Latest results on aspartame cancer risk

Hazard and risk assessment results for the non-sugar sweetener aspartame have been released by the International Agency for Research on Cancer (IARC) and the World Health Organization (WHO), alongside the Food and Agriculture Organization (FAO) Joint Expert Committee on Food Additives (JECFA).

Aspartame is an artificial (chemical) sweetener widely used in various food and beverage products since the 1980s, including diet drinks, chewing gum, gelatin, ice cream, dairy products such as yoghurt, breakfast cereal, toothpaste and medications such as cough drops and chewable vitamins.

“Cancer is one of the leading causes of death globally. Every year, 1 in 6 people die from cancer. Science is continuously expanding to assess the possible initiating or facilitating factors of cancer, in the hope of reducing these numbers and the human toll,” said Dr Francesco Branca, Director of the Department of Nutrition and Food Safety, WHO.

“The assessments of aspartame have indicated that, while safety is not a major concern at the doses which are commonly used, potential effects have been described that need to be investigated by more and better studies.”

IARC classified aspartame as possibly carcinogenic to humans (IARC Group 2B), but cited “limited evidence” for carcinogenicity in humans; while JECFA reaffirmed the acceptable daily intake of 40 mg/kg body weight.

The two bodies conducted independent but complementary reviews to assess the potential carcinogenic hazard and other health risks associated with aspartame consumption. This was the first time that IARC has evaluated aspartame and the third time for JECFA.

After reviewing the available scientific literature, both evaluations noted limitations in the available evidence for cancer (and other health effects).

The IARC and JECFA evaluations of the impact of aspartame were based on scientific data collected from a range of sources, including peer-reviewed papers, governmental reports and studies conducted for regulatory purposes. The studies have been reviewed by independent experts, and both committees have taken steps to ensure the independence and reliability of their evaluations.

IARC classified aspartame as possibly carcinogenic to humans (Group 2B) on the basis of limited evidence for cancer in humans (specifically, for hepatocellular carcinoma, which is a type of liver cancer). There was also limited evidence for cancer in experimental animals and limited evidence related to the possible mechanisms for causing cancer.

JECFA concluded that the data evaluated indicated no sufficient reason to change the previously established acceptable daily intake (ADI) of 0–40 mg/kg body weight for aspartame. The committee reaffirmed that it is safe for a person to consume within this limit per day. For example, with a can of diet soft drink containing 200 or 300 mg of aspartame, an adult weighing 70 kg would need to consume more than 9–14 cans per day to exceed the acceptable daily intake, assuming no other intake from other food sources.

IARC’s hazard identifications are the first fundamental step to understanding the carcinogenicity of an agent by identifying its specific properties and its potential to cause harm (ie, cancer). While IARC classifications reflect the strength of scientific evidence as to whether an agent can cause cancer in humans, they do not reflect the risk of developing cancer at a given exposure level. The IARC hazard evaluation considers all types of exposures (eg, dietary, occupational). The strength-of-evidence classification in Group 2B is the third-highest level out of four levels, and it is generally used either when there is limited, but not convincing, evidence for cancer in humans OR convincing evidence for cancer in experimental animals, but not both.

JECFA’s risk assessments determine the probability of a specific type of harm, ie, cancer, to occur under certain conditions and levels of exposure. It is not unusual for JECFA to factor IARC classifications into its deliberations.

“JECFA also considered the evidence on cancer risk, in animal and human studies, and concluded that the evidence of an association between aspartame consumption and cancer in humans is not convincing,” said Dr Moez Sanaa, WHO’s Head of the Standards and Scientific Advice on Food and Nutrition Unit. “We need better studies with longer follow-up and repeated dietary questionnaires in existing cohorts. We need randomised controlled trials, including studies of mechanistic pathways relevant to insulin regulation, metabolic syndrome and diabetes, particularly as related to carcinogenicity.”

Dr Alexandra Jones, a Senior Research Fellow (Food Policy and Law) at The George Institute for Global Health, said that for current consumers of diet drinks, the latest results weren’t cause for major alarm.

“Aspartame has been classed in IARC’s Category 2B, which means there’s limited evidence that it might cause cancer, not that it does or is likely to. The work from JECFA confirms that normal levels of consumption appear to be safe,” she said.

“Beyond this focus on aspartame and cancer specifically, we know the use of sweeteners in our food supply is increasing — in Australia, for example, the food industry has been turning away from aspartame for some time, with more use of ‘natural’ sweeteners such as stevia.

“As governments and consumers have looked to reduce sugar intake, we’re seeing an increase in sweetener use across the food supply — not just in drinks. It’s important that we continue to study the long-term effects of this on a range of health outcomes.”

Jones added that, given other recent guidance from the World Health Organization that non-sugar sweeteners should not be used as a means of achieving weight control or reducing the risk of heart disease or diabetes, it might still be wise to think about the overall benefits to health from trading a soft drink habit of any kind for healthier alternatives such as tap water.

Clare Hughes, Chair of Cancer Council’s Nutrition, Alcohol and Physical Activity Committee, said that recent Australian research suggests the use of aspartame in the Australian food supply is declining and that most Australians are not consuming aspartame at levels considered unsafe. However, like Jones, Hughes believed that the IARC classification of aspartame presented a timely reminder for Australians to consider the choices they make when it comes to what they eat and drink.

“While ‘sugar-free’ or ‘diet’ drinks containing intense sweeteners might once have been marketed as a means of weight management, recent evidence shows that replacing sugars with intense low-kilojoule sweeteners does not support weight management in the long term and is potentially associated with increased risk of type 2 diabetes and cardiovascular diseases,” Hughes said.

“What Australians can do to lower their risk of cancer is maintain a healthy diet with minimal processed foods, be physically active every day for at least 30 minutes, quit smoking and limit their alcohol use. By following these recommendations, Australians can decrease their cancer risk and live long and healthy lives.”

IARC and WHO will continue to monitor new evidence and encourage independent research groups to develop further studies on the potential association between aspartame exposure and consumer health effects.

Image credit: iStock.com/Ratana21