition are based on n-6 fatty acid-rich vegetable oils such as soyabean oil. This practice may not be optimal because it may present an excessive supply of linoleic acid. Alternatives to the use of soyabean oil include its partial replacement by so-called medium-chain TAG (MCT), olive oil or fish oil, either alone or in combination. Lipid emulsions containing MCT are well established, but those containing olive oil and fish oil, although commercially available, are still undergoing trials in different patient groups. Emulsions containing olive oil or fish oil are well tolerated and without adverse effects in a wide range of adult patients. An olive oil–soyabean oil emulsion has been used in quite small studies in critically-ill patients and in patients with trauma or burns with little real evidence of advantage over soyabean oil or MCT–soyabean oil. Fish oil-containing lipid emulsions have been used in adult patients post surgery (mainly gastrointestinal). This approach has been associated with alterations in patterns of inflammatory mediators and in immune function and, in some studies, a reduction in the length of stay in the intensive care unit and in hospital. One study indicates that peri-operative administration of fish oil may be superior to post-operative administration. Fish oil has been used in critically-ill adults. Here, the influence on inflammatory processes, immune function and clinical end points is not clear, since there are too few studies and those that are available report contradictory findings. One important factor is the dose of fish oil required to influence clinical outcomes. Further studies that are properly designed and adequately powered are required in order to strengthen the evidence base relating to the use of lipid emulsions that include olive oil and fish oil in critically-ill patients and in patients post surgery.

Pennington Lecture Teams, strategies and networks: developments in nutritional support; a personal perspective

Chris Pennington was an archetypal team player, strategist and networker. Clinical nutritional support has progressed remarkably since the 1970s and it has been a privilege to work in this field over this period during which teamwork, strategy development and networking have been crucial. British experience has been characterised by groups of individuals of differing professions and specialties coming together to enable progress to be made. This approach was initially in the form of nutrition support teams orientated to patient-centred ward-based care, then as hospital strategic committees and the concept of the ‘patient journey’. Indeed, the formation of the British Association for Parenteral and Enteral Nutrition (now known as BAPEN) in 1992 required the statesmanlike burying of jealousies as societies came together into a multiprofessional association. With the understanding that disease-related malnutrition was highly prevalent it became apparent that it must be managed on a broad and organised clinical front. In the Organisation of Food and Nutritional Support in Hospitals a group of professionals developed for BAPEN concepts of hospital-wide organisation to tackle malnutrition that were based on previous reports, both national and international, and were made easily accessible from the BAPEN website, especially the ‘Malnutrition Universal Screening Tool’ and the National Institute for Health and Clinical Excellence nutrition guidelines. The coming together of six national clinical societies to develop evidence-based consensus guidelines for intravenous saline therapy (also on the BAPEN website) has shown that BAPEN can catalyse opinion well beyond its own nutritional constituency. In England Chris Pennington's Scottish lead is being followed by developing a patient-centred strategic framework for a managed home parenteral nutrition and intestinal failure national network. In research, education or clinical practice the engines of progress have been teams, strategies and networks.

Regulation of omega-3 fish oil emulsion on the SIRS during the initial stage of severe acute pancreatitis

The aim of this study was to explore the effects of parenteral supplementation with omega-3 fish oil emulsion (Omegaven) on systemic inflammatory response syndrome (SIRS) during the initial stage of severe acute pancreatitis (SAP). In a prospective, randomized and controlled trial, 60 patients with SAP were randomized either to treat with conventional therapy (Con group, n=30) or conventional therapy plus intravenous supplementation with omega-3 fish oil emulsion 0.2 g/kg every day (FO group, n=30). The effects were analyzed by the SIRS-related indexes. The results showed that APACHE-II scores in FO group were significantly lower, and the gap increased much farther after the 4th day than those in Con group (P<0.05). Fluid equilibrium time became shorter markedly in FO group than in Con group (5.1+/-2.2 days vs 8.4+/-2.3 days). In FO group, SIRS scores were markedly decreased and the SIRS state vanished after the 4th day; Plasma level of TNF-alpha was significantly reduced, while IL-10 decreased markedly, most prominently between the 4th and 7th day, and the ratio of IL-10/TNF-alpha raised as compared with Con group (P<0.05). During the initial stage of SAP, parenteral supplementation with omega-3 fish oil emulsion could efficiently lower the magnitude and persistence time of the SIRS, markedly retrieve the unbalance of the pro-/anti-inflammatory cytokines, improve severe condition of illness and may provide a new way to regulate the SIRS.

Long-chain polyunsaturated fatty acids influence the immune system of infants

Several events occur during the first months of life that allow the immune system to become competent and functional. The aim of this article is to review the rationale and evidence of an influence of (n-3) long-chain PUFA (LCPUFA) on the immune system of infants. The (n-3) LCPUFA exert their immunomodulatory activities at different levels. The (n-3) LCPUFA metabolites induce eicosanoid production, alter gene expression, and modify lipid raft composition, altering T-cell signaling; all contribute to immunological functional changes. However, the roles of these mechanisms and the types of T or other immunological cells involved remain unclear at present. Moreover, the effect of (n-3) LCPUFA on the immune system of infants may vary according to dose, time of exposure, and profile of the immune system (T-helper, Th1/Th2). Most of the interventional studies in infancy have been performed for the prevention of allergy. They all confirmed influence on T-cell function and cytokine profiles, but clinically beneficial effects are more conflicting. Supplementation of the maternal diet in pregnancy or early childhood with (n-3) LCPUFA is potentially a noninvasive intervention strategy to prevent the development of allergy, infection, and possibly other immune-mediated diseases. However, any long-term in vivo effects on (n-3) LCPUFA early in life for immunomodulatory defense in infants and later on immune status and health remain to be assessed.

Omega-3 fatty acids-supplemented parenteral nutrition decreases hyperinflammatory response and attenuates systemic disease sequelae in severe acute pancreatitis: a randomized and controlled study

BACKGROUND

The objective of this study was to investigate whether altering the fatty acid (FA) profile by omega-3 FA supplementation affects inflammatory response and systemic disease sequelae in severe acute pancreatitis.

METHODS

Forty severe acute pancreatitis patients were enrolled and randomly assigned to receive parenteral nutrition (PN) for 5 days in a double-blind manner. Patients received PN with identical amounts of amino acids (1.25 g/kg/d), glucose (3 g/kg/d), and fat (1 g/kg/d) but different lipid compositions: the control group received a soybean oil (SO; Lipovenos 20%; Fresenius, Germany)-based fat solution and the omega-3 FA group was supplemented with 0.15 - 0.2 g/kg/d fish oil (FO; Omegaven 10%; Fresenius, Germany). Serum concentrations of eicosapentaenoic acid (EPA), interleukin-6, C-reactive protein (CRP), white blood cell count, and routine respiratory and renal parameters were measured before PN, and again on day 6 after starting PN. Outcomes such as infection morbidity, mortality, intensive care unit time, and length of hospital stay were recorded.

RESULTS

Patients treated with FO had a significantly higher EPA concentration (P < .01), lower CRP level (P < .05), and better oxygenation index (P < .05) after 5 days of PN. Moreover, the number of days of continuous renal replacement therapy (CRRT) in the omega-3 FAs group was significantly less than that in the control group (P < .05).

CONCLUSIONS

PN supplemented with omega-3 FAs diminishes the hyperinflammatory response by the EPA increase and the proinflammatory cytokine decrease in severe acute pancreatitis. This, together with improved respiratory function and shortened CRRT time, suggests that the systemic response to pancreatic and organ injury is attenuated.

Anti-inflammatory properties of omega-3 fatty acids in critical illness: novel mechanisms and an integrative perspective

INTRODUCTION

Fish oil-based nutrition is protective in severe critical care conditions. Regulation of the activity of transcription factor NF-kappaB is an important therapeutic effect of the major omega-3 fatty acids in fish oil, eicosapentaenoic and docosahexaenoic acid (EPA and DHA).

METHODS AND RESULTS

Using the articles obtained by a Pubmed research, this article reviews three aspects of NF-kappaB/inflammatory inhibition by fish oil. (1) Inhibition of the NF-kappaB pathway at several subsequent steps: extracellular, free omega-3 inhibits the activation of the Toll-like receptor 4 by endotoxin and free saturated fatty acids. In addition, EPA/DHA blocks the signaling cascade between Toll-like/cytokine receptors and the activator of NF-kappaB, IKK. Oxidized omega-3 also interferes with the initiation of transcription by NF-kappaB. (2) The altered profile of lipid mediators generated during inflammation, with production of the newly identified, DHA-derived inflammation-resolving mediator classes (in addition to the formation of less pro-inflammatory eicosanoids from EPA). Resolvin D1 and Protectin D1 are potent, endogenous, DHA-derived lipid mediators that attenuate neutrophil migration and tissue injury in peritonitis and ischemia-reperfusion injury. Their production is increased in the later stages of an inflammatory response, at which time they enhance the removal of neutrophils. (3) Modulation of vagal tone with potential anti-inflammatory effects: vagal fibers innervating the viscera down-regulate inflammation by activating nicotinic receptors upon infiltrating and resident macrophages. Stimulation of the efferent vagus is therapeutic in experimental septic shock. Fish oil supplementation increases vagal tone following myocardial infarction and in experimental human endotoxinemia.

CONCLUSION

It remains to be shown whether these pleiotropic actions of EPA/DHA contribute to fish oil's therapeutic effect in sepsis.

Impact of postoperative omega-3 fatty acid-supplemented parenteral nutrition on clinical outcomes and immunomodulations in colorectal cancer patients

AIM: To investigate the effect of omega-3 fatty acid parenteral supplementation postoperatively on clinical outcomes and immunomodulation in colorectal cancer patients.

METHODS: Forty-two patients undergoing radical colorectal cancer resection with an indication for total parenteral nutrition postoperatively were enrolled in this prospective, double-blind, randomized, controlled study. Patients received total parenteral nutrition supplemented with either soybean oil (LCT; Intralipid^®, Fresenius-Kabi, SO group, n = 21) or a combination of omega-3 fish oil and soybean oil (LCT:fish oil = 5:1, fish oil; Omegaven^®, Fresenius-Kabi, FO group, n = 21), up to a total of 1.2 g lipid/kg per day for 7 d postoperatively. A same volume calorie and nitrogen was administrated. Routine blood test, biochemistry, systemic levels of IL-6 and TNF-α, percentage of CD3⁺, CD4⁺, and CD8⁺ lymphocytes were evaluated preoperatively and on postoperative d 1 and 8. Patient outcome was evaluated considering mortality during the hospital stay, length of postoperative hospital stay, and occurrence of infectious complications.

RESULTS: Both lipid regimens were well tolerated. No differences between the two groups were noticed in demographics, baseline blood test, biochemistry, serum levels of IL-6 and TNF-α, percentage of CD4⁺, CD8⁺ lymphocytes, and ratios of CD4⁺/CD8⁺. Compared with those on postoperative d 1, serum IL-6 levels on postoperative d 8 were significantly depressed in the FO group than in the reference group (-44.43 ± 30.53 vs -8.39 ± 69.08, P = 0.039). Simultaneously, the ratios of CD4⁺/CD8⁺ were significantly increased in the FO group (0.92 ± 0.62 vs 0.25 ± 1.22, P = 0.035). In addition, depression of serum TNF-α levels (-0.82 ± 2.71 vs 0.27 ± 1.67, P = 0.125) and elevation of CD3⁺ and CD4⁺ lymphocyte percentage (12.85 ± 11.61 vs 3.84 ± 19.62, P = 0.081, 17.80 ± 10.86 vs 9.66 ± 17.55, P = 0.084, respectively) were higher in the FO group than in the reference group. Patients in the FO group trended to need a shorter postoperative hospital stay (17.45 ± 4.80 d vs 19.62 ± 5.59 d, P = 0.19). No statistically significant difference was found when stratified to mortality and occurrence of infectious complications.

CONCLUSION: Postoperative supplementation of omega-3 fatty acids may have a favorable effect on the outcomes in colorectal cancer patients undergoing radical resection by lowering the magnitude of inflammatory responses and modulating the immune response.

Fish oil in critical illness

PURPOSE OF REVIEW

The aim of this review is to discuss recent advances in the role of n-3 lipids derived from fish oil in clinical nutrition in an intensive care setting.

RECENT FINDINGS

Fish oil supplies n-3 fatty acids which compete with arachidonic acid (n-6) for the conversion to lipid mediators, influence lipid-bound second messenger generation and dependent cellular functions, and are a source for resolvins necessary for the resolution of inflammation. Enteral nutrition with n-3 fatty acids improved ventilation time in patients with acute lung injury and in one study reduced mortality in septic patients. Using a high-dose short-term infusion of fish oil-based lipid emulsion, rapid immunologic changes and effects on the endotoxin-induced stress response may be achieved. Inclusion of n-3 fatty acids in parenteral nutrition improved immunologic parameters and length of stay in surgical patients.

SUMMARY

Inclusion of fish oil in nutrition may influence the immune response and clinical outcomes by balancing the negative effects of n-6 fatty acids. Application as a part of enteral immunonutrition in surgical or acute respiratory distress syndrome patients and in lipid emulsions in surgical patients has beneficial effects. In septic patients, data on enteral use are highly controversial. Prospective data from randomized trials, however, are lacking.

Pharmaconutrition: a new emerging paradigm

PURPOSE OF REVIEW

This paper highlights recent studies of interest and provides rationale for why deficiencies with the current scientific paradigm of immunonutrition has produced studies with conflicting results, and why it should be replaced with a new paradigm termed 'pharmaconutrition'.

RECENT FINDINGS

Considering the overall treatment effect of immune-modulating nutrients, parenteral glutamine is recommended in patients receiving parenteral nutrition, while enteral glutamine should be considered in burn and trauma patients. Antioxidants, particularly selenium, should be considered for critically ill patients, and enteral formulas enriched with fish oils are recommended in patients with acute respiratory distress syndrome. Arginine-supplemented diets are not recommended. There are currently insufficient data to enable useful recommendations on the optimal route, timing, duration and dosage of each nutrient. The pending results of a large, rigorously designed, randomized trial, however, in which nutrients are viewed and tested as pharmacological agents, promise to clarify some of the current ambiguities and inform future practice.

SUMMARY

This review provides insights into why the current paradigm of immunonutrition has failed to consistently demonstrate a beneficial effect of key immunomodulating nutrients, and offers a timely solution through the new paradigm of pharmaconutrition.

Maximizing efficacy from parenteral nutrition in critical care: appropriate patient populations, supplemental parenteral nutrition, glucose control, parenteral glutamine, and alternative fat sources

The gastrointestinal tract is the preferred route for nutritional support in hospitalized patients. Patients with a functioning gastrointestinal tract, including those with pancreatitis or inflammatory bowel disease and those receiving chemotherapy, should be fed enterally. Parenteral nutrition (PN) should be limited to patients with gastrointestinal failure, including those with short gut syndrome, high-output fistula, prolonged ileus, or bowel obstruction. PN is associated with numerous complications, most notably increased risk of serious infection. Emerging data suggest that immunologic complications of PN may result from hyperglycemia and use of n-6 polyunsaturated fatty acids. Safety may be improved with a low-calorie formula and ensuring tight glycemic control with an insulin protocol. A lipid emulsion containing fish oil, olive oil, or both should replace soybean-containing emulsions. Supplemental glutamine, 0.2 g/kg/d to 0.5 g/kg/d, has been shown to reduce the risk of infection and to improve glycemic control.

Immune-modulating enteral formulations: optimum components, appropriate patients, and controversial use of arginine in sepsis

Nutrients have traditionally been viewed as a means to provide basic calories to sustain homeostasis. However, critically ill, surgical, and trauma patients are in a constant dynamic state between systemic inflammatory response (SIRS) and compensatory anti-inflammatory response (CARS). Results from ongoing research strongly support the use of specific nutrients to modulate the immune and/or metabolic response. These agents can now be considered therapeutic tools in the management of complex hypermetabolic diseases. The principle of using nutrients as a therapeutic strategy rather than just as "nutritional support" requires a shift in the current dogma. The most common nutrients found in currently available enteral immune-modulating formulas are omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid), antioxidants, nucleotides, glutamine, and arginine. Multiple individual reports and at least five meta-analyses using combinations of immune-modulating nutrients have reported almost uniform beneficial results. However, certain conflicting hypotheses continue to revolve around the use of arginine in septic patients.

Influence of adding fish oil to parenteral nutrition on gut-associated lymphoid tissue

BACKGROUND

Lack of enteral nutrition reduces gut-associated lymphoid tissue (GALT) mass and function, a mechanism underlying the increased morbidity of infectious complications in severely injured or critically ill patients. Strategies to restore parenteral nutrition (PN)-induced changes of GALT mass and function have been pursued. However, the influences of adding fish oil to PN on gut immunity remain to be clarified.

METHODS

Male Institute of Cancer Research (ICR) mice (n = 50) were randomized to 4 groups: ad libitum chow (chow), fat free PN (fat (-)-PN), PN + fish oil (FO-PN), and PN + safflower oil (SO-PN). The PN groups were given isocaloric and isonitrogenous PN solutions. The FO- and SO-PN groups received 20% of total calories from fat emulsions. After 5 days of feeding, lymphocytes from Peyer's patches (PPs), the intraepithelial space (IE), and the lamina propria (LP) of the entire small intestine were isolated. GALT lymphocyte numbers and phenotypes (CD4+, CD8+, alphabetaTCR+, gammadeltaTCR+, B220+ cells) were determined. Immunoglobulin A (IgA) levels of small intestinal washings were also measured by enzyme-linked immunosorbent assay. Another set of mice (n = 24) was used to determine plasma fatty acid compositions after feeding.

RESULTS

Lymphocyte numbers from PPs and the LP and intestinal IgA levels were significantly lower in the PN groups than in the chow group, with no significant differences between any 2 PN groups. The FO- and SO-PN groups showed moderate recovery of IE cell numbers compared with the fat (-)-PN group. Omega-3 and omega-6 fatty acid levels were increased with fish and safflower oil additions, respectively, compared with the fat (-)-PN group.

CONCLUSIONS

Adding fish oil to PN does not exacerbate PN-induced GALT changes but rather partially reverses these changes, with increased plasma omega-3 fatty acid levels.

Antioxidant supplementation in sepsis and systemic inflammatory response syndrome

OBJECTIVE

Summarize the current knowledge about oxidative stress-related organ dysfunction in inflammatory and septic conditions, and its potential prevention and treatment by antioxidants in critically ill patients, focusing on naturally occurring antioxidants and clinical trials.

STUDY SELECTION

PubMed, MEDLINE, and personal database search.

SYNTHESIS

Plasma concentrations of antioxidant micronutrients are depressed during critical illness and especially during sepsis. The causes of these low levels include losses with biological fluids, low intakes, dilution by resuscitation fluids, as well as systemic inflammatory response syndrome-mediated redistribution of micronutrients from plasma to tissues. Numerous clinical trials have been conducted, many of which have shown beneficial effects of supplementation. Interestingly, among the candidates, glutamine, glutathione, and selenium are linked with the potent glutathione peroxidase enzyme family at some stage of their synthesis and metabolism.

CONCLUSIONS

Three antioxidant nutrients have demonstrated clinical benefits and reached level A evidence: a) selenium improves clinical outcome (infections, organ failure); b) glutamine reduces infectious complication in large-sized trials; and c) the association of eicosapentaenoic acid and micronutrients has significant anti-inflammatory effects. Other antioxidants are still on the clinical benchmark level, awaiting well-designed clinical trials.

Enteral immunonutrition during sepsis prevents pulmonary dysfunction in a rat model

BACKGROUND

Sepsis often results in severe pulmonary dysfunction. Via the thoracic duct, the lung is the first organ exposed to gut-derived inflammatory mediators released into mesenteric lymph during sepsis.

AIM

To investigate whether an enteral immunonutrition during sepsis improves pulmonary function.

METHODS

Mesenteric lymph was obtained from lymph fistula donor rats after intra peritoneal (i.p.) saline (control lymph) or lipopolysaccharide (sepsis lymph) injection. Sepsis lymph was also collected during enteral immunonutrition with omega-3 enriched, long-chain fatty acids (SMOF lipid). Control, sepsis, or sepsis-SMOF lymph was reinfused into the jugular vein of separate recipient rats. The lungs were then harvested, stained with hematoxylin-eosin, and analyzed for: (1) perpendicular parenchyma thickness of the alveolar wall; (2) myeloperoxidase-positive cells; and (3) terminal deoxynucleotidyl transferase Biotin-dUTP nick end labeling (TUNEL)-positive cells.

RESULTS

Enteral immunonutrition during sepsis reduced the release of TNFalpha into mesenteric lymph by about 4.5-fold within the first 2 h. Infusion of sepsis lymph into recipient rats induced thickening of alveolar walls, inflammatory reaction, and apoptosis. Infusion of sepsis lymph obtained during enteral immunonutrition did not cause anatomical changes, induced only a mild inflammatory reaction, and prevented apoptosis in the lungs of recipient rats.

CONCLUSIONS

Mediators in sepsis lymph induce pulmonary dysfunction such as an increased distance for oxygen transport, inflammatory reaction, and apoptosis. The lung may be protected by an enteral immunonutrition containing long-chain fatty acids.

Adequacy of dietetic service provision to adult critical care: a survey of 33 centres in Northern England

BACKGROUND

Nutrition interventions improve morbidity, mortality and length of stay in the critically ill. Dietitians play a central role in facilitating these interventions. However, data regarding the current level and adequacy of dietetic service provision to critical care in the UK is lacking. This study aimed to clarify current service trends in Northern England for critical care, in relation to dietetic funding, grading and activity characteristics and comparisons with nationally recognized standards of care.

METHODS

A work profile questionnaire was sent to 53 dietitians in Northern England. Data was collected on funding, activity patterns, organization of nutrition support, pay banding/grade and arrangements for cover during absence.

RESULTS

The response rate was 66% (35/53). Thirty-three hospitals were represented. No critical care centre funding or actual activity achieved national guidance for funded dietetic full-time equivalents (FTE). Total sample deficit for funding against recommendations was 32.9 FTE. Staff pay bands/grades were inconsistent. Routine patient review occurred on a daily basis by 31% dietitians and 23% were members of a nutrition support team. Cover during absence was limited or provided by a dietitian at a lower staff grade in 67% of centres.

CONCLUSIONS

Serious deficiencies exist in dietetic services to critical care in the sample studied. Further work is now required to identify inter-regional and national trends and to define appropriate dietetic job profiles for critical care.

Immune modulation by parenteral lipid emulsions

Total parenteral nutrition is the final option for nutritional support of patients with severe intestinal failure. Lipid emulsions constitute the main source of fuel calories and fatty acids (FAs) in parenteral nutrition formulations. However, adverse effects on patient outcomes have been attributed to the use of lipids, mostly in relation to impaired immune defenses and altered inflammatory responses. Over the years, this issue has remained in the limelight, also because technical advances have provided no safeguard against the most daunting problems, ie, infectious complications. Nevertheless, numerous investigations have failed to produce a clear picture of the immunologic characteristics of the most commonly used soybean oil-derived lipid emulsions, although their high content of n-6 polyunsaturated FAs (PUFAs) has been considered a drawback because of their proinflammatory potential. This concern initiated the development of emulsions in which part of the n-6 FA component is replaced by less bioactive FAs, such as coconut oil (rich in medium-chain saturated FAs) or olive oil (rich in the n-9 monounsaturated FA oleic acid). Another approach has been to use fish oil (rich in n-3 PUFA), the FAs of which have biological activities different from those of n-6 PUFAs. Recent studies on the modulation of host defenses and inflammation by fish-oil emulsions have yielded consistent data, which indicate that these emulsions may provide a tool to beneficially alter the course of immune-mediated conditions. Although most of these lipids have not yet become available on the US market, this review synthesizes available information on immunologic characteristics of the different lipids that currently can be applied via parenteral nutrition support.

Practicalities of nutrition support in the intensive care unit

PURPOSE OF REVIEW

Nutrition support improves clinical outcomes in the critically ill and our understanding of its effects has advanced significantly over the last few years. Three recently published evidence-based guidelines have made generally consistent and thorough recommendations to assist clinicians in providing nutrition support. This review will focus on various aspects of these recommendations, concentrating on the practicalities of nutrition support in the intensive care unit, such as its optimal mode and composition.

RECENT FINDINGS

Enteral nutrition is preferred to parenteral nutrition unless there is a major gut condition which will delay commencement of enteral nutrition. Nasogastric feeding should begin within 24 h, but if intolerance develops, small bowel feeding or pro-motility drugs (erythromycin or metoclopramide) should be attempted before resorting to supplementary parenteral nutrition. Enteral nutrition should not routinely be supplemented with arginine or glutamine, but it should contain a package of eicosapentaenoic acid, gamma-linolenic acid and antioxidants if the patient has acute lung injury or sepsis. Parenteral nutrition should be glutamine supplemented and the prescription should be limited in energy to avoid hyperglycemia. Whether using enteral nutrition or parenteral nutrition, most patients should receive intravenous selenium, and may also need zinc and copper supplementation.

SUMMARY

Intensive care unit patients should have nutrition support based on recent evidence-based guidelines with a preference for nasogastric feeding. If intolerance occurs, pro-motility drugs and small bowel feeding should be attempted. Clinicians should also consider carefully the composition of the nutrition support regimen with regard to lipid content (especially eicosapentaenoic acid and gamma-linolenic acid), antioxidants, glutamine and other micronutrients.

Intravenous fish oil blunts the physiological response to endotoxin in healthy subjects

OBJECTIVE

To assess the effects of intravenous fish oil fat emulsion on the metabolic alterations induced by lipopolysaccharide (LPS) challenge in healthy volunteers.

DESIGN

Two groups of eight healthy subjects were randomized to receive either two pharmacological doses of intravenous FO fat emulsion or no treatment. The FO group received twice 0.5 g/kg 10% emulsion (Omegaven) 48 and 24h before investigation. LPS (2 ng/kg) was injected as a bolus on the investigation day. Systemic parameters, indirect calorimetry, heart rate variability, and platelet membrane phospholipid composition were measured.

RESULTS

Basal EPA and DHA content in platelet phospholipids was low (0.28% and 2.54%, respectively) and increased significantly after FO to 1.68% and 3.32%. LPS induced reproducible effects in all subjects. Fever was higher in the control [corrected] group than in FO group [corrected] the difference was significant from t (120) until t (360). FO blunted the neuroendocrine response: the rise in plasma norepinephrine was sevenfold lower at t (120) while the ACTH peak was fourfold lower. Tumor necrosis factor alpha was significantly lower between t (360) and t (180) in the FO group.

CONCLUSIONS

Two doses of intravenous FO fat emulsion modified the phospholipid composition of platelets in healthy subjects. FO blunted fever and increased the neuroendocrine and the inflammatory responses to LPS.

Immunomodulation by n-3- versus n-6-rich lipid emulsions in murine acute lung injury--role of platelet-activating factor receptor

OBJECTIVE

Cytokines, platelet-activating factor (PAF), and eicosanoids control local and systemic inflammation. Conventional soybean oil-based lipid emulsions used for parenteral nutrition may aggravate the leukocyte inflammatory response or adhesion to the vessel wall. Fish oil-based lipid emulsions, in contrast, may exert an anti-inflammatory effect.

DESIGN

We investigated the impact of lipid emulsions on leukocyte invasion, protein leakage, and cytokines in two murine models of acute inflammation.

SETTING

Research laboratory of a university hospital.

SUBJECTS

Wild-type mice and PAF-receptor knockout mice.

INTERVENTIONS

Mice received an infusion of normal saline, fish oil- or soybean oil-based lipid emulsions before lipopolysaccharide challenge.

MEASUREMENTS AND MAIN RESULTS

Preinfusion with soybean oil resulted in increased leukocyte invasion, myeloperoxidase activity, and protein leakage and exaggerated release of tumor necrosis factor (TNF)-alpha as well as macrophage inflammatory protein (MIP)-2 into the alveolar space after intratracheal lipopolysaccharide challenge. In contrast, preinfusion with fish oil reduced leukocyte invasion, myeloperoxidase activity, protein leakage, and TNF-alpha as well as MIP-2 generation. Corresponding profiles were found in plasma following intraperitoneal lipopolysaccharide application: Soybean oil increased but fish oil decreased the TNF-alpha and MIP-2 formation. When PAF-receptor-deficient mice were challenged with lipopolysaccharide, leukocyte invasion, lung tissue myeloperoxidase, cytokine generation, and alveolar protein leakage corresponded to those observed in wild-type animals. Fish oil and soybean oil lost their diverging effects on leukocyte transmigration, myeloperoxidase activity, leakage response, and cytokine generation in these knockout mice. Similarly, the differential impact of both lipid emulsions on these lipopolysaccharide-provoked changes was suppressed after pretreating animals with a PAF-receptor antagonist.

CONCLUSIONS

Fish oil- vs. soybean oil-based lipid infusions exert anti- vs. proinflammatory effects in murine models of acute inflammation. The PAF/PAF-receptor-linked signaling appears to be a prerequisite for this differential profile.

Management of perioperative nutrition support

PURPOSE OF REVIEW

Perioperative nutrition has been extensively studied, but numerous questions remain unanswered. This review focuses on new developments in nutrient delivery in the immediate perioperative period. Issues specifically addressed include which patients are most likely to benefit from perioperative nutritional supplementation, and the optimal route, timing, and quantity of nutrient delivery.

RECENT FINDINGS

Visceral proteins, particularly albumin, play an important role in nutritional and perioperative risk assessment. Although the recommendation to use the enteral route for delivery of nutrition whenever possible is clear, the cautious introduction of enteral feeds in the labile group of patients with circulatory failure is essential. Preoperative use of immune-modulating enteral formulas, preoperative carbohydrate loading, and the concept of early enteral feeding are important developments. Supplementary arginine, glutamine, and omega-3 fats play a potential role in nutritional management, as does 'permissive' hypocaloric feeding.

SUMMARY

The particulars of nutritional support for perioperative and critically ill patients remain controversial. Recent studies addressing specific issues in this diverse discipline perhaps raise more questions than are answered. However, each new contribution to the literature brings us closer to an understanding of optimal nutritional management in the metabolically stressed patient.

[Nutrition and immunonutrition in septic patients]

Nutrition in septic patients is more than just caloric support. Not all nutritional concepts in general intensive care may be applied to septic patients. A tight glycemic control successfully used in post-operative intensive care patients has to be modified for the septic patient. Enteral immunonutrition leading to reduced length of stay in post-operative patients may be associated with increased mortality in patients suffering from severe sepsis. Newly developed lipid emulsions for parenteral nutrition became available. Application of these emulsions may prove to be beneficial in septic patients. An intravenous supplementation with glutamine of long-term exclusively parenterally fed intensive care patients may reduce their mortality. A nutrition individually optimized and adapted to the severity of the disease is considered to be an adjunct therapeutic measure in the treatment concept in sepsis.

Lipoproteins in inflammation and sepsis. II. Clinical aspects

BACKGROUND

Systemic inflammation and sepsis are accompanied by severe metabolic alterations, including insulin resistance together with increased levels of triglycerides (TGs) and decreases in high- and low-density lipoproteins. Clinical studies have clearly established a link between lipid metabolism and systemic inflammation. Lipoproteins were shown to neutralize LPS and to exert direct anti-inflammatory actions. High- and low-density lipoproteins are thus thought to be important regulators of the host immune response during endotoxemia, which may also have the potential of improving the care of patients with Gram-negative sepsis.

DISCUSSION

Nutritional lipids supplied during critical illness have been shown to modulate the host response to inflammation. In particular, inclusion of omega-3 fatty acids seems to have beneficial effects on cellular immunity and helps to maintain the balance between pro- and anti-inflammatory cytokines thereby preventing hyperinflammatory complications. In addition to improvements in the profile of lipid mediators generated, omega-3 fatty acids act as activating ligands of peroxisome proliferator-activated receptors and directly inhibit nuclear factor kappaB mediated proinflammatory signaling. We present an overview on the alterations in the metabolism of serum lipoproteins during sepsis and present data from clinical studies and discuss the significance of nutritional lipids and their role in immunomodulation with special emphasis on omega-3 fatty acids.

Omega-3 fatty acid effects on biochemical indices following cancer surgery

Epidemiological studies have indicated that a high intake of saturated fat and/or animal fat increases the risk of colon and breast cancer. Laboratory and clinical investigations have shown a reduced risk of colon carcinogenesis after alimentation with omega-3 fatty acids, as found in fish oil. Mechanisms accounting for these anti-tumor effects are reduced levels of PGE(2) and inducible NO synthase as well as an increased lipid peroxidation, or translation inhibition with subsequent cell cycle arrest. Further, omega-3 eicosapentaenoic acid is capable of down-regulating the production and effect of a number of mediators of cachexia, such as IL-1, IL-6, TNF-alpha and proteolysis-inducing factor. In patients with advanced cancer, it is possible to increase energy and protein intake via an enteral or parenteral route, but this seems to have little impact on progressive weight loss. Fish oil administration improved patients' conditions in cancer cachexia and during radio- and chemotherapy. In patients undergoing tumor resection surgery we observed improvement of liver and pancreas biochemical indices when omega-3 fatty acids were administered. This paper is a review of recent developments in the field of nutrition in cancer patients with emphasis on the acute phase response following cancer surgery and the beneficial aspects of fish oil administration.

Docosahexaenoic acid administered in the acute phase protects the nutritional status of septic neonates

OBJECTIVE

We tested the hypothesis of whether a pharmacologic, orogastric dose of docosahexaenoic acid (DHA) administered during the acute phase of sepsis protects the nutritional status of neonates.

METHODS

A randomized, placebo-controlled trial was conducted. Neonates who developed sepsis after a surgical procedure were randomly assigned to receive daily 100 mg of DHA or 100 mg of olive oil as placebo for 14 d. At selection, illness severity was evaluated and a blood sample was obtained to measure erythrocyte fatty acid composition. Energy intake and type of feeding were recorded daily. Body composition was also determined at selection and after 14 d of follow-up with the deuterium dilution technique. Body composition differences between d 14 and baseline were calculated and compared between groups. Confounders were analyzed in a multiple regression model.

RESULTS

In all, 16 DHA and 11 placebo cases were followed up. Both groups showed an increase in length and head circumference, but length gain tended to be greater in neonates with DHA (P = 0.07). The DHA group presented increases in body mass (50 g, P = 0.03) and fat mass (70 g, P = 0.03), whereas infants in the placebo group did not show an increase in any body composition components. Gain in fat mass was positively related with the DHA of erythrocytes and whether or not infants received DHA.

CONCLUSIONS

Orogastric DHA administered in the acute phase of infection likely protects the nutritional status of neonates with sepsis.