The scientific basis of immunonutrition

Abstract

Substrates with immune-modulating actions have been identified among both macro-and micronutrients. Currently, the modes of action of individual immune-modulating substrates, and their effects on clinical outcomes, are being examined. At present, some enteral formulas are available for the clinical setting which are enriched with selected immune-modulating nutrients. The purpose of the present paper is to review the scientific rationale of enteral immunonutrition. The major aspects considered are mucosal barrier structure and function, cellular defence function and local or systemic inflammatory response. It is notable that in critical illness the mucosal barrier and cellular defence are impaired and a reinforcement with enteral immunonutrition is desirable, while local or systemic inflammatory response should be down regulated by nutritional interventions. The results available from clinical trials are conflicting. Meta-analyses of recent trials show improvements such as reduced risk of infection, fewer days on a ventilator, and reduced length of intensive care unit and hospital stay. Thus, a grade A recommendation was proclaimed for the clinical use of enteral immune-modulating diets. Improvement in outcome was only seen when critical amounts of the immune-modulating formula were tolerated in patients classified as being malnourished. However, in other patients with severe sepsis, shock and organ failure, no benefit or even disadvantages from immunonutrition were reported. In such severe conditions we hypothesize that systemic inflammation might be undesirably intensified by arginine and unsaturated fatty acids, directly affecting cellular defence and inflammatory response. We therefore recommend that in patients suffering from systemic inflammatory response syndrome great caution should be exercised when immune-enhancing substrates are involved which may aggravate systemic inflammation.

Immune response in Eimeria sp. and E. coli challenged broilers supplemented with amino acids

“…The availability of substrates is currently considered the main tool in maintaining the structure and function of the mucosal barrier (Suchner et al 2000). Potential regulatory activities of functional amino acids must be included in determining the nutritional requirements of broilers (Wang et al 2015).…”

Modulation of Mast Cell Function by Amino Acids In vitro: A Potential Mechanism of Immunonutrition for Wound Healing.

“…For instance, enteral nutrition supplemented with a combination of immunonutrients, including Arg, Gln, omega-3 fatty acids, and nucleotides, has been demonstrated to prevent infectious complications and decrease mortality rates in critically ill and surgical patients compared with standard enteral nutrition [24][25][26]. In addition, these amino acids have been indicated in the regulation of lymphocyte function [27]; however, their effect on mast cells has remained mostly unclear.…”

Nutritional support for patients suffering from intestinal graft‐versus‐host disease after allogeneic hematopoietic stem cell transplantation

“…Hence, it is reasonable to suggest that dietary foods in EN adequately maintain an isotonic status as well as nutritional status to improve immunologic function. An intact GI system is vital for maintaining normal immune functions, and a novel concept of nutrition support, ''immunonutrition,'' has been introduced, which focuses on the maintenance of the comprehensive biological protection system against external pathogens to maintain normal immune function [10]. Clinical benefits of immunonutrition, including improvement of nutritional parameters, decreased risk of infection, and shorter duration of hospitalization, have been reported in patients in the perioperation period and in those who required care in the ICU [11,12].…”