Bias and limitations in a systematic review by mandrioli et al raise serious concerns about its conclusions regarding industry-supported research on low calorie sweeteners
01 September 2016
ISA statement in response to the systematic review by Mandrioli et al
The International Sweeteners Association (ISA) strongly refutes the misleading and biased conclusions in an article by Mandrioli et al in Plos One claiming that industry-supported research on low calorie sweetened beverages and weight outcomes is more likely to show favourable results. The authors fail to recognise a series of important biases and limitations in their systematic review, which raise serious concerns about the quality of the study and the accuracy of its outcomes.
Importantly, as regards the methodolody used, the authors have not followed the inclusion criteria set for this systematic review, as for example, they state that published conference presentations were excluded from their analysis, however the publication by Hervé Nordmann in Agro Food Industry Hi-Tech is clearly a review based on the outcomes of the International Sweeteners Association’s conference in 2011. Furthermore, the Nordmann review is listed as an ISA-funded review, when in fact the ISA did not provide any funding in support of this publication.
With regards to the limitations of this study, the systematic review by Mandrioli et al reach their questionable conclusions based only on four industry-supported review studies, a very small number to draw safe conclusions. Moreover, it is based on a highly heterogeneous sample of studies including both reviews that summarised data quantitatively (with meta-analysis) as well as only qualitatively reviews. However, these type of studies are not comparable in terms of their methodology and hierarchy of evidence, with meta-analysis to be generally considered to be the most valuable form of research evidence, while qualitatively reviews may summarise the evidence but do not necessarily include explicit criteria for selecting evidence and certainly rank much lower in the hierarchy of evidence. In this context, for example, it is important to highlight that two out of the four industry-supported reviews include also a meta-analysis, and therefore the comparison conducted in this systematic review between industry-supported and non-industry funded studies is simply biased. Other parameters that the Mandrioli et al publication does not take into consideration is the change in the standards about funding disclosure and conflicts of interest throughout the period that is examined in this review (1978-2014).
The International Sweeteners Association (ISA) strongly believes that the food industry support in research can contribute the most to advancing scientific evidence in nutrition science. ISA fully supports a transparent relationship between scientists and industry funding and actively encourages full disclosure of all conflicts of interest.
- Mandrioli D, Kearns CE, Bero LA (2016) Relationship between Research Outcomes and Risk of Bias, Study Sponsorship, and Author Financial Conflicts of Interest in Reviews of the Effects of Artificially Sweetened Beverages on Weight Outcomes: A Systematic Review of Reviews. PLoS ONE 11(9): e0162198. doi:10.1371/journal.pone.0162198
- Nordmann H. (2012) Low calorie foods, beverages and sweeteners Can they really contribute to a healthier future? Agro Food Industry Hi Tech.