What is aspartame?
Aspartame is an artificial sweetener that was discovered by accident in 1965 during a research project aimed at developing a treatment for gastric ulcers. Today, it is renowned for being roughly 200 times sweeter than sugar (sucrose) and is commonly used in a variety of low-calorie foods. However, its widespread use has generated considerable debate. Some health experts have linked aspartame to mood changes and alterations in the gut microbiome, which may contribute to glucose intolerance.
Furthermore, some professionals classify aspartame as harmful, proposing connections to birth defects, cancer, brain tumors, and alterations in the nervous system. It has also been associated with a higher risk of type 2 diabetes and cardiovascular diseases. Notably, one study has shown that aspartame can induce the release of insulin—the hormone responsible for managing blood glucose levels—potentially leading to plaque buildup in the arteries.
Despite ongoing calls for a ban, aspartame remains approved for use in various food items, including sodas, yogurt, and chewing gum.
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How is aspartame used?
In the United States, diet sodas are the largest source of aspartame consumption. In the UK, products labeled as ‘sugar free’ frequently contain aspartame as an alternative sweetener. However, it is important to note that aspartame does not withstand heat well, limiting its use in cooking and baking.
Nutritional profile of aspartame
Aspartame consists of three components: aspartic acid (40%), phenylalanine (50%), and methanol (10%). Aspartic acid and phenylalanine are amino acids, while methanol is a substance commonly found in food. The concern surrounding methanol arises from its metabolism in the body, which produces small amounts of formaldehyde—a substance that can be toxic in high quantities.
When checking food labels, look for the terms ‘aspartame’ or ‘E951’ to identify its presence.
Are there health benefits to aspartame?
The health claims surrounding aspartame are often conflicting. In the UK, the Food Standards Agency (FSA) deems aspartame safe for general consumption, aside from individuals diagnosed with a genetic disorder known as phenylketonuria. While moderate use of non-nutritive sweeteners may serve as a short-term dietary aid, long-term consumption of minimal sugar or sweeteners is recommended.
Much of the debate hinges on aspartame’s effectiveness in appetite control. Current research does not conclusively demonstrate that aspartame fosters the same sensation of fullness as table sugar. This discrepancy arises because studies indicate that the brain requires calories, in addition to sweet flavor, to signal satiety.
Is it better for you than sugar?
Like many artificial sweeteners, the comparison between aspartame and sugar can be complex. Calorically sweet foods trigger dopamine release in the brain, producing feelings of pleasure and activating the appetite-regulating hormone leptin, signaling fullness. In contrast, sweet foods without calories, like those containing aspartame, can lead to a mismatch where the brain still anticipates calories that are not provided. This may result in overeating and, over time, could heighten the risk of weight gain and insulin resistance.
In the UK, about 16 percent of adults derive their free sugar intake from sugary sodas, a figure that nearly doubles for adolescents aged 11-18 years. The introduction of the Soft Drink Industry Levy in April 2018 has prompted many manufacturers to reformulate their products, reducing sugar content from 10g to under 5g per 100ml in some cases.
These reclassified drinks commonly utilize approved low-calorie sweeteners, with aspartame being one of the most favored options. Consumers often gravitate toward sugar-free beverages, viewing them as a means to enjoy sweet flavors without the associated caloric intake.
However, some studies indicate that drinks sweetened artificially may be linked to health issues, such as diabetes, with one analysis suggesting a connection to dementia and stroke. Yet, these studies have yet to establish a definitive cause-and-effect relationship, necessitating further research before drawing any conclusive judgments.
Is aspartame safe for everyone?
A report released by the World Health Organisation in July 2023 states that while additional studies are warranted, aspartame is regarded as safe for human consumption at levels up to 40 mg/kg of body weight. However, those with phenylketonuria (PKU), a genetic condition impeding the breakdown of phenylalanine, should avoid it.
While the conversation about the health implications of aspartame continues, it is clear that it should be limited or avoided by individuals who experience seizures or have other neurological conditions, and pregnant women may also want to reduce their intake.
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This page was reviewed on 17 February 2025 by Kerry Torrens.
Jo Williams is a registered nutritionist (RNutr) with the Association for Nutrition, specializing in public health. Follow her on X @nutri_jo.
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