The World health organization recently issued new guidelines about using non-sugar sweeteners that are commonly known as artificial sweeteners, attributing their long-term use to the risk of conditions such as type 2 diabetes and cardiovascular diseases. However, reviewing their analysis shows a common fallacy behind these conclusions.
As a diabetic and skeptic, I am always the first to receive the links of related news, usually news about the final “cure” of diabetes (where the news usually doesn’t distinguish even between type 1 and type 2 diabetes), but this time it was a warning against one of our main diet allies – the artificial sweeteners. It was big news because the warning came from WHO, as it almost conquers the first page of Google search when trying to find the most recent news about artificial sweeteners. WHO had recently advised, “not to use non-sugar sweeteners for weight control”. For a while, I thought that the news is misinterpreting WHO’s new guidelines about artificial sweeteners, but as soon as I read the news article on the WHO website, it turned out that WHO is attributing long-term use of artificial sweeteners with “increased risk of type 2 diabetes (T2D), cardiovascular diseases (CD), and mortality in adults”. But on what basis? Where did this strange conclusion come from?
WHO recently issued new guidelines regarding the use of non-sugar sweeteners (WHO, 2023), which contradicts some of the guidelines published in the most recent guidelines about non-sugar sweeteners (NSS) in 2022 (World-Health-Organization, 2022) based on a meta-analysis that covered 263 studies. The 2022 analysis and guidelines were more rational to conclude that “no clear consensus on whether non-sugar sweeteners are effective for long-term weight loss or if they are linked to other long-term health effects at habitual intakes within the acceptable daily intake.” (Guidelines, 2022) rather than warning of type 2 diabetes risk, while confusingly denying any suspicions about its safety at the beginning of this year’s analysis and that diabetics shouldn’t change their consumption of NSS based on it.
Both of the reviews from this year and last year can show many facts, some might look contradict each other or be very difficult to be understood by the public as not contradicting. Therefore, and due to the nature of meta-analysis studies, it is difficult to declare such bold warnings based on the results. Meta-analysis studies could easily be misused, misinterpreted, or abused (Gavura, 2021) for many reasons related to the design, the choice of study, and more importantly, the indecisiveness of the resulting correlations if not supported by other sorts of evidence, which seems to be the case in WHO’s review here. The review’s conclusion seems to be falling into the simple fallacy of attributing causes to the correlation.
The review was different from WHO’s 2022 one in the fact that it introduced long-term randomized controlled trials to study the long-term use of NSS, in which it found a correlation with T2D, CD and mortality in adults, in addition to many other correlations such as an insignificant reduction in body fat when compared with sugary beverages, another negative correlation between children’s dental issues with the use of NSS, and few others related to pregnancy and infant health that show no consistent relationship between preterm birth (positive correlation) and NSS use.
The review is already answering itself by explaining that “significant effects were not observed on intermediate markers of disease such as fasting glucose, fasting insulin or blood lipids when assessed in short-term RCTs”. And also, it states that: “Results from meta-analyses of RCTs suggested no significant effect of NSS on biomarkers used in the assessment and diagnosis of diabetes and insulin resistance, including fasting glucose, fasting insulin, and hemoglobin A1c (HbA1c)”. Which reduces the possibility of a causal relationship between NSS consumption and T2D.
We cannot claim the opposite for sure and say confidently that NSS has no long-term effects on health, but at the same time, it is not acceptable to sell review results in this way. The results of the WHO review could correctly lead to a conclusion such as: “NSS cannot protect from cardiovascular diseases or type 2 diabetes”, rather than being a risk factor on the basis of systematic review results. There are at the same time many other possibilities that could provide an explanation for the negative or positive correlations found, but none should be in the news unless there was a different type of evidence such as studies that conclude some direct relationship that could be proven chemically for using NSS.
Finally, it may not be the first time that WHO shows inaccuracies, it even promoted pseudoscience such as traditional Chinese medicine before (Nature, 2019) or worked in partnership with traditional healers in Africa to fight HIV (Novella, 2010), which makes a mistake such as the correlation-causation fallacy a minor mistake for the world health organization. However, few people know that the size, the fund or the authority of such an organization does not necessarily mean that it is always right or that it has the ability or the organization that academia and peer-reviewed journals have.
Gavura, S. (2021, November 25). The misuse and abuse of meta-analyses. Retrieved from Science Based Medicine.
Guidelines, W. (2022, July 7). Online public consultation: draft guideline on use of non-sugar sweeteners. WHO Guidelines.
Nature. (2019). World Health Organization. (2019)’s decision about traditional Chinese medicine could backfire. 570(7759)(5). Retrieved from Nature.
Novella, S. (2010, September 1). WHO Partnering with Traditional Healers in Africa. Retrieved from sciencebasedmedicine.org: https://sciencebasedmedicine.org/who-partnering-with-traditional-healers-in-africa/
WHO. (2023, May 15 ). Use of non-sugar sweeteners. WHO guidelines, pp. ISBN 978-92-4-007361-6.
World-Health-Organization. (2022, April 12). Health effects of the use of non-sugar sweeteners: a systematic review and meta-analysis. pp. 978-92-4-004642-9. Retrieved from https://www.who.int/publications/i/item/9789240046429