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Aspartame Safety

ADI, Metabolism, Estimated Intakes and Common Concerns

Aspartame is one of the most thoroughly studied food ingredients, with more than 200 scientific studies confirming its safety. It is used in more than 6,000 products around the world.

Discovered in 1965 and approved for use by U.S. Food & Drug Administration (FDA) in 1981, aspartame is permitted for use in food and beverage products in more than 100 countries around the world. Authorities that have recognized and/or approved aspartame include the Joint FAO/WHO Expert Committee on Food Additives (JECFA), the U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA) and the Agence Française de Sécurité Sanitaire des Aliments (French Food Safety Agency – AFSSA).

Aspartame is safe for use by nearly all populations. The only exception is people born with a rare genetic disorder called phenylketonuria (PKU). People with PKU cannot metabolize a common amino acid called phenylalanine and therefore need to avoid foods and beverages that contain it. Phenylalanine is primarily found in protein foods, including milk, milk products, eggs and meats. It is also a component of aspartame. The regulations of most countries require that aspartame-containing foods and beverages carry a statement on the label alerting people with PKU to the presence of phenylalanine.

Acceptable Daily Intake (ADI)

Qualified scientific experts establish a safe level of consumption for every food additive used in foods and beverages, including aspartame and other low- and no-calorie sweeteners. This level, called the Acceptable Daily Intake (ADI), is stated in milligrams per kilograms of body weight and represents the amount that can be consumed on a daily basis over a person’s lifetime without any adverse health effect. The ADI is based on an extensive body of safety studies.

The US FDA has set the ADI for aspartame at 50 mg/kg body weight for adults and children. This means a 150-pound (68 kg) person can safely consume 3400 mg of aspartame every day over his or her lifetime without adverse effects. The amount in Diet Coke sold in the U.S. is 185 mg per 12-fl. oz. serving.*

*Amount as of May 2012; rounded up to the nearest 5 mg.


Aspartame is fully metabolized into naturally occurring compounds that are found in other foods and beverages.

Aspartame is composed of two amino acids, aspartic acid and phenylalanine (building blocks for many proteins). These amino acids are the same as those obtained from the human diet when we consume protein-containing products such as eggs, meat, fish, cheese, dairy products and nuts.

When aspartame is digested, the body breaks it down into aspartic acid, phenylalanine and methanol. Compared to amounts obtained from an aspartame-sweetened beverage, these components are consumed in much greater amounts from a variety of foods, including milk, meat, dried beans, fruits and vegetables. For example, a serving of non-fat milk provides about six times more phenylalanine and 13 times more aspartic acid than an equivalent serving of a low- or no-calorie diet beverage sweetened 100% with aspartame. Likewise, a serving of tomato juice provides about six times more methanol, compared to an equivalent serving of a beverage sweetened with aspartame.

Phenylalanine, Aspartic Acid & Methanol Content of Common Foods (mg)

Food/Beverage Portion Size Phenylalanine* Aspartic Acid* Methanol
Diet Coke 8 fl. oz. (240 ml) 60 48 12
Milk 8 fl. oz. (240 ml) 404 592 -
Banana medium 58 146 21
Tomato juice 8 fl. oz. (240 ml) 39 231 71

*Amino acids

Estimated Intakes

Aspartame consumption is well within safe levels, even at highest estimated intakes and in children. A recent expert review on the safety of aspartame included an evaluation of current intake levels in the U.S. based on the 2001-2002 National Health and Nutrition Examination Survey (NHANES) food intake data and known concentrations of aspartame in different foods and beverages. The results showed that, even using the worst-case assumption that aspartame was the only low or no-calorie sweetener available in the food supply and was used in every reduced-calorie food and beverage survey participants reported consuming, mean consumption among adults of aspartame was only about 10% of the US ADI and even among those with the highest level of intake, consumption was less than one-third of the US ADI. Average consumption among 6- to 11-year-old children was 11% of the US ADI.

Aspartame Intakes (Estimated, U.S.) vs. US ADI*

Low- and No- Calorie Sweetener Users Est. Aspartame Intake
mg/kg bw/day
Percent of US ADI
U.S.ADI=50 mg/kg bw/day
All Low-Calorie Sweetener Users
50th Percentile 4.8 10%
95th Percentile 13.3 27%
Children, 6-11 yrs (subgroup)
50th Percentile 5.5 11%
*Assumes aspartame is the only low or no-calorie sweetener available for use in foods & beverages

Research Addresses Common Concerns

In 2010, national experts from the European Union reviewed the safety of aspartame and did not find any new evidence to question the safety of this ingredient.

Cancer: Questions regarding the safety of aspartame were raised in 1996 by a report suggesting that an increase in brain tumor rates between 1975 and 1992 might be associated with the introduction of aspartame in the United States. However, an analysis by the National Cancer Institute showed that the brain and central nervous system cancers began rising 8 years prior to the approval of aspartame and continued to rise until 1985, and that the increase in incidence occurred primarily in people age 70 and older – a group with low exposure to aspartame.

In 2011, the European Food Safety Authority (EFSA) reviewed studies which alleged an association with the exposure of mice to aspartame with the development of carcinogenic tumors. EFSA also reviewed a second study which showed an alleged association between the consumption of artificially-sweetened drinks with premature birth in a sample of 59,334 pregnant women. EFSA concluded there is no scientific evidence to support a causal relationship between the consumption of aspartame –used to manufacture beverages and food, with premature birth in pregnant women, or with the development of carcinogenic tumors.

In other studies, the U.K. Food Standards Agency (FSA) issued a report in March 2011, which states that the FSA Independent Committee on Toxicity has concluded that long-term exposure to methanol consumed through food, including from aspartame, is unlikely to be harmful to health. And lastly, research has shown there is no association between aspartame consumption and an increase in human brain tumor rates.

In 2006, the U.S. National Cancer Institute examined data from over a half million retirees and concluded that “[i]ncreasing consumption of aspartame-containing beverages was not associated with the development of lymphoma, leukemia, or brain cancer.

Headaches: Most studies investigating a relationship between aspartame and headaches show no effect. However, results from some small studies have shown a positive connection between aspartame intake and headaches, suggesting a susceptible population subset, although there is no biological explanation. Inconsistent findings may be caused by lack of objective measurements for headache onset or duration.



Magnuson BA, Burdock GA, Doull J, Kroes RM, Marsh GM, Pariza MW, Spencer PS, Waddell WJ, Walker R, Williams GM. (2007) Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies. Critical Reviews in Toxicology, 37:629-727.

EFSA Report of the Meetings on Aspartame with National Experts

European Food Safety Authority. Statement of EFSA on the scientific evaluation of two studies related to the safety of artificial sweeteners. 2011.

Food Standards Agency (U.K.). Committee on Toxicity opinion on methanol safety. 04 April 2011.

To learn more about aspartame and methanol metabolism, see Expert Review of the Safety of Aspartame.

More Information

For an in-depth review of aspartame, see Q&A About Aspartame (EUFIC)