A new study has reawakened a decades-old debate over the safety of artificial sweeteners, suggesting a small association can be detected between sugar substitutes such as aspartame or acesulfame-K and increased cancer risk. The authors of the new study call for a re-evaluation of these artificial sweeteners by food safety regulators, however, experts not affiliated with the research claim the findings are weak and mistake causation with correlation.
For years researchers have argued over the health impacts of artificial sweeteners in humans. While these controversial food additives may not necessarily be completely benign, there has been consistently conflicting evidence regarding potential deleterious health impacts.
This new study focuses on one especially thorny ongoing argument: Do artificial sweeteners cause cancer?
Over the last 50 years sporadic animal and lab studies have raised the possibility that artificial sweeteners could cause cancer, but observational research in humans has rarely identified significant associations. This new research set out to offer a more precise epidemiological investigation into the relationship between what people eat and their cancer risk.
The research looked at data from an ongoing project called the NutriNet-Santé study. Initiated in 2009, the project is tracking the relationship between nutrition and health in more than 100,000 French participants.
The data in the NutriNet-Santé study offers slightly more detail than general observational studies that rely on self-reported food intake. Every six months participants in the study fill out three non-consecutive 24-hour dietary records listing everything they consumed that day, including all commercial brand information. Because artificial sweeteners are added to thousands of different foods it can be difficult to accurately quantify consumption, so this study offers a reasonably robust way to track the intake of specific food additives.
The big headline finding is those subjects in the study consuming high levels of artificial sweeteners were found to experience greater incidences of cancer compared to those with low to no intake of artificial sweeteners. In particular, aspartame and acesulfame-K were linked to higher risk of breast and obesity-related cancers.
“Our findings do not support the use of artificial sweeteners as safe alternatives for sugar in foods or beverages and provide important and novel information to address the controversies about their potential adverse health effects,” the researchers concluded in the new study. “While these results need to be replicated in other large-scale cohorts and underlying mechanisms clarified by experimental studies, they provide important and novel insights for the ongoing re-evaluation of food additive sweeteners by the European Food Safety Authority and other health agencies globally.”
Zooming in the details of the study has led many outside experts to question the relevance of the findings. Duane Mellor, a researcher from Aston University, said the study found high consumption of artificial sweeteners increased a person’s relative risk of developing cancer by 13 percent. But Mellor explained this equals only three new cases of cancer in every 10,000 people over an eight year period, and on top of that the findings may be due to reverse causality.
“…when looking at the differences between the groups the authors did not account in their analysis that higher consumers of artificial sweeteners also consumed more highly processed foods, drank more sugary drinks and reported more attempts to try to lose weight,” Mellor said. “This could suggest the risk of consuming artificial sweeteners could be partly linked to a poorer overall quality of their diets or that their diet may have been altered more to try and lose weight, something called reverse causality.”
Michael Jones, from the Institute of Cancer Research in London, makes a similar point arguing the data shows little consistent relationship between artificial sweetener dose and cancer risk. This, according to Jones, indicates the cancer risk is likely due to other behavioral factors and not the artificial sweeteners specifically.
“…the ‘dose-response’ relationship was not strong,” said Jones. “For some results, risk of cancer was higher in the lower consumer group than the higher consumer group, despite higher consumers reporting 10 times the total artificial sweetener consumption than lower consumers. This also suggests that cancer risk may be raised in the type of person who uses artificial sweetener rather than the sweetener itself.”
Essentially, the argument is that those people most likely to consume high volumes of artificial sweeteners are also more likely to be overweight with other health conditions and behaviors that can increase cancer risk. Whereas those less inclined to consume artificial sweeteners may engage in more healthy lifestyles that reduce their overall risk of developing cancer.
So while it may be inevitable that this new research will be accompanied by headlines claiming artificial sweeteners can cause cancer, the reality is these findings are far from definitive. Alan Barclay, an honorary associate at the University of Sydney, says although the research is novel and the findings interesting, the study is not proof artificial sweeteners cause cancer in humans.
“Due to the relatively small size of the associations in this new study, the results are most likely to be subject to confounding,” Barclay said. “More high-quality research (e.g. randomized controlled trials) is required to answer this question definitively.”
The new study was published in the journal PLOS Medicine.