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Aspartame

What is aspartame?

Aspartame is one of the most common artificial sweeteners in use today. It is sold under the brand names NutraSweet® and Equal®. Aspartame is composed mainly of 2 amino acids, aspartic acid and phenylalanine. Amino acids are the building blocks of proteins and are found naturally in many foods.

Aspartame is used in many foods and beverages because it is about 200 times sweeter than sugar, so much less of it can be used to give the same level of sweetness. This, in turn, lowers the calories in the food or beverage.

Rumors claiming that aspartame causes a number of health problems, including cancer, have been around for many years. Many of these continue to circulate on the Internet.

How are people exposed to aspartame?

Aspartame has been used in the United States since the early 1980s. It is now found in thousands of different food products. Aspartame is commonly used as a tabletop sweetener, as a sweetener in prepared foods and beverages, and in recipes that do not require too much heating (since heat breaks down aspartame).

How is aspartame regulated?

In the United States, artificial sweeteners such as aspartame are regulated by the Food and Drug Administration (FDA). These products must be tested for safety and approved by the FDA before they can be used. The FDA also sets an acceptable daily intake (ADI) for each sweetener, which is the maximum amount considered safe to consume each day during a person's lifetime. The ADI is set to be about 100 times less than the smallest amount that might cause health concerns, based on studies done in lab animals.

The FDA has set the ADI for aspartame at 50 milligrams per kilogram (mg/kg) of body weight. (In the European Union, the European Food Safety Authority has recommended a slightly lower ADI for aspartame, at 40 mg/kg.)

To put the ADI for aspartame in perspective, this would be 3,750 milligrams per day for a typical adult weighing 75 kilograms (about 165 pounds), far more than most adults take in daily. A can of diet soda usually contains about 180 milligrams of aspartame, so a typical adult would have to drink about 21 cans of diet soda a day to go over the recommended level.

Does aspartame cause cancer?

Researchers use 2 main types of studies to try to determine if a substance or exposure causes cancer. (A substance that causes cancer or helps cancer grow is called a carcinogen.)

In studies done in the lab, animals are exposed to a substance (often in very large doses) to see if it causes tumors or other health problems. It's not always clear if the results from these types of studies will apply to humans, but lab studies are the best way to find out if a substance has the potential to cause cancer in humans before widespread exposure occurs.

Another type of study looks at cancer rates in different groups of people. Such a study might compare the cancer rate in a group exposed to a substance versus the rate in a group not exposed to it, or compare it to what the expected cancer rate would be in the general population. But studies in people can sometimes be hard to interpret, because there may be other factors affecting the results that are hard to account for.

In most cases neither type of study provides definitive evidence on its own, so researchers usually look at both lab-based and human studies if they are available.

Studies done in the lab

Many studies have looked for health effects in lab animals fed aspartame, often in doses higher than 4,000 mg/kg per day over their lifetimes. These studies have not found any health problems that are consistently linked with aspartame.

Two studies published by a group of Italian researchers suggested that very high doses of aspartame might increase the risk of some blood-related cancers (leukemias and lymphomas) in rats. However, both the FDA and the EFSA have called these results into question, citing a lack of some important data in the published studies and other concerns.

Studies in people

Most studies in people have not found that aspartame use is linked to an increased risk of cancer.

One early study suggested that an increased rate of brain tumors in the US during the 1980s might have been related to aspartame use. However, according to the National Cancer Institute (NCI), the increase in brain tumor rates actually began back in the early 1970s, well before aspartame was in use. And most of the increase was seen in people age 70 and older, a group that was not exposed to the highest doses of aspartame, which might also make this link less likely. Other studies have not found an increase in brain tumors related to aspartame use.

In the largest study of this issue, researchers from the NCI looked at cancer rates in more than 500,000 older adults. The study found that, compared to people who did not drink aspartame-containing beverages, those who did drink them did not have an increased risk of lymphomas, leukemias, or brain tumors.

What expert agencies say

Expert agencies in the United States and elsewhere that have evaluated aspartame have found it safe for use.

The Food and Drug Administration (FDA) regulates the use of aspartame and other artificial sweeteners in the United States. In 2007, the FDA stated:

    Considering results from the large number of studies on aspartame's safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food.

The European Food Safety Authority (EFSA) assesses the safety of sweeteners such as aspartame in the European Union. According to a 2009 report from its Panel on Food Additives and Nutrient Sources Added to Food:

    Overall, the Panel concluded, on the basis of all the evidence currently available… that there is no indication of any genotoxic or carcinogenic potential of aspartame and that there is no reason to revise the previously established ADI for aspartame of 40 mg/kg [body weight].

Though research into a possible link between aspartame and cancer continues, these agencies agree that studies done so far have not found such a link.

Does aspartame cause any other health problems?

Complaints of various health issues have circulated since aspartame first appeared on the market in the 1980s. But for most people, no health problems have clearly been linked to aspartame use.

Phenylketonuria (PKU)

Phenylketonuria is a rare genetic disorder (present at birth) in which the body can't break down phenylalanine, an amino acid found in many foods. Levels of phenylalanine can build up in the blood, which prevents other important chemicals from getting to the brain. Unless phenylalanine intake is severely limited, children with PKU suffer from abnormal brain development.

PKU is usually detected in babies by a routine blood test shortly after birth. People with PKU need to follow a phenylalanine-restricted diet. This is especially important in children, whose brains are still developing.

Because phenylalanine is a component of aspartame, it's important that people with PKU limit their intake of aspartame-containing foods and drinks.

Other health complaints

Claims have been made that aspartame is related to health effects ranging from mild problems such as headache, dizziness, digestive symptoms, and changes in mood, to more serious health issues such as Alzheimer disease, birth defects, diabetes, Gulf War syndrome, attention deficit disorders, Parkinson disease, lupus, multiple sclerosis, and seizures. However, studies done to date have not found any consistent evidence of harm. Research into the safety of aspartame continues.

Should I limit my exposure to aspartame?

Aside from the possible effects in people with phenylketonuria, there are no health problems that have been consistently linked to aspartame use. Research on artificial sweeteners, including aspartame, continues today.

For people who want to avoid aspartame, the easiest way to do this is to check the labels before buying or eating foods or drinks. If aspartame is in the product it will be listed in the ingredients. NutraSweet® and Equal® are brand names for aspartame, so these can be avoided as well.

Other artificial sweeteners on the market include sucralose (Splenda®), acesulfame K (Sweet One®, Sunett®), and saccharin (Sweet'N Low®, SugarTwin®), but some of the same types of health concerns have been raised about these products as well.

Additional resources

More information from your American Cancer Society

We have some related information that may also be helpful to you. These materials may be ordered from our toll-free number, 1-800-227-2345.

Known and Probable Human Carcinogens

National organizations and Web sites

In addition to the American Cancer Society, other sources of information and support include*:

Food and Drug Administration
Toll-free number: 1-888-463-6332 (1-888-INFO-FDA)
Web site: www.fda.gov

National Cancer Institute
Toll-free number: 1-800-422-6237 (1-800-4-CANCER)
Web site: www.cancer.gov
Artificial sweeteners and cancer: www.cancer.gov/cancertopics/factsheet/Risk/artificial-sweeteners

*Inclusion on this list does not imply endorsement by the American Cancer Society.

No matter who you are, we can help. Contact us anytime, day or night, for information and support. Call us at 1-800-227-2345 or visit www.cancer.org.

References

Council on Scientific Affairs. Aspartame: review of safety issues. JAMA. 1985;254:400-402.

European Food Safety Authority. Opinion on a request from the European Commission related to the 2nd ERF carcinogenicity study on aspartame. 2009. Accessed at www.efsa.europa.eu/en/scdocs/scdoc/945.htm on April 13, 2010.

Flamm GW. Letter to the Editor. J Neuropathol Experimental Neurol. 1997:5:105-106.

Food and Drug Administration. FDA Statement on European Aspartame Study. April 20, 2007.

Gallus S, Scotti L, Negri E, et al. Artificial sweeteners and cancer risk in a network of case-control studies. Ann Oncol. 2007;18:40-44.

Gurney JG, Pogoda JM, Holly EA, et al. Aspartame consumption in relation to childhood brain tumor risk: results from a case-control study. J Natl Cancer Inst. 1997;89:1072-1074.

Lim U, Subar AF, Mouw T, et al. Consumption of aspartame-containing beverages and incidence of hematopoietic and brain malignancies. Cancer Epidemiol Biomarkers Prev. 2006;15:1654–1659.

National Cancer Institute. Artificial sweeteners and cancer. 2009. Accessed at www.cancer.gov/cancertopics/factsheet/Risk/artificial-sweeteners on April 14, 2010.

National Cancer Institute. Aspartame and cancer. 2006. Accessed at www.cancer.gov/cancertopics/factsheet/risk/aspartame on April 14, 2010.

Olney JW. Farber NB, Spitznagel E, Robins LN. Increasing brain cancer rates: is there a link to aspartame? J Neuropathol Experimental Neurol. 1996:55:1115-1123.

Soffritti M, Belpoggi F, Tibaldi E, et al. Life-span exposure to low doses of aspartame beginning during prenatal life increases cancer effects in rats. Environ Health Perspect. 2007;115:1293-1297.

Yost D. Clinical safety of aspartame. Am Fam Physician. 1989;39:201-206.


Last Medical Review: 02/17/2011
Last Revised: 02/17/2011