The Role of Protein and Amino Acids in Sustaining and Enhancing Performance (1999) / Chapter Skim
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Executive Summary
Executive Summary
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Longer periods of intense physical exertion and possible food deprivation; advanced weaponry requiring maximum attention, precision, and decision-making ability; and greater threats of infection, injury, and exposure to environmental stressors are quickly becoming the reality that soldiers face. Military scientists charged with maintaining and optimizing the health and performance of their personnel are looking to the role that nutrition may play in this process, and have expressed particular interest in the body of current research suggesting the importance of protein and amino acids.
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The committee recommended further research on the ability of the amino acid tyrosine to enhance several measures of cognitive performance in stressful situations. The CMNR conducted a similar workshop in 1996 to examine the influence of dietary factors, including protein and amino acids, on immune fimction.
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FINDINGS Effect of Stressors on Protein Requirements of Military Personnel Baseline Protein and Amino Acid Requirements Current estimates of protein and amino acid requirements are based on studies employing the technique of nitrogen balance assessment. A 1985 report of the Food and Agriculture Organization, in collaboration with the World Health Organization and the United Nations University (FAO/WHO/UNU, 1985)
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Young's hypothesis regarding adult IAA requirements is based on estimations of obligatory indispensable amino acid oxidation computed from obligatory nitrogen (N) losses and studies of amino acid oxidation using stable isotopically labeled amino acid infusion.
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First, increases in protein intake result in increases in the catabolic processes that oxidize amino acids. This adaptation has significant implications for individuals who habitually consume high-protein diets: these individuals may face the risk of significant loss of protein stores if circumstances such as field operations suddenly force them to curtail protein intake.
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Similarly, protein needs are not increased in cold temperatures. The need to increase fluid intake when consuming a high-protein diet has led to recommendations that excesses in dietary protein intake be avoided in environments where access to drinking water may be a problem.
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The MRDA of 80 g/d would therefore be sufficient to meet the apparent protein requirements of pregnant or lactating women. Benefits and Risks of Protein and Amino Acid Supplements and Alternative Sources of Dietary Protein Evidence from recent Army surveys suggests that in addition to the high dietary protein intake of the average soldier, many soldiers use protein and amino acid supplements in the belief that these products will improve performance (Wartier et al., 1996~.
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in the diet. In laboratory animals, the rates of synthesis of these transmitters respond to changes in tryptophan and tyrosine concentrations that occur following single meals, as well as to chronic changes in dietary protein content.
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Although there is considerable research interest in the potential for supplemental protein or amino acids to increase muscle protein synthesis or physical performance, little evidence supports such a role in the absence of anabolic steroids. The "central fatigue" theory, which hypothesized that the administration of branched-chain amino acids would decrease or delay the central nervous system and muscle fatigue that resulted from increased brain tryptophan, is not supported by evidence.
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At present, there is limited evidence to suggest that high dietary protein intake may be a risk factor for osteoporosis. Calcium balance appears to remain close to equilibrium with protein intakes up to 74 g/d and calcium intakes of 500-1400 mg/d.
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Lack of safety data on the consumption of high levels of individual amino acids by normal, healthy individuals suggests that their use be limited until further research is performed. Protein and Amino Acid Supplements and Pregnancy Evidence from a major nutritional supplementation study suggests that the use of high-prote~n supplements (to achieve a protein intake that represents 34 percent of the total daily energy intake, In contrast to the more usual 11-14 percent)
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Benefits and Risks of Supplemental Protein, Amino Acids, and Alternative Sources of Dietary Protein Research fails to support the use of protein supplements to facilitate muscle building under conditions of adequate energy and protein intake. Given adequate nutritional intake, soldiers should not use protein supplements for muscle building.
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There is no evidence of increased health risks from a high intake of dietary protein; however, an amino acid imbalance may be created with use of single amino acid or protein supplements. Although no data are available from groups similar in age and fitness characteristics to military personnel, a review of the information available shows that high protein intake is not associated with direct effects on renal dysfunction.
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1993. Requirements for indispensable amino acids in adult humans: Longer term amino acid kinetic study with support for the adequacy of the Massachusetts Institute of Technology amino acid requirement pattern.
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