Bittersweet news! Artificial sweetener aspartame may soon be named a ‘possible carcinogen’ by WHO

Read about aspartame — found in diet Coke and sugar-free gum — and IARC's carcinogen classification. Here's what doctors have to say.

ByChetana Belagere

Published Jun 29, 2023 | 9:08 PM Updated Jun 29, 2023 | 9:08 PM

Is aspartame a carcinogen? WHO may soon declare the artificial sweetener a 'possible carcinogen'. (Creative Commons)

In a matter of concern for consumers worldwide, aspartame, a widely used artificial sweetener found in various products, including diet sodas, sugar-free chewing gum, and certain beverages, is on the verge of being included on the International Agency for Research on Cancer’s (IARC) list of substances classified as “possibly carcinogenic to humans”.

According to a report by Reuters, reliable insider sources have revealed that the IARC, the esteemed cancer research arm of the World Health Organisation (WHO), is poised to assign this classification to aspartame for the first time in July.

What WHO says

Despite numerous studies consistently suggesting that aspartame does not present a cancer risk, the potential listing of aspartame as a possible carcinogen by the WHO would signify a departure from previous findings.

The listing by the WHO, if it comes, will break from those earlier findings, “pitting it against the food industry and regulators”, the Reuters report stated.

Confirming that the evaluation will be made available on 14 July, the WHO, in an email response to South First, said, “The IARC has assessed the potential carcinogenic effect of aspartame (hazard identification). Following this, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) will update its risk assessment exercise on aspartame, including the reviewing of the acceptable daily intake and dietary exposure assessment for aspartame.”

“The result of both evaluations will be made available together on 14 July, 2023,” WHO stated.

Also Read: Consuming artificial sweeteners may lead to heart disease

What is aspartame? 

According to the American Cancer Society, aspartame is an artificial sweetener that is commonly used as a sugar substitute in a wide range of food and beverage products. It is a low-calorie sweetener that provides sweetness without adding significant calories.

Aspartame used in many products including coca cola may be declared as Carcinogenic in humans. (Wikimedia Commons)

Aspartame used in many products, including Diet Coke, may be declared a passible carcinogen in humans. (Wikimedia Commons)

Aspartame is composed of two amino acids — phenylalanine and aspartic acid — that are naturally-occurring compounds found in many protein-containing food.

Aspartame is known for its intense sweetness, approximately 200 times sweeter than table sugar (sucrose). Due to its high sweetness potency, only a small amount of aspartame is needed to achieve the desired level of sweetness in food and drinks.

This makes it a popular choice for manufacturers looking to reduce the caloric content of their products or cater to individuals who are managing their sugar intake, such as those with diabetes or following a low-calorie diet.

Regulatory bodies around the world, including the US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA), have deemed aspartame safe for consumption within recommended limits for the general population.

Doctors only warn that aspartame should be avoided by individuals with a rare genetic disorder called phenylketonuria (PKU), as they cannot properly metabolise phenylalanine.

The question now arises: Will the IARC’s announcement leave the medical fraternity confused?

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What does the IARC announcement mean?

The anticipated declaration by the IARC has raised significant concerns within the food industry and regulatory circles. Aspartame’s extensive presence in a wide array of consumer goods makes this announcement particularly noteworthy.

The potential risk associated with its consumption, if proven true, could have far-reaching implications for manufacturers, consumers, and government agencies responsible for safeguarding public health.

However, it is important to note that the IARC’s ruling solely focuses on determining the potential hazard of a substance and does not consider safe consumption levels for individuals.

Recommendations regarding safe consumption levels come from a separate expert committee on food additives known as JECFA (Joint WHO and Food and Agriculture Organisation — FAO — Expert Committee on Food Additives), in addition to determinations made by national regulators.

Previous IARC rulings on different substances have garnered attention from consumers, resulting in concerns, lawsuits, and manufacturers reformulating their products or exploring alternative options.

This trend has led to criticism regarding the public’s perception of the IARC’s assessments, which some argue can be confusing.

In parallel with the IARC’s decision, JECFA is currently reviewing the use of aspartame this year. Their meeting, which commenced at the end of June, is expected to unveil its findings on the same day as the IARC’s announcement, on July 14.

This simultaneous scrutiny from both the IARC and JECFA underscores the importance of comprehensive evaluations to ensure public health and safety.

While the IARC ruling holds significance in terms of potential hazards, the upcoming JECFA findings will shed light on the safe consumption levels of aspartame, providing a more comprehensive perspective for consumers, manufacturers, and regulators.

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What do Indian doctors say about aspartame?

Speaking to South First, Dr Rajeev Vijayakumar, HOD and Senior Consultant, Medical Oncology, Hemato-Oncology, and BMT Physician at BGS Gleneagles Global Hospital in Bengaluru, said: “The IARC is an agency of the WHO and is responsible for evaluating and classifying the carcinogenicity of various substances, including chemicals, physical agents, biological agents, and lifestyle factors”.

IARC's carcinogenic classification. (

IARC’s carcinogenic classification. (

He explained that the classification system used by the IARC consists of several categories, ranging from Group 1 (carcinogenic to humans) to Group 4 (probably not carcinogenic to humans). The “possibly carcinogenic to humans” category, known as Group 2B, is used when there is limited evidence of carcinogenicity in humans.

The classification of aspartame as a potential carcinogen has been a topic of debate and controversy before.

Dr Vijayakumar said, “It is coded as ‘not classifiable’ as per the WHO. Some studies done on rats showed aspartame to cause lymphoma/leukaemia in the subjects. However, this has not been seen in humans as we consume far less quantity.”

Dr Vijayakumar added that the FDA and EFSA have concluded that aspartame is safe for human consumption and does not pose a significant risk of cancer.

“At present, based on the totality of the the scientific evidence, aspartame is considered safe for consumption within the acceptable daily intake (ADI) limits, established by regulatory authorities,” he noted.

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Meanwhile Dr US Vishal Rao, Dean, Head and Neck Oncology, HCG Cancer Care Hospital, opining the same, said that the IARC has examined the cancer-causing effects of aspartame. After this assessment, the Food and Agriculture Organization (FAO) and the WHO will jointly review all the evidence from the studies that have been conducted to understand the potential harms of aspartame.

“There is an initial discussion suggesting that aspartame could potentially fall into Group 2B, which means it is possibly carcinogenic to humans. We should wait for the detailed report form IARC Volume 134 monograph before drawing any firm conclusions,” Dr Vishal Rao said.

He added that it is important to note that the classification of being a “possible carcinogen” (Group 2B) is assigned when there is limited evidence of it being carcinogenic in humans, or there is sufficient evidence of it being carcinogenic in experimental animals, or that there is some kind of mechanistic or structural evidence that the molecule resembles known carcinogens.

Also Read: No level of alcohol consumption is safe for our health, warns WHO

Few studies show it is carcinogenic

Dr G Vamshi Krishna Reddy, Director, Oncology Services, Yashoda Hospitals in Hyderabad, said that Non-Nutritive Sweeteners (NNS) are high-intensity sweeteners and typically have little to no calories. Due to recommendations to limit sugar intake, these sweeteners have become widely used in a variety of different food products.

Representative pic

Aspartame is 200-300 times sweeter than regular sugar. (Creative Commons)

“Aspartame is the most commonly used synthetic sweetener and has 200 to 300 times sweetening power compared to sucrose. Although a majority of aspartame is used in diet beverages, it is also used in over 6,000 other products, including food, pharmaceutical, and personal care products,” Dr Reddy explained to South First.

He said that the Ramazzini Institute (RI), an independent, non-profit research laboratory in Bologna, Italy, initiated a series of large-scale toxicological studies on the possible carcinogenicity of aspartame and confirmed that aspartame caused increased incidence of malignant tumours in multiple organs in rodents.

Dr Reddy spoke about the the NutriNet-Santé study based on 1,02,865 adults of the French population. The study found that artificial sweeteners like aspartame were associated with cancer risk.

“These results suggest that artificial sweeteners may represent a modifiable risk factor for cancer prevention. The debate over safety may continue, but in view of the larger public interest, it is suggested to choose healthy natural sweeteners,” Dr Reddy said.

Also Read: Study says drinking hot tea may lead to oesophageal cancer

A warning worth heeding 

Food scientists feel that this classification, if done, underscores the urgent need for individuals to remain vigilant and informed about their consumption habits.

While the full details and implications of this classification will be disclosed in due course, it is crucial for individuals to be aware of the potential risks associated with aspartame-containing products.

Speaking to South First, Dr Arun Gupta, Convener of Nutrition Advocacy for Public Interest (NAPi), stresseed, “It’s high time our food regulators acted in the interest of public health. The WHO earlier shared a report that non-sugar sweeteners are bad for health if used long-term.

“Now, this report may soon classify aspartame as a ‘possible carcinogen for humans’. An urgent warning, at least on the front of the food/beverage pack, is warranted till a complete ban on the use of aspartame is implemented.”

Dr Gupta added that this also alerts us about consumption of other ultra-processed food or beverages containing so many chemical additives.

“Many are linked to inflammation and cancers. Urgent regulation is the need of the hour for such food and beverages, both to control marketing advertising and put in warning labels,” he said.