Aspartame: What We Know So Far

Aspartame is a low-calorie artificial sweetener that is around 200 times sweeter than sugar. Since the 1980s, it has been used in diet drinks, chewing gum, ice cream, yoghurt, toothpaste and many other foods. Consumers may recognise it under familiar trade names including NutraSweet, Equal, Pal Sweet and Canderel.

In July 2023, the International Agency for Research on Cancer (IARC) which is part of the World Health Organization (WHO) published an evaluation of aspartame. IARC classified aspartame as:

Possibly carcinogenic to humans (Group 2B)

This means some studies have observed a potential link between high intake of artificially sweetened beverages and certain cancers such as liver cancer. However, the evidence was judged as limited and does not demonstrate that aspartame causes cancer in humans.

IARC cancer categories: what they actually mean

IARC assesses hazard which means whether a substance could cause cancer under some conditions. It does not measure the risk at real world exposure levels.

Group 2B indicates limited evidence in humans and animals and limited mechanistic data. It does not confirm cancer causation.

What about safety at normal consumption levels

A second WHO body, the Joint FAO WHO Expert Committee on Food Additives (JECFA), separately reviewed the safety of aspartame and reaffirmed the Acceptable Daily Intake (ADI):

40 milligrams per kilogram of body weight per day

For an adult who weighs 70 kilograms, this would be equal to drinking about nine to fourteen half litre cans of diet soft drink per day, assuming no other dietary sources of aspartame.

Therefore:

Typical consumption is not expected to increase cancer risk for most people

People with phenylketonuria (PKU) must avoid aspartame because they cannot properly metabolise phenylalanine, one of its components.

Should you be concerned

The current evidence supports a balanced and practical interpretation:

• Moderate consumption is not expected to cause harm
• Total exposure can add up when multiple products contain aspartame
• There is still some scientific uncertainty at very high intake levels

A healthy lifestyle with a varied diet and limited highly processed food intake is far more important for long term disease prevention than any single food additive.

Key points for consumers

• Aspartame is one of the most widely studied food additives
• Regulatory authorities including FDA USA, EFSA Europe and Health Canada approve it within ADI limits
• Those wishing to reduce intake can do so by moderating diet drinks and other sweetened products

*Aspartame. Available at: https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/62 (Accessed: 23 Aug 2023).