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2 Military Dietary Reference Intakes: Process to Establish, Uses, and Delivery Methods Nutrient standards are developed to ensure that different populations' (indi- viduals or groups) nutrients needs are met--they serve as criteria for dietary nutrient adequacy. In the United States, the Dietary Reference Intakes (DRIs) recommended in various Institute of Medicine (IOM) reports (IOM, 1997, 1998a, 2000b, 2001, 2002/2005, 2005) are used as the nutrient standards to ensure a healthy U.S. population (see Table 1-1). The DRIs are comprised of the follow- ing four nutrient-based reference values established by gender and age group-- the Estimated Average Requirement (EAR), the Recommended Dietary Allow- ance (RDA), the Adequate Intake (AI), and the Tolerable Upper Intake Level (UL). The IOM EARs and RDAs are the average intake levels that meet respec- tively the requirements of 50 and 9798 percent of the healthy individuals in a population in a particular life stage and gender group. An RDA is the reference value--derived mathematically from the EAR population distribution--for plan- ning individual intakes. If an EAR cannot be determined because of a lack of experimental data (e.g., balance studies), then the AI (estimated intake by a population, based on observed or experimentally determined approximations of nutrient intakes) is used for planning individual intakes. The IOM UL is the highest intake level likely to pose no risk of an adverse health effect to almost all individuals. As mentioned previously, changes in the DRIs are the prerogative of the IOM DRI committee and will be considered and applied as new relevant information becomes available. Military personnel engage in activities that may require higher intakes of specific nutrients to maintain health. If the objective is not only to maintain health, like with the IOM DRIs but also to optimize performance, then the nutri- 36
MILITARY DIETARY REFERENCE INTAKES 37 ent needs might change even more. The establishment of standards specific to the military population requires not only expertise in nutrient metabolism but also in-depth knowledge of the military scenarios and factors that need to be considered thereof. Such standards--the Military Dietary Reference Intakes (MDRIs) and the nutritional standards for operational rations (NSORs)--were last published in 2001 Army Regulation (AR) 40-25 (U.S. Departments of the Army, Navy, and Air Force, 2001) before the publication of numerous IOM reports, including those that have provided revised IOM DRI values for some minerals (IOM, 2001). Table 1-1 in Chapter 1 shows the MDRIs, the NSORs, and the IOM RDAs (or AIs) for men and women. MDRIs are intended to serve menu developers and other nutritional special- ists with ensuring adequate nutrition of military personnel during garrison activi- ties, that is, when the personnel are eating primarily from cafeteria-style menus in dining facilities, not from operational rations. In contrast, the NSORs have been established to represent the minimal levels of nutrients that operational rations should contain; these levels would provide adequate nutrition for most military personnel doing moderate or intense physical activity and are based on the MDRIs (see Chapter 1). AR 40-25 (U.S. Departments of the Army, Navy, and Air Force, 2001)--the 2001 regulation stating the MDRIs and NSORs--will be revised soon (Baker-Fulco, 2005; see Appendix B) to possibly reflect updated DRI values that take into account new EARs (e.g., for iron and zinc) or nutrients previously without MDRIs (e.g., copper and manganese). The 2001 MDRIs were based entirely on the DRIs but were applied to the military population, which in general tends to be a little heavier and more active than the U.S. population (Baker-Fulco, 2005; see Appendix B). Many of the MDRI values are similar to the DRIs, with the notable exception of sodium. Although the following discus- sion on the process of establishing mineral standards for the military might be applicable to other nutrients, the Committee on Mineral Requirements for Cog- nitive and Physical Performance of Military Personnel has focused its delibera- tions on standards for minerals, therefore, these recommendations apply mainly to the establishment of mineral standards. There are two main types of feeding schedules in the military: garrison and operational rations. Garrison feeding refers to food consumption by military personnel who are under a variety of scenarios that range from administrative duties (e.g., office workers completing physically inactive tasks) to support tasks performed by personnel (e.g., hospital personnel involved in moderate levels of activity) to soldiers training for or performing missions while living on a military base (e.g., Rangers training at high levels of physical activity). Operational feeding refers to the consumption of either full- or restricted- calorie rations while engaged in military operations (e.g., sustained operations as defined in Chapter 3) or training. The MDRIs are used to establish the NSORs for full-calorie, standard operational rations as well as for restricted-calorie ra- tions. There is an expectation that operational rations will be used by men and
38 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL woman who undergo much more rigorous physical activity than the average person in the same age range in the U.S. general population. This report is concerned with soldiers in garrison who perform a moderate- to high-level of physical activity (referred to throughout the report as "garrison training" and defined in Chapter 3) and with soldiers in sustained operations while eating operational rations [i.e., first strike rations (FSRs)]. MILITARY NUTRIENT STANDARDS Is There a Need for Specific Military Nutrient Standards? Because of the different environmental and physiological circumstances of- ten encountered by the Armed Forces, the MDRIs (traditionally variants of the IOM DRIs) have been developed to plan appropriate intakes and rations for enlisted personnel. There are several good reasons to establish the MDRIs, dis- tinct from the IOM DRIs for the U.S. general population. First, the reference anthropometric standards for the military are different from those for civilians. The reference military person is slightly different in height, weight, and body fat and lean mass compared to the civilian person. Second, the MDRIs are targeted to individuals who are 1750 years old, the age range of the vast majority of enlisted men and women (for those who are 1718 years old, AR 40-25 includes exceptions to the MDRI levels, indicated as foot- notes to the MDRI tables) (U.S. Departments of the Army, Navy, and Air Force, 2001). The MDRIs are stated as a single value for men and women when they are used to establish NSOR, that is, the highest gender-specific reference value for 1750 year olds is used. The MDRIs could be adapted for specifying differ- ent recommendations for males and females, should that be necessary. There are no ULs specifically for the military, because the UL values are judged to be the same as those for civilians. Second, the process of developing the MDRIs involves examination and deliberation about the specific requirements of the military, not taken into ac- count when establishing the DRI for the general population. For example, MDRIs specify appropriate nutrient intakes in especially stressful environments (e.g., those with extremes in weather) or under different levels of activity. Other groups within the military that might need special nutrient requirements are those con- suming calorie-reduction diets or suffering from illnesses, such as infections or those performing tasks that demand appropriate maintenance of cognitive func- tions (e.g., attention or alertness). Hence, it would be possible to specify condi- tions for various special circumstances, such as garrison training and sustained operations, each with its own idiosyncrasies that might result in different nutri- ent recommendations. In fact, although the MDRIs are based generally on the IOM DRIs, there are already some exceptions to them based on unique situa- tions; the rationale for these exceptions is stated explicitly in an accompanying
MILITARY DIETARY REFERENCE INTAKES 39 document (Baker-Fulco et al., 2001), which is updated periodically by the U.S. Department of Defense. As the science addressing the unique nutrient needs of the military personnel emerges, additional exceptions will have to be made, as illustrated in the mineral level recommendations listed in Chapter 3. The importance of establishing military-specific nutrient standards lies in the fact that the MDRIs serve as a useful basis for devising menus for the troops. The MDRIs are used as a sort of minimum standard to be supplied in developing rations for which the military provides most or all of the food. This is a critical and practical application of the MDRIs. It may be that some rations' nutrient levels would be inadequate--especially when soldiers face extreme environmen- tal or stressful situations--if the IOM DRIs for the general population were used. The third reason for establishing and periodically revising the MDRIs is to demonstrate that the Armed Forces have duly noted and carefully considered and updated recommendations for feeding enlisted men and women. Maintaining and promoting the health of the military who are serving public interests should be among the utmost priorities and deserve the highest consideration. RECOMMENDATION: The MDRIs should continue to reflect the IOM DRIs. Modifications should be made to specific nutrient re- quirements if there is sufficient scientific evidence that circum- stances call for different requirements and intakes, whether to maintain nutrient or health status or to improve performance. In particular, some recommended values for minerals should reflect enhanced mineral losses caused by high performance activity. Also, the MDRIs can be used for rations development for the individual soldier. Establishment of Nutrient Military Standards The MDRIs have not been established using the more systematic approach followed for deriving the IOM DRIs because critical experimental studies to develop them were lacking. The foundation for setting RDAs is the EAR for a given gender and life stage within a population. As mentioned previously the EAR is the nutrient intake level for a population group that would meet the needs for 50 percent of that population and should be based on appropriate experimen- tal data that allow an estimate of average requirements. The RDA then can be set by adding two standard deviations (SDs) of the EAR to the EAR if the require- ment is normally distributed. Thus, the RDA = EAR + (2 × SDEAR). Often the SD of the EAR's distribution is unknown, and a coefficient of variation of 10 percent around the EAR is used. In any case, it follows that establishing an EAR is necessary for setting an RDA. Although, ideally, one should collect new data under the special circumstances that occur in the military (e.g., higher energy
40 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL expenditures and excessive sweating) to establish a new military EAR, it is unlikely that such data will be collected specifically for military personnel. In the absence of these data, adjustment of the existing EAR for appropriate age and sex groups may be necessary to set an RDA for military personnel. If an IOM EAR for the U.S. population does not exist, then the U.S. population's AI (which allows estimating an intake level that will be adequate for practically everyone in a particular life stage and gender) could be used as a guide to ensure adequacy. There is less confidence, however, in using an AI as a nutrient stan- dard than there is in using an RDA. Moreover, using an AI as a criterion for planning rations and menus as well as for assessing intake adequacy presents special challenges (IOM, 2000a, 2003). Thus, the committee urges that research studies be designed to determine the EAR adjustments needed for those nutrients whose requirements will most likely change under the environmental conditions of higher energy expenditure and stress that accompany garrison training and other unique military situations. In addition, the standard deviation of such experimental data should be derived in order to calculate an RDA for military personnel. For example, sweat losses of minerals during garrison training should be measured and factored into a new garrison-training EAR; in other words, to calculate the military standard, the IOM EAR should be modified accordingly (see the following section, Factors Affecting Nutrient Needs for Military Personnel, for other considerations). Using an approach that is similar to the derivation of IOM RDAs, the new military RDA for garrison training for each nutrient could be calculated by using the new EAR's standard deviation. Such an approach will result in a new level estimated to be adequate to fulfill the needs of 9798 percent of the military personnel in garrison training. The committee concluded that the new RDAs could not appro- priately be called military RDAs, because they are meant to meet the unique needs of those in garrison training, not all military personnel. For the purpose of this report, the committee will refer to these new RDAs as RDAs for military garrison training or RDAMGT (also EARMGT or AIMGT). The following two-part equation--using the example of mineral losses during garrison training-- demonstrates how the new standard will be calculated: 1. Current IOM EAR + additional mineral sweat losses = EARMGT 2. EARMGT + 2 × SD (EARMGT) = RDAMGT RECOMMENDATION: Nutrient standards for the military in gar- rison training should be derived as follows: 1. EARMGT = Modify the current IOM EAR by adjusting for the variable of interest (e.g., level of sweat losses) 2. RDAMGT = Add 2 × SD of the EARMGT, to ensure 9798 percent of soldiers will have adequate intake
MILITARY DIETARY REFERENCE INTAKES 41 Factors Affecting Nutrient Needs for Military Personnel There are at least five different ways in which nutrients deficiencies may develop: (1) reduced intake, (2) impaired intake due to disease or trauma, (3) increased losses, (4) impaired utilization, and (5) increased requirements. One or more of these factors may be involved in increasing an individual's vulnerability toward nutrient deficiency. Except for those individuals in the military who are responsible solely for administrative tasks, military life encompasses unique cir- cumstances that, for some nutrients, may result in nutrient requirements different from those of the general population. For example, soldiers are involved rou- tinely in training, combat, and support operations; these activities carry with them a number of stresses that are extremely demanding, both physically and mentally, for each individual. It is important to periodically examine the nutrient needs of various groups within the military and to adjust or develop new MDRIs accordingly. In addition to any altered nutrient requirements that emerge as a result of the unique situations in military life, it is necessary to distinguish between the nutri- ent requirements as defined in previous IOM reports and the nutrient require- ments that will be recommended in this report, which are referred to as standards for individuals for various military situations (e.g., RDAMGT). An underlying principle of the RDAs set by the IOM is that the desired outcome was to main- tain health in already healthy people; improving performance was not relevant. Following this principle, the IOM levels are based on calculations of the amounts that must be provided to meet physiological needs under relatively normal con- ditions. In contrast, the task given to this committee was to determine mineral requirements that sustain but also improve military performance, including physi- cal and cognitive performance. Accordingly, the RDAMGT or AIMGT recom- mended by this committee have taken into account not only requirements to meet physiological needs, but also any scientific evidence that would support potential benefits of a particular nutrient level on military performance. Out- comes that have been considered by this committee are mostly those included in the cognitive and behavioral systems, immune and endocrine systems, and mus- culoskeletal system. Currently the MDRIs-based NSOR are meant for the healthy military popu- lation; they are supposed to cover the needs of military personnel under operat- ing conditions, whether simulated or actual combat. The major feature that cur- rently distinguishes the MDRIs from the IOM DRIs is a need for additional sodium for individuals who do hard physical work. Future reiterations of the Army Regulations should reflect other unique requirements of military per- sonnel undergoing physical exercise under stress and extreme environmental conditions. Variables such as nutrients' bioavailability, interactions with other nutrients, and nutrient degradation due to long-term storage should be factored in when
42 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL designing rations. The rations should contain at least the level of nutrients required, plus an amount of nutrient that reflects nutrients' bioavailability or losses during food processing or storage. RECOMMENDATION: As more evidence becomes available, the committee recommends that military nutrient standards for unique circumstances in the military (e.g., soldiers engaging in sustained operations or in garrison training) be updated periodically by con- sidering scientific evidence from studies on the benefits of specific nutrients (e.g., for improved cognitive function) or from studies re- vealing altered nutrient metabolism due to military performance (e.g., increased sweat losses). Use of Nutrient Military Standards To recommend levels for mineral nutrient standards that are scientifically- based as well as practical, it is important to consider the intended use of such standards. With this in mind, the committee asked for guidance from military personnel with experience in implementing the military nutrient standards, both the 2001 MDRIs and the previous standards, the 1985 MRDAs. In addition, the committee requested opinions from military professionals (including physicians, dietitians, and Quartermaster Corps) regarding the need for distinction between the MDRIs and the IOM DRIs. The requests revealed that the MDRIs were used as basis for the NSORs, which are used for rations planning and assessment; consequently, they affect the Combat Feeding Program for both training and combat (e.g., sustained operations) more directly than they affect the menu de- signs or dietary counseling activities in garrison situations. In summary, there is a place for the MDRIs as nutrient standards in the context of military operations, but they are not as useful as a basis for the garrison training situations during which cafeteria-style food is offered ad libitum. As with other dietitians, those in the military rely on the DRIs for counsel- ing clients or for planning garrison menus. The major goal for garrison menus is to provide variety of healthy options to military personnel who eat in the dining facilities, especially for those who are trying to lose weight. Dietitians use basic and flexible menu standards; devising menus primarily by using food-based guidelines, such as the Department of the Army Pamphlet 30-22, Operating Procedures for the Army Food Program (U.S. Department of the Army, 2002), rather than the nutrients standard in AR 40-25 (U.S. Departments of the Army, Navy, and Air Force, 2001). Although installation commanders are told to pro- mote a comprehensive nutrition program for all operational dining facilities through AR 30-22, The Army Food Program (U.S. Department of the Army, 2005), respondents to the committee's queries indicated that implementation and oversight varied greatly by commander. Food Operations Sergeants (FOS) are
MILITARY DIETARY REFERENCE INTAKES 43 asked to consider nutritional adequacy in accordance with the Nutrition Stan- dards and Education, AR 40-25 (U.S Department of the Army, 2002) when they make adjustments to the dining facility menus--AR 40-25 regulations are cited in various places in Department of the Army Pamphlet 30-22. The most practical use of the IOM DRIs is in the dietary planning and assessment for populations and individuals; these uses have been described in two reports (IOM, 2000a, 2003) that illustrate the processes with practical ex- amples. Generally, the IOM DRIs are used for planning to ensure a low preva- lence of inadequate nutrient intakes. For example, the IOM DRIs can be used by an individual to plan his or her diet and food purchases or by a food service manager to plan menus for an institution. To plan menus or rations for a large group, the EAR (the average intake for nutrients by the target population) or AI and its distribution should be known. To plan diets for individuals, however, it is appropriate and sufficient to use only the RDAs. Both the group and individual planning also use the UL as well. Similar to the IOM DRIs, the MDRIs could be used to plan and assess menus for military personnel. The difficulty in assessing the nutritional adequacy--whether nutrient com- position satisfactorily will meet nutrient needs--of menus for soldiers in garri- son training is the lack of data on the intake distribution. The distribution is likely to be broad when individuals are sometimes eating cafeteria food ad libi- tum, as soldiers do when in garrison training. This lack of data is a limitation that partially explains the fact that the MDRIs are not typically used to plan or assess menus for soldiers with free access to cafeteria food. This committee speculates that the MDRIs could be used by cafeteria menu planners as a useful benchmark for what levels of nutrients are needed in foods on the menu. However, that task is beyond the scope of this report. The IOM report Applications in Dietary Plan- ning (IOM, 2003) should serve as a guide on using MDRIs for dietary planning for populations. For the present, managers should make sure that cafeteria food is nutritionally diverse and adequate and that it contains all of the food groups so as to meet an individual's MDRIs. Food service managers should include dieti- tians and nutritionists who also are capable of applying nutrition guides, such as the Dietary Guidelines for Americans (http://www.healthierus.gov/dietaryguide lines/) and MyPyramid (http://www.mypyramid.gov/), to the design of cafeteria food choices. The committee encourages studies by the military on nutrient in- take distribution data that would assist the military in using the MDRIs to plan menus. Conversely, although the nutrient intake levels for those eating rations is not known, it can be assumed safely that such levels will not vary too much if all of the rations issued are fully consumed. Under such circumstances, group- planning methods are not needed. Instead, the goal will be that each individual eating the rations gets the recommended intake, which can be expected since each individual within the group will be provided the same level of nutrient (mineral). In particular, to plan the levels of minerals in operational rations for
44 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL garrison training, rations should meet the new military RDAs (e.g., RDAMGT) for minerals, which should be established specifically depending on the operation and environment (e.g., garrison training versus sustained operations). In this report, the assumption is made that most soldiers in military opera- tions will consume their complete rations. Since males and females may differ in requirements, and given that the Army cannot particularize its rations, the rec- ommended mineral amounts in the rations for groups with gender differences should be set at the highest standards. In every case, this recommended level should be lower than the UL for the age range. Accordingly, the current NSOR are established to represent the minimal levels (or those that are maximums) of nutrients in operational rations and, when adjusted as described (where the aver- age menu meets one-third of the NSOR and no single menu is 20 percent below set minimums or above set maximums of one-third the NSOR limits [Baker- Fulco et al., 2001]), would provide adequate levels for military personnel under specific military situations. RECOMMENDATION: The committee supports the use of NSORs as minimum levels of minerals in operational ration; NSORs should be established based on new military RDAs (e.g., RDAMGT), devel- oped as new scientific data become available. The NSORs might be different for specific military situations; for example, NSORs for military garrison training and those for sustained operations might differ. THREE STRATEGIES TO INCREASE NUTRIENT INTAKE The following three basic strategies can be used to improve intake and nutri- tional status of enlisted personnel: food-based approaches, fortification, supple- mentation (IOM, 1998b). The uses, advantages, and disadvantages of each strat- egy are described in the following sections. Typical Food-Based Approaches The most common food-based strategies to raise nutrient intake are those that encourage dietary diversification and frequent consumption of particularly nutrient-rich food sources. Uses and Advantages The advantages of these strategies include greater acceptability by the target population, the ability to provide many nutrients simultaneously, and the rela- tively low cost. Also, concentrated doses of nutrients that may be problematic or associated with toxicities are avoided. Finally, there are potentially beneficial
MILITARY DIETARY REFERENCE INTAKES 45 bioactive food components that, because they are not nutrients, are not added to foods as fortificants or supplements. Food-based strategies are relatively long- term strategies if changing diets or food habits is necessary, but they can be combined with shorter-term strategies to achieve needed results. In an ideal situation--if food access, availability, and diversity were optimal--the nutrient needs of the general population would be met solely from food sources, since there are many different food combinations in diets that sustain good health. The optimal food combinations depend on the food characteristics and the larger environments, economics, and other factors (e.g., accessibility) that may apply only to the military. There is a general perception that nutrients from food are healthier than those that come from supplements. Although it is true that some forms of vita- mins and minerals are different or more bioavailable in foods than in supple- ments, this is not true in all cases; bioavailability varies from nutrient to nutrient. In fact, some nutrients (e.g., various forms of calcium) are more bioavailable in fortificants and supplements than they are in food form. Many constituents that exist in a food matrix may influence not only nutrient bioavailability but also their functions in the body. In general, if the diet is complete and balanced, no supplement is needed to meet the DRI. For these reasons, most nutrition science experts favor food-based strategies and dietary patterns instead of ones that em- phasize dietary supplements (Lichtenstein and Russell, 2005). Also, even though it has not been possible to show a decreased incidence of cardiovascular disease or other chronic degenerative diseases with simple single-nutrient supplementa- tion or fortification programs, total dietary patterns do seem to make a greater difference. For example, the Dietary Approaches to Stop Hypertension (DASH) diet--which uses regular food items to provide a moderate- to low-fat diet high in calcium, potassium, and magnesium (elements that have been associated with a decreased risk of heart disease)--does seem, in fact, to have a beneficial effect on blood pressure, especially when dietary sodium is also lower (Appel et al., 1997; Harsha et al., 1999). Disadvantages One of the disadvantages associated with food-based strategies is that it is a long-term strategy; thus, when more immediate results are necessary, they may not be achievable in a short time period. A second disadvantage is that dietary strategies involving ordinary foods are rarely helpful therapeutically. Once dis- ease is present more radical measures, including diet therapy and supplementa- tion, are likely to be needed. Third, educators need to be involved extensively, and, if the food is not already available, then the agricultural sector must become involved to produce it. Also, long-held food beliefs, cultures, and behaviors may need to be changed. Some advocates of supplements claim that although most Americans consume enough nutrients in their diets to prevent dietary deficiency
46 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL diseases, they consume less than the amount necessary for good health. While this is an interesting hypothesis, it has yet to be tested, and at present cannot be used as a justification for supplementation. Finally, it may not be possible to obtain the necessary nutrient amounts from food sources alone, so other mea- sures may then be taken. Fortification Fortification describes adding to a food nutrient levels that are above the naturally-occurring levels; in some cases, it means adding a nutrient to a food in which it normally would not be present. Restoration is a form of fortification that involves the replacement (either partial or full) of nutrients that were lost during a stage of food production or distribution. In theory, it should be possible to add pure forms of nutrients present in minimally processed foods to highly processed foods to obtain nutritional equivalency. The original food should be an important source of one or more nutrients, especially if there is nutrient inadequacy in the population group. One standard for this is that the food that provides at least 10 percent of the Daily Value for a specific nutrient (U.S. FDA, 1999). Nutritionally improving widely consumed foods by fortification (also called enrichment), without trying to change food habits, is a common way of ensuring and improving the food supply's nutritional adequacy. This strategy also is use- ful when food choices are limited or when available foods are not nutritionally complete or acceptable. Other cases exist, too, when fortification may be neces- sary (e.g., to meet certain nutrient standards). The term fortification is used to refer to the addition of nutrients not only to food but also to water and salt. Key conditions for successful fortification include the following: · Fortification should focus as narrowly as possible on a target population. For example, when the benefits from higher nutrient intakes extend across the population, the entire population is the target, and appropriate fortification of staple foods ensures reaching the targeted population. On the other hand, when only a subgroup of the population is deficient in a nutrient, then fortification of specific foods eaten by those at risk is more appropriate. Dietary surveys may be needed to describe the amounts and distributions of nutrient intakes in the popu- lation and to identify the most suitable food vehicle. · Fortificants must be bioavailable. · Fortification must be acceptable from the standpoint of final food prod- uct taste and appearance, as some fortificants, such as iron salts, change food quality. · The food vehicle used to carry a fortificant must be easily accessible and eaten regularly in portions that are large enough to provide the appropriate dose. · The production capacity, instructions, and monitoring of fortification must be in place.
MILITARY DIETARY REFERENCE INTAKES 47 Fortification increases costs to food manufacturers because of the cost of mixing the fortificants, quality control procedures, and the cost of acquiring particular fortificants at selected levels. Foods fortified solely for the military are more costly than foods already fortified for the civilian menu because of losses in economies of scale. In the United States, most ready-to-eat breakfast cereals have been fortified voluntarily--with a range of vitamins and iron at levels of 17 to 50 percent of the RDAs--for many years (e.g., iron levels see Johnson et al., 1998). Bread and flour have been fortified not only for iron but also, in the United Kingdom, for calcium; these fortifications appear to be acceptable even at fairly high levels. Orange juice, meal-replacement products, and sport drinks are examples of other calcium-fortified foods. Uses and Advantages of Fortification Fortification is best used as a preventive strategy or to decrease the risk of nutrient inadequacy. Its time course of effect is between that of the supplement, which is relatively rapid in achieving the change in micronutrient status (owing to the high specificity and relatively high doses), and the less rapid effects ob- served from eating usual diets. The fortification strategy is sustainable under most conditions, and it is often cost effective as well. Fortification is defined by statute for certain nutrients but not for others. For example fortification is used in the United States for restoring certain nutrients to flour. Enriched products in the United States have a standard of identity that requires nutrients to be added in accordance with U.S. Food and Drug Adminis- tration (FDA) regulations, for example folic acid (U.S. FDA, 1996). The FDA also specifies enrichment and fortification levels for nutrients that are known to be essential such as minerals and it is recommended that they are fortified at levels proportional to the caloric content of the food they are added to. In the majority of cases, these specifications are FDA guidelines and are not mandated. Thus, public health measures--specified by law or regulation--that rely on for- tification and enrichment have clear guidelines that must be followed. No spe- cific fortification levels are set as regulations for other nutrients (e.g., chromium, selenium, potassium) as well as for some nutrients in other foods (e.g., for cal- cium in orange juice). Disadvantages One of the disadvantages of fortification is that it is rarely used for more than a few nutrients. However, some nutrients occurring in foods may function better together with or only in the presence of other nutrients. For example, the B-complex vitamins have closely interrelated metabolic functions. Failure to provide sufficient dietary amounts of one or more of those nutrients that work
48 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL together may impair the functions of other B vitamins. This scenario also might be true for some combinations of minerals. The risk of excessive intakes of specific nutrients due to voluntary, market- driven food fortification or overconsumption of the fortified food is of concern, especially when the IOM UL is relatively close to the RDA. Also, there are concerns about the potential for public confusion about nutrition education mes- sages. For example, fortifying candies and carbonated beverages is not sup- ported fully among nutritionists because it might be perceived as sending an inconsistent message. Another disadvantage of providing nutrients, especially minerals, in large amounts from single sources is that bioavailability may decrease when nutrient interactions are favored by the high nutrient concentrations. Supplementation The FDA defines a dietary supplement as a product (other than tobacco) that adds to the diet and contains one or more of the following dietary ingredi- ents: a vitamin; a mineral; an herb or other botanical; an amino acid; a dietary substance that supplements the diet by increasing the total daily intake; or a concentrate, metabolite, constituent, extract; or combinations of these ingredi- ents (U.S. FDA, 1995). Dietary supplements that provide nutrients or non- nutrients by oral means come in various forms (e.g., pills and powders) other than food and beverages. Uses International bodies, such as the Codex Alimentarius (FAO, 2005), re- cently have released guidelines for the use of supplements. The guidelines state that individuals should be encouraged to select a balanced diet from which sufficient amounts of the vitamins and minerals can be obtained. Hence, supple- ments should be used only in cases where food does not provide sufficient vitamins and minerals. The Scientists from an International Conference on Nutrition suggests that supplementation be restricted to vulnerable groups that cannot meet their nutrient needs through food alone. Such groups include women of childbearing age, infants and young children, the elderly and the poor, those who are displaced, refugees, and those in other emergency situa- tions (FAO and WHO, 1992). Factors to consider when choosing supplementation as a strategy include the following: · The intake amounts that can be obtained normally from food relative to the amounts that are needed. · The target group or population.
MILITARY DIETARY REFERENCE INTAKES 49 · The targeted individuals' willingness to consume supplements. · The inability to use another strategy (e.g., nutrient-rich food sources or fortified foods). Advantages Supplementation is suitable for nutrient deficiency prevention in healthy individuals, but it is especially appropriate for therapeutic purposes. However, the efficacy of using dietary supplements to provide high levels of nutrients for altering chronic disease risk is less well established (Caballero, 2003). Criteria for recommending mineral supplementation vary among expert groups. Supplementation can generate changes in micronutrient status relatively quickly. However, when compared with fortification or dietary diversification, the approach reaches relatively small numbers of consumers and requires action on the part of many individuals to comply. For some nutrients to reach the targeted individuals in sufficient amounts supplementation is justified (Perelson and Ellenbogen, 2002). Unlike the other strategies mentioned, dietary supplements do not require major changes in the food supply, food processing, or distribution. Moreover, in a heterogeneous population, only those who are in certain age, gender, or lifestyle groups may require dietary supplements. Within these groups, further tailoring may be possible and desirable. For example, in the past there has been a one- size-fits-all recommendation that pregnant women should use iron supplements; however, it has been suggested more recently that only pregnant women who exhibit certain hematological parameters indicative of deficits should use iron supplements (IOM, 1998b). In general, the IOM reports have endorsed supple- mentation with specific nutrients (including the minerals) only for situations in which there is clear evidence of potential harm due to their inadequacy. If very high levels of mineral intakes are necessary to achieve optimal health benefits, supplementation may be the only recourse. Nonetheless, the advisabil- ity of providing such high levels of nutrients must be justified, and for many nutrients (including some of the minerals) the relationship between high-nutrient levels and associated benefits is still unclear. While there is little disagreement about the usefulness of dietary supplements in boosting nutrient intake shortfalls and thus achieving IOM RDA levels (for example, in situations of weight loss or illness), the value of consuming nutrient levels higher than the IOM RDAs con- tinues to be debated (Lichtenstein and Russell, 2005; Perelson and Ellenbogen, 2002). There is a strong consensus that intervention studies are needed to dem- onstrate conclusive nutrienthealth benefit links before high levels of nutrients can be recommended to the general population. The proposition that taking a multivitamin mineral supplement each day is advisable to decrease the risk of chronic degenerative disease in adults is also debatable. It presents economic as well as public health concerns if the intake is beyond the UL.
50 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL Disadvantages The efficacy of most supplements in preventing chronic degenerative dis- eases has not been demonstrated; however, they are helpful in preventing nutri- ent deficiency diseases (e.g., folic acid helps fight neural tube defects) and chronic degenerative disease (e.g., vitamins A, D, C, iron). Attempts at using supplements to prevent cardiovascular disease and lung cancer have been disap- pointing, and the evidence to date is stronger for the association between dietary patterns and decreased chronic disease risk than it is for individual nutrients. There are other disadvantages in using supplements. When supplementary doses of nutrients are high, nutrient interactions tend to be accelerated. There might be unknown consequences from shifting the emphasis away from food and toward nutrient supplements (Caballero, 2003; Lichtenstein and Russell, 2005), in which unusual nutrient profiles could be created and lead to alteration in absorption or metabolism of other constituents. Finally, genetic polymor- phisms in the population might lead not only to increased requirements and needs for nutrients but also to lower thresholds for adverse effects from large doses of nutrients. Combined Strategies The Armed Forces may find it useful to consider combined strategies that involve usual diets, fortified foods, and dietary supplements--the combination could work toward a long-term goal while rapidly remedying immediate prob- lems. In fact, a comprehensive approach could be implemented to provide pre- ventive measures with nutrients at normal levels for the general population of soldiers and therapeutic treatment with nutrients at pharmacological levels for those with proven deficiencies. Complementary Public Health Measures Regardless of the strategy adopted, complementary public health measures are also essential. For example, to prevent anemia in regions where malaria parasites (Plasmodium falciparum) are present in the environment, de-worming and taking antimalarial measures are vital, as is consuming iron in adequate amounts. Sanitary water and food are indispensable since intestinal disease will cause excessive malabsorption or excretion of most nutrients. Choosing the Best Strategies The best choice among these strategies for raising nutrient intakes depends on several factors and varies from one nutrient to another. Considerations in- clude the following:
MILITARY DIETARY REFERENCE INTAKES 51 · The prevalence and severity of a population's nutritional inadequacy. · The consequences of failing to raise intakes to RDAs or other nutrient standard levels. · The number of nutrients that require intervention. · The time required to affect the health outcomes linked to the nutrient in question. · The phase, appropriateness, and feasibility of the intervention. · Other characteristics that are unique to the particular setting (e.g., the military). · Other characteristics of the mineral under consideration. The recent report Nutrient Composition of Rations for Short-Term, High- Intensity Combat Operations (IOM, 2006) offered recommendations and sug- gestions that address providing the appropriate amounts of nutrients to the mili- tary personnel. The three main points made by that report's committee are the following: · Macronutrients should be provided in whole foods, and fortification and the use of supplementation should be limited to the extent possible due to the potential for nutrient interactions. The committee acknowledges the need for fortification in some cases due to the type of foods included in some rations, for example, those rations where shelf-stability is a priority. · Fortification with labile nutrients presents unique challenges because of potential interaction with other compounds and decreased bioavailability with storage. Shelf-life should be a factor to consider when calculating the level of fortificant in the food, and encapsulation for some nutrients may be necessary. · Because taste is an important factor in soldiers' food preferences and operational rations should be eaten entirely, providing a variety of acceptable and palatable products becomes a primary concern. Zinc, calcium, magnesium, and other nutrients have objectionable tastes to some individuals at the levels used in fortificants. Use of appropriate chemicals with better taste or encapsula- tion or other means to mask objectionable tastes should be given high priority for food developers. WATER AS A MATRIX TO INCREASE INTAKE OF MINERALS Background The military promotes consumption of water during periods of heavy exer- cise and elevated ambient temperatures. In addition to being a potential vehicle for nutrients and hydration, water can be a feasible vehicle for providing miner- als that help meet mineral requirements as long as soldiers are consuming daily 210 L of water. The changes in drinking water sources that occur during mili-
52 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL tary deployment could affect the balance of the essential dietary minerals that are provided. The amounts of minerals in the U.S. public water supplies, in bottled water, and in field purification water may vary. The U.S. Environmental Protection Agency (EPA) administers the tap water (drinking water) quality standards as well as those for local and state water (U.S. EPA, 2005). The EPA standards recognize that some minerals--such as heavy metals, copper, and iron--need to be regulated for high levels. In addition to enforced levels, quality factors are considered when changing the levels of min- erals in water. For instance, elevated levels of calcium make most water unpalat- able and difficult to use because of associated brine qualities (WHO, 2004). Mineral levels in U.S. tap water vary in quantity depending on the origin of the freshwater supply (See Table 2-1; NRC, 1980). For example, from the Na- tional Health and Nutrition Examination Survey III (NHANES III) data on water intake, it can be calculated that individuals consuming hard water (water with high calcium and magnesium levels) can supplement their mineral intake with tap water (median intake between 9001,000 ml/day) (IOM, 2005). Generally, this is considered advantageous if dietary sources do not provide adequate in- takes (see Combs, 2005 in Appendix B; NRC, 1980). Hard water generally con- tains 10500 mg/L of calcium carbonate and traces of magnesium as compared with soft water, which contains lower levels of calcium (< 10 mg/L) (WHO, 2003). This high level of calcium can be altered with water treatments, and sodium levels may be exchanged for calcium, thus providing soft water with elevated levels of sodium (NRC, 1980; WHO, 2004). Water Treatment Ground or well water is treated by various methods, including filtration and chlorination. The final mineral levels depend on the source water, for example, ground water is hard water and rain water is soft water. Combination methods like filtration, reverse osmosis, and distillation are used in some parts of the world because the local water is high in salt and debris. Desalination is used to TABLE 2-1 U.S. Tap Water Mineral Levels Mineral Typical levels (mg/L) Higher levels (mg/L) Calcium 26.00 145.00 Magnesium 6.25 120.00 Iron 0.24 2.20 Copper 0.10 0.45 Zinc 0.20 1.50 Selenium 0.00 0.01 Sodium 28.00 220.00 SOURCE: NRC (1980).
MILITARY DIETARY REFERENCE INTAKES 53 treat water that is high in salt content, (e.g., some lakes and the ocean). Treat- ments such as distillation, deionization using membranes, electrodialysis, re- verse osmosis, and other technologies, significantly reduce the mineral content. Bottled water can be obtained from tap water, treated water, and other ground water sources. In the United States, bottled water standards are under the admin- istration of the FDA (Bullers, 2002). In general, the FDA's standards for bottled water are the same as the EPA's standards for tap water. If the bottled water is labeled purified water, then it is manufactured by distillation, reverse osmosis, or other suitable processes that meets the definition set by the U.S. Pharma- copeia (http://www.usp.org/). Purified water has a low mineral content unless the manufacturer adds minerals especially to improve taste. There are no known health advantages from consuming bottled water except in areas where local drinking water does not meet health standards. Table 2-2 lists an example of the mineral content from bottled water prepared for the military operations in Iraq. Minerals and Taste Most sensory evaluation studies indicate that low-salt waters have poor taste for most people. The addition of calcium (at least 4 meq/L of CaSO4), sodium (1.5 meq/L NaHCO3), and magnesium (3 meq/L of Mg[HCO3]) enhanced posi- tive taste results (Zoeteman, 1980). On the other hand, overly high levels of calcium and sodium can decrease taste acceptability. Results vary, but in general levels of calcium that are above 100 mg/L and of sodium that are above 200 mg/L (WHO, 2004; Zoeteman, 1980) are unacceptable. In fact, when water treatment results in low mineral content, calcium and magnesium may be added back to improve taste and to prevent the leaching of TABLE 2-2 Mineral Content of Bottled Water in Iraq (Danone Hayat, Product of Istanbul) Compound Content (mg/L) Calcium 25.650 Magnesium 7.050 Fluoride 0.030 Chloride 4,900 Chlorine -- NH3 -- Sulphate 2.560 NO2 -- Nitrate 1.236 Silica 1.000 pH 7.480 SOURCE: Personal communication, J. Kent, Darnall Army Community Hospital U.S. Army, August 25 (2005).
54 MINERAL REQUIREMENTS FOR MILITARY PERSONNEL minerals from pipes (Cotruvo, 2005; Kozisek, 2005; Monarca et al., 2005; WHO, 2004; Zoeteman, 1980). The process results in the provision of calcium and magnesium as dietary sources. The addition of dissolved salts and calcium may be around 100 mg/L and 30 mg/L, respectively (Kozisek, 2005). Another factor that might change mineral content of water is the leaching of minerals (espe- cially of cadmium and lead depending on nature of pipe) from pipes that occurs with desalted water (Cotruvo, 2005). Finally, water might be blended, that is, some salt water is added to increase the overall salt levels after the desalination treatment. This results in an increase primarily of sodium (Cotruvo, 2005). Minerals in Water and Cardiovascular Disease Many epidemiological studies have been conducted to determine if consum- ing hard water decreases the risk of cardiovascular diseases (Altura and Altura, 1995; Hopps and Feder, 1986; Kousa et al., 2004; Maheswaran et al., 1999; Pocock et al., 1980; Rubenowitz et al., 2000). Studies suggest an inverse relationship between calcium and magnesium concentrations in tap water and cardiovascular mortality in the United States (Hopps and Feder, 1986), England (Pocock et al., 1980), Europe (Sonneborn et al., 1983), and Finland (Kousa et al., 2004). Re- cently, Monarca et al. (2005) reviewed the literature between 1979 and 2003 re- garding the role of calcium and magnesium content of water on prevention of cardiovascular diseases. These studies were conducted in many geographical loca- tions and report case-studies and correlation studies between both naturally occur- ring hard water and water treated to reduce hardness; this entailed replacement of calcium and magnesium with sodium, an electrolyte that at high dietary levels may be related to hypertension, which might have confounded the results. Aside from this limitation, most case-control studies show and inverse relationship between mortality (but not incidence) from cardiovascular disease and magnesium levels but not calcium levels. Most studies show an inverse correlation between water hardness and mortality from cardiovascular disease, but not all. Although many of these studies have large sample sizes and include longitudinal data to document the efficacy of hard water, government agencies (Combs, 2005; see Appendix B) do not support adding calcium and magnesium to drinking water to prevent cardio- vascular diseases. There are indications that reducing hard water by the substitu- tion of calcium and magnesium with sodium replaces valuable dietary calcium and magnesium; also, high-sodium diets may be related to hypertension for some people. Apart from the studies suggesting the benefits of consuming hard water, there are no data that show increased cardiovascular disease in communities where rain water (soft water) is the primary source of drinking water (Hopps and Feder, 1986; Maheswaran et al., 1999; Pocock et al., 1980). Also, the consumption of purified water (e.g., bottled water) showed no enhancement of health except in cases where local water cannot meet U.S. EPA standards for chemical and micro- biological contaminents (Bullers, 2002). In summary, chronic consumption of soft water has been related to cardio-
MILITARY DIETARY REFERENCE INTAKES 55 vascular disease in some studies but not all. Altogether, these studies were not deemed strong enough for the WHO to recommend the addition of calcium and magnesium to drinking water, but they do indicate potential importance of water as a nutrient source of calcium and magnesium. Bioavailability The bioavailability of each mineral from water will vary with the salt form (Hopps and Feder, 1986; Sonneborn et al., 1983). Except for some epidemiologi- cal research (see section on Epidemiological Cardiovascular Disease Studies), there has been little evidence showing that adding calcium and magnesium to drinking water enhances mineral nutritional status. However, calcium and magne- sium in hard water are well absorbed and can provide additional sources of these nutrients to meet dietary requirements (Kozisek, 2005). This additional source may be important when other food sources of calcium and magnesium are low. Water Quality During Military Operations The military's primary concern is to provide water that meets U.S. EPA standards for chemicals and microbiological levels. During foreign deploy- ments, drinking water may come from local water supplies and undergo addi- tional treatments, such as chlorination for bacterial control and filtration for the removal of dissolved solids. The mineral levels with this type of treated water depend on the mineral levels of the source water, that is, hard water, which is high in minerals--primarily calcium and magnesium--would retain its minerals after treatment. In some situations, water may be treated by reverse osmosis or distillation, both of which remove minerals. Thus, as mentioned previously, most treatment plants add minerals, especially calcium and magnesium, to prevent metal leach- ing and to improve the water's palatability. Bottled water generally has low concentrations of minerals. Typical levels of minerals in tap water are similar to those in bottle water used in Iraq (Table 2-1 and 2-2). Based on these typical levels, on the known treatment processes applied to water, and on the typical consumption of 3 L of water/day the committee concluded that, differences in mineral content of water would not be such that will affect the total intake levels of minerals by military personnel. The committee also concluded that the addition of calcium and mag- nesium to water consumed by military personnel is warranted only when im- proving the taste is the desirable outcome. There is no evidence to suggest that the addition of substantial levels of calcium and magnesium would be an effi- cient strategy to meet nutritional standards; in addition, there is little research on bioavailability of minerals from water. Additional cost evaluation of using water as a vehicle for minerals should be conducted if it is to be considered for implementation.
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