الفهرس 
RELATION BETWEEN NUTRITION AND IMMUNITYOnly 14 pages are availabe for public view
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Abstract
Surgery, trauma, burns and injury induce an inflammatory response that can become excessive and damaging in some patients. This hyperinflammation can be followed by an immunosuppressed state which increases susceptibility to infection. The resulting septic syndromes are associated with significant morbidity and mortality. A range of nutrients are able to modulate inflammation (and the associated oxidative stress) and to maintain or improve immune function. These include several amino acids, antioxidant vitamins and minerals, long-chain n-3 fatty acids, probiotics and nucleotides. Each of these nutrients have a role in surgical, injured or critically ill patients
One of these immunonutrients is arginine amino acid. Arginine supplementation increases NO formation and the mitotic response of peripheral lymphocytes to standard stimuli in healthy subjects and postoperative patients. Moreover, arginine in combination with other immunonutrients reduces infectious complications, days on ventilator and hospital stays particularly in patients undergoing elective surgery.
Immunonutrition with arginine can be safely used in surgical patients. Patients with SIRS, sepsis and organ failure have had adverse effects when given immunonutritional formulas containing high concentrations of arginine as it may increase systemic inflammation and compromise clinical outcomes.
Another immunonutrient is glutamine. Glutamine administration reduces GI bacterial translocation and increases the synthesis of DNA and RNA, the activation and proliferation of lymphocytes and macrophages and the expression of interleukins IL-1and IL-2. Glutamine supplementation protects the GI mucosa in different models of injury probably by preserving intracellular glutathione levels and by stimulating cell proliferation and protein synthesis
glutamine supplementation apart from improving GI function, sustains systemic immune function and nitrogen balance. In surgical and critically ill patients, glutamine supplementation reduces the incidence of infection, hospital stay and costs. Glutamine appears to be an ideal and necessary compound of nutrition in severe burn injury.
Enteral provision of glutamine decreased the incidence of pneumonia, bacteraemia and severe sepsis in critically ill patients. Parenteral glutamine decreased the incidence of infections in recipients of bone marrow transplantation and changed the pattern of mortality in patients in intensive care. These clinical benefits of glutamine seem to be associated with improvements in intestinal integrity and in cellular immune function
Also glycine has a wide spectrum of protective properties against different diseases and injuries. As such, glycine represents a new antiinflammatory, immunomudulatory and cytoprotective agent. Glycine suppresses the inflammatory response, tissue damage and multiple organ failure thus protecting against ischemia-reperfusion injury. Glycine appears to moderate immunological reactions and may prove useful in diminishing rejection after transplantation. Glycine decreases organ injury and improves survival after hemorrhagic shock/resuscitation so Glycine therefore could be an effective therapy for shock. Glycine ameliorate liver fibrosis, possesses significant anti-ulcer, cytoprotective activity and anticancer property.
Omega-3 PUFAs also show protective effects against the development of tumours, metastases and cachexia. It seems that among PUFAs only EPA can reverse in vivo the metastatic process. The w-3 PUFAs seem to play a predominant role in low rates of coronary arterial diseases observed in populations consuming fish-based food (e.g., Inuits). A diet rich in w-3 PUFAs decreases the incidence of renal and cardiovascular diseases (e.g., hypertension, arrhythmia) probably by inhibiting thrombogenesis and cytokine-dependent inflammation. In patients with pancreatic cancers, fish oil supplementation helps to reduce inflammation and stabilizes energy expenditure. This might explain the prolonged survival observed among patients with metastatic cancer, consuming an w-3 PUFA- enriched diet.
The microbiota of the human large intestine influences health and well-being. whereas it has long been accepted that gut bacteria play a role in host pathogenesis, current opinion is that certain microflora components called probiotics can have beneficial effects on gastroenteritis resistance, blood lipids, antitumor properties, lactose tolerance and gastrointestinal immunity.
Nucleotide supplementation, has become an area of intensive research and significant interest in immunomodulation for maintenance of cellular immune responses. Exogenous nucleotide supplementation is beneficial in the maintenance and restoration of the immune response during stress condition and in critically ill patients
Nucleotide infusions have been used in several clinical situations. Infusions of adenosine and ATP produce potent vasodilatation in treatment of haemorrhagic shock, tissue ischemia, pulmonary hypertension and have also been used in differential diagnosis of coronary artery disease. Alterations in intracellular aerobic metabolism may lead to ATP or adenosine release and local vasodilation. Adenosine therefore acts as a homeostatic.
(20) Plasma antioxidant micronutrient concentrations are depressed during critical illness and especially during sepsis, as the result of losses, low intakes, dilution by resuscitation fluids, and the SIRS-mediated redistribution to tissues, creating a circulating antioxidant defense deficit. The evidence is increasing that antioxidants supplementation contributes in limiting tissue and organ damage caused by sepsis mediators.
(21) Three antioxidant nutrients already have undergone successful clinical testing reaching a top level of evidence, selenium improves clinical outcome (infections, organ failure), glutamine reduces infectious complication in large trials; and the association of eicosapentaenoic acid and micronutrients blunted endotoxin response. Other antioxidants as N-acetylcysteine, Vitamin E, Vitamin C and zink have had clinical benefits in critically ill patients with different conditions as antioxidants and immune enhancing diet.
Immunonutrient mixtures which contain one or more of omega-3 fatty acid, glutamine, arginine and nucleotides benefit specific groups of patients. Immunonutrient mixtures do not work in all patient groups due to the feeding method, the amounts administered and the timing of feeding.