Aspartame, a widely-used artificial sweetener, has been reclassified as a substance that may cause cancer. What does this mean for you?
In July 2023, the International Agency for Research on Cancer (IARC) and the Joint FAO/WHO Expert Committee on Food Additives (JEFCA) published a joint evaluation of the potential health risks from the artificial sweetener, aspartame.
Aspartame is an artificial sweetener that has been used for many years by food and drinks companies to cut the amount of added sugar we consume. It’s around 200 times sweeter than sugar, so much less is needed to match the sweetness of sugar.
It’s known by brand names around the world, such as: Nutrasweet, Equal, Pal Sweet and Canderel.
Most people know of aspartame in some diet versions of soft or fizzy drinks, such as Coke Zero, Diet Coke and Pepsi Max.
However, food manufacturers also use aspartame in products such as:
You’ll need to look at each product’s ingredients list – check for the name aspartame or the E number (E951).
IARC has looked at the evidence relating to potential carcinogenic effects of aspartame (whether it could cause cancer), as part of its Monographs programme.
It found limited evidence that aspartame is carcinogenic in humans – the evidence from animal studies and experimental studies is also limited. Therefore, it classified aspartame as ‘possibly carcinogenic’.
JECFA reviewed the general health and nutrition risks of aspartame at usual consumption levels. They found insufficient evidence linking aspartame to the risk of cancer or other diseases, such as Type 2 diabetes and heart disease.
They concluded that the previous acceptable daily intake should not change (see below for what that is).
The new reports have categorised aspartame as “possibly carcinogenic to humans” and given it an evidence grading level known as 2B.
The evidence for a direct link between aspartame and cancer is not strong and therefore the harm for an individual from aspartame is likely to be limited, especially when consumed within the ‘acceptable daily intake’.
The current acceptable daily intake of aspartame – set by the World Health Organization (WHO) – is 0-40mg per kg body weight.
This works out as up to 2,800mg for a man of average weight (70kg), which is the equivalent of 9-14 cans of Diet Coke a day, assuming you don’t consume aspartame in any other products.
The evidence that aspartame causes cancer is not strong, so the harm is likely to be low. It’s rare that a single food or drink causes cancer – it’s the combination of behaviours over decades, along with other factors (such as body weight, genetics, getting older) that leads to a cancer developing.
One of our Cancer Prevention Recommendations is to limit consumption of sugar sweetened drinks, and to drink mostly water and unsweetened drinks. This is consistent with these new evaluations and remains appropriate.
Following our cancer prevention recommendations is the best way to reduce the chances of developing a preventable cancer.
These reports clearly state that aspartame should only be consumed within the ‘acceptable daily intake’ and that this level doesn’t need to change.
Numerous different sweeteners are used in foods and drinks, for example:
The current report focuses on aspartame. It does not look at other sweeteners or make any suggestion about harm from other sweeteners.
JECFA reviewed the general health and nutrition risks of aspartame at usual consumption levels. They found insufficient evidence linking aspartame to the risk of cancer or other diseases, such as Type 2 diabetes and heart disease.
However, WHO advises against the use of artificial sweeteners as a way to control weight, because long-term use is not associated with weight loss. Instead it recommends people choose unsweetened food and drink.
IARC and WHO each look at certain factors at regular intervals. IARC looks at something called ‘hazard identification’, in other words trying to spot something that might cause harm or ill-health. It has not previously looked at aspartame.
WHO analyses what the safe levels of a substance or factor are. The WHO last reviewed the evidence on aspartame in 1981.
One of our Cancer Prevention Recommendations is to limit consumption of sugar sweetened drinks, and to drink mostly water and unsweetened drinks. This is still in line with these new reports.
If you do eat or drink artificial sweeteners, then make sure it’s within the ‘acceptable daily intake’. Ideally, drinks should be unsweetened, for example water or unsweetened tea and coffee.
Our Cancer Prevention Recommendations are based on all the available evidence, which is meticulously reviewed through the Global Cancer Update Programme.
Our Expert Panel carefully reviews and judges all this evidence to draw conclusions about the likelihood of risk factors (relating to diet, nutrition, body weight, physical activity) contributing to the development of a range of cancers. These conclusions form the basis of our Recommendations.
Following our Recommendations is the best way to reduce the chances of developing a preventable cancer.
You may be concerned about these findings and it’s an important topic, because aspartame is used so widely in foods and drinks globally.
We support the research recommendations that, in the future, well-conducted studies should seek to better understand the relationship between aspartame and cancer risk.
This research should investigate the relationship in humans, as well as experimental (animal) studies to explore potential biological pathways (ie how things cause cells to change in the body).
We’ll continue to support better research in these areas, in order to strengthen our understanding of how diet, nutrition, physical activity and body weight influence cancer risk.
