Health- and fitness-conscious individuals worldwide opt for artificially sweetened beverages (ASBs) over their sugar-sweetened counterparts (SSBs), but the health advantages of ASBs remain debated within the scientific community. In a recent umbrella review published in the journal Advantages in Nutrition, researchers examined the results of previous systematic reviews and meta-analyses to verify the credibility of medical and ASB-industry-funded research to evaluate whether AIBs truly meet the health gains that their manufacturers market. Their findings from 11 meta-analyses and seven systematic reviews indicate that frequent ASB consumption can lead to a higher risk of obesity, all-cause mortality, hypertension, type 2 diabetes (T2D), and cardiovascular disease (CBD), contrary to current consumer belief.
Review: Artificially Sweetened Beverages and Health Outcomes: An Umbrella Review. Image Credit: VTT Studio / Shutterstock
What are AIBs?
Artificially sweetened beverages (ASBs) are beverages containing sucrose-replacing sweeteners, including saccharin, sucralose, neotame, and advantame. Since they contain little to no conventional sugar (sucrose), they have little calorific value and are marketed as healthier alternatives to traditional sugar-sweetened beverages (SSBs). These drinks are trendy amongst health- and fitness-minded individuals and those overweight or obese based on the assumption that fewer calories, all else being equal, is better than more.
Recent medical research has challenged these assumptions, with a growing body of literature suggesting that ASBs may be linked to rapid unwanted changes in the gut microbiome and associated with increased all-cause mortality risk. Alarmingly, some studies have reported ABSs as contributing to cancers and cardiovascular disease (CVD), while others have found no such association. These conflicting medical reports are further complicated by industry-funded research, most of which gives ASBs their approval as safe for human consumption.
Umbrella reviews are a novel class of reviews that summarize and evaluate the results of previous reviews and meta-analyses while also verifying the technical and scientific soundness of the methodology and analyses that led to those results. They present an ideal means of cutting through the fluff, especially when multiple scientific reports suggest starkly contradictory outcomes (healthy versus not healthy) of the same treatment (ASB consumption).
About the study
The present umbrella review aims to examine the certainty of claimed health outcomes due to ASBs and identify potential biases or inconsistencies in the literature. This review further evaluates the methodologies employed in previous reviews and meta-analyses both as a test for credibility and to inform future authors of the best practices to use when conducting ASB-health studies.
This study adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Data was collated from three publication repositories, PubMed, Embase, and the Web of Science, from their inception until 25 May 2022. Inclusion criteria comprised all systematic reviews, meta-analyses, cohort, and case-control studies testing the associations between ASBs and health. However, cross-sectional studies were excluded due to the inherent weakness of evidence the study design suffers from. Results from systematic reviews comprising mixed study designs (cross-sectional alongside others) were filtered to remove the cross-sectional results, with the remaining results reanalyzed.
Collated data included the first author's name, the year of study publication, PECO (population, exposure, comparison group, outcome), exposure and outcome variables, and effect sizes. Additionally, the funding source of studies, both the meta-analyses and their constituent publications, were recorded.
The A MeaSurement Tool to Assess systematic Reviews (AMSTAR) tool (specifically AMSTAR-2) was used to evaluate the methodological soundness of included studies. The tool comprises 16 items that guide researchers in verifying the quality of systematic reviews.
"1) use of PECO elements in the description of aims and methods of the review, 2) adherence to a well-developed study protocol, 3) justification of the selection of study designs, 4) use of a comprehensive literature search strategy, 5) study selection in duplicate, 6) data extraction in duplicate, 7) provide a list of excluded studies and justification, 8) description of included studies in adequate detail, 9) proper technique used to assess risk of bias of included studies, 10) reporting of the sources of funding of selected studies, 11) appropriate methods for statistical analyses of the meta-analysis, 12) results of risk of bias assessments were considered in meta-analyses, 13) results of risk of bias assessments were discussed, 14) the sources of statistical heterogeneity were discussed, and 15) publication bias was assessed and discussed."
A random-effects model using the lowest study-specific ASB consumption as a standardization parameter was used to estimate the average effects of each 'high-quality' systematic review to test the effects of inter-study heterogeneity. This was then compared to results from a fixed-effects model assuming a lack of inter-study heterogeneity. Inconsistency between studies was computed using I2, a metric that presents the amount of variability in effect results due to heterogeneity rather than study sampling error. Egger's test was used to compute slight study effect bias.
The initial repository sweep identified 7,218 publications, of which 68 met inclusion criteria following title and abstract screening—of these 68, full-text screening and the exclusion of cross-sectional studies resulted in seven systematic reviews and 11 meta-analyses reporting PECO that were included in the statistical pipeline.
Collectively, the included studies reported the associations between ASB consumption and 13 health outcomes. Of these, present study analyses revealed that high- and regular ASB consumption depicted a positive association with CVD risk, CVD-associated mortality, chronic kidney disease, obesity, all-cause mortality, hypertension, T2D, and pancreatic cancer. Following AMSTAR assessments of the studies reporting these findings, however, the association between ASBs and CVD-associated mortality, chronic kidney disease, and pancreatic cancer was found to be weak and inconclusive.
Dependable study results revealed that sucralose and saccharin used in most ASBs have a rapid and severely detrimental impact on the human cardiovascular system, impairing glucose tolerance in hitherto healthy adults following only two weeks of daily ASB consumption. Human and animal studies further showed that some artificial sweeteners stimulate immune inflammatory responses in the gut wall.
"Results obtained with the AMSTAR-2 tool indicate that most authors of systematic reviews are not making use of predefined study protocols, which may increase the risk of making unfounded decisions during all the stages of the systematic review. Furthermore, all reviews did not add information of the sources of funding of the literature reviewed. The Cochrane handbook for systematic reviews of intervention recommends to examine closely the conflicts of interest of lead and corresponding authors, based on information reported in the present or previous publications or even searching in additional databases."
- Diaz, C., Rezende, L. F., Sabag, A., Lee, D. H., Ferrari, G., Giovannucci, E. L., & Rey-Lopez, J. P. (2023). Artificially Sweetened Beverages and Health Outcomes: An Umbrella Review. Advances in Nutrition, 14(4), 710-717, DOI – https://doi.org/10.1016/j.advnut.2023.05.010, https://www.sciencedirect.com/science/article/pii/S2161831323003150