What is aspartame?

Next, read up on whether agave syrup and stevia are good for you. Plus, find out if honey is healthier than sugar.

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.

Are there health benefits to 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.

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.

In the UK, 16 per cent of adults get their free sugar intake from fizzy drinks like cola – this nearly doubles for children aged 11-18 years. The introduction of the Soft Drink Industry Levy (often called the sugar tax) in April 2018 prompted widespread reformulation of these products, reducing many from 10g of sugar per 100ml to less than 5g per 100ml.

Many of these reformulated drinks use the approved low-calorie sweeteners, one of the most popular being aspartame. These sugar-free drinks are popular because they are seen as a way of getting a sweet fix without consuming sugar.

However, studies suggest that artificially sweetened drinks may be linked to various health concerns, including diabetes. One 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'. So, for the time being, we need to wait for more studies before we can draw clear conclusions.

Is aspartame safe for everyone?

The World Health Organisation released a report in July 2023 which, which states that although further studies are needed, aspartame is considered 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.

While the debate over the implications of aspartame for health continue it is clear that it should be avoided by people who experience seizures or have other neurological diseases, and it should be reduced or avoided by those who are pregnant.

Enjoyed this? Now read ….

Sugar substitutes – xylitol explained
Is stevia good for you?
Are fizzy drinks bad for you?
How much sugar is in a can of cola?
Healthy dessert recipes

This page was reviewed on 17 February 2025 by Kerry Torrens.

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

All health content on goodfood.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.