Dietary omega-3 fatty acids decrease mortality and Kupffer cell prostaglandin E2 production in a rat model of chronic sepsis

A randomized trial of isonitrogenous enteral diets after severe trauma. An immune-enhancing diet reduces septic complications

OBJECTIVE

The authors randomized patients to an enteral diet containing glutamine, arginine, omega-3 fatty acids, and nucleotides or to an isonitrogenous, isocaloric diet to investigate the effect of septic outcome. A third group of patients, without enteral access but eligible by severity of injury, served as unfed controls and were studied prospectively to determine the risk of infection.

SUMMARY BACKGROUND DATA

Laboratory and clinical studies suggest that diets containing specialty nutrients, such as arginine, glutamine, nucleotides, and omega-3 fatty acids, reduce septic complications. Unfortunately, most clinical trials have not compared these diets versus isonitrogenous, isocaloric controls. This prospective, blinded study randomized 35 severely injured patients with an Abdominal Trauma Index > or = 25 or a Injury Severity Score > or = 21 who had early enteral access to an immune-enhancing diet ([IED] Immun-Aid, McGaw, Inc., Irvine, CA; n = 17) or an isonitrogenous, isocaloric diet (Promote [Ross Laboratories, Columbus, OH] and Casec [Mead-Johnson Nutritionals, Evansville, IN]; n = 18) diet. Patients without early enteral access but eligible by severity of injury served as contemporaneous controls (n = 19). Patients were evaluated for septic complications, antibiotic usage, hospital and intensive care unit (ICU) stay, and hospital costs.

RESULTS

Two patients died in the treatment group and were dropped from the study. Significantly fewer major infectious complications (6%) developed in patients randomized to the IED than patients in the isonitrogenous group (41%, p = 0.02) or the control group (58%, p = 0.002). Hospital stay, therapeutic antibiotics, and the development of intra-abdominal abscess was significantly lower in patients receiving the IED than the other two groups. This improved clinical outcome was reflected in reduced hospital costs.

CONCLUSIONS

An IED significantly reduces major infectious complications in severely injured patients compared with those receiving isonitrogenous diet or no early enteral nutrition. An IED is the preferred diet for early enteral feeding after severe blunt and penetrating trauma in patients at risk of subsequent septic complications. Unfed patients have the highest complication rate.

Nutrition support in critical illness

Sepsis, shock, multiple trauma, and burns are often associated with altered metabolism characterized by severe catabolism, wasting of the lean body mass, immune dysfunction, and compromised wound healing. Nutrition support is one of the mainstays in the management of these critically ill patients and is aimed at minimizing these complications. The purpose of this article is to compare stress hypermetabolism and starvation metabolism, to review current recommendations for the provision of energy and substrate to the critically ill patient, and to review pertinent literature regarding enteral vs parenteral nutrition. Finally, this article will provide a brief overview of new and future therapies with emphasis on specific substrates and growth factors and the potential for their use in the critically ill patient.

Effect of a diet deficient in essential fatty acids on the translocation of intestinal bacteria

Normal intestinal bacteria can initiate systemic disease by translocating out of the intestinal lumen to extraintestinal sites such as the mesenteric lymph nodes (MLN), liver, and spleen. To determine whether dietary essential fatty acids can affect the incidence of bacterial translocation, separate groups of mice were fed one of two diets for 8 days: an essential fatty acid-replete diet (EFA-R) containing a basal formula supplemented with arginine, yeast RNA, menhaden oil, and safflower oil, or an essential fatty acid-deficient diet (EFA-D) containing the same ingredients with the safflower oil replaced by menhaden oil. Mice were given either diet alone, diet plus 50 micrograms of intraperitoneal lipopolysaccharide (LPS), or diet plus 3 days of 4 mg of intramuscular metronidazole (MET) three times a day. (Both LPS and MET have been shown to increase the incidence of bacterial translocation to the MLN.) Within treatment groups there were no significant differences in the total numbers of viable ileal bacteria (separate quantitation of strict anaerobes, aerobic, and facultative Gram-positive results, and aerobic and facultative Gram-negative results). The incidence of bacterial translocation to the MLN was increased in mice fed EFA-D as compared with EFA-R in mice treated with diet alone (17% vs 0%; p less than .005) and in mice treated with diet plus LPS (71% vs 48%; p = .027). There was no difference in the incidence of bacterial translocation in mice fed EFA-D or EFA-R and treated with MET (83% vs 81%).