Nutrient Composition of Rations for Short-Term, High-Intensity Combat Operations (2006) / Chapter Skim
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2 Answers to the Military Questions
2 Answers to the Military Questions
Pages 30-132
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From page 30... ...
These assumptions were compiled throughout the deliberations of the committee, open sessions with sponsor representatives and other military personnel, information from a field survey conducted in Afghanistan, and available literature. As a result, a worst-case scenario was constructed so that the recommended assault ration would diminish, to the extent possible, significant losses of body fat and protein, which, if allowed to occur, might prevent soldiers completing an assault mission from being redeployed to a subsequent mission in the immediate future.
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From page 31... ...
With the expected energy expenditures of 4,500 kcal/day during the missions, it is possible that some soldiers might lose as much as 10 percent body weight before the end of the month, even with refeeding between missions; this degree of weight loss could result in adverse, but mild performance decrements. However, there is not likely to be any serious consequences for health.
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From page 32... ...
The committee assumes that the soldiers' diet prior to the assault mission is ad libitum from a field kitchen without fresh fruits or vegetables. Alcohol Consumption Although military policy strictly prohibits alcohol consumption in the field operations, some alcoholic beverages are probably available in the local environment in many theatres of military operations.
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From page 33... ...
Physical Activity and Energy Expenditure The energy expenditure of soldiers while on an assault mission is reported to be approximately 4,500 kcal/day due to intermittent periods of high energy expenditure (> 50 percent VO2max) and periods of low-intensity, sustained movement.
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From page 34... ...
It is not known what or how much was thrown away. The committee assumes that, if palatable, when provided with an assault ration of 2,400 kcal or less per day, soldiers expending 4,500 kcal per day will consume virtually 100 percent of the ration.
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From page 35... ...
In line with the committee's philosophy of assuming the worst-case scenario, when sweat losses of minerals are significant (i.e., could lead to adverse health effects) , an extra amount of the nutrient was included to cover the losses endured by soldiers engaged in significant energy expenditure (4,500 kcal)
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From page 36... ...
While this level does not maximize energy density, this is the average daily energy intake that has frequently been reported for soldiers during training. Choosing this caloric level minimizes the possibility of discarding food items that might result in inadequate intakes of necessary micronutrients; however, in case ration items are discarded, micronutrients should be distributed as evenly as possible throughout the food items in the ration (rather than clustering them in a few items)
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From page 37... ...
A second option was to design a ration that would provide the usual energy needs of soldiers when not on assault operations; such energy needs are assumed to be approximately 3,500 kcal/day. The major advantage of this second option is that it would create a comparatively small energy deficit when energy expenditure is at the level of 4,500 kcal/day.
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From page 38... ...
. BOX 2-1 General Design of the Recommended Assault Ration Basic Ration: Protein 100120 g (400480 kcal; 1720% kcal)
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From page 39... ...
Rationale for Energy Content Energy expenditures of soldiers during combat assault missions have been reported to be high (about 4,500 kcal/day)
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From page 40... ...
Research Needs Related to Energy Content · Test the acceptability of the prototype assault ration under field condi tions and determine the actual amounts eaten. The extent of discarding ration items under combat conditions needs to be evaluated in field sur veys, and the findings must be taken into account in ration development and refinement.
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From page 41... ...
that would optimize such an assault ration to enhance performance during combat missions? Protein RECOMMENDATION: The protein level of the ration should be 100120 g total protein (based on 1.21.5 g/kg of body weight for an 80 kg average male soldier)
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From page 42... ...
In addition to the effects due to a hypocaloric diet, the loss of muscle protein may also be exacerbated by the intensity of the physical activity. Evidence from studies on very strenous physical activity and muscle metabolism in rats (Anthony et al., 1999)
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From page 43... ...
. Increases in energy expenditure through physical activity do not markedly alter protein requirements; thus, despite a likely energy deficit of 50 percent under combat mission conditions, protein intakes of somewhat less than 1.5 g/kg body weight/day would probably be sufficient for optimal sparing of lean tissue.
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From page 44... ...
Another criterion to be considered is the proper functioning of antioxidant systems. The stress response, whether due to intense physical activity or systemic inflammatory response leading to oxidative stress, may impair the amino acid and protein component of the antioxidant systems (Jackson et al., 2004)
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From page 45... ...
However, with the expected energy expenditures of 4,500 kcal/day during the missions, it is possible that some soldiers might lose as much as 10 percent body weight before the end of the month, even with refeeding between missions; this degree of weight loss could result in adverse, but mild, performance decrements. However, this level of weight loss is not likely to be of any serious consequences for health.
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From page 46... ...
Research Needs · Investigate the effects of the higher protein level recommended compared to maintenance protein intakes under high energy expenditure situations resulting in hypocaloric conditions and stress on muscle loss, physical and cognitive performance, and immune function. Muscle loss should be assessed by state-of-the-art techniques such as dual energy X-ray absorptiometry or whole-body nitrogen measurement.
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From page 47... ...
· Study body composition and physical activity as factors that influence protein sparing and prevention of muscle loss. Carbohydrate RECOMMENDATION: The carbohydrate in the basic ration should be 350 g to optimize physical performance.
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From page 48... ...
Carbohydrate is more efficient than fat as a fuel, and the rate of supply of ATP for muscle contraction is faster than that of fat. Therefore, maintaining muscle glycogen and blood glucose levels is important for optimal physical performance.
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From page 49... ...
To evaluate the effect of supplemented carbohydrate on total food intake and activity, the voluntary energy and carbohydrate intake of Marines who were randomly assigned to either a carbohydrate-beverage supplement or a noncaloric placebo beverage during an 11-day field training exercise was estimated, along with energy expenditure (Tharion et al., 2004)
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From page 50... ...
Total energy expenditure was 4,380 kcal (18.4 MJ) and 3,840 kcal (16.1 MJ)
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From page 51... ...
. Studies of the effects of nutritional interventions on cognitive performance in more challenging settings of high-energy output and physical or psychological stress are therefore more germane to the uses of the assault ration.
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From page 52... ...
Although carbohydrate supplementation appeared to enhance cognitive performance in individuals engaged in sustained, intense physical activity (Lieberman, 2003) , it should be noted that no eucaloric control was used.
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From page 53... ...
In this way, the total recommended amount of carbohydrate is 450 g. This amount is the minimal amount of carbohydrate needed to meet the needs of soldiers experiencing intense physical activity.
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From page 54... ...
Therefore, it is recommended that the range of dietary fiber in the assault ration be based on a minimum amount to avoid constipation to the extent possible and on estimates of the intake of young men in the US population. It is assumed that these amounts should prevent diarrhea and constipation.
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From page 55... ...
. Based on the median and 95th percentile intake adjusted for energy intake, the committee recommends including total dietary fiber in the range of 1517 g/day.
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From page 56... ...
The committee believes that, although increasing consumption is desirable, satiety is only one of the many factors that influence consumption, and the available data do not yet provide an unequivocal answer. A better understanding of the influence of nutrient composition on satiety is needed before considering it as the basis for nutrient level recommendations.
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From page 57... ...
. During military operations, high energy expenditure is likely to occur in the context of an energy deficit.
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From page 58... ...
to maximize energy and nutrient intakes. Energy intakes were lower than energy expenditure under all feeding conditions, over approximately 30 days.
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From page 59... ...
The ration should contain, at a minimum, the recommended amounts of linoleic and -linolenic acid to satisfy essential fatty acid needs. The effects of fatty acid type, including n-3 and n-6 fatty acids, on physical and cognitive performance, immune function, and gene expression.
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From page 60... ...
that could be added to such rations to enhance performance during combat missions? Vitamin A RECOMMENDATION: The assault ration should contain at least 300 µg retinol activity equivalents (RAE)
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From page 61... ...
. This level, 300 µg RAE, should be considered the minimum amount in the short-term assault rations.
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From page 62... ...
Vitamin C RECOMMENDATION: The assault rations should include a vitamin C level of 180400 mg. This level considers the current RDA for US males 1930 years old, 90 mg/day, plus 35 mg/day to account for the higher vitamin C requirements of smokers; to establish the lower limit of the range (180 mg)
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From page 63... ...
. Furthermore, significant effects on other aspects of the immune function have not been proven (IOM, 2000)
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From page 64... ...
· Investigate the effects of smokeless tobacco use on vitamin C Vitamin D RECOMMENDATION: The assault ration should contain 12.515 µg of vitamin D based on the amount of vitamin D needed to maintain a serum level of 70 nmol /L of 25(OH)
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From page 65... ...
In addition, the number of sunlight hours also affects the amount of endogenous synthesis. Therefore, latitude and season are factors that should be considered when determining the amount needed in the assault ration.
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From page 66... ...
. The possible need for amounts in excess of the AI, along with reports of apparent vitamin D deficiency in adolescents and young men, suggests that the level of vitamin D for the assault ration be set at 12.5 µg/day, a level that should maintain serum vitamin D levels at 70 nmol/L without depending on sunlight exposure or body liver stores to contribute to available vitamin D
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From page 67... ...
The median and the 95th percentile dietary intake of -tocopherol are 9 and 19 mg/day, respectively, for men 1930 years of age (NHANES III; IOM, 2000)
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From page 68... ...
Vitamin E and Immune Function. Vitamin E has been investigated as a potentiator of immune function.
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From page 69... ...
will be present as natural components of food in the ration. Research Needs · Investigate the potential synergistic effects of a mixture of antioxidants in a randomized trial on physical performance and immune function.
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From page 70... ...
In addition, vitamin K deficiency is rare. Thiamin RECOMMENDATION: Assuming an energy content of 2,400 kcal in the assault ration and an average energy expenditure of 4,500 kcal/day, the assault ration should contain a level of 1.63.4 mg of thiamin.
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From page 71... ...
Rather than basing the amount in the assault ration on its caloric level, given the restriction in energy intake of soldiers, a recommendation for thiamin based on energy expenditure is a reasonable approach. Assuming a 4,500 kcal/day energy expenditure, a minimum recommended daily intake of 1.6 mg of thiamin/day would be calculated, based on increasing the EAR of 0.3 mg/day/1,000 kcal by 20 percent for twice the assumed CV of requirements for thiamin of 10 percent (0.3 mg/day/1,000 kcal × 4.5 × 120 percent = 1.6 mg/day needed)
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From page 72... ...
Niacin RECOMMENDATION: Assuming an energy content of 2,400 kcal in the daily ration and an average energy expenditure of 4,500 kcal/day, the assault ration should contain a level of 2835 mg of niacin equivalents (NE)
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From page 73... ...
A minimum of 28 mg should be present in the ration, and not more than 35 mg be added to foods. Vitamin B6 RECOMMENDATION: Based on an estimated body protein loss of approximately 52 g/day due to the soldiers' negative energy balance and a minimum protein intake of 100 g/day, the assault ration should contain a level of 2.73.9 mg/day of vitamin B6; if a higher protein level is provided, this amount should be increased proportionally.
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From page 74... ...
Research Needs · Determine the requirements of niacin, riboflavin, thiamine, and vitamin B6 when individuals are consuming a hypocaloric diet under the environ mental conditions and high-stress situations of combat missions (e.g., intense physical activity, high energy expenditure, reduced caloric intake, and hot and humid conditions)
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From page 75... ...
. When a mixture of folic acid plus food folate is consumed, as in the assault ration, dietary folate equivalents are estimated as follows: µg of DFEs provided = µg of food folate + (1.7 × µg of folic acid)
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From page 76... ...
Biotin RECOMMENDATION: The committee assumes that enough biotin would occur naturally in the ration foods; therefore, additional biotin is not necessary. Background and Rationale Biotin is required for a number of metabolic functions related to physical activity.
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From page 77... ...
This range is based on a factorial approach to estimating calcium requirements and potential sweat losses during prolonged exercise, also taking into account concerns about renal stone formation. Background The AI for men 1930 years of age is 1,000 mg/day based on balance studies to determine intakes at which there are gains in bone mineral content.
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From page 78... ...
. Therefore, the major concerns considered in deriving the recommended range for calcium in the assault ration are sweat losses and the prevention of renal stone formation.
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From page 79... ...
will not be considered in setting the minimum amount of calcium for the assault ration for the following reasons: · increased urinary losses will be balanced to some extent by increased fractional absorption of calcium due to the higher level of physical activity expected (see above) ; and · there is concern about the increased risk of hypercalciuria and renal stones when fluid restriction is combined with a comparatively high amount of dietary calcium, such as the daily median dietary intake for calcium for young men in the United States (954 mg; IOM, 1997a)
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From page 80... ...
has been noted in soldiers in these theaters of operation, possibly due to lower fluid consumption concomitant with significant losses of sweat due to high environmental temperatures and a high level of physical activity. Renal stone formation is due to crystallization of calcium oxalate, calcium phosphate, or both (Tiselius, 1997)
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From page 81... ...
It is also assumed that, due to the increased level of physical activity and any additional body demand for calcium, fractional absorption of calcium will increase to cover some of the additional sweat losses. In summary, the level of 750850 mg/day of calcium is recommended.
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From page 82... ...
, food items in the ration will have enough chromium to meet the needs of soldiers. Given the lack of reports indicating deficiencies in individuals in the population, concerns about inadequate intake while consuming food based diets are minimal, especially for the short terms of combat missions.
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From page 83... ...
. Although copper status could affect energy metabolism based on its presence in key enzymes involved, there is no scientific literature supporting a benefit from supplementing copper on either cognition or physical performance.
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From page 84... ...
Research Needs · Measure copper sweat losses in studies which simulate the environment encountered by soldiers in similar types of operations (e.g., intense physical activity, high energy expenditure, reduced caloric intake, in hot and humid conditions) in order to evaluate the additional requirements for copper.
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From page 85... ...
Iron RECOMMENDATION: The assault ration should contain iron in the range of 818 mg per day. The lower level of the range is based on the RDA; the higher level of the range is based on increasing the RDA to account for the potential losses of iron in sweat during high energy expenditures and for a potential lower bioavailability from the ration foods.
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From page 86... ...
Rationale for Levels of Iron Iron Status and Physical Performance. The impact of adequate iron and iron supplements on maintenance and possibly enhancement of physical performance was evaluated during sports training and in endurance athletes (Newhouse and Clement, 1988)
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From page 87... ...
. Reallocation of available circulating and body iron stores occurs due to significant physical activity and resulting high energy expenditure and iron sweat losses may result in impaired immune function.
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From page 88... ...
Sweat iron concentrations during the second hour were approximately 0.10 mg/L at a rate of about 0.43 L/m2/hour while sweat concentrations during the first hour were approximately 0.17 mg/L at the same rate as the second; the average iron lost for the two-hour study period in the male subjects was about 0.23 mg. These studies alone show that during combat missions sweat losses may be appreciable due to high rates of energy expenditure (generating internal body heat)
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From page 89... ...
. If the assault ration is formulated primarily with cereal based food ingredients, it may contain more inhibitors of iron absorption, such as polyphenols in tea and coffee (Disler et al., 1975)
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From page 90... ...
, so it would be advantageous to limit the amount of calcium contained in individual ration components that have higher iron content. Recommending that the assault ration should contain such a high level of iron (25 or 31 g/day)
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From page 91... ...
As noted above, the committee concludes that US men have generally enough iron storages and iron deficiency would be rare and, therefore, low levels of iron intake for brief periods will have no appreciable effect on iron stores and no adverse physiologic effects. Research Needs · Measure iron fecal, sweat, and urine losses in studies which simulate the environment encountered by soldiers in similar types of operations (e.g., intense physical activity, high energy expenditure, reduced caloric intake, in hot and humid conditions)
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From page 92... ...
. Rationale for Levels of Magnesium Magnesium and Physical Performance.
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From page 93... ...
to patients who had at least two previous episodes of calcium oxalate stones markedly reduced the risk of recurrent stone formation (Ettinger et al., 1997)
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From page 94... ...
Research Needs · Study the effect of higher levels of magnesium on enhancing both physical and cognitive performance in studies which simulate the environment encountered by soldiers in similar types of operations (e.g., intense physical activity, high energy expenditure, reduced caloric intake, in hot and humid conditions)
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From page 95... ...
In addition, no deficiencies have been observed in healthy people and no symptoms of deficiency have been achieved in animals even when the activity of molybdoenzymes was greatly suppressed. Phosphorus RECOMMENDATION: The assault ration should contain 7002,500 mg/ day of phosphorus.
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From page 96... ...
While phosphorus is found both in bone and soft tissue, little evidence is available to suggest that additional requirements due to high rates of energy expenditure or high levels of physical activity demand higher intakes. Estimates of phosphorus content of sweat indicate negligible amounts (less than 2.6 mg/L)
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From page 97... ...
. Based on this concern, it is recommended that phosphate salts be used in the assault ration only to attain the level of 700 mg, but not to increase the daily intake above 2,500 mg.
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From page 98... ...
Potassium and Renal Stones. The role of potassium in preventing renal stones formation is relevant when establishing levels of potassium due to the high protein level recommended in the assault ration (100120 g/day)
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From page 99... ...
. It appears that providing 4.7 g/2,400 kcal in the assault ration may be difficult.
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From page 100... ...
On its own, however, selenium deficiency does not appear to be a real concern. Rationale for Levels of Selenium As with other micronutrients, the need to recommend a different selenium level from the established RDA for assault rations depends upon possible increased selenium needs for the soldiers due to stress, immune function, and level of physical activity.
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From page 101... ...
Research Needs · Investigate the effects on performance of supplementation with selenium for periods of high-energy expenditure and physical and mental stress comparable to those encountered by soldiers in assault missions. Sodium RECOMMENDATION: The assault ration should contain 3 or more grams of sodium, the specific amount depending on palatability and acceptability of the ration.
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From page 102... ...
accounts for sweat losses for unacclimatized individuals in addition to achieving balance in relatively sedentary individuals. There also is a large variability in sodium losses between individuals due in part to variations in adaptation to heat and exercise capabilities.
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From page 103... ...
In addition, when average daily temperatures increase above 30°C/day and work load exceeds 2,800 kcal/day, sweat losses may exceed dietary intakes (Figure 2-1)
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From page 104... ...
, the committee does not anticipate any adverse health effects on high blood pressure because the UL was established considering chronic intakes and not for short periods envisioned for the consumption of the assault ration; in any case, palatability issues will limit the amount of sodium in the ration and the tablet supplements should only be provided under medical guidance to individuals that lose excess salt or in extremely hot or strenuous situations. Research Needs · Evaluate the additional requirements for sodium and measure fecal, sweat, and urine losses in studies which simulate the environment encountered by soldiers in similar types of operations (e.g., exercise, high energy expenditure and reduced caloric intake, in high humidity and temperature)
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From page 105... ...
. When sweat losses were studied over 16 days in the heat and after submaximal exercise, zinc losses ranged from 13.7 mg/day (first 4 days)
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From page 106... ...
Meetings with the USARIEM representatives revealed that soldiers probably consume insufficient amounts of zinc during military operations, and that they could become mildly zinc deficient under stress. Due to these uncertainties (i.e., variable sweat losses, difficulties in assessing zinc status, marginal zinc status of many soldiers)
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From page 107... ...
Due to palatability issues, fortification with zinc should be done in foods, in which off-flavors can be masked, rather than in gels, candy, or powder forms. In addition to palatability issues, food developers should consider that the range of zinc recommended might affect appetite, a concern for soldiers in combat operations who already undereat.
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From page 108... ...
Stimulants such as caffeine have been shown to maintain cognitive performance. Finally, herbals such as ginkgo, ginseng, and tea and berry extracts contain potentially bioactive compounds and are reported in some studies to maintain or enhance performance.
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From page 109... ...
The committee discussed a variety of bioactive compounds or extracts (e.g., carnitine, creatine, Ginkgo biloba extract, glutamine) and concluded that, with the exception of caffeine, inclusion in the assault ration is not appropriate at this time.
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From page 110... ...
Caffeine has also been studied in connection with improving physical performance. One study showed that physical performance as measured by rating of perceived exertion, time to complete a task, and time to exhaustion was also
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From page 111... ...
. Improvements in physical performance with caffeine were also reported with high-intensity cycling studies (Doherty et al., 2004)
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From page 112... ...
Antioxidant nutrients such as vitamins C and E, the carotenoids, and selenium have received a great deal of scientific interest regarding their abilities to enhance a body's ability to cope with excess oxidative stress brought on by exercise. These nutrients and food components are also under study for their abilities to enhance or maintain cognitive functions.
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From page 113... ...
While outcomes of these studies need to be verified in vivo and in clinical trials and thus are less relevant to the combat soldier during assault missions, the general antioxidant effect of these compounds may be important to overall performance. More relevant to the combat soldier during assault missions is the maintenance of an antioxidant defense system that optimizes the body's ability to cope with oxidative stress during periods of high physical and mental activity.
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From page 114... ...
For example, assuming 4,400 kcal of energy expenditure, it can be estimated that sweat volumes could be as high as 6.5 and 10.5 L at 20 and 30°C, respectively. In addition to sweat losses and metabolic rate, water needs are governed by nutrient intake, primarily protein and salt intake.
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From page 115... ...
While the committee did not provide specific recommendations for water, adequate amounts of water must be consumed with this ration to maintain and optimize physiological function and performance. Considering the expected level of stress and sweat volumes and the nature of the ration, water in excess of the 45 L/day must be available to ensure optimal performance in combat missions in which energy expenditure is high or carried out in hot and humid environments.
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From page 116... ...
1996. Effects of changes in dietary fatty acids on isolated skeletal muscle functions in rats.
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From page 117... ...
2004. An increase in selenium intake improves immune function and poliovirus handling in adults with marginal selenium status.
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From page 118... ...
Med Sci Sports Exerc 27(6)
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From page 119... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations, Natick, MA. Institute of Medicine Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High Stress Situations.
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From page 120... ...
2004. Effect of dietary protein supplements on calcium excretion in healthy older men and women.
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From page 121... ...
Med Sci Sports Exerc 28(11)
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From page 122... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situa tions, Natick, MA. Institute of Medicine Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations.
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From page 123... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations, Natick, MA. Institute of Medicine Committee on Opti mization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations.
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From page 124... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High Stress Situations, Natick, MA. Institute of Medicine Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations.
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From page 125... ...
Med Sci Sports Exerc 29(8)
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From page 126... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations, Natick, MA. Institute of Medicine Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations.
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From page 127... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations, Natick, MA. Institute of Medicine Committee on Opti mization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations.
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From page 128... ...
Med Sci Sports Exerc 34(11)
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From page 129... ...
2000. Effect of micronutrient status on natural killer cell immune function in healthy free-living subjects aged >/=90 y.
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From page 130... ...
Optimization of Nutrient Composition of Military Rations for Short Term, High-Stress Situations: Sodium, Potassium and Other Electrolytes. Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Ra tions for Short-Term, High-Stress Situations, Natick, MA.
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From page 131... ...
Paper presented at the Institute of Medicine Workshop on Optimization of Nutrient Composition of Military Rations for Short-Term, High Stress Situations, Natick, MA. Institute of Medicine Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations.
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From page 132... ...
Med Sci Sports Exerc 30(11)
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