Sugar substitutes - aspartame explained

This artificial sweetener, sold in pill form or added to processed foods, has long divided opinion as to whether consumption is safe and if it's an effective way to cut back on sugar. Here we examine what we actually know about aspartame and whether it's a worthy substitute for the sweet stuff...

Aspartame and sweeteners

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 sucrose. Its rise to prominence has not been without controversy. Health professionals have linked it with changes in mood and to alterations in the gut microbiome, potentially leading to glucose intolerance.

Other health professionals go further, describing it as toxic, linking it to birth defects, cancers and brain tumors. However, international regulatory agencies continue to approve its general use in a range of foods, including carbonated soft drinks, yogurt and chewing gum.

Where you'll find it

Diet cola in a glass
Diet fizzy drinks are the largest dietary source of aspartame in the USA. Here in the UK, if the product claims to be ‘sugar free’, there’s a good chance it contains aspartame. It does not heat well so it cannot be used as a replacement in baking or cooking. It's commonly used to sweeten hot beverages such as tea and coffee.

The Food Standards Agency (FSA) suggests an Acceptable Daily Intake (ADI) of 40 milligrams of aspartame per kilogram of body weight per day. The ADI applies to all age groups, including children. The only exception is for people suffering from phenylketonuria (PKU), a genetic condition in which the body is unable to break down a particular amino acid. In the case of aspartame, an adult would have to consume 14 cans of sugar free drinks every day before reaching the ADI.

Nutritional information

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 as when metabolised by the body it produces small amounts of formaldehyde, which is toxic in large amounts. Aspartame is commonly sold in food products or under the brand names Equal or Nutrasweet and appears on ingredient lists either as ‘aspartame’ or 'E951'.

Health claims

There are plenty of conflicting health claims surrounding aspartame. The FSA endorses aspartame's safety (unless you suffer from PKU) with the majority of wider evidence being inconclusive. 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. It is uncertain whether aspartame provides the same satisfaction you get from table sugar as the brain is not content simply with the sweet taste without the calories to accompany it. Nutrient and energy content plays a prominent role in satiation and satiety and it is here that aspartame requires further investigation.

Is it better for you than sugar?

Sugar cubes and sweetener
As with all artificial sweeteners, the lines are blurred. What we do know is that when you eat something sweet that contains energy (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, since your body is still waiting for the calories. As a result you may end up overeating to satisfy this need, which over time increases 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, it would appear that the jury is still out on the effects of these products, and we will need to await the results of further studies before any clear conclusions can be drawn.

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

In 2013, National Experts of the European Food Safety Authority wrote a report regarding the safety of aspartame. The current weight of the evidence from that report is that aspartame is safe at current levels of consumption as a non-nutritive sweetener, unless you suffer from PKU.

This article was last reviewed on 24th September 2018 by Kerry Torrens.

Kerry Torrens is a qualified Nutritionist (MBANT) with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.

Jo Lewin works as a Community Nutritionist and private consultant. She is a Registered Nutritionist (Public Health) registered with the UKVRN. Visit her website at or follow her on Twitter @nutri_jo.

All health content on 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.

Whether you're looking for sweet substitutes, sugar-free baking guides or simply want to find out your recommended daily amounts find all the answers in our sugar hub:
All you need to know about sugar

Do you use artificial sweetners as a substitute for sugar and have you found it beneficial or detrimental to health? We'd love to hear your thoughts...


Comments, questions and tips

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16th Jan, 2015
I have had around 1 or 2 migraines a year since I was 17. Back in the mid-late 80s, I started to get 2 a week. Obviously worried I went to my doctor, examined the symptoms, and he said, "You drink Diet Pepsi don't you." I did. He went on to explain. They have just changed the sweetener from Saccharine to NutraSweet, (Aspartame) and that is nasty stuff. In many people it triggers Migraines, blurred vision, heart palpitations, stomach problems, severe headaches...." He said that at that point, it was the only thing in the UK that had it, but it would soon spread and to watch out for it. He also said that he was amazed that it had ever become licenced for use. I avoided NutraSweet, then, after the name change to aspartame, avoided that and was back to being pretty much Migraine free. However, last year, I started getting 2 a week again. Carefully checked my labels..... Found in the lime juice I was buying it contained, E951. Looked it up, Yep, Aspartame. Obviously the manufacturers were wary of people avoiding Aspartame so changed the name, or the way the name was shown to consumers again, to hide it. Avoiding E951 and I am back to being practically Migraine free again.
4th Mar, 2015
watch sweet misery. i haven't had aspartame since. it has been known to cause severe and deadly brain tumors.
2nd Jul, 2014
My daughter also has severe reactions to aspartame . If she comes in to contact with this substance she instantly develops large mouth and lip ulcers so reading product labels is essential for us. Aspartame is in so many items that you would not expect eg multivitamin tablets and so called full sugar chocolates. We were told by Hotel Chocolat that it is used in their products to prevent soft centres from crystallising but it is also in some breads to keep the bread softer for longer. So beware! I really feel this will be a future health scandal as more people are advised to cut sugar and calories and inadvertently consume more and more of this poison.I agree that it should be banned.
1st Jul, 2014
I developed an adverse reaction to sweetener, namely aspartame. I think it should be banned. I would used to drink a lot of diet cola (admittedly with my vodka) and would get seriously bad hangovers... Yes, I thought it was the alcohol and getting older (in my late 20's!) sparing the graphic details, we're talking horrific vomiting and severe stomach cramps. I quit diet soda, went back to normal cola, and all those symptoms went. I received 'normal' hangovers again. Same amount of vodka! More recently I bought a bottle of normal cherryade (as a treat and ask different mixer for my vodka). I drank nearly 2 litres of the cherryade, long glasses with a 1 cm of vodka. Next day, horrific vomiting and cramps. Couldn't understand why. I later checked the bottle and the cherryade had aspartame in it!
Stev0 Hein's picture
Stev0 Hein
6th Mar, 2018
You think aspartame should be bad because it apparently gave you a bad hangover? Despite the fact that (a) you probably shouldn't be drinking 2 litres of any fizzy pop, (b) the main cause was obviously alcohol and (c) the cherryade no doubt contained dozens of other constituents that may have worsened the hangover, which I'm frankly not convinced isn't just all in your head.
2nd Jul, 2014
My daughter also has severe reactions to anything with aspartame. If a product has this in it , she instantly reacts developing mouth and lip ulcers which are very painful so label reading of everything is essential for us. Surprisingly it is in so many things eg multivitamin tablets and lots of so called full sugar items like Hotel Chocolat chocolates where it is used to keep the chocolate centres soft and to avoid crystallisation which would happen if natural sugar was used. So beware! I too think it should be banned and predict that this will be a future health scandal.
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