After undertaking its own comprehensive review, the Joint Expert Committee said on Friday that it did not have convincing evidence of harm caused by aspartame, and continued to recommend that people keep their consumption levels of aspartame below 40mg/kg a day.
The Joint Expert Committee on Food Additives first set this level in 1981, and regulators worldwide have similar guidance for their populations.
Several scientists not associated with the reviews said the evidence linking aspartame to cancer is weak. Food and beverage industry associations said the decisions showed aspartame was safe and a good option for people wanting to reduce sugar in their diets.
The WHO said the existing consumption levels meant, for example, that a person weighing 60-70kg would have to drink more than 9-14 cans of soft drink daily to breach the limit, based on the average aspartame content in the beverages – around 10 times what most people consume.
“Our results do not indicate that occasional consumption could pose a risk to most consumers,” said Branca.
Reuters first reported in June that the International Agency for Research on Cancer would put aspartame in group 2B as a “possible carcinogen” alongside aloe vera extract and traditional Asian pickled vegetables.
The agency panel said this week it had made its ruling based on three studies in humans in the US and Europe that indicated a link between hepatocellular carcinoma, a form of liver cancer, and sweetener consumption, the first of which was published in 2016.
It said limited evidence from earlier animal studies was also a factor, although the studies in question are controversial. There was also some limited evidence that aspartame has some chemical properties that are linked to cancer, the agency said.
“In our view, this is really more a call to the research community to try to better clarify and understand the carcinogenic hazard that may or may not be posed by aspartame consumption,” said Mary Schubauer-Berigan, acting head of the International Agency for Research on Cancer monographs program.
Scientists with no links to the WHO reviews said the evidence that aspartame caused cancer was weak.
“Group 2B is a very conservative classification in that almost any evidence of carcinogenicity, however flawed, will put a chemical in that category or above,” said Paul Pharaoh, a cancer epidemiology professor at Cedars Sinai Medical Centre in Los Angeles. He said the Joint Expert Committee on Food Additives had concluded there was no “convincing evidence” of harm.
“The general public should not be worried about the risk of cancer associated with a chemical classed as Group 2B by [the International Agency for Research on Cancer],” Pharaoh said.
Nigel Brockton, vice president of research at the American Institute for Cancer Research, said he anticipates research into aspartame will take the form of large, observational studies that account for any intake in aspartame.
Some doctors expressed concern that the new classification of “possible carcinogen” might sway drinkers of diet beverages to switch to caloric sugar versions.
Therese Bevers, medical director of the University of Texas’ Cancer Prevention Centre, said that “the possibility of weight gain and obesity is a much bigger problem and bigger risk factor than aspartame could ever be”.
The WHO conclusion “once again affirms that aspartame is safe” said Kate Loatman, executive director of the International Council of Beverage Associations, based in Washington.
“Aspartame, like all low/no calorie sweeteners, when used as part of a balanced diet, provides consumers with choice to reduce sugar intake, a critical public health objective,” said Frances Hunt-Wood, secretary general of the Brussels-based International Sweeteners Association.
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