Aspartame is a possible carcinogen: the science behind the decision

Aspartame is utilized to add a sweet taste to numerous food and beverage items.

The cancer research division of the World Health Organization (WHO) has labeled aspartame, a low-calorie sweetener, as 'potentially cancer-causing'.

The IARC, located in Lyon, France, recently declared that their ruling, disclosed on July 14th, was grounded on restricted data regarding liver cancer obtained from research conducted on humans and rodents.

Nevertheless, the panel of experts from JECFA, which is a collaboration between FAO and WHO, asserted that the suggested maximum intake levels for this artificial sweetener, commonly present in numerous edibles and beverages, would remain unaltered.

Francesco Branca, the head of the WHO's Nutrition and Food Safety division, stated during a media briefing in Switzerland on July 12th that there is insufficient proof, based on both experiments and human studies, to suggest any negative impacts of aspartame consumption within the established guidelines set forth by the previous committee.

According to Mary Schubauer-Berigan, the person temporarily in charge of the IARC Monographs program, the recent categorization should not be seen as a definitive conclusion that aspartame definitely causes cancer. Rather, it is a request to the scientific community to delve deeper into studying and comprehending the potential dangers of consuming aspartame in relation to cancer.

Other substances categorized as 'potentially cancer-causing' consist of aloe vera extracts, traditional pickled vegetables from Asia, specific vehicle fuels, and certain chemicals employed in dry cleaning, carpentry, and printing. Additionally, the International Agency for Research on Cancer (IARC) has labeled red meat as 'likely cancer-causing' and processed meat as 'cancer-causing'.

Aspartame, a sweetener that is 200 times more potent than sugar, can be found in over 6,000 products globally. These include diet beverages, gum, toothpaste, and even chewable vitamins. The approval of this sweetener by the US Food and Drug Administration (FDA) dates back to 1974, while the JECFA set a safe amount to consume daily, known as the acceptable daily intake (ADI), in 1981. For an average adult, this translates to roughly 2,800 milligrams per day. This quantity is approximately equivalent to consuming 9 to 14 cans of diet soda.

The man-made sweetening substance has sparked numerous debates in the last forty years, as it has been associated with heightened chances of developing cancer and various health concerns. However, after conducting reviews, both the FDA and the European Food Safety Authority (EFSA) have concluded that there is not enough proof to lower the Acceptable Daily Intake (ADI).

During the year 2019, a committee advising the IARC suggested that a thorough evaluation should be conducted on various substances, such as aspartame, due to the emergence of new scientific findings. The IARC's findings regarding the potential association between aspartame and liver cancer were derived from three research studies that investigated the intake of artificially sweetened drinks.

A blog post published in 2014, available online, observed a group of 477,206 individuals across 10 European countries for over 11 years. This study revealed that the intake of sweetened carbonated beverages, including those containing aspartame, was linked to an increased likelihood of developing a type of liver cancer known as hepatocellular carcinoma1. In 2022, a study conducted in the United States found a correlation between the consumption of artificially sweetened drinks and an elevated risk of liver cancer in individuals with diabetes2. Another study, involving 934,777 participants from 1982 to 2016 in the US, discovered that men and women who consumed artificially sweetened beverages had a higher likelihood of developing pancreatic cancer.

The research utilized the consumption of artificially sweetened drinks as a substitute for measuring the amount of aspartame a person is exposed to. These substitutes are generally trustworthy, although they may not always offer an accurate assessment of the actual intake, explains Mathilde Touvier, an epidemiologist at the esteemed French National Institute of Health and Medical Research located in Paris.

Touvier collaborated on another research piece that was part of IARC's evaluation. This study examined the consumption of aspartame from various sources such as carbonated beverages, dairy products, and sweeteners used on tables. The findings revealed that out of the 102,865 adults in France, individuals who consumed larger quantities of aspartame (yet still within the recommended acceptable daily intake) experienced a heightened likelihood of developing breast cancer and cancers associated with obesity.

According to Touvier, the research indicates a notable rise in risk, which was consistently observed in various analyses. However, the study currently lacks sufficient statistical strength to delve into the matter of liver cancer.

The JECFA also examined research linking aspartame to liver, breast, and blood cancers but concluded that the results were inconclusive. The studies had certain flaws in their design, they were unable to eliminate factors that could skew the results, or they relied on individuals reporting their own daily consumption of aspartame.

According to William Dahut, the head researcher at the American Cancer Society in Bethesda, Maryland, keeping track of what we eat may not be the most trustworthy method. He explains that when it comes to aspartame, for example, we are not only consuming it alone but as part of a mixture of various substances and compounds.

Within the organism, the artificial sweetener decomposes into three metabolites: phenylalanine, aspartic acid, and methanol. According to Branca, these three substances are also present in the consumption of various other food or beverage items. Consequently, the identification of aspartame through blood examination becomes an unattainable feat. Branca describes this circumstance as a constraint on our comprehension of its impacts.

Methanol has the potential to cause cancer as it undergoes a process of being transformed into formic acid, which can harm our DNA. According to Paul Pharoah, a cancer expert from Cedars-Sinai Medical Center in Los Angeles, excessive amounts of methanol can harm the liver and pose a risk of developing liver cancer. However, it is important to note that the minuscule amount of methanol produced when aspartame breaks down is not a cause for concern.

The International Agency for Research on Cancer (IARC) states that further research is required to investigate the effects of aspartame on metabolic processes and its connection to various illnesses. Touvier also emphasizes that this study will contribute new evidence to the overall understanding of this matter worldwide.