Facts on the Link Between Aspartame and Cancer

Due to the adverse health effects of too much consumption of sugar, the World Health Organization recommends limiting free sugars in the diet. In order to meet the sweet taste sought after by consumers of sodas and other sweet products worldwide, food manufacturers have resorted to artificial sweeteners like aspartame to mimic the sweet taste of sugar without providing too many calories. It is for this reason that artificial sweeteners gained popularity.

In 2010, the Centers for Disease and Control and Prevention reported that one-fifth of all Americans consumed diet drinks that use artificial sweeteners like aspartame on a given day. However, since its first manufacture in 1965 and approval by the United States Food and Drug Administration (FDA) for use in foods in 1981, aspartame has raised controversies regarding its potential negative effects on health, including cancer, cardiovascular diseases, Alzheimer’s disease, seizures, and neurotoxicity, for decades.

With the great demand and wide consumption of aspartame-containing products, it is important to look into the current information available surrounding the link between aspartame and increased risk of cancer. This article will tackle what aspartame is, its properties, and evidence that describe its link to cancer.

What is aspartame?

Aspartame is an artificial sweetener primarily composed of amino acids phenylalanine and aspartic acid. The phenylalanine has a methyl group attached, which is the one responsible for its sweet taste.

Aspartame is one of the most widely used artificial sweeteners, with a yearly production of about 3,000 to 5,000 metric tons. It is an ingredient used in more than 5,000 food and beverage products, such as diet drinks, chewing gum, yogurt, instant coffee, and cereals. It is also used in low- or no-sugar sweet condiments and children’s medicines and vitamins. Due to its instability in the presence of heat, aspartame is not used in baked products and those that require heating.

FDA defines aspartame as a nutritive sweetener, which means that it contains calories but in a negligible amount. But since it is 200 times sweeter than table sugar, low- or no-sugar aspartame-containing products use much less of it. This is the reason why people who want to limit their sugar intake such as those trying to manage their weight and diabetes consume these products.

Does aspartame cause cancer?

When one takes aspartame in his body, the methyl ester group of aspartame is broken down into methanol. As of 2014, the biggest source of methanol in the American diet is aspartame. This is worrisome because, when consumed in large quantities, methanol is toxic. Also, during metabolism, the free methanol from aspartame can be further converted into formaldehyde, a known neurotoxin and carcinogen in the human body.

Several independent studies conducted over the past decades have found a connection between aspartame and a wide range of health problems, particularly brain tumor and cancer. From a descriptive analysis of the National Cancer Institute, increased brain cancer rates in the United States have been noted at the same time that aspartame was introduced into food products. This led to many other different studies from both FDA and independent researchers.

These studies used both animals and humans as samples, so it’s important to remember that neither gives definitive evidence because the results of animal studies do not always apply to humans. Also, human studies are hard to interpret due to so many factors.

  • Studies in animals

Due to rising concerns about the safety of aspartame, the Ramazzini Institute (RI), a not-for-profit research laboratory in Italy started in 1997 a series of large-scale studies regarding possible carcinogenicity of aspartame.

In 2006 and 2007, RI reported that high doses of aspartame increased leukemia, lymphoma, and other cancer risks for rats and mice. Even at low doses approaching the Acceptable Daily Intake (ADI), they also found that the sweetener increases cancer risk as well. This series of studies caught the attention of critics, including the Food and Drug Authority, the U.K.’s Food Standards Agency, and the European Food Safety Authority which ordered reviews. They found several flaws, including the doses given to rats which were equivalent to 8 to 2,083 cans of diet soda daily. Since these doses are not possible in real life, the regulatory agencies did not change their stance regarding the safety of aspartame.

In 2021, RI made a review to validate their previous conclusions. They came up with findings that aspartame is indeed a chemical carcinogen for rodents and that prenatal exposure of rodent offspring to aspartame increases their cancer risks.

  • Studies in humans

In 2012, researchers from Harvard reported an increased risk of non-Hodgkin lymphoma, multiple myeloma, and leukemia for 125,000 men, but not for women, who have taken aspartame. However, in the same year, the researchers expressed that data were weak due to the inconsistency of the effects on men and women.

To date, there is still a lack of robust epidemiological evidence of aspartame’s carcinogenicity, but recently, a cohort study by Debras et al investigated the associations between artificial sweeteners, including aspartame, and increased cancer risks for 102,865 French adults who had regular intake of products with artificial sweeteners for a course of over a decade. Risks were found to be higher for obesity-related cancer and breast cancer. Regardless of the found correlation, the results should be replicated in other large-scale studies to establish a causal link. The researchers added that these findings provide novel insights for the current re-evaluation of artificial food sweeteners by various health agencies worldwide.

With all this information, the U.S. FDA remains on its stance that aspartame is “safe for the general population under certain conditions”. The agency recommends an ADI of 50 milligrams per kilogram of body weight daily. However, persons with phenylketonuria should limit their intake of aspartame. This rare hereditary disease makes metabolism of phenylalanine, an active component of aspartame, difficult. For this reason, the FDA requires food manufacturers of aspartame-containing products to indicate on their labels that their product contains phenylalanine.

For other information on how to prevent cancer, read 10 Commandments of Cancer Prevention.

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