Aspartame is an intense sweetener used in soft drinks and foods like yoghurt and confectionery. Learn about aspartame, how it is used, and why it's safe to eat.

About aspartame

Aspartame has been used as a sugar replacement for many years, and is one of the most studied sweeteners on the market. Because it's at least 200 times sweeter than sugar, less of it needs to be added to food and drink products.

Aspartame can help people reduce their sugar intake, and it doesn't cause tooth decay.

How the body processes aspartame

Aspartame is made up of 2 amino acids – aspartic acid and phenylalanine. These amino acids are also found in foods that contain protein, like meats, grains and dairy products. Amino acids are the basic building blocks for proteins in the human body.

When you digest aspartame, it's broken down into aspartic acid, phenylalanine and methanol. These are absorbed, further metabolised and then excreted.

Methanol is toxic at high doses, but any food that contains aspartame only produces small amounts of methanol when digested. Your body is easily able to break down these amounts – in the same way it breaks down methanol produced when you digest foods like fats, fruits and vegetables.

Acceptable daily intake for aspartame

The acceptable daily intake (ADI) tells you how much of a specific food additive you can safely eat each day, over the course of your life.

The ADI for aspartame is 40 milligrams for each kilogram of body weight. To exceed this, a 70kg adult would have to drink at least 15 to 20 cans of diet soft drink a day – every day of their life.

Regulation of aspartame in New Zealand

All food additives, including aspartame, must be assessed for safety by Food Standards Australia New Zealand (FSANZ). The Food Standards Code sets out which foods can contain aspartame.

How we know aspartame is safe

Some claim aspartame can cause cancer or other health problems. At least 5 robust studies have concluded that aspartame does not have this potential. Even at high doses, the metabolites of this sweetener do not accumulate in toxic amounts. Aspartame is well tolerated by healthy adults and children.

In 2013, the European Food Safety Authority (EFSA) reviewed all available scientific research on aspartame and its breakdown products, and concluded these were all safe to eat at current levels

Aspartame is approved in other countries

Besides the EFSA, aspartame has also been assessed as safe by all major food authorities, including the United Kingdom Food Standards Agency, the Canadian Food Inspection Agency, and the United States Food and Drug Administration.

Health risk to people with phenylketonuria

Phenylketonuria (PKU) is an inherited disorder that affects a very small number of people. People with PKU can't metabolise the amino acid phenylalanine, which can accumulate to harmful levels in their bodies.

People with PKU must limit their intake of foods containing phenylalanine – mainly proteins. Aspartame also contains phenylalanine, but at levels that have been shown to be too low to cause toxic effects for PKU sufferers. However, to ensure these people are kept safe, all foods containing aspartame, or aspartame-acesulphame salt (a combination of aspartame and the sweetener acesulphame), must have a label warning.

Food labels must list aspartame

Food additives, including aspartame, must be listed on food labels by their function and name or international food number – for example, sweetener (aspartame). Aspartame's code numbers are 951 and 962 for aspartame-acesulphame salt.

Products with aspartame must also have a label warning that the product contains phenylalanine.

Find out more

Who to contact

If you have questions about aspartame in food, email

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