Scientific evidence is commonly categorized into levels based on quality of evidence, commonly referred to as the hierarchy of evidence. The complexity of evaluating study quality based on study design becomes problematic for dietary exposures and health outcomes with conflicting evidence observed in observational studies and RCTs. Such conflicting evidence is well documented for low calorie sweeteners (LCS), in which observational trials tend to identify adverse associations between LCS use and adiposity, type 2 diabetes (T2D), mortality, cardiovascular disease (CVD), and cancer while RCTs highlight benefits or no effect of LCS on body weight, energy intake, markers of T2D, and markers of CVD (6). One possible explanation for this is that observational trials and RCT are simply addressing different research questions, evaluating different exposures, comparators, and outcomes.
The objective of the proposed project is to educate stakeholders on how to interpret contrasting evidence from observational studies and RCTs based on methodological differences between study designs, using LCS as a case-study. A rapid review of systematic reviews and metaanalyses on LCS and various health outcomes will be conducted to highlight how different intervention/exposures, comparators, outcomes, and study designs produce varying conclusions regarding the efficacy and safety of LCS. The deliverables of this project will be a peer-reviewed publication and presentation of findings at a conference for nutrition and dietetics practitioners
Institution: USDA Agricultural Research Service
Principal Investigator: Kelly Higgins, MPH PhD; David Baer, PhD
Amount: $2K (Matthew Kramer, USDA ARS - retired); other costs covered by USDA’s congressional appropriation
This work was supported by the IAFNS Low- and No-Calorie Sweeteners Committee.