In a rigorous review of both animal and human studies on aspartame and its breakdown products, the European Food Safety Authority concludes that the artificial sweetener is safe for human consumption at current acceptable daily intake levels.

Dr. Alicja Mortensen, who chairs the European Food Safety Authority’s (EFSA) Panel on Food Additives and Nutrient Sources Added to Foods (ANS Panel), says:

“This opinion represents one of the most comprehensive risk assessments of aspartame ever undertaken. It’s a step forward in strengthening consumer confidence in the scientific underpinning of the EU food safety system and the regulation of food additives.”

Aspartame is an artificial, non-saccharide sweetener, approximately 200 times sweeter than sugar, that has been added to food and beverages around the world for more than 25 years. In the European Union, it is codified as E951.

Aspartame is found in thousands of products, including diet foods, sodas and other beverages, yogurts, chewing gum and other low-calorie or sugar-free foods.

As for many additives, food safety regulators set Acceptable Daily Intake (ADI) levels. This is usually an estimate of the amount a person can consume each day over a lifetime without risking their health.

In the case of aspartame in the UK, the ADI is set at 40 mg/kg of body weight, which amounts to around 2,800 mg for an average British adult. In the US, the ADI is slightly higher, at 50 mg/kg.

For most foods and beverages with added aspartame, people would have to consume an exceptional amount every day for the whole of their lives to exceed their ADI.

Phenylketonuria (PKU) is a serious, inherited metabolic disorder that affects around 1 in 10,000 people. If untreated, it can cause serious brain damage.

People with PKU cannot safely consume aspartame because their bodies cannot metabolize one of its breakdown products, the amino acid phenylalanine. Instead, it accumulates to dangerous levels, and it is particularly toxic to the developing fetus in women suffering from PKU.

In many countries, all products containing aspartame must be clearly labeled so people with PKU can avoid consuming these products.

Following their review of the evidence in animal and human studies, the EFSA’s ANS Panel concluded that the current Acceptable Daily Intake (ADI) of 40 mg/kg of body weight per day is “protective for the general population,” with the exception of people suffering from PKU, who have to avoid phenylalanine.

There has been speculation that aspartame causes cancer by damaging genes – for instance a study published in 2005 found that aspartame causes cancer in rats at levels approved for humans – but the panel ruled out this risk.

It also concluded that the food additive does not harm the brain or nervous system, or affect behavior or mental function in adults and children.

The panel also notes that apart from the already stated exception of women with PKU, there is no risk to the developing fetus from exposure to phenylalanine derived from aspartame at the current ADI.

The panel also points out that aspartame’s breakdown products (phenylalanine, methanol and aspartic acid) are naturally present in foods. For example, methanol can be found in many fruits and vegetables.

“The contribution of breakdown products of aspartame to the overall dietary exposure to these substances is low,” says an EFSA press statement.