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Stay within aspartame limits, cancer society says in wake of WHO findings

Canadian advice offered after World Health Organization reports sweetener ‘possibly carcinogenic’
A customer walks down a grocery store’s drinks aisle in Newcastle, Ont. on Thursday July 13, 2023. The Canadian Cancer Society and Health Canada are reviewing the World Health Organization’s classification of aspartame as “possibly carcinogenic.” THE CANADIAN PRESS/Doug Ives

The Canadian Cancer Society is recommending that people stay within existing daily limits of aspartame consumption and is encouraging more studies on the artificial sweetener after the World Health Organization deemed it “possibly carcinogenic.”

The classification “means that there’s limited evidence suggesting that it may cause cancer in humans and that additional research is needed,” said Elizabeth Holmes, director of health policy at the Canadian Cancer Society, in an interview on Friday.

Holmes said the society welcomes research proposals on aspartame and will consider funding them.

Two WHO-affiliated agencies conducted two independent reviews to assess health risks associated with consumption of aspartame, which is commonly found in diet beverages, gum and sugar-free sweet treats such as syrup or gelatin dessert.

In reviewing available studies in both humans and animals, the International Agency for Research on Cancer (IARC) and the Food and Agriculture Organization Joint Expert Committee on Food Additives (JECFA) found limited evidence that aspartame could be associated with a type of liver cancer.But the findings could not rule out the possibility that other variables might account for the link.

Better studies, including randomized controlled trials, are needed to determine more definitively whether or not aspartame causes cancer, the study summary said.

There was “no convincing evidence” to suggest current recommendations on safely eating or drinking aspartame should be changed, it said.

Health Canada and the WHO both recommend a daily limit of 40 mg of aspartame per kilogram of body weight.

A WHO news release breaks it down: since a can of diet soda contains about 200 – 300 mg of aspartame, an adult who weighs 70 kg would need to consume more than nine to 14 cans per day to exceed that limit.

David Ma, a professor of nutritional sciences at the University of Guelph, said the daily aspartame consumption of most Canadians likely falls within that limit.

“Unfortunately, there are probably a few individuals drinking (above) that level. So those would be the ones that should be most concerned about their intake,” Ma said.

In an emailed statement, Health Canada said it will review the research and “determine whether action is needed for aspartame in Canada based on the scientific data in the full reports.”

The WHO has four classification levels for items assessed for their potential to cause cancer: carcinogenic to humans, probably carcinogenic to humans, possibly carcinogenic to humans, and not classifiable as to its carcinogenicity to humans.

Those levels are based on how strong the evidence is that something, including food, drink, chemicals and environmental hazards, is linked with cancer. The classification levels aren’t a statement about the “degree of risk” of developing cancer. The risk often varies with the amount consumed or levels of exposure. The type of cancer the food or drink is linked to also varies.

Tobacco, alcohol and processed meat are among more than 120 items currently classified as carcinogenic on the WHO’s website. There are more than 90 items listed as “probable” carcinogens, including red meat.

When it comes to “possible” carcinogens such as aspartame, more than 320 items are listed. They include many chemicals, such as chloroform and lead.

It’s important to think of substances listed as carcinogenic, probably carcinogenic or possibly carcinogenic as “hazards” rather than “risks,” Ma said.

For example, driving a car is inherently a hazard, he said. But the risk of injury is lowered by actions that we take.

“We accept that because overall, on a daily basis, millions and millions of people drive and the risk is relatively low because we put on our seat belt, we follow the rules of the road, we do not drive dangerously at high speeds,” Ma said.

Similarly, aspartame is a “hazard” but “the level of risk is low” if we don’t consume too much, he said.

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