Implementing food-based dietary guidelines for - United Nations ...

Using nutrient intake values to assess intakes
similar foods. In this case, the full probability approach
should be used.
As explained in more detail elsewhere [2], the cutpoint
approach works for statistical reasons. It does
not mean that the ANR is an appropriate cutpoint for
screening individuals. That is, it cannot be assumed
that the individuals with intakes below the ANR are
the ones who should be targeted for dietary interventions.
Although it is true that intakes below the ANR
have at least a 50% probability of inadequacy, it is not
true that all of these individuals have intakes below
their requirements. Even at the ANR, an intake still
has a 50% probability of adequacy. Furthermore, some
individuals with intakes above the ANR are still not
meeting their requirements. As noted above, screening
at the individual level is difficult unless usual long-term
intakes have been measured. At the group level, however,
the prevalence of inadequacy could be reduced by
shifting the distribution of intakes so that fewer intakes
fall below the ANR; this approach is described below in
the section on Planning Nutrient Intakes for Groups.
Adjusting intake distributions
Both the full probability approach and the cutpoint
approach require that the distribution of intakes represents
usual intakes for the group of interest. Usual
intakes could be obtained by having many days of
observation for each individual, but this type of data
is seldom available. Alternatively, the distribution can
be statistically adjusted to remove the effect of day-today
variation (fig. 3). Several methods are available for
making these adjustments [2, 14–17], but all require an
estimate of the day-to-day variation in nutrient intakes
for the group. These methods may be used even if data
from only one day are available for each person, as long
as a second day of dietary data is collected for at least
a representative subset of the group of interest. Alternatively,
an estimate of day-to-day variation may be
obtained from multiday data for a similar population.
The ability to statistically adjust intake distribution to
remove the effect of day-to-day variation in intakes,
rather than collecting many days of data for each
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FIG. 3. Comparison of a distribution of one-day nutrient
intakes with a distribution of usual nutrient intakes. The proportion
of the group with intakes below the average nutrient
requirement (ANR) is greater for the one-day distribution
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person, makes the assessment of groups more feasible
than the assessment of individuals.
Assessing intakes with an AI
For nutrients without an ANR, it is possible to evaluate
the intake of a group if an adequate intake (AI) has
been set based on the mean intake of a healthy population.
If the group’s mean intake approximates the AI,
then the group can be assumed to have a low prevalence
of inadequacy. However, no such qualitative judgment
can be made if mean intake is below the AI. Because
the distribution of requirements is not known, it is possible
that mean intakes below the AI are also associated
with a low prevalence of inadequacy. For this type of
assessment, the intake distribution does not need to
be adjusted for day-to-day variation, because only the
mean intake is being examined.
Assessing the prevalence of potentially excessive intakes
To assess the prevalence of potentially excessive intakes,
the proportion of the group with usual intakes above
the UNL should be estimated. Because the UNL
includes an uncertainty factor, it should not be assumed
that everyone with an intake above the UNL is at risk
for adverse effects. However, as the prevalence of
intakes above the UNL increases, the likelihood that the
group is at risk also increases. Prior to this evaluation,
the intake distributions must be adjusted to remove the
effect of day-to-day variation, as described above.
Assessing energy intakes
As was the case for assessing individuals, the probability
approach cannot be used to evaluate the energy
intakes of a group. Instead, the average energy intake of
the group can be compared with the estimated average
energy requirement for the group, taking into consideration
the ages, sexes, and physical activity levels of
the individuals within the group. If the average energy
intake exceeds the estimated average requirement, then
the group, on average, is likely to be gaining weight,
assuming that the requirements and intakes have been
accurately calculated. If the reverse is true, then the
group may be, on average, losing weight. This type
of comparison does not require adjusting the intake
distribution for day-to-day variation, since only the
mean is being evaluated. Energy balance can also be
measured by weight changes, which can assist in assessing
whether a group’s energy intake is inadequate or
excessive.
Assessing macronutrient intakes
If AMDRs have been set, then the group’s macronutrient
intakes may be assessed using these standards.
The proportion of the group with intakes outside the
AMDR is a measure of how well the group is meeting
these standards. These would be interpreted as the
prevalence of intakes that are too high or too low. If