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Assessment of a Tolerable Upper Intake Level for Carbohydrates

The sponsors of the Standing Committee for the Review of the Dietary Reference Intake (DRI) Framework asked the committee to review and comment on the European Food Safety Authority (EFSA) Panel on Nutrition, Novel Foods and Food Allergens (NDA Panel) report, “Scientific Opinion on a Tolerable Upper Intake Level for Dietary Sugars” (NDA, 2022). The sponsors asked the committee to consider the proposed Tolerable Upper Intake Level (UL) as it relates to the conduct of systematic reviews for carbohydrates. The committee’s assessment of that report follows.

EFSA APPROACH FOR SETTING UPPER LIMITS FOR DIETARY SUGARS

Summary of the EFSA Report

EFSA’s “Scientific Opinion on a Tolerable Upper Intake Level for Dietary Sugars” is based on available data on chronic diseases, pregnancy-related end points and dental caries (NDA, 2022). The standing committee evaluated the applicability of the approach that was employed in the EFSA assessment for possible use in a future DRI review on carbohydrates but not fiber. As DRIs for macronutrients are reassessed through evaluating data from relevant peer-reviewed published evidence and systematic reviews relevant to macronutrient intake and health outcomes, an important question arises: What learnings can be accrued from the protocol used by the NDA Panel?

The NDA Panel defined the UL to be the “maximum level of chronic daily intake of (total/added/free) sugars from all dietary sources judged to be unlikely to pose a risk of adverse health effects to humans” (NDA, 2022, p. 3). As has been recommended in previous DRI reports (IOM, 2011; NASEM, 2019), the NDA panel stated that “the UL is not a recommended level of intake” (NDA, 2022, p. 3). The panel followed the principles and processes illustrated in the EFSA PROMETHEUS (PROmoting METHods for Evidence Use in Scientific assessments) project (EFSA, 2015). In this approach, it is key to define the strategy that will be used in advance to collect data and appraise the evidence to draw conclusions that will be the foundation for a scientific opinion.

The NDA Panel followed a four-stage risk assessment approach: hazard identification, hazard characterization, intake assessment, and risk characterization. Systematic reviews of the literature on dietary sugars and their sources and a variety of chronic metabolic diseases were carried out. Dose-response analyses were conducted when data allowed and intake levels of dietary sugars by European populations were also assessed.

A stepwise process to provide scientific advice on sugars was then developed by the NDA Panel. The panel used the Handbook for Conducting a Literature-Based Health Assessment Using the Office of Health Assessment and Translation (OHAT) from the U.S. National Toxicology Program Approach for Systematic Review and Evidence Integration (NTP, 2019) as a reference for conducting their systematic reviews on metabolic diseases and dental caries.

Assessment of the EFSA Report

In the original DRI reviews in which chronic disease outcomes were considered, the conceptual approaches to setting DRI values were initially limited to the Estimated Average Intake (EAR); Recommended Dietary Allowance (RDA), Adequate Intake (AI), and UL. However, DRI committees encountered conceptual and methodological challenges in attempting to use a UL or EAR/RDA model for evaluating and setting DRI values for nutrients with chronic disease relationships or in dealing with nonessential food substances and macronutrients. For example, in the initial DRI review of macronutrients, the Acceptable Macronutrient Distribution Range (AMDR) was developed to only provide guidance about the relative range of intakes from carbohydrates, proteins, and fats associated with reduced risk of chronic diseases while concurrently ensuring that intakes of macronutrients were nutritionally sufficient (IOM, 2002/2005).

Subsequently, a comprehensive study to evaluate and recommend a set of guiding principles to incorporate considerations of chronic disease risk was published (NASEM, 2017). In that report, the authoring commit-

tee assessed the emerging body of evidence suggesting possible roles for nutrients, or other food substances, in reducing risk of chronic diseases. The outcome was a set of guiding principles to serve as a foundation for a scientifically credible chronic disease DRI process. The report offered a range of options to apply the guiding principles in developing guidance to reduce chronic disease risk within the DRI framework.

A new Chronic Disease Risk Reduction (CDRR) category was created during the DRI update on sodium and potassium to provide an approach for evaluating relationships between those nutrients and chronic disease risk and for future DRI reviews (NASEM, 2019).

Based on this previous work, the standing committee concludes that the EFSA report on setting a UL for added sugars is not an appropriate application for the U.S.-Canadian DRI process because the UL is not based on chronic disease risk. When evaluating sugar intakes and chronic disease outcomes, the standing committee recommends that future DRI committees use the CDRR model. As noted above, the AMDR was developed to only provide guidance about the relative range of intakes, thus, future DRI committees on macronutrients should reevaluate the necessity of continued use of the AMDR when developing its recommendations.

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