Committee on Military Nutrition Research Activity Report 1994-1999 (1999) / Chapter Skim
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L: Conclusions and Recommendations from the Workshop Report: Military Strategies for Sustainment of Nutrition and Immune Function in the Field
L: Conclusions and Recommendations from the Workshop Report: Military Strategies for Sustainment of Nutrition and Immune Function in the Field
Pages 257-282
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Appendix L Conclusions and Recommendations from the Workshop Report; Mililrary Strategies for Sustainment of Nut;rilrion an c! :Immune Function in the Fielc!
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, which tempered weight loss to only 12.8 percent of initial body weight, appeared to minimize the adverse effects on immune 259
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· Prolonged moderate-to-heavy physical activity. The week-long Norwegian Ranger training studies with heavy exercise and limited sleep did not demonstrate significant weight loss or alterations in immune function, whereas the U.S.
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2. What methods for assessment of immune function are most appropriate in military nutrition laboratory research, and what methods are most appropriate for field research?
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First, under controlled conditions, normal healthy individuals can be studied; after an appropriate baseline period, a nutritional perturbation can be imposed and the changes in immune responses from baseline determined. This approach allows single nutrient or environmental perturbations to be studied while many other factors that also cause immune dysfunction are controlled.
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If clinical signs of infection are present or there has been significant weight loss induced by nutritional stress, a simple-touse basic screening panel of immune function tests such as CRP protein, ESR, a baseline battery (testing six or more antibody titers for several previously administered military vaccines, immunoglobulins G A, and M; and complete blood count with CD4 lymphocyte count and CD4:CD8 ratio should be employed initially.
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may be the most sensitive way to determine whether changes in immune responses are stress related. Such tests currently are being evaluated in many civilian research studies and may have very real potential value for suggesting the presence of cytokine-induced malnutrition in military personnel who are being exposed to the stresses of rigorous training exercises or ongoing operational missions.
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Further, the use of anti-inflammatory drugs for the management of minor traumas or infections (for example, upper respiratory tract infections) is well recognized and provides for sustained military performance during severe training exercises and operational missions.
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Expert Consultation examined upper safe levels for trace minerals and concluded that the toxicity and the potential for nutrient-nutrient interactions must be considered individually. Risks of pathology resulting from such interactions are higher when intakes of other essential nutrients with which they interact are low or marginal, accentuating the nutrient imbalance.
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From page 267... ...
In a military situation, it is likely that the potential reduction in immune function due to iron deficiency is of more significance than any effects of iron overload. Because of their higher iron requirement and lower intake of operational rations, the iron intake of female soldiers may be lower than recommended in the MRDA, increasing their risk for iron deficiency anemia.
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The results of one military study presented at the workshop showed no beneficial effects of glutamine supplementation on immune function parameters. The CMNR recently hosted a workshop (The Role of Protein and Amino Acids in Sustaining and Enhancing Performance)
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5. Are there areas of investigation for the military nutrition research program that are likely to be fruitful in the sustainment of immune function in stressful conditions?
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The magnitude of stressrelated increases in the production of proinflammatory cytokines can be determined in whole-blood stimulation assays and possibly in 24-h urinary samples obtained during periods of stress, infectious illness, and/or trauma; however, the practicality and validity of urinary cytokine measures for field research studies must be determined. Studies are necessary to determine if cytokine-related measurements have greater value, greater sensitivity, or greater stimulus-related specificity than the standard measurements of red blood cell sedimentation rates and CRP protein as indicators of systemic disease and/or as models of stress-induced release or suppression of proinflammatory cytokines.
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A key question involving the immune status of Special Forces troops is how acute nutrient deprivation during training may influence host defense on a longterm basis, and whether temporary nutritional and immune deficits incurred during training may produce long-term vulnerability (see recommendation in the CMNR's report of Ranger I studies [IOM, 19923~. Research also will be needed to determine if cytokine-induced losses of essential body nutrients are important concerns in military personnel exposed to other nonnutritional stresses.
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Nutritional Status Total energy intake appears to play the greatest role in nutritional modulation of immune function. Since it has been demonstrated that prolonged energy deficits resulting in significant weight loss have an adverse effect on immune function, emphasis should be placed on the importance of adequate ration intake during military operations to minimize weight loss.
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The latter observation may explain the apparent prevalence of Keshan disease, an endemic juvenile cardiomyopathy thought to be caused by a coxsackie virus, in areas of China experiencing periodic selenium deficiency. Glutamine has demonstrated potential for improving immune function in critical illness, and parenteral and enteral administration of glutamine has been observed to improve recovery following gastrointestinal surgery, but its usefulness in healthy populations has not been determined.
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, while at the same time, excessive intakes of some trace elements may be immunosuppressive. Excess iron as well as iron deficiency may compromise immune status.
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· Additionally, the CMNR recommends the use of methods to minimize psychological stresses, including training, conditioning, and structured briefing and debriefing. Optimizing Nutritional Status · In view of the compromised immune function noted in studies of Ranger trainees, the C1\1NR recommends that, where possible, individuals who have lost significant lean body mass should not be redeployed until this lean mass is regained.
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· At this time, the CMNR cannot recommend general supplementation of military rations above the lVIRDAs for the purpose of enhancing immune function. 1 Iron deficiency anemia is defined as a serum ferritin concentration of less than 12 ,ug/ml in combination with a hemoglobin of less than 120 g/L.
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In the past, the CMNR has suggested the development of a "field-feeding doctrine" (IOM, 1995) , with the guiding principle that the energy intakes of military personnel during training and combat operations should be adequate to meet their energy expenditures and to maintain body weight and lean body mass.
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· The CMNR recommends that research be conducted to determine the appropriate field measures for monitoring nutritionally induced immune responses, particularly for determining the presence of acute-phase reactions and changes in immune function of the type and degree that are likely to occur as a result of the nutritional insults suffered by soldiers in typical deployment situations. This will require basing field studies on appropriate clinical investigations, piloting experimental designs, and using a simple panel of standard tests that have been validated for the field.
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The committee acknowledges that insufficient data are available to identify any specific nutrient or combination of nutrients as having adequately demonstrated the ability to enhance immune function under the military operational conditions investigated. This would include vitamins C and E, as well as the amino acids glutamine and arginine.
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Army Ranger Training Class 11/91. A brief report of the Committee on Military Nutrition Research, Food and Nutrition Board.
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1995. Relationship between iron status and physical performance in female soldiers during U.S.
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