Questions and Answers
- What are Dietary Reference Intakes?
- What is an Estimated Average Requirement (EAR)?
- What is a Recommended Dietary Allowance (RDA)?
- What is an Adequate Intake (AI)?
- What is a Tolerable Upper Intake Level (UL)?
- Are ULs set for all nutrients?
- What is an Acceptable Macronutrient Distribution Range (AMDR)?
The DRI Values: Definitions
1. What are Dietary Reference Intakes?
The Dietary Reference Intakes (DRIs) are a set of scientifically based nutrient reference values for healthy populations. The DRIs for various groups of nutrients have been developed over a span of time, with reports on all of the nutrients published between 1997 and 2004. Recently, Dietary Reference Intakes for Calcium and Vitamin D have been re-examined, with an updated report on those two nutrients released by the IOM on November 30, 2010.
DRIs are used by nutrition practitioners, governments, and non-governmental organizations to assess and plan the nutrient intakes of individuals and population groups.
"Dietary Reference Intakes" (DRIs) is an umbrella term that describes four types of reference values:
- Estimated Average Requirement (EAR)
- Recommended Dietary Allowance (RDA)
- Adequate Intake (AI)
- Tolerable Upper Intake Level (UL)
The DRIs replace the 1990 Recommended Nutrient Intakes (RNIs) in Canada and the 1989 Recommended Dietary Allowances in the United States. The DRIs are established through a process overseen 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. Both American and Canadian scientists have participated in the development of the DRIs.
DRIs are established using an expanded concept that includes indicators of good health and the prevention of chronic disease, as well as possible adverse effects of excess intakes of nutrients. Each type of DRI refers to the average daily nutrient intake of healthy individuals over time.
Key differences in the DRI approach compared to the former RNIs include:
- working together with American scientists and harmonizing nutrient recommendations for Canada and the United States
- making use of the concepts of probability and risk to underpin the determination of DRIs and their application in assessment and planning
- considering the risks of excessive nutrient intakes and establishing upper levels of intake where data exist regarding risk of adverse health effects
- establishing multiple reference values for each nutrient, allowing for more diverse applications in assessing and planning diets
- reviewing components of food that may not meet the traditional concept of a nutrient but are of possible benefit to health
- making recommendations for future research directions based on the knowledge gaps identified
2. What is an Estimated Average Requirement (EAR)?
An Estimated Average Requirement (EAR) is the median usual intake value that is estimated to meet the requirement of half the healthy individuals in a life-stage and gender group. At this level of intake, the other half of the individuals in the specified group would not have their needs met. The EAR is based on a specific criterion of adequacy, derived from a careful review of the literature. Reduction of disease risk is considered along with many other health parameters in the selection of that criterion. The EAR is used to calculate the RDA.
In the case of energy, an Estimated Energy Requirement (EER) is established rather than an EAR. An EER is defined as the average dietary energy intake that is predicted to maintain energy balance in healthy, normal weight individuals of a defined age, gender, weight, height, and level of physical activity consistent with good health. In children and pregnant and lactating women, the EER includes the needs associated with growth or secretion of milk at rates consistent with good health.
3. What is a Recommended Dietary Allowance (RDA)?
A Recommended Dietary Allowance (RDA) is the average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a particular life-stage and gender group.
- If the distribution of requirements in the group is assumed to be normal, then the RDA can be calculated from the EAR and the standard deviation of requirements (SDREQ) as follows: RDA = EAR + 2 SDREQ
- If the distribution of requirements is known to be skewed, other methods are used to identify the 97th to 98th percentile of the requirement distribution and to set the RDA at this level.
The RDA is used as a goal for usual intake of individuals. Because the RDA is calculated based on the EAR, an RDA can only be set for a particular nutrient if there is sufficient scientific evidence to establish an EAR for that nutrient.
4. What is an Adequate Intake (AI)?
If sufficient scientific evidence is not available to establish an EAR and set an RDA, an AI is derived for the nutrient instead. An AI is based on much less data and incorporates substantially more judgment than is used in establishing an EAR and subsequently the RDA. The issuance of an AI indicates that more research is needed to determine, with some degree of confidence, the mean and distribution of requirements for that specific nutrient.
The AI is a recommended average daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people who are assumed to be maintaining an adequate nutritional state. Examples of adequate nutritional states include normal growth, maintenance of normal levels of nutrients in plasma, and other aspects of nutritional well-being or general health. For example:
- For young infants, the AI is usually based on the daily mean nutrient intake supplied by human milk for healthy, full-term infants who are exclusively fed human milk.
- For adults, the AI may be based on data from one type of experiment (e.g. the AI for choline), based on estimated dietary intakes in apparently healthy population groups (e.g. the AIs for biotin and pantothenic acid), or result from a review of data from different approaches (e.g. the AI for calcium, based on calcium retention, factorial estimates of requirements, and limited data on bone mineral density and bone mineral content changes in adult women).
The AI is expected to meet or exceed the needs of most individuals in a specific life-stage and gender group. When an RDA is not available for a nutrient (because there is no EAR), the AI can be used as the goal for an individual's intake. However, the AI has very limited uses in assessments of any type.
5. What is a Tolerable Upper Intake Level (UL)?
A Tolerable Upper Intake Level (UL) is the highest level of continuing daily nutrient intake that is likely to pose no risk of adverse health effects in almost all individuals in the life-stage group for which it has been designed.
- As intake increases above the UL, the potential risk of adverse effects increases.
- The term "tolerable" intake was chosen to avoid implying a possible beneficial effect. Instead, the term is intended to specify a level of intake with a high probability of being tolerated biologically. The UL is not intended to be a recommended level of intake.
- Unless specifically identified in the nutrient reports (e.g. for folate in the prevention of neural tube defects), there is no currently established benefit to healthy individuals of ingesting nutrients in amounts exceeding the RDA or AI.
- At intakes between the RDA and UL, the risks to the individual of inadequacy and of excess are both close to zero.
The need to establish ULs grew out of the increasingly common practice of fortification of foods with nutrients and the increased use of dietary supplements. The adverse health effects used to determine a UL vary from nutrient to nutrient. ULs are based on evaluations conducted using the Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients adopted in 1998 for the DRI process by the Institute of Medicine. The risk assessment model was designed specifically to address the potential for adverse effects from overconsumption of nutrients.
6. Are ULs set for all nutrients?
No. For some nutrients, the data are not sufficient at this time to establish a UL. This indicates the need for caution in consuming high intakes of those nutrients. It should not be interpreted as meaning that high intakes pose no risk of adverse effects. For example, arsenic is known to be toxic in high doses but it has no UL because not enough data exist on chronic intake of lower doses to set a UL. When a UL cannot be determined, it is important to be careful about consuming levels above the RDA or AI.
7. What is an Acceptable Macronutrient Distribution Range (AMDR)?
An Acceptable Macronutrient Distribution Range (AMDR) is defined as a range of intakes for a particular energy source that is associated with reduced risk of chronic disease while providing adequate intakes of essential nutrients. An AMDR is expressed as a percentage of total energy intake. If an individual consumes below or above this range, there is a potential for increasing the risk of chronic diseases shown to affect long-term health, as well as increasing the risk of insufficient intakes of essential nutrients. AMDRs have been established for protein, carbohydrate, fat, and linoleic (n-6) and alpha-linolenic (n-3) polyunsaturated fatty acids.
The DRI Review Framework
1. Who is responsible for developing the Dietary Reference Intakes?
The Dietary Reference Intakes are established by expert panels of Canadian and American scientists, through a review process overseen by the US Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences (NAS). The NAS is a private, non-profit society of distinguished scholars with a mandate to advise the US government on scientific and technical matters.
2. What are the National Academy of Sciences, the Institute of Medicine and the Food and Nutrition Board?
The National Academy of Sciences (NAS) is an American, private, non-profit society of distinguished scholars engaged in scientific and engineering research, dedicated to the advancement of science and technology and to their use for the general welfare of the public. The Academy's mandate requires it to advise the US federal government on scientific and technical matters.
For more information, visit National Academy of Sciences.
The Institute of Medicine was established by the National Academy of Sciences to secure the services of appropriate experts in the examination of policy matters pertaining to the health of the public. The Institute acts under the mandate of the NAS as an adviser to the US federal government and, upon its own initiative, to identify issues of medical care, research, and education.
For more information, visit Institute of Medicine.
The Food and Nutrition Board (FNB) is a unit of the Institute of Medicine, which is part of the NAS in the US. The FNB is a multidisciplinary group of scientists with expertise in nutrition, food sciences, biochemistry, medicine, public health, epidemiology, food toxicology and food safety. Its major focus is to evaluate emerging knowledge of nutrient requirements and relationships between diet and reduction of chronic disease risk. It also relates this knowledge to strategies for promoting health and preventing disease. (Note: The FNB was responsible for developing the previous RDAs in the United States.)
For more information, visit Food and Nutrition Board.
Health Canada's Role in the DRI Development Process
1. Why did Health Canada decide to collaborate with the US to review nutrient requirements?
Health Canada has reviewed and made recommendations on nutrient requirements on a periodic basis since 1938. The last update on nutrient requirements, which were termed Recommended Nutrient Intakes (RNIs), was published in 1990 as part of Nutrition Recommendations: The Report of the Scientific Review Committee. There were rapid advances in nutritional science and by 1994, it was clear that it was time to initiate another review of the scientific data.
At the same time, the Food and Nutrition Board of the National Academy of Sciences was beginning a consultation process on the review of the 1989 Recommended Dietary Allowances. Health Canada considered that participating in a joint review with the US would offer several advantages to Canada. These were as follows:
- The science underlying nutrient requirements knows no borders. Scientists everywhere are utilizing the same knowledge produced from studies conducted all over the world.
- The knowledge base on nutrients and foods and their impact on health is increasing rapidly in scope and complexity. This increases the need for specialized expertise. Participating in the US review permits Canada to expand the base of scientific expertise that can be utilized.
- International trade considerations, including NAFTA, suggest that the harmonization of the science base underlying nutrition policy will facilitate harmonization of such trade-related matters as nutrition labelling and food composition.
2. Did Health Canada consult with stakeholders before embarking on this process?
Health Canada and the National Institute of Nutrition co-sponsored a forum in April 1995 to consider the issue of harmonization of nutrition recommendations. Representatives of the dietetic and medical professions, academic research community, food industry, and other levels of government attended. From this dialogue between users of the Nutrition Recommendations emerged a general agreement that it would be desirable to achieve a unified set of reference intake values between Canada and the US.
3. Are Health Canada scientists members of the review committees?
No. The National Academy of Sciences operates at arm's length from government and neither Canadian nor US government scientists can take part in the review.
4. What has Health Canada funded?
Health Canada has provided funds to support the work of various expert panels and subcommittees over the length of the DRI process. Financial contributions from the Public Health Agency of Canada have also been made in the last several years.
Reports on the Dietary Reference Intakes
1. What reports on the Dietary Reference Intakes have been issued?
The DRI reports contain substantial information reflecting the current state of knowledge on nutrients, the indicators used to establish nutrient requirements, the influence of nutrition on health and disease, as well as identifying knowledge gaps and potential areas for future research. The reports are valuable resources for practitioners, researchers and students.
For a list of reports that have been published, including links to the available online versions, see the Dietary Reference Intake Report List.
2. How can the reports on the Dietary Reference Intakes be accessed?
Electronic versions of and ordering information for the DRI publications are available through the website of the National Academy Press.
Use of the Dietary Reference Intakes by Health Canada
1. How does Health Canada use the Dietary Reference Intakes?
Health Canada uses the DRIs in a variety of policies and programs that benefit the health and safety of Canadians. The DRIs are an important part of the totality of evidence examined when considering policy options. As such the DRIs influence the development of regulatory standards, assessment of dietary intakes, and the development of dietary guidance for the general population and for specific life stages.
2. What is the Canadian Inter-Departmental/Inter-Agency DRI Steering Committee?
Health Canada chairs the Canadian Inter-Departmental/Inter-Agency DRI Steering Committee on Dietary Reference Intakes (Canadian DRI Steering Committee).
This group is made up of representatives from various Federal departments and agencies, including Health Canada, the Public Health Agency of Canada, the Canadian Institutes of Health Research, Agriculture and Agri-Food Canada, the Canadian Food Inspection Agency, the Department of National Defense, and Correctional Services Canada.
Meetings are held several times a year, where information is exchanged on the role and application of the DRIs in policies and programs in each department and agency. This group also works to determine the extent and type of participation of the Government of Canada in DRI review activities. Linkages with the U.S. Federal DRI Steering Committee allow coordination of Canadian and U.S. support and funding of DRI-related work as well as discussions on future work needed.
3. How does Health Canada obtain expert advice on implementation of the DRIs into Canadian policies, regulations, and guidance?
Health Canada will be making use of an Expert Advisory Committee on Dietary Reference Intakes to advise on potential intervention options, which could include changes to dietary guidance, policies related to the food supply, or targeted education.
The Expert Advisory Committee advising on the implementation of the 2010 Dietary Reference Intakes for Calcium and Vitamin D is independent of government and is managed by the Canadian Academy of Health Sciences.
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