The world has been buzzing about aspartame, a synthetic sweetener, since June 29 when Reuters broke the news that the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), decided to add aspartame to its carcinogen classification. Aspartame joined the existing list of carcinogens, which includes over 1,100 substances categorized from Group 1 to Group 3.

The IARC's classifications cause a lot of confusion. They base their categorization of substances as carcinogens or possible cancer-causing agents on the strength of scientific evidence. However, the classification does not indicate the severity of carcinogenicity or the amount needed for harm. For instance, substances like very hot drinks and the pesticide DDT are both classified as Group 2A. Does this mean they are equally dangerous? Not at all. It only signifies that scientists have studied them to a similar extent. In October 2015, processed meat was grouped together with smoking and alcohol as Group 1 carcinogens. However, it's important to note that there are significantly more cancer deaths attributed to smoking (estimated to be 30 times more) and alcohol (estimated to be 20 times more) than from excessive consumption of processed meat.

As the IARC classified aspartame as Group 2B carcinogen on July 14, this places aspartame in the same group as bracken fern, aloe vera extract, and pickled vegetables like kimchi and pickles. However, it remains a controversial classification. A study on the relationship between aspartame consumption and cancer risk tracked 100,000 French adults for almost eight years, revealing a slight increase in cancer risk. But observational studies like this cannot establish cause and effect definitively. Furthermore, the participants in this study consumed less aspartame than the general population from the beginning. When divided into two groups, those who consumed only half the French average of alternative sweeteners showed an association with cancer risk. Nevertheless, critics argue that it is difficult to rule out the possibility that something other than aspartame might have contributed to the observed difference.

In 2019, a study conducted by the British Medical Journal examined 35 observational studies and 21 clinical trials regarding alternative sweeteners. The study concluded that these sweeteners have a modest benefit in terms of weight loss, but they are not significantly harmful and do not increase the risk of cancer. Most studies seem to agree with this finding. While alternative sweeteners, such as aspartame, may not improve blood sugar levels in diabetics or aid in managing overweight and obesity, they are generally considered safe. According to the WHO’s Joint Expert Committee on Food Additives (JECFA), a 60-kilogram adult is not at risk unless they consume an excessive amount, such as drinking 12-36 cans of zero soda a day. In modern diets, the emphasis should be on quantity rather than quality. We should not forget that it’s wise to do everything in moderation.

Jeong Jae-hoon is a food writer and pharmacist. He covers a variety of subjects, including trends in food, wellness and medications. This column was originally published in Korean in Joongang Ilbo on July 6, 2023. – Ed.