The WHO is set to classify the popular artificial sweetener Aspartame as a possible carcinogen this month, in defiance of the food industry.
Aspartame, found in a multitude of foods, will be listed in July as “possibly carcinogenic to humans” by the International Agency for Research on Cancer (IARC) and the WHO’s cancer research body.
The IARC ruling, finalised earlier in June, considered aspartame’s potential level of risk based on all the published evidence from RCTs (including 1,300 studies), but did not consider how much of the product a person could safely consume.
The Joint WHO and Food and Agriculture Organization’s Expert Committee on Food Additives (JECFA) also reviewed aspartame this year and is due to announce its findings on 14 July, the same day that the IARC will announce its decision.
The decision aligns with the recently published WHO Guideline on the Use of non-sugar sweeteners, which found that NSS use in any manner resulted in reduced sugars and energy intake, lower body weight and lower BMI in short-term RCTs, the majority of which lasted less than three months.
However, NSS use did not significantly affect other measures of body fatness or intermediate markers of cardiometabolic health, including glucose, insulin, or blood lipids, and evidence from a small number of longer-term trials did not suggest an effect on body weight.
Dr Rosemary Stanton OAM, Nutritionist and Visiting Fellow at the University of NSW’s School of Medical Sciences, said there was ample evidence that artificial sweeteners were of no benefit for weight loss or for those with diabetes.
“At this stage, the evidence may not be strong enough as to whether most people would consume enough to provide a substantial increase in the risk of various cancers,” she said.
“However, there is no doubt that artificial sweeteners maintain a ‘sweet tooth’. And for that alone, we should certainly focus – as the WHO has done – on encouraging policy makers to focus on reducing the consumption of sugar and its substitutes in infants and young children still forming taste preferences.”
Understandably, the leak has caused a furore among the food industry and Mr Frances Hunt Wood, the secretary general of the International Sweeteners Association (ISA) told Reuters the IARC is not a food safety body.
“And their review of aspartame is not scientifically comprehensive and is based heavily on widely discredited research,” he said on behalf of the body, whose members include Mars Wrigley, a Coca-Cola unit and Cargill,
The ISA told Reuters it had “serious concerns with the IARC review, which may mislead consumer.”
Controversially, the long-term studies were “difficult to interpret because of many differences in how these trials were conducted and results reported,” and the WHO concluded that “the overall certainty in the evidence was as assessed as very low to low certainty of evidence.”
Given this admission, the decision has also created controversy among Australian experts, with some expressing hesitation in embracing the findings.
Dr Ian Musgrave, a Senior Lecturer of Pharmacology at the University of Adelaide pointed out that classifying aspartame as a class 2B carcinogen (possibly carcinogenic) was hardly concerning.
“To put this in perspective, hot beverages are in the IARC class 2A (probable carcinogens). So, we have less evidence for aspartame being a carcinogen that for drinking hot beverages,” he said.
“While aspartame might possibly induce cancer under some circumstances, most people may not be exposed to the risk.”
“We really need to wait and see the full IARC evaluation before we can make any firm conclusions. Without that, we are really shooting in the dark,” added RMIT’s Professor of Chemistry, Dr Oliver Jones.
“Like other food additives, aspartame had to undergo robust safety evaluation before it was approved for use in food. It is the world’s most widely used artificial sweetener and current evidence is that it is safe at current levels of consumption.”
Medical Forum reported earlier this year that erythritol, another popular artificial sweetener, was associated with up to a 21% increased risk of death, heart attack and stroke, according to a study by the Cleveland Clinic.
The study, published 27 February 2023 in Nature Medicine, involved over 4,000 people in the US and Europe and found that erythritol also made platelets easier to activate and form a clot.
Senior author Dr Stanley Hazen, chair of the Department of Cardiovascular & Metabolic Sciences in Lerner Research Institute and co-section head of Preventive Cardiology at Cleveland Clinic, said that with the growing worldwide obesity epidemic, there needs to be more in-depth research into their long-term effects.
“In fact, artificial sweeteners have even been detected in ground and tap water,” Dr Hazen said.
“Sweeteners like erythritol have rapidly increased in popularity in recent years but: cardiovascular disease builds over time, and as heart disease is the leading cause of death globally, we need to make sure the foods we eat aren’t hidden contributors.”
He pointed out that RCTs examining the long-term safety of consuming artificial sweeteners have not been performed, even for more early adopted forms such as aspartame and sucralose.
“Indeed, despite the growing incorporation of artificial sweeteners into the food chain, their cardiovascular risks have seldom been investigated,” Dr Hazen said.
“Erythritol’s safety has been assessed by short-term animal toxicity studies and reported human clinical studies with ingestion up to 4 weeks.”
Based on these studies, along with its natural occurrence both endogenously in human tissues and in food (albeit at levels 1,000-fold lower than added to processed foods), erythritol is ‘generally recognized as safe’ by both the EU and the FDA, which means there is no requirement for long-term safety studies.
However, Dr Hazen explained that measuring artificial sweeteners is already challenging, as like all polyols, the separation of erythritol from its structural isomer is difficult, hindering its analysis and quantification, but research is further hampered by minimal labelling requirements that seldom list individual compounds.
“Artificial sweeteners’ are typically reported in aggregate due to nondisclosure policies on food labels. This limits the specification of individual sweeteners on labels and the ability to monitor adverse long-term outcomes with individual sweeteners in clinical studies,” he said.
“Many observational epidemiological studies report that artificial sweetener use is associated with various adverse health outcomes including CVD mortality, while others do not.”