Using the Dietary Reference Intakes
This factsheet provides a brief introduction to appropriate uses of the
Dietary Reference Intakes (DRIs) for dietary assessment and planning.
It does not include sufficient detail needed for the competent application
of the DRIs. Nutrition and health professionals should consult the resources
listed in the section, Use of the DRIs in Community Nutrition and Dietetic
Practice.
Understanding the background, the functional indicators of nutritional
adequacy upon which the DRIs are based, the statistical underpinnings
for the various uses of the DRI values, and the difference between use
with individuals and groups is critical for the appropriate application
of the DRIs.
Overview of the Dietary Reference Intakes
The Dietary Reference Intakes (DRIs) are nutrient reference values that
replace the 1990 Recommended Nutrient Intakes (RNIs) in Canada and the
1989 Recommended Dietary Allowances in the United States. The DRIs are
established using an expanded concept that includes functional indicators
of good health and prevention of chronic disease, as well as adverse health
effects from excessive nutrient intakes. As was the case with the RNIs,
each type of DRI refers to the average daily nutrient intake of healthy
individuals over time.
The introduction of the DRIs, especially the Estimated Average Requirement
(EAR) and the Tolerable Upper Intake Level (UL), provides better tools
for use in dietary assessment and planning for individuals and for groups.
The DRIs were developed anticipating a variety of uses such as:
- assessment of diets of individuals and groups;
- design and evaluation of diets in a variety of institutions;
- creation of nutrition guidelines and education programs;
- development of regulations around the nutritional quality of the food
supply.
The figure below illustrates relationships among the different types
of Dietary Reference Intakes. The table that follows summarizes the DRI
definitions and the concepts illustrated by the figure.
FIGURE: Relationship of DRI values to risk of nutrient inadequacy
and risk of adverse health effects
View
TABLE: DRI
Definitions and Relationship to Risk of Inadequacy and Risk of Adverse
Effects
Use of the DRIs by Health Canada
The Dietary Reference Intakes (DRIs) are established by the National
Academy of Sciences, which is a private, non-profit society of distinguished
scholars with a mandate to advise the US government on scientific and
technical matters. Health Canada supports the DRI process and will be
using the new values in its programs and policies. The DRIs will influence
the development of regulatory standards, assessments of dietary patterns,
and the development of food and nutrition advice delivered to the Canadian
public.
Health Canada has an internal working group with representation from
the different bureaus working with the DRI. This group guides the steps
that Health Canada is taking to implement the DRIs to ensure consistency
in their use and application throughout Health Canada.
Consultations were held in June 1998 with Canadian stakeholders, including
representatives of provincial and territorial governments, non-governmental
organizations, and the food and supplement industry, to discuss the creation
of a rational and timely process for the implementation of the DRIs in
Canada. Based on comments received from these stakeholders, Health Canada
assembled an Expert Advisory
Committee on Dietary Reference Intakes in September 2002. The role
of this Committee is to provide advice and informed feedback on the implications
of the DRIs on public health and advise on potential intervention options
identified by Health Canada. Options could include changes to dietary
guidance, policies related to the food supply, or targeted education.
Use of the DRIs in Community Nutrition and Dietetic Practice
DRI Reports
The reports of the Subcommittee on Interpretation and Uses of Dietary
Reference Intakes provide useful guidance to nutrition practitioners using
the DRIs:
Each report presents the theoretical and statistical underpinnings for
the various uses of the DRI values, presents sample applications, and
provides guidelines to help professionals determine when specific uses
would be inappropriate.
Professional Education
Dietitians of Canada has developed a  professional
education program for nutrition and health professionals to learn
about DRIs, the science behind them, and how to use them appropriately
in practice.
Scientific Articles
To help health professionals understand the DRIs, articles are also being
published in scientific journals.
Appropriate Use of DRIs - Overview
Most applications of the DRIs fall into two broad categories: assessment
and planning.
- Dietary assessment involves a comparison
of usual nutrient intakes with nutrient requirements, and examines the
probability of inadequate or excessive intakes.
- Dietary planning aims to plan usual diets
that have an acceptably low probability of nutrient inadequacy or excess.
Clearly, these two general applications are interrelated. In most situations,
planning is an ongoing activity in which planners set goals for usual
intake, assess whether the goals are achieved and then modify their planning
procedures accordingly.
Dietary assessment and dietary planning can be conducted for an individual
or for a group. The methods and the appropriate DRI value to use differ
in each case.
The following chart provides a summary of the appropriate uses of the
DRIs but lacks the detail needed for their correct application. For more
details on using the Dietary Reference Intakes, refer to the Food and
Nutrition Board reports on Applications
in Dietary Assessment (2000) and Applications
in Dietary Planning (2003).
It is also important to note that DRIs are standards for apparently healthy
people, and not meant to be applied to those with acute or chronic disease
or for repletion of previously deficient individuals.
View
Table: Summary
of Appropriate Uses of Dietary Reference Intakes
Use of the DRIs in Dietary Assessment
For more details on using the Dietary Reference Intakes
for dietary assessment, refer to the Food and Nutrition Board report on Applications
in Dietary Assessment (2000).
Whether assessing diets of individuals or of groups, two types of information
are needed:
- accurate knowledge of the usual (long-term) intake of the individual
or group
-the number of days needed to accurately assess usual intake differs
among nutrients, as well as among individuals or groups
- nutrient requirement(s) of the individual or group
-requirement is the lowest continuing intake level of a nutrient that,
for a specified indicator of adequacy, will maintain a defined level
of nutritional adequacy
Assessing Individual Diets
Interpreting nutrient intake data in relation to the DRIs can enhance
the assessment of an individual's diet; however, the information obtained
must be interpreted cautiously as it is only one small component of a
nutritional status assessment. Ideally, intake data are combined with
clinical, biochemical, and/or anthropometric information to provide a
valid assessment of nutritional status. These physiological data can be
used to supplement or confirm estimates of inadequacy based on dietary
data. For example, a usual intake well below the RDA or AI would be a
reason to further assess the individual's nutritional status through laboratory
testing or clinical examination. Individuals whose usual intake exceeds
the UL may be at risk of adverse health effects.
Assessment of dietary adequacy for an individual is difficult because
of the imprecision involved in estimating an individual's usual intake
and the lack of knowledge of an individual's requirement. The individual's
true usual intake and true requirements must be estimated. Thus, assessment
of dietary adequacy for an individual must be interpreted cautiously in
combination with other types of information about the individual.
Assessing Group Intakes
Dietary assessment of groups (for example, a population survey) can provide
information on the prevalence of nutrient inadequacy and the prevalence
of nutrient excess. Researchers may also study diets of smaller groups
with common characteristics to determine whether their intakes are adequate
or whether there is a proportion of the group at risk for adverse health
effects. Assessing the diets of groups can be used to develop food and
nutrition policy and can also be useful in determining whether food and
nutrition programs are effective. Depending on the results of the assessment,
intervention strategies might be developed to address any problem areas.
Dietary assessment at the group level typically involves comparing usual
nutrient intakes with nutrient requirements to assess the prevalence of
inadequacy among the group. Two approaches have been developed:
- the probability approach, which involves determining the risk of
inadequacy to each individual in the group and summing the probabilities
(weighted average of the risk of inadequacy)
- the EAR cut-point method, a simplified version of the probability
approach that can be used when specific conditions are met, to approximate
the proportion of the group with intakes below requirements
The RDA should not be used as a cut-point for assessing nutrient intakes
of groups because a serious overestimation of the proportion of the group
at risk of inadequacy would result.
For nutrients with an AI, the best that can be done is to look at mean
and median intake relative to the AI. When the AI has been set based on
the mean intake of a healthy group, similar groups with mean intakes at
or above the AI can be assumed to be adequate. When the AI has been experimentally
derived or developed from a combination of experimental and intake data,
there is less confidence in the assessment. When mean intakes of groups
are below the AI, nothing can be inferred about the adequacy of the group's
intake.
The UL can be used as a cut-point against which to measure usual intakes
in order to estimate the proportion of a group at potential risk of adverse
effects from excessive intake of a nutrient.
Dietary Assessment Summary
View
Table: Dietary
Assessment Summary
Use of the DRIs in Dietary Planning
For more details on using the Dietary Reference Intakes
for dietary planning, refer to the Food and Nutrition Board report on Applications
in Dietary Planning (2003).
Whether diets are being planned for individuals or for groups, the goal
is to plan usual diets that are nutritionally adequate (such that the
probability of nutrient inadequacy or excess is acceptably low).
- For individuals, the goal of planning is to achieve usual intakes
that are close to the RDA or the AI.
- For groups, the goal is to determine a usual intake distribution that
results in a low prevalence of intakes that are inadequate or at risk
of being excessive.
When using the DRIs for planning dietary intakes for individuals or for
groups, it is helpful to consider the process and functional indicators
used for developing the DRIs for specific nutrients. Special considerations
for planning include factors that affect nutrient bioavailability, such
as the source, chemical form and dietary matrix, as well as the physiological,
lifestyle and health factors that may alter nutrient requirements and
therefore recommended intakes.
Planning Individual Diets
The goal of planning diets for individuals is to have a low probability
of inadequacy while minimizing potential risk of excess for each nutrient.
The RDA or AI is used as the target nutrient intake for individuals, and
planners should be aware that there is no recognized benefit to usual
intakes in excess of these levels. Food-based nutrition education tools,
such as Canada's
Food Guide to Healthy Eating, are often used to help an individual
plan a healthy diet.
Planning Diets for Groups
The goal of planning for groups is to achieve a distribution of usual
nutrient intakes that provides for a low prevalence of inadequate intakes
and a low prevalence of intakes that may be at potential risk of adverse
effects due to excessive intake. To do this, an acceptable prevalence
of inadequacy must be defined and the distribution of usual intakes in
the group must be estimated. The target usual intake distribution can
then be determined. The procedure used for planning intakes of groups
differs depending on whether the group is relatively homogeneous or is
composed of a number of subgroups that differ in nutrient and energy requirements.
In most situations, planning diets for groups is an ongoing endeavour
in which dietary intakes are planned, intakes are assessed to judge the
success of the planning activity, and planning efforts are modified accordingly.
View
Image: Schematic
decision tree for dietary planning
Dietary Planning Summary
View
Table: Dietary
Planning Summary
© Her Majesty the Queen in Right of Canada
(2003). All rights reserved.
Cat. H44-49/2003E-HTML
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