The Journal of Nutrition

Supplement: Efficacy and Safety of Protein Supplement Use

by Military and Other Physically Active Populations

Training Table to the Battlefield: Protein

Recommendations for Warfighters13
Nancy R. Rodriguez*
Department of Nutritional Sciences, University of Connecticut, Storrs, CT

Abstract
Warfighters represent a population of athletes for whom routine training and physical expectations for military operations
parallel, and very often exceed, those of their civilian counterparts. Like athletes, warfighters require nutrition support to
optimize physical condition to maintain training, sustain performance, speed recovery, and prevent injury and illness.
Specifically, energy and protein requirements have been tailored for these populations. Like athletes, warfighters consider
protein a critical component of their diet and often incorporate protein supplements into daily diet plans. This article
recommendations in the context of protein supplementation, and asserts that translating these recommendations to the
warfighter is appropriate and necessary. The recommended range of protein intake of 1.21.8 g
kg21
d21 can be
extended to the warfighter. Because energy balance is pivotal to optimal protein utilization, adequate energy intake or lack
thereof such that a state of negative energy balance exists, should be given particular consideration for the warfighter.
Routine protein supplementation is recommended to reduce protein breakdown, support protein synthesis, and promote a
positive net protein balance throughout various deployment situations and when energy intake is insufficient. J. Nutr.
143: 1834S1837S, 2013.

Introduction
Nutrition requirements are unique for athletes because of routine
physical and mental challenges associated with intense training
and competition. In particular, consuming adequate energy is
requisite for athletes and necessary for optimal physical performance. Although current dietary protein recommendations assert that there is a range for optimal protein utilization, the RDA

Presented at the Efficacy and Safety of Protein Supplements for U.S. Armed
Forces Personnel meeting, held at the U.S. Army Research Institute of Environmental
Medicine, Natick, MA, 78 November 2012. The summit was sponsored by
the Department of Defense, Center Alliance for Dietary Supplements Research.
The views expressed in these papers are not necessarily those of the Supplement
Coordinator or Guest Editors. The Supplement Coordinator for this supplement
was Krista G. Austin, U.S. Army Research Institute of Environmental Medicine.
Supplement Coordinator disclosures: Krista G. Austin had no conflicts to disclose.
This supplement is the responsibility of the Guest Editor to whom the Editor of
The Journal of Nutrition has delegated supervision of both technical conformity
to the published regulations of The Journal of Nutrition and general oversight of
the scientific merit of each article. The Guest Editor for this supplement was
Kevin Schalinske. Guest Editor disclosure: Kevin Schalinske had no conflicts to
disclose. Publication costs for this supplement were defrayed in part by the
payment of page charges. This publication must therefore be hereby marked
"advertisement" in accordance with 18 USC section 1734 solely to indicate this
fact. The opinions expressed in this publication are those of the authors and
are not attributable to the sponsors or the publisher, Editor, or Editorial Board
of The Journal of Nutrition.
2
Supported by the U.S. Army Military Research and Material Command.
3
Author disclosures: N. R. Rodriguez, no conflicts of interest.
* To whom correspondence should be addressed. E-mail: nancy.rodriguez@
uconn.edu.

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remains at 0.8 g
kg21
d21 (1), an amount considered insufficient to sustain synthesis of new muscle proteins, maintain lean
body mass, and repair muscle damage after strenuous exercise
training and intense athletic competition. Current recommended
protein intakes for athletes, which range from 1.2 to 1.8 g
kg21
d21,
are well within the Acceptable Macronutrient Distribution Range
(AMDR) of the DRIs but exceed the RDA (2). The exceptional
energy and protein needs of athletes constitute the premise for a
training table where menus are developed and meals are provided with consideration given to the specific nutritional demands
associated with human performance.
Sports nutrition protocols often include dietary supplements
to assist athletes with meeting individual nutrient and energy needs,
achieving goals specific to body weight and composition, supporting training, and enhancing recovery. Protein supplements
are among the most popular supplements used by athletes, because abundant scientific evidence exists demonstrating the benefits
of protein and amino acid supplementation on muscle protein
synthesis, maintenance, and repair in physically active individuals.
Of significance in this report are sports nutrition recommendations
specific to protein intake and energy balance for athletes and
whether such recommendations can be extended to warfighters4.
4

The term warfighter is used by the U.S. Department of Defense to refer to

any member of the U.S. Armed Forces. Warfighter is intended to be neutral
regarding military service or branch, sex, and service status and replaces previously used terminology including soldier, service member, and military
personnel.

2013 American Society for Nutrition.

Manuscript received March 5, 2013. Initial review completed May 7, 2013. Revision accepted July 24, 2013.
First published online September 11, 2013; doi:10.3945/jn.113.176958.

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highlights sports nutrition principles that target energy and protein needs of athletes, considers the basis of these

Warfighters require nutrition support to optimize physical condition to sustain performance, speed recovery, and prevent injury
and illness. Although nutrition requirements may be similar to
those in athletes, operational stressors affecting the warfighter
are unique, given that the extenuating conditions embedded within
the deployment cycle may compromise the ability of the warfighter to consistently consume sufficient energy and nutrients,
particularly protein. The exceptional metabolic and psychological demands placed on the warfighter not only make good
nutrition crucial but difficult to obtain when performance expectations are greatest. This report highlights sports nutrition
principles that constitute a basis for targeting energy and protein
needs of athletes, considers the basis of these recommendations
with specific regard for protein supplementation, and contends
that translating these recommendations to the warfighter is not
only appropriate but necessary.

Concepts of Protein Utilization Relevant to

Sports Nutrition Protein Recommendations

Factors affecting protein turnover

Protein turnover is affected by protein intake, exercise, and
energy availability. In the context of sports nutrition, there is
constant interplay between these variables that must be considered for ideal training and performance outcomes.
Protein intake. Dietary protein intake influences rates of protein
turnover such that consuming protein in excess of the RDA typically
increases basal rates of protein synthesis and protein breakdown,
whereas adaptation to low-protein diets often results in a reduction
in protein turnover. The literature is replete with evidence demonstrating that consuming dietary protein or its constituent amino
acids stimulates protein synthesis at rest and in response to exercise.
In the fed state, when amino acids are abundant, protein synthesis
exceeds protein breakdown, resulting in a positive net protein balance and an anabolic state in which gains lean body mass can be
achieved. In contrast, during the fasted state, endogenous protein
stores are degraded to replenish the free amino acid pools, causing
protein breakdown to exceed protein synthesis, and a negative net
protein balance, or catabolic state, results. Habitual protein intake at
amounts above the RDA, but within the AMDR, may attenuate
lean body mass losses when a state of energy balance exists (6) or
when a defined period of energy deficit is imposed (4).
Exercise. Muscle is constantly remodeling, particularly in response
to routine exercise training because exercise increases protein

Energy balance. A dynamic relationship exists between protein

intake, energy balance, and the efficient use of dietary protein by
the body in response to exercise training. Protein turnover and
amino acid/nitrogen metabolism are energy dependent, thereby
making energy balance central to the bodys efficient use of protein. Negative energy balance results in the oxidation of amino
acids to meet energy needs. Conversely, protein is spared and
protein utilization improved with increasing energy intake for a
given amount of protein consumed. Whereas scientific evidence
supports high protein intakes when energy demands are great
and negative energy balance exists, increasing protein intake
while at a constant energy intake does not necessarily improve
protein utilization. Energy balance, or the consumption of sufficient energy to meet expenditure, is likely more important than
total protein intake, especially when protein intakes are at the
lower range of the AMDR. Because exercise training contributes
significantly to energy expenditure in athletes, it is critical to
replace calories expended during exercise and maintain energy
balance to promote optimal protein turnover. Restricting energy
intake to accomplish reductions in body mass should be reasonable and combined with adequate protein intake such that fat
mass is lost and muscle mass is maintained. When an unintended
but inevitable state of negative energy balance occurs consequent to high levels of energy expenditure associated with intense training and physical work, the consumption of protein in
amounts that exceed the RDA and span the higher range of the
AMDR for protein is recommended (4,5,7).

Extending Sports Nutrition Principles to

the Battlefield
Acknowledging that warfighters have nutrition requirements
similar to athletes in many situations, but unique under operational conditions, is central to the present discussion. The former
is a logical premise considering that all military personnel undergo initial military training (e.g., basic combat training and
advanced individual training). Indeed, several analogies exist.
The Active Duty Deployment Cycle can be compared to the
various levels of training and competition of an athlete. In the
predeployment phase, service members undergo traditional
physical training as well as military taskspecific training with
their units to prepare for activities required for specific military
occupations. This phase is similar to the offseason of many
athletes. Training is ongoing, and energy and protein needs will
exceed those of individuals who do not engage in routine exercise training (8,9). Meal times are generally routine, and the
training table or dining facility will reflect menus and provide
meals that meet energy and nutrient needs without significant
challenges.
Protein recommendations for warfighters

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Protein turnover
Protein turnover refers to the dynamic exchange between free
amino acid pools and proteins in the body and represents the
process of protein synthesis and degradation. The difference between protein synthesis and breakdown represents net protein
balance. Given this relationship, a positive or negative net protein balance suggests an anabolic or catabolic state, representing
the accretion or loss of muscle proteins, respectively. As such,
amino acid availability, and therefore dietary protein intake, is
pivotal to protein turnover. Protein intake must be adequate,
thereby supplying amino acids to replenish amino acid pools,
support protein synthesis, and limit protein breakdown. Inadequate dietary energy (negative energy balance) or amino acid
intake, or excessive utilization (oxidation) of amino acids during
exercise, will compromise amino acid availability and negatively
affect net protein balance (35).

turnover. The specific effects of exercise on protein synthesis and

degradation, and ultimately net protein balance, are dependent
on the mode, intensity, and duration of exercise, as well as the
nutritional status of the athlete. For muscle growth and repair,
protein synthesis must exceed breakdown such that net protein
balance is positive. For this to occur, protein intakes higher than
the RDA are recommended (2,3). And although experts continue to evaluate the effect of training status on protein utilization, it is generally accepted that as athletes become more
trained, they require less protein than their less-trained counterparts because long-term training enhances protein utilization
efficiency. As such, energy balance remains an integral factor
during exercise training (7).

Parallel challenges in optimizing protein utilization. Athletes, like warfighters, consider protein to be a critical component of their diet and they are very willing to eat foods that
provide high-quality protein or incorporate protein supplements
into their daily diet regimens. There are, however, 2 major
challenges to ensuring optimal use of dietary protein by these
individuals. First, more often than not, a sound understanding of
the importance of consuming adequate calories in concert with
protein is not common. Second, a variety of circumstances can
occur that make it difficult for athletes, as well as warfighters, to
achieve energy balance because energy intake is compromised.
Certainly, educating the athlete and the warfighter is an important component of optimizing protein utilization, but it is not
within the purview of this report. In any case, even the most
well-informed athletes or warfighters will encounter situations
that limit their ability to consume adequate calories to meet their
needs.
Concerns regarding adequate energy and protein intake are
more easily managed when routine meals composed of healthy
foods are readily accessible. This typifies a training table or dining hall situation. Nutrition efforts are directed at meeting nutrient needs by consuming 3 meals daily and integrating nutrition
supplements as required. Ideally, protein intake is distributed
throughout the day in meals and snacks to maximize an anabolic
environment with respect to body protein stores and prevent
prolonged postabsorptive periods and the accompanying catabolic condition. In addition, protein supplementation can easily
be implemented in the proximity of strenuous workouts to complement training goals and enhance recovery.
When athletes travel, or warfighters are deployed, different
challenges are presented. For athletes, these barriers to consuming sufficient energy and protein are often acute and more easily
managed because competitive events are scheduled in advance
and competitive venues are predetermined. The short-term imposition of negative energy balance and subsequent weight loss
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Supplement

on performance can be accommodated with relative ease. However, for the warfighter, changes in location, travel overseas,
often to remote locations, and access to food are more significant
and the timeframe more prolonged.
Suboptimal energy and nutrient consumption is an ongoing
challenge for military personnel during deployment (8,9). The
extent to which underconsumption occurs has been documented
and is directly related to occupational demands for specific warfighters (e.g., Special Forces, U.S. Army Rangers). For such warfighters, reduced intake of food/rations in the face of similar or
most often increased energy expenditure is often the reality of
deployment. Therein lies the conundrum specific to maximizing
protein utilization in the warfighter. If the soldier completely consumes 3 MREs (meals, ready-to-eat) daily, energy intake will approximate 3900 calories providing 123 g of protein. This amount of
protein approximates 1.5 g
kg21
d21 and is within the range
recommended for competitive athletes and reflects the lower end
of the recommended protein intake of 1.52.0 g
kg21
d21
(10,11). As conditions become more extreme for the warfighter
and operations more sustained, the inevitable reduction in calorie
and protein intake combined with increased energy expenditure
constitute a metabolic demand and catabolic situation that mandate
innovative approaches to minimize loss of body mass, reductions in lean body mass, and decreases in physical performance.
Protein supplementation in combination with situation-specific
rations is a reasonable and viable approach to offset these
documented effects of underconsumption during deployment.
Rationale for protein supplementation. From a sports nutrition perspective, the basic rationale for nutritional supplementation, protein supplementation in particular, is that meeting
energy or nutrient needs or both cannot be reasonably accomplished by eating meals composed of healthy, whole foods. In the
context of deployment and the aforementioned limitations to
achieving energy balance and consuming adequate protein in the
circumstances of military operations, protein supplementation
should be considered a routine of dietary protocol for the warfighter. The rationale for this approach is straightforward: consuming protein throughout the day may offset the loss of muscle
mass by minimizing endogenous protein breakdown to replenish
the bodys amino acid pools. Furthermore, when energy balance
is negative, evidence suggests that consuming protein in amounts
that approximate 1.52.0 g
kg21
d21 confer lean mass protection
despite reductions in total body mass.
In conclusion, warfighters represent a population of athletes
for whom routine training and physical expectations for military
operations parallel and often exceed, respectively, those of their
civilian counterparts. Current sports nutrition recommendations
for protein intake can be translated to the warfighter. However,
given that energy balance is key to optimizing protein use by the
body and muscle, additional considerations specific to energy
intake, or lack thereof, and the consequences of negative energy
balance on protein utilization by the warfighter are critical. The
ability to attenuate protein losses as reflected by reductions in
lean body mass and physical performance relies on nutrition
interventions based on existing evidence, which documents improved net protein balance with protein intakes in excess of the
RDA but within the AMDR for this macronutrient. Routine
protein supplementation as a component of meals or in snacks
(e.g., bars, beverages) consumed throughout the day will provide
the warfighter with the opportunity to reduce protein breakdown, support protein synthesis, and sustain a positive net protein balance when energy intake is sufficient. When prolonged
conditions of negative energy balance are encountered, routine

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The deployment phase involves the relocation of warfighters

and their respective units from their original duty station to the
designated site, or theater of operation, which can be domestic
or overseas. This situation can be considered similar to the preseason for athletes. The environment has changed, and there is
more intent with regard to training and preparation for competition. Energy expenditure typically increases, which translates to increased calorie needs and a respective increase in protein
intake to maintain muscle mass and support recovery from training. Energy intakes of the warfighter range from ~2700 to 3300
kcal/d for the purpose of maintaining energy balance in garrison
situations (8). Menus are designed to provide meals that contribute the required calories and nutrients to sustain these individuals; however, because various time demands and required
physical performance can be barriers to routine access to meals
and consumption of sufficient food, warfighters often have access to nutritional supplements on military exchanges that may
assist with meeting nutritional requirements.
During deployment, various operational responsibilities become a priority. For some units, soldiers may be subjected to prolonged periods of low to moderate exercise intensity not unlike
that of the endurance athlete. In other situations, such as carrying heavy loads, physical work may reflect that associated with
strength and power athletes. Although these comparisons seem
reasonable, situations do exist where the physical and mental
demands of the warfighter are unique and, in certain instances,
make meeting the energy and protein needs of this population a
more significant challenge.

protein supplementation may serve to minimize muscle losses and

offset performance detriments during periods of operational stress.
Acknowledgments
N.R.R. author acknowledges Andrew J. Young, Harris R. Lieberman,
Krista G. Austin, and Stefan M. Pasiakos for their support in the
development of this symposium and manuscript. The sole author
wrote and approved the final manuscript.

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Protein recommendations for warfighters

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