Charting the Chronology of Research on Added Sugars: A Scoping Review and Evidence Map

Abstract

The objective of this study was to conduct a scoping review and produce a publicly available database characterizing the design and reporting elements of the literature on dietary added sugars and select health outcomes. Relevant studies published from 1990 to 2021 were identified to create a database containing information on study and population characteristics, reported added sugars source and concentrations, dietary energy balance, total energy intake, and outcome measures related to body composition, obesity, cardiovascular disease, and diabetes mellitus. There were 245 publications identified, 22% of which describe interventions, and 78% describe observational studies. Publications pertaining to added sugars have risen dramatically since 2010, led by studies primarily assessing body composition (36%) or cardiovascular health (32%), including adults (65%), measuring liquid-only sources of added sugars (56%). Over 65% of studies reported total energy intake, 61% controlled for total energy intake in the design and analysis, and fewer than 5% of studies reported the energy balance of subjects. There has been a significant increase in research on added sugars since 2010, with substantial heterogeneity across all facets of methodology-study designs, exposures and outcomes of interest, terminology, and reporting of dietary intake data-thus limiting the ability to synthesize evidence in this scope of the literature. This evidence map highlights gaps and important areas for improvement to strengthen the state of research and better inform future policies and dietary recommendations on added sugars.

Keywords: added sugars; dietary intake; sugar-sweetened beverages.

Figure 1

Literature search and selection flow diagram.

Figure 2

Venn diagram of citation overlaps for all references included in the final database. For visual purposes, “Cohort Studies” includes both case–control and case–cohort studies. References from the IOM were not included in this overlap as they contributed only 5 unique studies.

Figure 3

Cumulative growth of publications (n = 245) from 1990 to 2021, by (A) terms used in the title/abstract, (B) study design, (C) source of added sugars, (D) included age group, and (E) primary outcomes. Infant, <12 months old; toddler, 12 months to <3 years old; child, 3–11 years old; adolescent, 12–17 years old; adult, 18–64 years old; senior, 65 years and older. #, Number of.

Figure 4

Distribution of reported added sugars intake (% TEI) by study types for (A) source, (B) form, and (C) energy control. Note that this figure represents a subset of the included studies, as only those that quantified added sugars intake at the % TEI level are represented (111/247 studies). These intakes are means, medians, or quartiles for all participants or stratified by participant characteristics (e.g., sex, BMI category, etc.). The dashed line represents the median.

Figure 5

Heat map of all measured outcomes (rows) compared to primary outcomes (columns). “Other” outcomes include risk of metabolic syndrome, inflammatory markers, appetite, dietary intake, and other unrelated outcomes. Color and value indicate the number of articles.

Figure 6

Heat map bubble plot of outcome categories, study duration, and sample size by source of added sugars among observational studies.

Figure 7

Heat map bubble plot of outcome categories, study duration, and sample size by source of added sugars among intervention studies.