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OCR for page 55
3
Using Dietary Reference
Intakes in Planning Diets
for Groups
SUMMARY
The framework for group planning presented in this chapter
focuses on the distribution of usual nutrient intakes as the basis for
planning. This chapter describes the framework as it applies to plan-
ning for groups that are homogeneous in regard to life stage and
gender, while Chapter 4 presents an approach to planning for hetero-
geneous groups.
The overall goal of planning for groups is to achieve usual intakes
in the group that meet the requirements of most inclivicluals, but
are not excessive. This is accomplished by combining information
on the group's nutrient requirements with information on its usual
nutrient intakes. This information is used to plan for a usual nutri-
ent intake distribution in which intakes will meet the requirement
of all but a specified proportion of the group. This framework
importantly shifts the focus of planning away from past practices of
using dietary recommendations or Recommended Dietary Allow-
ances to decide what to serve, toward what is ultimately desired in
terms of the distribution of usual intakes as measured by actual
consumption. To apply the framework presented here, an accept-
able prevalence of inacloquacy must be clefineci and the distribution
of usual intakes in the group must be estimated. The target usual
intake distribution can then be cletermineci by positioning the clis-
tribution of usual intakes relative to the Estimated Average Require-
ment or nutrient requirement distribution so as to achieve the de-
sireci prevalence of inacloquacy. When positioning the distribution,
OCR for page 56
~6
DIETARY REFERENCE INTAKES
the prevalence of intakes above the Tolerable Upper Intake Level
(UL) also must be consiclereci. Because the goal of planning is to
achieve a clesireci distribution of usual intake, it is clear that to judge
the success of the planning activity, assessment must occur. In most
situations, planning group cliets is an iterative, ongoing effort in
which planners set planning goals for usual intake, assess whether
the goals are achieved, and then mollify their planning procedures
accordingly.
GENERAL CONSIDERATIONS
Planning cliets for groups is a multistep process. It involves iclentify-
ing the specific nutritional goals, determining how best to achieve
these goals, and, ultimately, assessing if these goals are achieved.
Planning the cliets of groups also involves multiple components.
Planners must clecicle what foocis to purchase, what foocis and com-
binations of foocis to offer, how the foocis should be prepared, and
the quantities to serve. Planners must also recognize that inclivicluals
within a group look at what foocis are offered and then clecicle what
foocis to select and, finally, what foocis to eat.
To aciciress all these planning components would be an ambitious
effort; many of these issues are not specifically related to using and
interpreting the Dietary Reference Intakes (DRIs). This report fo-
cuses primarily on the ultimate goal of group planning as achieving
a usual intake distribution with a low prevalence of inacloquate or
excessive intakes. In this chapter, the focus is on planning for groups
that are homogeneous in terms of life stage and gender, while Chap-
ter 4 presents an approach to planning for groups that vary in life
stage and gentler.
In planning cliets for groups, planners often adopt broaci nutri-
tional goals and then design their programs to offer meals and cliets
that meet recognized nutritional stanciarcis. For example, when
clecicling how to plan meals for an institution like a boarding school
or an assisted living facility, the objective is often to provide food
with a given level of nutrients. However, it would be more appropri-
ate to know how much of the offered food is actually consumed and
what the resulting distribution of nutrient intakes is likely to be.
Unless the distribution of intakes is consiclereci, the amount being
offered may not be sufficient for a substantial proportion of the
residents to obtain enough of a nutrient to meet their requirements.
This approach is also illustrated by some of the national food assis-
tance programs. The objective of the Food Stamp Program, for
example, is to provide low-income households with benefits so they
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USING DRIs IN PLANNING DIETS FOR GROUPS
~7
can purchase a low-cost, nutritionally acloquate cliet. However, the
current goal is to offer (i.e., make available) an acloquate cliet, which
floes not necessarily translate into a low prevalence of inacloquate
intakes among the eligible households.
The group-feecling framework proposed in this report differs from
how many planning applications are currently clesigneci. Because
this framework considers the distribution of usual nutrient intakes
of the group as the basis for planning, it shifts the focus of planning
away from using clietary recommendations in clecicling what to offer,
to what is ultimately clesireci in terms of the distribution of usual
nutrient intake.
By focusing explicitly on the distribution of nutrient intakes of a group as
the goal of group planning, the framework presented below is, in many
respects, a new paradigm, and it should be tested before beingimplemented
in large-scale group-feeding situations.
It is important to remember, however, that while planners may
have clesirecT nutrient intakes of the group as their ultimate objec-
tive, they typically can control only what is offered to inclivicluals in
the group. In this proposed framework, therefore, the link between
planning and assessment is crucial. That is, since the goal of plan-
ning is to achieve a usual intake distribution with a high group
prevalence of nutrient acloquacy (i.e., an acceptably low group prev-
alence of inadequacy), then it is clear that to judge the success of
the planning activity, assessment must occur.
When planning the cliets of population groups, it is important to
consider how usual intakes will be distributed, not just the mean or
meclian intake. For some planning applications, the goal is to
correctly position an intake distribution, but not to intentionally
change its shape (see Figure 3-1 as an example of repositioning a
distribution. In other situations it may be desirable to change the
shape of the intake distribution for one or more nutrients, perhaps
by targeting inclivicluals in the tails of the distribution. This chapter
first aciciresses group fouling where changing the shape of the clis-
tribution is not an explicit goal, and then discusses the aciclitional
challenges of planning intakes for interventions when the goal is to
alter some part of the distribution. However, it is very important to
keep in mincT that any intervention that is clesignecT to affect intakes
of all or just some inclivicluals in a group will more than likely result
in an intake distribution that differs from the baseline distribution
not only in location, but also in shape.
The framework presented in this chapter assumes that the group
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~8
DIETARY REFERENCE INTAKES
is large enough so that planning and assessing do not occur at the
incliviclual level. That is, one can neither plan for specific inclivicluals
within a group nor assess the results of group planning for specific
inclivicluals in the group. In some situations, however, it may not be
clear whether planners should follow procedures to plan cliets for
inclivicluals or for groups. Usually the decision is driven by the infor-
mation available for inclivicluals within the group, as well as by the
availability of resources to tailor cliets to incliviclual neecis.
In group-feecling situations such as the National School Lunch
Program, information about inclivicluals is generally not available,
and it is clear that group-planning procedures should be used. How-
ever, when the characteristics of inclivicluals are well known to plan-
ners (e.g., a small group home for children with a variety of physical
and developmental clisabilities), planning may occur primarily at
the individual level. Or, among groups of hospitalized patients,
information about incliviclual characteristics is potentially available,
but is used only in certain cases. Planners will know whether a given
incliviclual is following a therapeutic cliet (e.g., cholesterol lowering,
diabetic, renal) and will also have access to aciclitional personal
information (e.g., age, sex, body size). However, for most patients
on nontherapeutic cliets, incliviclual information is usually not used
in planning thus, a "hybrid" approach to planning may be aclopteci
in which a group planning approach is used for most patients, while
those on therapeutic diets may be planned for as individuals.
It is clear from the above discussion that group-feecling situations
can vary considerably, and in some situations, planners may com-
bine elements of group and individual planning. The following dis-
cussion, however, focuses only on group planning.
OVERVIEW OF PLANNING FOR NUTRIENT INTAKES
OF GROUPS
Planning nutrient intakes for a group is difficult because incliviclu-
als in a group, even if offered the same meal, vary in the amount
and selection of foocis that they eat. Planning for group fouling
typically focuses on planning for institutional feeding, which includes
such settings as residential schools, prisons, military garrisons, hos-
pitals, and nursing homes. By a slight extension, this category of
planning also includes many food and nutrition assistance programs
such as the Food Stamp Program, child nutrition programs, and
emergency food assistance programs.
The underlying principle for group planning is that the resulting distr`-
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USING DRIs IN PLANNING DIETS FOR GROUPS
~9
button of usual nutrient intakes mill have a low prevalence of inadequate
or excessive intake, as dined by the prop~ian of individuals in the
group zenith usual intakes less than the Estimated Average Requirement
(E4R) or greater than the Tolerable Upper Intake Level (UL).
To explain this framework it is important to review briefly the
methods available for assessing the prevalence of inacloquate intakes
of groups. As cliscussecT in detail in the DRI assessment report (IOM,
2000a), two related methods can be used to estimate the prevalence
of inacloquate intakes in a group:
meets.
. .
1. Probability approach. The probability approach involves deter-
mining the probability of inacloquacy for each usual intake level in
the population and then averaging the incliviclual probabilities of
inacloquacy across the group to obtain an estimate of the group
prevalence of inacloquacy. This method of clietary assessment clepencis
on two key assumptions: intakes and requirements are inclepenclent,
and the distribution of requirements is known.
2. EAR cut-point method. Uncler certain conclitions, the prevalence
of inadequate intakes for a group can be estimated as the propor-
tion of the group with usual intakes less than the EAR. The EAR
cut-point method is an approximation of the probability approach
and can be used in most situations proviclecT the following assump-
tions are met: ( 1 ) intakes and requirements are inclepenclent,
(2) the requirement distribution is symmetrical around the EAR,
and (3) the variance in intakes is larger than the variance in require-
Concept of a Target Usual Nutrient Intake Distribution
Suppose a planner is interested in planning a group diet with a
high probability of nutrient adequacy (e.g., such that the preva-
lence of inadequacy in the group is no more than 2 to 3 percent).
Given this targeted prevalence, and assuming that the EAR cut-point
method can be used in assessment, the usual intake distribution of
the group should be positioned such that only 2 to 3 percent of
individuals in the group have usual intakes less than the EAR (see
Figure 3-1, Panel B. as an example). To achieve this goal of a low
prevalence of nutrient inadequacy, it may be necessary to modify
the baseline usual nutrient intake distribution. The change may be
as simple as a shift (up or down) of the entire baseline distribution
or it may include changes in both the location and the shape of the
distribution. In either case, the appropriate changes to the baseline
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60
DIETARY REFERENCE INTAKES
usual nutrient intake distribution are intencleci to result in the
clesireci distribution of usual intakes. This clesireci distribution is
referred to as the target usual nutrient intake distribution.
The simplest approach to determining the target usual nutrient
intake distribution is to shift the baseline distribution, with the
assumption that there will be no change in its shape. This is illus-
trateci in Figure 3-1 for a hypothetical nutrient. Panel A shows the
baseline usual intake distribution in which the prevalence of inacle-
quate intakes (percentage of the group below the EAR) is about 30
percent. If the planning goal was to attain a prevalence of inacle-
quacy of no more than 2 to 3 percent, the target usual nutrient
intake distribution could be achieved by simply shifting the baseline
usual intake distribution up, as shown in Panel B.
The appropriate shift (up or down) can be calculated as the addi-
tional (or clecreaseci) amount of the nutrient that must be con-
sumeci to attain the prevalence of usual intakes below the EAR that
is the planning goal. For example, the EAR for zinc for girls 9 to 13
years old is 7 mg/ciay. Current ciata from the Third National Health
and Nutrition Examination Survey (NHANES III, as reported in
IOM, 2001) show that about 10 percent of the girls have usual in-
takes below the EAR. If the goal were to plan intakes so that only 2
to 3 percent are below the EAR, intakes would have to be increased.
When the intervention is clesigneci to increase everyone's usual zinc
intake, then the amount of the increase can be calculated as the
difference between the current intake at the 2nci to 3rci percentile
(which is 6.2 mg/ciay) and the clesireci intake at the 2nci to 3rci
percentile (the EAR of 7 mg/ciay); the difference is thus 0.8 ma/
clay. That means that the distribution of usual intakes neecis to shift
up by 0.8 mg/ciay in order to have only 2 to 3 percent of the girls
with intakes below the EAR.
The same goal of 97 to 98 percent acloquate intakes could, in
theory, be achieved by planning an intervention that is clesigneci to
increase the usual zinc intake of only those inclivicluals who have
low baseline zinc intake levels. However, in most group-planning
situations it is not possible to identify who these inclivicluals are,
making this type of planning procedure difficult to implement.
The target usual nutrient intake distribution should also be exam-
ineci to determine if it meets the goal of a low prevalence of poten-
tially excessive intakes. For zinc, the UL for girls 9 to 13 years old is
23 mg/day. The 99th percentile of their current intake distribution
is 15.5 mg/day, so even if the distribution is shifted up by 0.8 mg/day,
the 99th percentile (16.3 mg/ciay) is well below the UL.
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USING DRIs IN PLANNING DIETS FOR GROUPS
The Median of the Target Usua;t Nutrient Intake Distribution
61
The meclian of the target usual nutrient intake distribution is a
useful summary measure. As will be cliscusseci later in this chapter
(see "Planning Menus to Achieve Target Usual Nutrient Intake Dis-
tributions"), it may be used as a tool in the menu planning process.
Assuming that the shape of the intake distribution does not change as a
result of planning, the median of the target usual nutrient intake d?stribu-
[i~n ?S calculated as the median of the current usual intake d?stributian,
plus (or minus) the amount that the d?stributian needs to shift to make it
the target usual nutrient intake distribution.
Figure 3-1 illustrates this concept. In this example, the planning
goal is to achieve a distribution of usual intake such that only 2 to 3
Panel A
c'
c'
EAR Median
30% ~
Requirement Distribution
Intake Distribution
Baseline Usual Intake
Panel B
EAR Median
Ok '-I-'
_....~....~
-
in.
1
Requirement Distribution
Intake Distribution
Target Usual Intake
FIGURE 3-1 Concept of a target usual intake distribution. Panel A shows the
baseline usual nutrient intake distribution, in which the prevalence of inadequate
intake (percentage below Estimated Average Requirement) is about 30 percent.
Shifting the baseline distribution up so that the prevalence of inadequate intakes
reflects the planning goal (in this example, 2 to 3 percent) attains the target usual
nutrient intake distribution (Panel B).
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62
DIETARY REFERENCE INTAKES
percent of the group has usual intakes below the EAR. The amount
that the baseline usual nutrient intake distribution (Panel A) neecis
to shift so that it becomes the target usual nutrient intake clistribu-
tion (Panel B) can be cletermineci as the difference between intake
at the 2nci to 3rci percentile of the baseline distribution and the
EAR. This amount, acicleci to the meclian of the baseline clistribu-
tion, defines the meclian of the target intake distribution. (Uncler
the assumption of normality of the usual intake distribution, the
meclian of the target usual nutrient intake distribution can be calcu-
lateci directly as the EAR + 2 stanciarci deviations tSD] of intake.)
Assuming that the shape of the intake distribution floes not change
when it is shifted, only 2 to 3 percent of the inclivicluals in the group
will have usual intakes less than the EAR when the target clistribu-
tion is positioned in this manner.
How does the median of the [target usual nutrient intake distribution
compare with the Recommended Dietary Allowance (RDA) ?
The relationship between the median of the target usual nutrient intake
distribution and the RDA depends on the selected prevalence of inadequacy.
With a prevalence of inadequacy of 2 to 3 percent, the target median intake
usually exceeds the RDA.
In the zinc example used above for girls 9 to 13 years of age, the
distribution neecis to be shifted by an aciclitional 0.8 mg/ciay. The
median of the current zinc distribution for these girls is 9.4 mg/day, so
the meclian of the target usual nutrient intake distribution would
be 9.4 + 0.8 = 10.2 mg/day.
The median of a target usual nutrient intake distribution exceeds
the RDA because the variance in usual intakes typically exceeds the
variance of the requirement. Recall that in the case of a normal
distribution of requirements, the RDA equals the EAR + 2 SDs of
the requirement. However, the target usual nutrient intake clistribu-
tion (ancT therefore, its meclian) is cleterminecT basest on the vari-
ability of intakes. In the zinc example, the RDA for girls is 8 mg/day,
but the target median intake is 10.2 mg/day. Thus, selection of the
RDA levels as the meclian of the target usual intake distribution is
not recommenclecT as it results in a percentage of inacloquacy great-
er than would likely be selected with more careful consideration.
In positioning the distribution of usual intakes relative to the EAR,
the same three assumptions clelineatecT earlier as being required to
use the EAR cut-point method in the clietary assessment of groups
must be satisfied (IOM, 2000a). Later in this chapter, methods are
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USING DRIs IN PLANNING DIETS FOR GROUPS
63
clescribeci for estimating the target usual nutrient intake clistribu-
tion when these assumptions are not valid.
CONSIDERATIONS IN PLANNING FOR A TARGET USUAL
NUTRIENT INTAKE DISTRIBUTION
Planning for a target usual nutrient intake distribution involves
several considerations, which form the basis of the following cliscus-
sion. These include:
· estimating the existing or baseline distribution of usual nutrient
intake;
· selecting the target prevalence of inacloquacy;
· estimating the target usual nutrient intake distribution;
· assessing the feasibility of obtaining the target usual nutrient
intake distribution; and
· planning for groups when assumptions of the Estimated Average
Requirement cut-point method are violated.
Estimating the Existing or Baseline Distribution of
Usual Nutrient Intake
Estimating the target usual nutrient intake distribution requires
information about the shape of the existing distribution of usual
nutrient intakes. Specifically, the distribution of usual intakes is
neecleci, with the effect of ciay-to-ciay variation removed. The
between-person variance in usual intakes is typically less than the
variance of the observed distribution of intakes in a group, because
the latter includes both within-person (ciay-to-ciay) variation and
between-person (individual-to-individual) variation. Thus, the
observed intake distribution must be acljusteci to approximate the
distribution of true usual intakes in the group.
To estimate the distribution of usual intakes directly for the group
of interest, the actual intakes of a representative sample of the group
must be assessed over at least two nonconsecutive days or three
consecutive days and an adjustment procedure applied (IOM,
2000a). Food frequency questionnaires are not recommencleci for
use in assessments of usual nutrient intakes because of concerns
about the accuracy of nutrient intake estimates cleriveci from this
approach (see the Dietary Reference Intakes assessment report
tIOM, 2000a] for a full discussion of this issue). Rather, intakes
should be assessed through the use of 24-hour clietary intake recalls
or diet records.
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DIETARY REFERENCE INTAKES
Procedures to adjust observed intake distributions to remove the
effect of within-person variation have been developed (IOM, 2000a;
NRC, 1986; Nusser et al., 1996~. It should be noted, however, that
the most appropriate adjustment method depends in part on the
size of the group, with the Iowa State University method (Nusser et
al., 1996) recommended for large groups, but the National Research
Council (NRC, 1986) method perhaps offering advantages in the
adjustment of intake distributions for small samples (defined here
as groups smaller than 40 to 50 people). A discussion of these
methods is presented in Appendix E. Using the adjusted distribu-
tion, planners can identify the percentiles of intake that describe
the distribution of usual intakes.
In many group-planning activities, a baseline or current usual
nutrient intake for the group being planned for may not be avail-
able. In these situations it may be possible to approximate the per-
centiles of usual intake for the target group from existing data on
usual intakes for a group with similar characteristics. Distributions
of usual nutrient intake derived from general population surveys
are presented in appendixes to the DRI reports (IOM, 1997, 1998a,
2000b, 2001, 2002a), and these percentiles of intake may be appro-
priate for use in some planning activities. Where such secondary
sources are used, however, planners must be careful to consider
factors in the target group that contribute to between-person varia-
tion in usual intakes and verify that the same types of factors are
present in the group from which the distribution of usual intakes is
inferred. For example, if one were planning diets for a group of
elderly residents in a long-term care facility, it would probably not
be appropriate to estimate the distribution of usual intakes from
data on a free-living elderly group. The latter group would likely
display greater heterogeneity in intakes and thus larger between-
person variation in usual intakes than the institutionalized group.
When estimating the distribution of usual intakes, whether from
primary or secondary sources, the planner should keep in mind
possible sources of error associated with self-reported intakes.
Despite corrections to remove the effect of within-person variation,
additional random error occurs as a result of errors in dietary assess-
ment methodology, sampling variability, and inaccuracies in nutri-
ent databases. In addition, the underestimation of actual energy
intakes is well documented Johansson et al., 1998; Mertz et al.,
1991), and related nutrients may be systematically underestimated
as well. Although there is currently no acceptable method to cor-
rect for this underestimation, the planner should be aware that
such an underestimation of intake could lead to an overestimation
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USING DRIs IN PLANNING DIETS FOR GROUPS
65
of the prevalence of inacloquate nutrient intakes, and thus of the
actual neeci for increased intakes to recluce nutrient inacloquacy.
While the planner is encouraged to plan for acloquate nutrients
consumed, rather than just acloquate nutrients offered or served,
the accurate assessment of and subsequent planning for cliets as
consumed is challenging.
Selecting the Target Prevalence of Inadequacy
In planning cliets for groups, the target prevalence of inacloquacy
is ultimately a matter of judgment. A conservative approach is to
aim for a prevalence of 2 to 3 percent. In this case, the likelihood
that a randomly selected incliviclual in the group has an inacloquate
intake would be between 2 and 3 percent, representing a probability
of between 0.02 and 0.03. A higher prevalence could be selected,
though, and the selected prevalence of inacloquacy could vary by
nutrient, clepencling upon available resources.
In setting planning goals for groups, two scenarios are particularly
interesting to consider. The first is planning so that the resulting
distribution of usual intakes has all inclivicluals in the group con-
suming at least the Recommencleci Dietary Allowance (RDA), a goal
that might appear to be consistent with what practitioners often
counsel clients to achieve with their incliviclual cliets (Figure 3-2,
Panel B). The second is planning such that the meclian of the target
distribution of usual intakes in the group equals the RDA (Figure
3-2, Panel C). This goal appears consistent with current planning
applications where inclivicluals in a group are offered foocis and
meals that provide 100 percent of the RDA. Presumably, this goal
reflects the notion that if inclivicluals consume, on average, what is
offered, that mean intake will equal the RDA. As shown below,
neither of these two scenarios is being proposed or promoted for
group planning because each has potentially negative implications.
To examine the implications of these two scenarios, Figure 3-2
compares the target usual nutrient intake distribution for a hypo-
thetical nutrient with an EAR of 50 units, a stanciarci deviation (SD)
of requirement of 7.5 units (coefficient of variation tCV] of require-
ment = 15 percent), and an RDA of 65 units. The intake clistribu-
tion will simplistically be assumed to be normal, with a standard
deviation of usual intake of 18 units. Panel A, with a group preva-
lence of inadequacy of 2 to 3 percent, is similar to the target usual
nutrient intake distribution portrayoci in Figure 3-1, while Panels B
and C show the two scenarios clescribeci above. Several important
conclusions are clear from Figure 3-2:
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DIETARY REFERENCE INTAKES
seen that the average expenditure of the group is 2,971 kcal/ciay. If
2,971 is used as the average planned intake for this group, it exceeds
the estimated requirement of five of the men, and is below the
estimated requirement of one large, very active man (in a larger,
more homogeneous group, one would expect the estimate to be
inacloquate for half the men and above the requirement for the
other half). However, because intakes and requirements are highly
correlated, and assuming that all members of the group have access
to food, most members of the group will consume an amount of
energy equal to their expenditure. Thus, planning for a mean group
intake that approximates the mean estimated requirement should
allow a distribution of intakes that corresponds to the distribution
of actual requirements.
As with other planning applications, assessing the plan for energy
intakes of a group following its implementation would leaci to fur-
ther refinements. In the case of energy, however, assessment would
be baseci on monitoring body weight rather than on reported energy
intake (IOM, 2002a).
Planning the Macronutrient Distribution
In aciclition to planning for a group's mean energy intake, anoth-
er goal could be to plan for a macronutrient distribution in which
the percentages of energy intake of most group members fall within
the Acceptable Macronutrient Distribution Ranges that have been
recommencleci for inclivicluals. These ranges exist for total carbo-
hycirate, total fat, n-6 polyunsaturated fatty acids, n-3 polyunsaturat-
eci fatty acids, and protein. For adults, the suggested ranges are
45 to 65 percent, 20 to 35 percent, ~ to 10 percent, 0.6 to 1.2 per-
cent, and 10 to 35 percent of energy, respectively (IOM, 2002a).
As an example, consider the distribution of usual intake of energy
from protein, carbohydrate, and total fat in women age ci 31 to 50
years, shown in Table 3-4, and assume that the planning goal is to
have no more than ~ percent below the lower end and no more
than ~ percent above the upper end of the acceptable range. For
protein, the prevalence of usual intakes both below and above the
acceptable range is essentially zero, so one might plan to maintain
the current usual intake distribution with a meclian intake of 15.6
percent of energy.
For carbohydrate, however, approximately 20 percent of women
have usual intakes below 45 percent of energy, the lower end of the
range. If one uses the approach outlined above to plan for nutri-
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USING DRIs IN PLANNING DIETS FOR GROUPS
79
TABLE 3-4 Selected Percentiles for Usual Daily Percentage of
Total Energy from Protein, Carbohydrate, and Fat for Women
Aged 31 to 50 Years, Continuing Survey of Food Intakes by
Inclivicluals, 1994-1996, 1998
Percentile
AMDRa
(%)
1 st 5th 10th 25th 50th 75th 90th 95th 99th
Protein 10-35 10.3 11.8 12.5 13.9 15.6 17.4 19.2 20.4 22.7
Carbohydrate 45-65 35.2 40.1 42.6 46.8 51.3 56.0 60.4 63.2 68.9
Fat 20-35 20.2 23.9 25.9 29.3 32.8 36.4 39.6 41.6 45.2
a AMDR = Acceptable Macronutrient Distribution Range.
NOTE: Estimates are based on two daily intakes for each respondent in the sample. The
Iowa State University (ISU) method was used to estimate individual usual intakes of
energy from protein, carbohydrate, fat, and total energy. One gram of protein was
assumed to provide 4 kcal of energy, 1 g of carbohydrate was assumed to provide 4 kcal
of energy, and 1 g of fat was assumed to provide 9 kcal of energy. A modification of the
ISU method was then implemented to estimate the distribution of the nutrient density
(Goyeneche et al., 1997).
DATA SOURCE: ARS (1998).
SOURCE: ENVIRON International Corporation and Iowa State University Department
of Statistics, as reported in IOM (2002a).
ents and begins by planning to recluce the prevalence of low carbo-
hycirate intakes to ~ percent, one would shift the distribution so
that the Sth percentile of intake was 45 percent, or an increase of
about ~ percentage points from the observed distribution. The
meclian of that distribution would be 56.3 percent of energy from
carbohydrate, compared to the observed 51.3 percent. However,
assuming that the shape of the distribution clici not change, intake
at the 90th percentile would increase to 65.4 percent, such that
10 percent would have carbohydrate intakes above the upper end
of the range, rather than the desired ~ percent.
In contrast, for fat the prevalence of intakes below 20 percent of
calories is essentially zero (< 1 percent), but over 25 percent of women
have usual intakes above the upper end of the range (> 35 percent).
To decrease this to ~ percent, one would plan to position the usual
intake distribution such that intake at the 95th percentile was 35 per-
cent rather than the observed 42 percent, a decrease of 7 percent-
age points. The median of that distribution would be 25.8 percent
of energy from fat (32.8 - 7 = 25.8~. However, assuming the shape
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DIETARY REFERENCE INTAKES
of the distribution clici not change, the resulting intake distribution
would be such that more than 10 percent of women would have
intakes below the lower end of the range (23.9 - 7 = 16.9~.
One approach to minimizing the proportions of a group that fall
below or exceed the acceptable ranges would be to first plan for a
low prevalence of inacloquate protein intakes (i.e., a low proportion
with intakes below the EAR). Because adult women appear to have
a low prevalence of inacloquacy for total protein, protein intakes
could be maintained at the current 15.6 percent of energy, leaving
the remaining 84.4 percent of energy to be allocated between fat
~ 1 I
and carbohydrate. Starting with fat, one might plan for a meclian
intake at the midpoint of the acceptable range, or in this case, about
28 percent of energy. Because macronutrient intakes expressed as a
percentage of energy appear to have reasonably symmetrical usual
intake distributions (IOM, 2002a), planning for the midpoint would
balance the proportions below and above the acceptable range.
Finally, the planned meclian intake of carbohydrate would be cleter-
mineci by difference. In this example, planning for a meclian intake
of 15.6 percent of energy from protein and 28 percent of energy
from fat would leave the remaining 56.4 percent to come from
carbohydrate. This example floes not consider the possible contri-
bution of energy from alcohol. If alcohol is consumed, its energetic
contribution should be counted as part of the fat intake (IOM,
2002a). For example, if alcohol contributed 3 percent to energy
intake, this amount would be subtracted from the Acceptable
Macronutrient Distribution Range for fat, leaving 17 to 32 percent
of energy from fat.
The above approach to planning ranges of macronutrient intake,
however, might still leaci to a situation in which undesirably high
proportions of the group have fat or carbohydrate intakes below or
above the acceptable range. Accordingly, planners may need to plan
an intervention that would change the shape of the macronutrient
distributions, perhaps focusing on reducing the proportions above
the upper boundary of the range for total fat and below the lower
boundary of the range for carbohydrate.
PLANNING MENUS TO ACHIEVE TARGET USUAL
NUTRIENT INTAKE DISTRIBUTIONS
After the planner has estimated a target usual nutrient intake
distribution for each nutrient of interest, this information then
neecis to be incorporated into a plan of how to feeci a group such
that the target usual nutrient intake distribution is achieved.
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USING DRIs IN PLANNING DIETS FOR GROUPS
81
Depending upon the planning context, planning how to achieve
this may involve different considerations. As examples, planning
may involve developing a menu for a meal to serve at an elderly
nutrition center; it may involve determining which foods to offer as
a school lunch or as a meal in a prison or other institution; it may
mean devising an emergency food ration; or it may require develop-
ing a food plan to serve as the basis for a food assistance program or
a food guide to use in planning menus for groups.
Regardless of the planning context, planning to achieve the target
nutrient intake distribution ultimately involves determining what to
offer or serve the individuals in a group. Yet, regardless of what is
offered to a group, intakes the ultimate goal of group planning-
will differ from what is offered. Members of the group will vary in
what they consume of the foods offered and in the amount of foods
that they consume from other sources. Moreover, in most situa-
tions, what is offered itself varies. For example, a given menu may
offer milk, which may include a choice of whole, reduced fat, skim,
or chocolate.
Unfortunately, limited information is available on the link between
what is offered and intake, and what information is available most
certainly reflects the context in which the planning occurs. Never-
theless, after the planner has estimated a target usual intake distri-
bution for each nutrient of interest, this information needs to be
operationalized into a menu or any other instrument (such as food
vouchers). Menu planning involves several steps:
1. establishing an initial goal for the nutrient content of the menu
that is based on the target usual nutrient intake distribution;
2. determining what foods to offer that will most likely result in a
distribution of usual nutrient intake that approximates the target,
and thus attains the desired probability of nutrient adequacy; and
3. determining the quantities of foods to purchase, offer, and
serve.
Each of these steps is discussed in greater detail below.
Establishing an Initial Goa;lfor the Nutrient Content of the Menu
In a simple situation, where it was assumed that nutrient intake
equaled the estimated nutrient content of the foods provided, and
that only a single combination of foods is to be offered, it might
appear logical to use the median of the target usual nutrient intake
distribution as a goal for the nutrient content of a menu. As
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DIETARY REFERENCE INTAKES
clescribeci earlier, this would be projected to leaci to an intake clistri-
bution with the clesireci prevalence of nutrient acloquacy, provicleci
that the shape of the distribution clici not change. However, in most
group-planning situations, nutrient intakes are less than the esti-
mateci nutrient content of the foocis provicleci (i.e., food is not
completely consumed. Furthermore, many planning applications
involve offering a variety of menu options from which the members
of the group will select foocis. For these reasons, the planner might
aim for a menu that offers a variety of meals with a nutrient content
range that includes, or even exceeds, the meclian of the target usual
nutrient intake distribution.
Determining What Foods to Offer
After all the nutrient targets have been set, the planner must select
foocis that will provide this average level of nutrient intake and clivicle
these foocis into different meals and snacks. To convert nutrient
intake targets into food intakes, planners will usually rely on food
guides such as the Food Guicle Pyramid, published menus, and pre-
viously used menus to design a menu that is likely to result in the
target level of acloquacy. This will typically be an iterative process,
often assisted by nutrient calculation software that allows interactive
changes to menus and recalculation of the nutrient levels at each step.
Determining the Quantities of Foods to Purchase, Offer, and Serve
Designing menu offerings to meet an intake target is a difficult task.
Because food selections and food waste vary among groups, and
among menus within groups, the appropriate procedures for cleter-
mining the foocis to purchase and offer clepenci heavily on the par-
ticular planning context. Few ciata are available on the relationship
between offerings and intakes, and it is therefore difficult to offer
the planner a concrete goal in terms of menu planning when the
targets have been cletermineci in terms of nutrient usual intakes. In
an attempt to offer practical guidance to planners, several still-to-
be-testeci assertions may be of use:
· Offering meals with an average nutrient content equal to the
meclian of the target usual nutrient intake distribution is likely to
result in lower than planneci-for acloquacy of intakes. This is because
inclivicluals in a group tend to consume less than what is offered to
them.
· The relationship between offerings and intakes is likely to be
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USING DRIs IN PLANNING DIETS FOR GROUPS
83
clepenclent on context. For example, in planning situations in which
inclivicluals' choices are constrained to the offered meal (as in an
assisted living facility, perhaps), the intake goals might be easier to
achieve than in those cases where inclivicluals get to choose foocis
from a wicle range of options that provide varying levels of specific
nutrients (such as in a school cafeteria).
· The shape of the intake distribution is likely to change as menus
offered to groups change. Thus, even if the menu offered is clesigneci
to achieve the target intake distribution and associated level of
nutrient acloquacy, it is very important to evaluate the impact of the
new menu on intakes, as cliscusseci later in this chapter.
The discussion above clearly highlights the neeci for more research
in this area. As stated, planners must be able to translate the nutri-
ent intake goals into menu offerings, and the knowledge necessary
to do so effectively is not available at this time. Experienced planners
will draw from their own expertise to construct menus that are more
likely to meet nutrient acloquacy goals, but research that uncovers
the relationship between offerings and intakes in various planning
contexts is neecleci.
Planning Menus for Nutrients with an Adequate Intake
For nutrients where there is insufficient evidence to determine an
Estimated Average Requirement, an Acloquate Intake (AI) has been
established. The AI is expected to maintain a clefineci nutritional
state or criterion of acloquacy in essentially all members of a healthy
population. The AI has been estimated in a number of different
ways (IOM, 1997, 1998a, 2000b, 2001, 2002a). In some cases the AI
is based on the observed mean intakes by groups that are maintain-
ing health and nutritional status consistent with meeting require-
ments. In these cases the AI is similar conceptually to the meclian of
a target usual nutrient intake distribution. In other cases the AI is
the level of intake at which subjects in an experimental study met
the criterion of acloquacy. In these cases the AI is not directly com-
parable to a target meclian intake.
Because the derivation of the AI differs substantially among nutri-
ents and among age and gentler subgroups, it also is the case that
its use in planning group cliets varies. The AI can be used as a
planning goal as the target median intake of a group if the variability
in usual intake of the target population is similar to the variability
in intake of the population used to set the AI. However, if the AI is
not based on a group median intake of a healthy population, plan-
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DIETARY REFERENCE INTAKES
ners must recognize that there is a reduced level of confidence that
achieving a median intake at the AI will result in a low prevalence of
inadequacy. Furthermore, the AI cannot be used to estimate the
proportion of a group with inadequate intakes (IOM, 2000a). Thus,
regardless of how the AI has been estimated, it is not possible to use
the AI to plan a target distribution of usual intakes with a known
prevalence of inadequacy.
Table 3-5 presents a summary of the nutrients for which AIs have
been estimated, and notes the cases in which these estimates reflect
group mean intakes. The comparability of the target group to the
population used to set the AI can be verified by referring to the
original DRI reports for the nutrients of interest.
Assessing the Results of Planning
The final step in planning intakes is to assess the effectiveness of
the planning process. Such an assessment would follow the recom-
mended procedures for assessing group intakes (IOM, 2000a).
There are several reasons why assessment is a crucial component of
the framework for group planning. First, planners typically can con-
trol only what is offered to individuals in the group, not what they
actually eat. Because the goal of planning is to achieve an accept-
able group prevalence of inadequacy, then it is clear that to judge
the success of the planning activity, intake assessment must occur.
furthermore, the d~str~buhon ot Intakes that was chosen as the
starting point for the planning activity often will not be taken from
the group for which intakes are being planned. For example, it may
be necessary to start with intake distributions from national surveys.
Thus, the planner is making an assumption about the applicability
of the distribution to the group of interest.
In addition, a crucial assumption is made when establishing the
targets for planning that shifting the distribution of intakes to a
new position does not change the shape of the distribution. If the
shape changes, then the estimated target percentiles (including the
median) of intake may be incorrect. The shape of the distribution
is likely to depend on many factors, including food preferences, the
types of foods served, and the amount of food needed to meet each
person's energy needs. Thus, there are several reasons to believe
the distribution's shape would change if a different selection of
foods is served.
Planning group diets is an iterative, ongoing effort in which plan-
ners set goals for usual intake, plan menus to achieve these goals,
~ , . ,. .. , .. , . ~ . . . .. . .
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USING DRIs IN PLANNING DIETS FOR GROUPS
TABLE 3-5 Nutrients with Acloquate Intakes
Nutrient
85
Life Stage Group
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
0-12 mo
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
0-12 mo
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
0-12 mo
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
0-12 mo
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
Group Mean Intake
Total fiber
n-6 Polyunsaturated
fatty acids
n-3 Polyunsaturated
fatty acids
Calcium
Fluoride
Magnesium
Phosphorus
Selenium
Biotin
Choline
0-12 mo
0-12 mo
0-12 mo
0-12 mo
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
0-12 mo
1-18 y
19-50 y
> 50 y
Pregnancy and lactation (all ages)
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
No
No
No
continues
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86
TABLE 3-5 Continucci
DIETARY REFERENCE INTAKES
Nutrient Life Stage Group Group Mean Intake
Folate 0-12 mo Yes
Niacin 0-12 mo Yes
Pantothenic acid 0-12 mo Yes
1-18 y Yes
19-50 y Yes
> 50 y Yes
Pregnancy (all ages) Yes
Lactation (all ages) NO
Riboflavin 0-12 mo Yes
Thiamin 0-12 mo Yes
Vitamin B6 0-12 mo Yes
Vitamin B12 0-12 mo Yes
Vitamin C 0-12 mo Yes
Vitamin D 0-12 mo No
1-18 y No
19-50 y No
> 50 y No
Pregnancy and lactation (all ages) Nc
Vitamin E 0-12 mo Yes
Vitamin A 0-12 mo Yes
Vitamin K 0-12 mo Yes
1-18 y Yes
19-50 y Yes
> 50 y Yes
Pregnancy and lactation (all ages) Yes
Chromium 0-12 mo Yes
1-18 y Yes
19-50 y Yes
> 50 y Yes
Pregnancy and lactation (all ages) Yes
(Jopper 0-l mo Ye
continued
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USING DRIs IN PLANNING DIETS FOR GROUPS
TABLE 3-5 Continued
87
Nutrient Life Stage Group Group Mean Intake
Iodine 0-12 mo Yes
Iron 0-6 mo Yes
Manganese 0-12 mo Yes
1-18 y Yes
19-50 y Yes
> 50 y Yes
Pregnancy and lactation (all ages) Yes
Molybdenum 0-12 mo Yes
Zinc 0-6 mo Yes
SOURCE: IOM (2000a, 2002a).
assess whether the planning goals were achieved, and then modify
their planning procedures accordingly.
PLANNING INTERVENTIONS TO CHANGE THE SHAPE OF
THE INTAKE DISTRIBUTION
In the above approach to group planning, the implicit assump-
tion is that the shape of the usual intake distribution is relatively
stable and that planning for group feeding simply involves deter-
mining the location of the usual intake distribution. However, many
interventions will also alter the shape of this distribution, either
intentionally or unintentionally.
ne.~ireH ch~n~.~ in the .~h~ne of the into Hi.~trih~tion might he
. . . . . .. ~ . .. .. . . . . . . .
to shrink both tails ot the d~str~bubon or to shrink only the lower or
upper tail. Interventions targeted to only those in the lower tail, if
successful, would reduce the prevalence of inadequate intakes, while
interventions targeted to those in the upper tail would reduce the
prevalence of excessive intakes. An intervention to reduce the total
variance in usual intakes might reduce the prevalence of both inade-
quate and excessive intakes. Several types of interventions might be
designed to change intake distributions. For example, food fortifi-
cation programs might select foods that are consumed more by the
targeted portion of the group. Nutrition education classes might be
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DIETARY REFERENCE INTAKES
held for the proportion of the group particularly at risk of low
intakes (perhaps those with less education or those who choose not
to eat certain types of foocis). Food and nutrition assistance pro-
grams target low-income families on the assumption that they are at
higher risk of inacloquate intakes. Some of these applications are
cliscusseci in Chapter 5.
It is not surprising that even perfectly planned interventions may
not result in the expected changes in intake. Unfortunately, limited
guidance can be offered to planners at this time because cletaileci
examinations of the impact of various types of interventions on the
shape of an intake distribution are almost nonexistent. Further
research is clearly neecleci to guide planners when selecting inter-
vention approaches.
Representative terms from entire chapter:
usual intake
