[Reading Science] Should You Eat or Avoid 'Zero Calorie' Foods?

IARC Classified Aspartame as a Potential Carcinogen on the 14th
What Scientists Say... "A Call for Further Research"

The sweetener aspartame, widely used in so-called 'zero-calorie' foods, has been classified as a potential carcinogen. However, it has not been banned immediately, and expert opinions vary. So, is it safe to continue consuming it or not? Regarding this, the international academic journal Nature cautiously stated that "further research on potential risks is needed."

Aspartame is an artificial sweetener approved by the U.S. Food and Drug Administration (FDA) in 1974. It is over 200 times sweeter than sugar but has very low calories, and it is used in more than 6,000 products worldwide. It is widely included in diet sodas, chewing gum, toothpaste, and chewable vitamins. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) set the acceptable daily intake (ADI) in 1981 at less than 40 mg per kilogram of body weight. For an average adult, this is about 2,800 mg per day, equivalent to the amount contained in 9 to 14 cans of diet soda.

For over 40 years, the safety of aspartame has been continuously debated. The FDA and the European Food Safety Authority (EFSA) have conducted re-evaluations but have not found sufficient evidence to reduce the recommended daily intake due to risks.

However, in 2019, the International Agency for Research on Cancer (IARC), under the WHO, recommended a re-evaluation based on studies suggesting that consumption of beverages containing artificial sweeteners like aspartame may cause liver cancer, sparking renewed controversy. The recommendation was based on three studies. One study published in 2014 involved 477,206 people over 11 years in 10 European countries. It found that people who consumed beverages containing sweeteners, including aspartame, had a higher risk of hepatocellular carcinoma. A 2022 study conducted in the United States also concluded that diabetic patients who consumed artificially sweetened beverages had an increased risk of liver cancer. A long-term follow-up study from 1982 to 2016 involving 934,777 new Americans reported an increased risk of pancreatic cancer.

The IARC also conducted its own investigation in France involving 102,865 adults and concluded that even without exceeding the daily recommended intake, higher consumption of aspartame increased the risk of breast cancer and obesity-related cancers. Mathilde Touvier, a researcher at the French National Institute of Health and Medical Research and co-author of the study, said, "We confirmed a statistically significant increase in cancer risk associated with aspartame consumption."

However, there are differing opinions. Some argue that the accuracy and reliability of the investigations themselves are questionable. In this regard, JECFA also investigated the relationship between aspartame and liver cancer, breast cancer, and blood cancers but did not reach any significant conclusions. The study design had limitations, as it was impossible to accurately determine the amount of aspartame in the foods consumed by participants, relying instead on self-reported dietary records. William Dahut, Chief Scientific Officer (CSO) of the American Cancer Society, said, "Dietary records are not always highly reliable," adding, "Aspartame is not consumed as a single food but mixed with various compounds and other nutrients."

Aspartame breaks down in the human body into three substances: phenylalanine, aspartic acid, and methanol. These substances are identical to those found in other beverages and foods. This is why aspartame cannot be detected in blood tests. Due to current technological limitations, scientists cannot accurately determine the effects of aspartame on the body. For example, methanol is metabolized into formic acid, which can damage DNA and is classified as a potential carcinogen. However, the amount of methanol produced from aspartame breakdown is minimal. The IARC acknowledged that "additional investigation is needed regarding the effects of aspartame metabolism on cancer and other diseases in the human body." Marie Schwaiger-Brigan, head of research at IARC, explained, "This classification as a potential carcinogen should not be interpreted as definitive evidence that aspartame consumption increases cancer risk. It is a call for in-depth research by the academic community to better understand the risks of aspartame."

In fact, JECFA has stated that it currently has no plans to change the daily intake guidelines for aspartame. Francesco Branca, Director of the WHO Department of Nutrition and Food Safety, said, "There is no conclusive evidence from empirical data or human studies showing adverse effects from consuming aspartame within the established limits."