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Summary The military devotes major efforts to ensure the continuous safety, health, and performance of soldiers who are deployed to serve in combat. One such effort has focused on improving the nutrient intake levels of soldiers and, thereby, the nutrient levels of ration designs. Relevant findings from nutrition studies in the civilian population have been vital in this endeavor. However, because of the unique demands from the multiple stressors endured during many military situa- tions, direct application of civilian-derived dietary recommendations and nutri- tional data is not always appropriate. For example, even though the widely ap- plied Institute of Medicine Dietary Reference Intakes (IOM DRIs)--nutrient intake reference values for healthy U.S. and Canadian populations1--traditionally have been the basis of Military Dietary Reference Intakes (MDRIs), the military's nutrient standards, some values have had to be adjusted for application in mili- tary situations. In the case of essential minerals, the current military standards are the same as the IOM DRIs and are used to plan operational rations for military personnel. Military surveys suggest that soldiers' mineral intakes might not achieve the levels recommended in the MDRIs. Mineral losses (mainly via sweat) will occur because of the physical (e.g., training or combat) and environmental (e.g., ex- treme temperatures) stressors. The combination of potentially low intakes and increased losses puts soldiers at greater risk of mineral deficiencies (e.g., iron, especially in women, or zinc). 1The DRIs include the Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), Adequate Intake (AI), and Tolerable Upper Intake Level (UL). 1
2 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL The potential for adverse effects of marginal mineral deficiencies among soldiers engaged in training or military operations and the prospect of improving military performance through mineral intakes have spurred the military's interest in this area of nutrition. Thus, the U.S. Department of Defense (DoD) asked the IOM to study and assess mineral requirements and recommended intakes for military personnel in garrison training. The recommendations in this report also might be applicable to others who encounter situations similar to military train- ing, such as athletes or fire fighters. COMMITTEE'S TASK AND APPROACH Under the auspices of the Standing Committee on Military Nutrition Re- search, the Committee on Mineral Requirements for Cognitive and Physical Per- formance of Military Personnel was established to assess the need for setting nutrient intake reference levels specific to the military population and distinct from the IOM DRIs, and, if necessary, to recommend mineral intake levels for military personnel. Specifically, the committee was asked to select essential min- erals of importance to military performance and, for those selected minerals, to recommend dietary intake levels for military personnel engaged in garrison train- ing (i.e., training or performing operations from garrison). The basis for the recommended intake levels should be maintenance or improvement of physical and cognitive functions significant to military performance. In addition, the DoD requested an evaluation of the mineral levels in selected operational rations used in garrison training or sustained operations [i.e., meals, readytoeat (MREs) and first strike rations (FSRs)]. Finally, the committee also was asked to com- ment on the mineral recommendations for assault rations (e.g., FSRs) in the IOM 2006 report Nutrient Composition of Rations for Short-Term, High-Intensity Combat Operations. To address its task, the committee convened a workshop in Washington, D.C., on June 1315, 2005, during which speakers addressed the issues brought to the committee by the DoD. These presentations were the basis for the commit- tee's deliberations and recommendations and are included in Appendix B of this report as individually authored papers. The committee considered the unique circumstances that distinguish mili- tary garrison training from civilian lifestyles as well as the criteria used to establish the IOM DRIs for the general population. Next, the committee delib- erated about the need to have MDRIs distinct from IOM DRIs, the risks of mineral deficiencies during garrison training as well as the potential benefits from higher mineral intakes, and the recommended mineral requirements for soldiers engaged in garrison training. Based on those new recommended intakes, the committee evaluated the mineral content of current operational rations.
SUMMARY 3 DIETARY NEEDS FOR MILITARY PERSONNEL IN GARRISON TRAINING Adjustment of Military Dietary Reference Intakes Although the discussion that follows might be applicable to other nutrients, this committee has focused its deliberations on essential minerals. The current MDRIs for minerals [and the corresponding nutrient specifications for opera- tional rations (NSORs) based on the MDRIs] are the same as the corresponding IOM DRIs. Based on discussions regarding the establishment of MDRIs, the committee reached the following recommendation: MDRIs should continue to reflect the IOM DRIs. Modifications should be made to specific nutrient requirements if there is sufficient scientific evidence that circumstances call for different requirements and intakes, whether to maintain nutrient or health status or to improve performance. In particular, recommended values for some minerals should take into ac- count enhanced mineral losses caused by high-performance activity. Also, the MDRIs can be used for ration development for individual soldiers. The RDAs represent the nutrient intake levels that would meet the needs of nearly all of the people in a given life stage and gender group (i.e., the EAR) and are used as goals for an individual's nutrient needs. The RDA is calculated by adding two standard deviations to the EAR for the population. Often the variance of the EAR's distribution is unknown, so a standard deviation of 10 percent is used. Ideally, researchers should collect new data under the special circumstances that occur in the military (e.g., higher energy expenditures and excess sweating) to establish a new military EAR and RDA, but these data are lacking. In the absence of these data, the committee agreed that basing the current MDRIs on the IOM DRIs is appropriate and recommended that the IOM EARs for appropriate age and gender groups should be adjusted when necessary to set EARs and RDAs for military personnel. In the absence of an IOM EAR, the IOM AI (an estimated intake level that guarantees nutrient adequacy for practically everyone) could be used as a guide to ensure ad- equacy for an individual. For example, sweat losses of minerals during garrison training should be measured and factored into a new garrison training EAR, and the corresponding RDA should be calculated by using the coefficient of variation of the new EAR. This new RDA will likely fulfill the needs of 9798 percent of the military personnel in garrison training. The committee concluded that the new RDA could not appropriately be called military RDA, because the recommendations are meant to meet the unique needs only of soldiers in garrison training, not of all military personnel. For the purpose of this report, the committee refers to this new RDA as RDA for military garrison training or RDAMGT (and, similarly, EARMGT or AIMGT) (see Box S-1).
4 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL BOX S-1 Establishment of Nutrient Military Standards Nutrient standards for military personnel in garrison training should be derived as follows: 1. EARMGT: Modify the current IOM EAR by adjusting with an adequate level of the variable of interest (e.g., sweat losses). 2. RDAMGT: Add 2 × SD (standard deviation) of the EARMGT to ensure 9798 percent of soldiers will have adequate intake. Do Soldiers in Garrison Training Require Greater Mineral Intakes? Following the recommendation to establish new reference intakes for sol- diers in garrison training, the committee assessed the following research data in support of higher mineral intake requirements: (1) mineral losses with physical, psychological, or environmental stress; (2) the effects of weight loss on mineral requirements; and (3) the effects of mineral intakes on performance. In addition, the diversity in water sources as a variable for mineral intakes was evaluated (see Box S-2 for the overall finding). The committee agreed to focus the discussions and recommendations on calcium, copper, iron, magnesium, selenium, and zinc as minerals of most concern based on literature reviews about their importance to physical and cognitive performance and maintaining health status. BOX S-2 Overall Findings on Mineral Requirements for Military in Garrison Training The committee concluded that there is strong evidence that sweat mineral losses of copper, iron, and zinc might be significant during garrison training. There are not sufficient data on sweat losses for calcium, magnesium, and selenium to recommend an increase in dietary intake. Research demonstrating that an in- crease in intake of a particular mineral imparts benefits to physical or cognitive performance is still in an exploratory phase and warrants more studies. Therefore, only requirements for copper, iron, and zinc are adjusted on the basis of increased sweat losses, and revised RDAMGT are proposed for those minerals. The commit- tee recommends using the current IOM AI for calcium and the current IOM RDAs for magnesium and selenium as the military requirements. All of the recommended requirements should be updated as new or confirmatory data from appropriately designed studies emerge regarding mineral losses and effects from higher intake doses of specific minerals. The derivations for the new RDAMGT and AIMGT are in Table S-1.
SUMMARY 5 Mineral Requirements Due to Stressors There is evidence to suggest that the mineral losses through sweat primarily, but also through feces and urine, might be significant with physical stress. How- ever, many of the studies addressing mineral secretion with exercise either can- not be applied to the military environment or have design flaws, or both. For example, many studies were too brief and, therefore, ignored any acclimatization effects that could result in sweat losses decreasing over time. Also, it is a collec- tion and that for more accurate determinations samples should be collected from whole-body sweat instead of from patches in specific sites, as collected in many studies. Nevertheless, because the majority of studies suggest that the losses are real, the committee has estimated the increased losses for iron, copper, and zinc, based on the best available data. It was estimated that average additional sweat losses for copper, iron, and zinc during garrison training would be respectively 0.5, 1, and 2 mg/day for men. To estimate losses for women, it was assumed that mineral losses amount to 30 percent less than in men. There is not enough evi- dence on other minerals' losses. These values should be revisited when studies designed as described in Chapter 4 become available. Mineral Requirements to Improve Performance There is no definitive evidence indicating that specific mineral supplemen- tation beyond the current MDRIs will improve soldiers' physical or cognitive performance; therefore, there is no recommendation to this effect. There are, however, scientific studies that strongly suggest the potential for improved per- formance with higher mineral intakes. For example, a positive interaction be- tween physical activity and calcium intake has been demonstrated in the bones of postmenopausal women; however, the same interactions have not been stud- ied in groups that would better reflect the ages and lifestyles relevant to the military. Increased calcium intake also appears to improve mood states but needs to be demonstrated under garrison training scenarios. Anecdotal data suggest that iron status might not be adequate for many women entering the military. The initial iron status likely will be aggravated by intense physical activity typical of garrison training. There is convincing evidence that iron supplementation improves physical performance of civilian women with low iron stores but no anemia. The data show that in women with low iron stores, iron supplementation improved endurance and the benefits of aerobic training and decreased muscle fatigability, functions that are highly rel- evant to military needs. There is also suggestive evidence that, in civilians, iron status is associated with improved cognitive functions and behavior. Recent stud- ies demonstrated that civilian women who reached the highest iron status had improved measurements of attention, learning skills, and memory functions. Studies conducted to determine the effects of iron supplementation on mood
6 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL states indicated that depression severity declines if iron deficiency is treated. Although there is no doubt that the data are promising, all studies linking cogni- tion and behavior with iron status have been done in civilians. Therefore, the committee concluded that before iron requirements are increased with the objec- tive of improving performance, more research should be conducted with the subjects and environment of interest. A limited number of studies have examined the potential relationship be- tween magnesium and sleep of military personnel. The association between sele- nium and zinc and mood states has also gained some interest, but the data for these relationships are merely suggestive and still preliminary. Mineral Deficiencies During Weight Loss Diets Weight-loss diets are prominent among military personnel, mainly due to expectations to meet military standards for weight. If nutrient intake is not man- aged properly, the health and performance of individuals on weight loss diets could be compromised. For example, there is strong evidence that weight loss is associated with a loss of bone mass and a related increase in fracture risks in overweight and obese subjects as well as in postmenopausal women; calcium supplementation has been shown to minimize such bone loss. Recommending higher protein intakes and calcium intakes of at least 1,000 mg/day and as much as 1,5001,700 mg/day is prudent to ensure minimal bone loss during weight- loss regimes. However, confirmatory research that these amounts are adequate for military personnel should be conducted. For other minerals, there is little evidence that following weight-loss diets necessitates increased requirements, especially when protein intake is high enough so that catabolism and, therefore, mineral losses are minimized. The committee emphasizes, though, that when following weight-loss diets mineral intakes should meet, at a minimum, the lev- els recommended in this report. Uses of Military Dietary Reference Intakes DRIs are used for dietary planning and assessment for populations (IOM, 2000, 2003). In order to plan menus or rations for a large group, such as soldiers in garrison training, the EAR and the variability in intakes in a specific popula- tion are needed. In the absence of intake distribution data, the EARMGT cannot be used for the actual planning of cafeteria menus for soldiers, and, for the present, managers should make sure that the food available in the cafeteria contains all the food groups so that the MDRIs are likely to be met and the menus follow nutrition guides such as the Dietary Guidelines for Americans and MyPyramid. Conversely, although variability of nutrient intakes for military personnel eating operational rations is unknown, it can be safely assumed that it will be small if they completely consume the rations issued; therefore, planning rations for individuals (as opposed to planning rations for groups) would be appropriate
SUMMARY 7 and can be done by using the RDA as the reference value. In that case, rations should meet the new military RDA for minerals established in the manner de- scribed in Box S-1. In cases of a gender difference, the recommended amount in the rations should be the highest one, but lower than the UL for the age range. Accordingly, the current NSORs (based on MDRIs) are established to represent the minimal levels of minerals in operational rations and, when adjusted as de- scribed, would provide adequate levels for military personnel under specific military situations. The committee supports the use of NSORs as minimum levels of miner- als in operational rations; NSORs should be established based on new mili- tary RDAs (e.g., RDAMGT), developed as new scientific data become avail- able. The NSORs might be different for specific military situations; for example, NSORs for military garrison training and those for sustained op- erations might differ. Are the Mineral Contents of Operational Rations Adequate? Do the Mineral Levels in Water Contribute to Total Mineral Intake? The average mineral composition of various menus for three different MREs and three different FSRs provided by the U.S. Army Research Institute of Envi- ronmental Medicine was used to assess adequacy. Although on average, most mineral content in rations meet the recommendations of this committee, some menus should be revised so that they meet the RDAMGT and AIMGT for both men and women, assuming that women will consume two MREs and men will con- sume three MREs. Exceptions of minerals whose average levels do not meet the recommenda- tions of this committee are the content of iron for women (RDAMGT = 24 mg versus an average of 18 mg in two MREs), zinc for men (RDAMGT = 15 versus an average of 14 mg in three MREs), or zinc for women (RDAMGT = 11 mg versus an average of 9 mg in two MREs). The mineral content of the FSRs appears to meet the recommendations of the current committee, except for calcium, whose average content in FSRs (673 mg) is slightly lower than the one recommended (750 mg, see Table S-1). Regarding mineral levels in water, the committee concluded that, due to sanitation processes applied to fresh water for human consumption, differences in the mineral content of water are not such that will affect the total intake levels of minerals by military personnel. The committee concluded that the addition of calcium and magnesium to water consumed by military personnel is warranted only when improving the taste is the desirable outcome. FUTURE NEEDS The committee stresses that the recommendations in this report regarding specific mineral requirements need confirmation based on data collected from
8 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL TABLE S-1 Mineral Intakes: Institute of Medicine Dietary Reference Intakes, Current Military Dietary Reference Intakes, Recommended Intakes for Garrison Training (EARMGT, RDAMGT, or AIMGT), and Recommended Levels for Assault Rations IOM RDA RDAMGT Levels for Nutrient or AI MDRI or AIMGT Assault Rations* Calcium (mg) Male 1,000 1,000 1,000 750850 Female 1,000 1,000 1,000 Copper (µg) Male 900 ND 1,800 9001,600 Female 900 ND 1,500 Iron (mg) Male 8 10 14 818 Female 18 15 24 Magnesium (mg) Male 420 420 420 400550 Female 320 320 320 Selenium (µg) Male 55 55 55 55230 Female 55 55 55 Zinc (mg) Male 11 15 15 1125 Female 8 12 11 NOTE: AI = Adequate Intake; EAR = Estimated Average Requirement; MDRI = Military Dietary Reference Intake; MGT = Military Garrison Training; ND = Not Determined; RDA = Recommended Dietary Allowance. *IOM (2006). controlled studies designed for specific military objectives and carried out under military-like environments. Conducting a comprehensive research agenda to an- swer all questions about mineral requirements for the military would not be feasible; therefore, the committee delineated a research agenda by prioritizing the questions on the basis of military needs and strength of the evidence, assum- ing that other pertinent, but less essential, information about minerals will be emerging through research at nonmilitary institutions. First, studies to clarify concerns about soldiers' potential marginal mineral deficiencies were given the highest priority. To address those concerns, two overall, cross-cutting studies that apply to more than one mineral are proposed and further explained in the following section. Then, the most important studies to pursue have been listed and prioritized according to the strength of the available evidence, with the first study being the highest priority and so on (see specific research priorities for each mineral listed in alphabetical order at the end of this section). These are studies that would
SUMMARY 9 BOX S-3 Key Research Needs The committee recognizes that the proposed studies will be expensive to con- duct; therefore, among all of the outlined research questions the following should take precedence. Highest Research Priorities · What are the effects of military garrison training conditions on mineral losses? · What is the iron status at entry, deployment, and throughout military service? What is the total intake of calcium (i.e., from food, dietary supplements, and calcium-containing medications) at entry, deployment, and throughout military service? Other Research Priorities · Does iron supplementation prevent iron deficiency? What is the best strategy to prevent iron deficiency? · How does physical activity during military garrison training influence calcium requirements in military personnel? · Do iron intake amounts above the levels recommended in this report have beneficial effects on cognitive functions? · Do magnesium intake amounts above the levels recommended in this report offer protection from sleep deprivation disturbances? · Do zinc intake amounts above levels recommended in this report result in improved physical and cognitive performance? confirm existing data on any potential higher requirements due to exercise or on any potential performance benefits from supplementation. The committee recog- nizes that the proposed studies will be expensive to conduct; therefore, a list of necessary key research questions that will assist in establishing new require- ments for military personnel in garrison training has been extracted (see Box S-3). Priority #1: Study the Effects of Military Garrison Training on Mineral Losses and Performance Questions How do the physical, psychological, and environmental stressors encoun- tered by military personnel (e.g., heat, physical activity, and possibly sleep re- striction) effect mineral losses and what is the related impact on physical and mental performance? What are the dietary intake levels required to replenish the losses and to optimize performance?
10 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL General Design These questions could be addressed through a study design conducted with a population representative of the military, including both women and men. Each subject would participate in a baseline phase (versus a stress phase with heat and heavy exercise) that includes the consumption of a controlled diet based on either the current typical MRE or rations with the NSOR mineral levels. Subse- quently, each subject would receive all dietary treatments (cocktails of higher and lower mineral levels) in randomized order while being subjected to heat and physical demands similar to those experienced by military personnel. Consider- ing possible nutrient interactions of the diet interventions is critical when design- ing the study and interpreting the results. Conditions could be controlled by using an environmental chamber and supervising physical activity. Because train- ing and operational exercises may involve significant reductions in total sleep and disruptions of the normal sleepwake cycle, both of which reliably result in severe decrements in cognitive function and mood, sleep restriction should be considered as an additional intervention. Measurement of Outcomes This experimental design evaluates a doseresponse effect of minerals on ameliorating mineral losses due to heat and sweat and can be used to assess a doseresponse effect of minerals on physical and mental performance. Daily, 24-hour whole-body sweat analysis and potential acclimatization over a short term (five days) and a long term (two or three weeks) can be measured. During baseline and each treatment, cognition and behavior outcome mea- sures could include assessments of sleep patterns; mood states; cognitive function, including attention, memory, and decision making; and psychomotor skills. The most important physical performance measurements are those for aerobic and mus- cular endurance, and the military should select those that have been proven to reflect the reality of military environments and physical performance demands. Priority #2: Mineral Status and Food and Dietary Intakes Questions What is the mineral status or dietary intake level (especially of calcium and iron) of soldiers at various times from entry to training, deployment, or combat? Iron Status The committee concluded that women's iron status is an important criterion that will determine whether a strategy to increase women's iron intake is needed;
SUMMARY 11 if a strategy is needed, it is critical to identify which would be the most efficient in correcting the deficiencies. Also, surveillance programs should be established to monitor iron status (measured by serum ferritin levels) at the end of all inten- sive training phases as well as periodically during military service. Calcium Intake Because of calcium's potential role in preventing stress fractures during training or combat and in modulating emotional health, calcium intake from food beverages, dietary supplements, and calcium-containing medications should be surveyed periodically. There is no biomarker for calcium that can indicate calcium status; instead, an indication of status is suggested from the total dietary intake. The same studies used to analyze rations for calcium levels and to assess dietary intake could be adapted with a minimum of additional resources to ana- lyze copper, magnesium, selenium, and zinc. Specific Research Priorities: Calcium · Quantify calcium losses due to the stressful conditions of garrison train- ing (i.e., heat and physical exertion) (see priority #1 above). · Assess for calcium intake the current diets of military personnel under the various environments as a practical approach to assess calcium status. This should include calcium intakes from food, beverages, dietary supplements, and calcium-containing medications (see priority #2 above). · Conduct balance and kinetic studies to understand the role of physical activity on calcium metabolism and requirements. · Study the potential adverse effects of weight loss and interactions with calcium supplementation in bone loss. · Study the potential effects of dietary calcium on counteracting the nega- tive interaction of exercise and oral contraceptives on women's bones. · Study the association between calcium intakes above 850 mg/day and the risk of kidney stone formation. · Study the relationship of calcium intake and mood, premenstrual syn- drome, depression, and other psychological factors that affect performance. Specific Research Priorities: Copper · Quantify copper losses due to the stressful conditions of garrison training (i.e., heat and physical exertion) (see priority #1 above). · Determine the copper concentrations of food items in operational ra- tions, including MREs and FSRs; estimate the dietary intake levels of military personnel.
12 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL Specific Research Priorities: Iron · Quantify iron losses due to the stressful conditions of garrison training (i.e., heat and physical exertion) (see priority #1 above). · Determine the prevalence of iron deficiency in women at entry to train- ing camp and deployment; regularly survey their status to monitor the stability of their mineral nutritional status (see priority #2 above). · Determine the relationship between iron status and cognitive and behav- ioral functions within the context of military garrison training. · Determine if supplemental iron or dietary intervention approaches, or both, can alleviate the drop in iron status of female soldiers in garrison training versus iron supplementation only after screening. Specific Research Priorities: Magnesium · Quantify magnesium losses due to the stressful conditions of garrison training (i.e., heat and physical exertion) (see priority #1 above). · Determine whether increasing magnesium intake will improve sleep, pro- tect against the effects of sleep deprivation, or regulate mood states of soldiers in garrison training. · Determine the magnesium concentrations of food items in operational rations, including MREs and FSRs; estimate the dietary intake levels of mili- tary personnel. Specific Research Priorities: Selenium · Quantify selenium losses due to the multiple stressors of garrison train- ing (i.e., heat and physical exertion) (see priority #1 above). · Determine whether selenium supplementation of nondeficient subjects can improve immune function. · Determine the selenium concentrations of food items in operational ra- tions, including MREs and FSRs; estimate the dietary intake levels of military personnel. · Determine whether increasing selenium intake will benefit military per- sonnel's mood states, especially depression. Specific Research Priorities: Zinc · Quantify zinc losses due to the multiple stressors of garrison training (i.e., heat and physical exertion) (see priority #1 above). · Evaluate the possible benefit of zinc supplementation on physical performance. · Evaluate the potential benefits of zinc supplementation to enhance cogni- tive function. · Determine the zinc concentrations of food items in operational rations, including MREs and FSRs; estimate the dietary intake levels of military personnel.