Since 1997, the United States and Canada have developed harmonized Dietary Reference Intakes (DRIs) that represent nutrient-based reference values for use in planning and assessing diets for individuals and groups in both countries. In 2022 the Federal DRI Joint U.S.–Canadian Working Group (working group or WG) asked the National Academies of Sciences, Engineering, and Medicine (NASEM) to review and update the previous DRI values for energy (IOM, 2002/2005). At the same time, the working group asked NASEM to appoint a standing committee to review the DRI framework, structure, and process for future DRI reviews.
In preparation for this assignment, the Standing Committee for the Review of the DRI Framework (standing committee) considered the past discussions, experiences, and learnings from previous DRI reports. As a first step the specific task was to respond to questions from the working group and the Committee to Review DRIs for Energy (DRI committee or EC) relevant to the DRI framework and structuring of new—or updates to existing—DRI reviews and other questions in order to inform future DRI committees, including those for macronutrients. The standing committee met in open session with the working group and the DRI committee to consider these questions as relevant to their task as follows:
Question WG1: Who should be included in the “healthy population” definition to adequately characterize the population covered by the DRIs?
Question WG2: Is it assumed that subpopulations with risk factors for chronic diseases (such as overweight or obesity, high blood pressure, hyper-
cholesterolemia or prediabetes) are considered to meet the current definition since they do not meet the exclusion criteria listed above?
In response to both questions, the standing committee advises that, first, the “apparently healthy population” includes those with or at risk for chronic disease, and second, that each DRI committee should establish exceptions that apply specifically to the nutrient(s) under review.
Question WG3: How should overweight and obesity be considered given the high prevalence of obesity? The standing committee suggests inclusion of populations with overweight and obesity because they represent the majority of individuals in most age, sex, and race/ethnicity categories in both countries. The exception are those categorized with severe comorbidities that should be excluded from the DRI population if their particular disease, health condition, disability, or medication or drug prescriptions is known to alter energy or nutrient requirements.
Question WG4: Should a different term be considered other than “apparently healthy population” since the DRIs are developed to determine the recommended intake of nutrients to meet the needs of the majority of the general population and the health status of this population has shifted? The standing committee advises that the term “general population” should be used to describe new DRI populations and that the term “exception” should be used in place of “exclusion” to describe the characteristics in the subgroups not to be included in the general population for the DRIs (see Box S-1).
Question WG5: How should, or can, evidence from populations that are not “apparently healthy” be used to develop the DRIs? What about data from populations with clinical disease? The standing committee advises that once a future DRI committee for a given nutrient determined the criteria to characterize the general population, the same criteria can be used to identify the evidence for review.
Question WG6: How should this definition inform the use of the DRIs for their various purposes? The standing committee advises that specific exceptions to the general population should be determined on a nutrient-by-nutrient basis. Further, specific exceptions and their rationale should be specified and guidance to managing exceptions be included in a “special considerations” section in the report. Exceptions would be based on evidence that a particular disease, health condition, disability, or medication is likely to alter the requirement for the nutrient under review.
The DRI committee also posed six questions to the standing committee as follows:
Question EC1: Should a DRI committee approach identifying a general or healthy population based on inclusion or exclusion criteria? The standing committee advises that the general population base be as broad as possible, adding that each DRI committee should consult with the standing committee on their rationale for exceptions to the general population.
Question EC2: What is the standing committee’s recommendation for managing limitations in data needed to support a rationale for recommendations? The standing committee recognizes that data limitations are inherent within a DRI review and thus DRI committees should remain flexible in weighing and considering the evidence. The process of reviewing the evidence is in itself useful to better summarize and address relevant uncertainties in the data and propose next steps to close knowledge gaps.
Question EC3: If data on some subpopulations are limited, how do you determine when to use the data as a criterion to exclude that group from the defined general population? The standing committee reiterated that DRI committees should consider the strength of evidence for all life-stage groups and determine whether there is justification to extrapolate data. The importance of transparency and inclusion of uncertainties and limitations in the data need to be described in the report.
Question EC4: Does the standing committee want to make a statement about using International Classification of Diseases (ICD) codes to exclude population groups in a DRI review? The standing committee concluded that ICD codes are too broad and not useful for setting DRI exceptions.
Question EC5: Are extreme outliers included in the general population? What about normal body composition when body mass index (BMI) is less than or equal to 18.5? The standing committee endorsed careful examination of the data to determine if there is clear evidence to exclude outliers. Specifically, unless there is evidence for exclusion based on metabolic disorders that alter requirements, outlier population groups should be included in the general population for the DRIs.
Question EC6: Since the DRIs for energy are different from other nutrients, how should the committee manage limitations in data needed to support the rationale for a recommendation? The standing committee advises that when
extrapolation is needed due to limitations in the data, the DRI committee should clearly specify the rationale used to identify data gaps and the approach used to extrapolate. Finally, the standing committee concluded that delineation of gaps in knowledge should be clearly elucidated with the goal to stimulate funding opportunities to provide critical information for future DRI reviews.