What is aspartame?

Aspartame was accidentally discovered in 1965 by a chemist working on a treatment for gastric ulcers. Today it is a widely used, artificial low-calorie sweetener, approximately 200 times sweeter than sugar (sucrose). Its rise to prominence has not been without controversy. Health professionals have linked it with changes in mood and alterations in the gut microbiome, potentially leading to glucose intolerance.


Other health professionals go further, describing it as toxic, linking it to birth defects, cancer and brain tumours as well as nervous system changes. However, international regulatory agencies are satisfied that it can be approved for general use in a range of foods, including carbonated soft drinks, yogurt and chewing gum.

Close up of cola on a white background

How is aspartame used?

Diet fizzy drinks are the largest source of aspartame in the USA. Here in the UK, if the product claims to be ‘sugar free’, there’s a reasonable chance it contains aspartame. It does not heat well so it cannot be used as a replacement in baking or cooking.

Nutritional profile of aspartame

Aspartame is made up of three chemicals: aspartic acid (40%), phenylalanine (50%) and methanol (10%). Aspartic acid and phenylalanine are amino acids, methanol is also commonly encountered in the diet. It is the presence of methanol that concerns people most because when metabolised by the body it produces small amounts of formaldehyde, which may, if enough is present, be toxic.

When reading food labels, look for ‘aspartame’ or 'E951' on ingredient lists.

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What are the health benefits of aspartame?

There are plenty of conflicting health claims surrounding aspartame. In the UK the Food Standards Agency (FSA) endorses aspartame's safety unless you have been diagnosed with a genetic condition called phenylketonuria. What we do know is that although the moderate use of non-nutritive sweeteners may be useful as a short term dietary aid, only minimal amounts of sugar or sweeteners should be consumed in the long term.

Health debates often focus on aspartame's ability to control appetite, to date it is uncertain whether aspartame provides the same fullness satisfaction as that of table sugar. This is because studies suggest the brain is not content with the taste of sweetness alone – it requires calories to accompany it for appetite to be suppressed.

Sugar and sweeteners

Is it better for you than sugar?

As with all artificial sweeteners, the lines are blurred. What we do know is that when you eat something sweet that contains calories your brain releases dopamine and you experience a feeling of pleasure. This, in turn, activates the appetite-regulating hormone leptin, which informs the brain that you’re full. In contrast, when you consume something sweet without the calories, your brain’s pleasure pathway is still activated by the sweet taste but there is nothing to deactivate it, because the body is still waiting for the calories. Consequently, you may end up overeating and over time this may even increase the risk of obesity and insulin resistance.

Sugar-free drinks are popular because they are seen as a way of getting a sweet fix without consuming sugar. However, some studies have suggested that artificially sweetened drinks may be associated with various health concerns, including diabetes. A similar study reported a link between artificially sweetened drinks and dementia and stroke. However, both of these studies failed to provide a science-backed 'cause and effect' for their conclusions. This is because the research was observational and based on the collation of food and drink questionnaires. So, for the time being, the jury is still out on the effects of these products, and we will need to await the results of more studies before we can draw clear conclusions.

In the meantime, plain water or unsweetened tea and coffee are undoubtedly a cheaper and healthier option.

Is aspartame safe for everyone?

The World Health Organisation released a report into aspartame in July 2023 which, although stating that further study was recommended due to 'potential effects', concluded that aspartame is safe for human daily consumption up to a level of 40mg/kg of body weight. That is, unless you suffer from phenylketonuria (PKU), a genetic condition in which the body is unable to break down the amino acid, phenylalanine.

Do you consume products sweetened by aspartame? Do you find it a useful sweetener? Share your experience in the comments below..

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Jo Lewin is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Follow her on Twitter @nutri_jo.


All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

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