Aspartame (NutraSweet) Update

Many of my patients have inquired about a report concluding that a rat study has linked aspartame to cancer. I have also heard broad statements concluding that aspartame is toxic to the human brain. I would like to take this opportunity to provide you with the facts. The study that is being quoted is the Soffritti study. Morando Soffritti is the Scientific Director at the Ramazzini Institute in Bologna, Italy. The Ramazzini Institute plans to publish the study in THEIR OWN publication. Their publication, the European Journal of Oncology, has been excluded from the Medline (National Library of Medicine) database, the world?s leading source of scientific literature. The researchers at Ramazzini have not followed the internationally established protocol for evaluation of animal carcinogenicity study findings. It is important to note that the researchers? pathology slides HAVE NOT BEEN peer reviewed. The National Toxicology Program (NTP) has established guidelines for pathology peer review in order to provide scientific consensus that study conclusions are valid. Ramazzini researchers were asked several times to subject their findings to the NTP review process but have NOT responded to the requests.

Now, on to the basics:

All of the approved low-calorie sweeteners have been determined to be safe by the U.S. Food and Drug Administration (FDA), and other scientific and regulatory authorities worldwide. Aspartame has been safely consumed for nearly a quarter of a century, and is one of the most thoroughly studied food ingredients, with more than 200 scientific studies confirming its safety. The studies were conducted in laboratory animals and humans, including healthy infants, children and adults, lactating women, people with diabetes, obese individuals, and people who are carriers of the rare genetic disease phenylketonuria (PKU). In addition to the FDA, the Joint Expert Committee on Food Additives (JECFA) of the World Health Organization and Food and Agriculture Organization, the Scientific Committee on Food of the European Union, and regulatory agencies in 130 countries have reviewed aspartame and found it to be safe for use. Four long-term carcinogenicity studies on aspartame conducted in accordance with international standards have found no relationship between aspartame and any form of cancer. The studies were submitted to numerous regulatory agencies, such as the FDA, which conducted exhaustive reviews of the data. When the FDA approved aspartame, the FDA commissioner noted: "Few compounds have withstood such detailed testing and repeated, close scrutiny, and the process through which aspartame has gone should provide the public with additional confidence of its safety."


Aspartame is composed of two amino acids, aspartic acid and phenylalanine, and methanol as the methyl ester. Amino acids are the building blocks of protein. Aspartic acid and phenylalanine are found naturally in protein containing foods, including meats, grains, and dairy products. Methyl esters are also found naturally in many foods such as fruits and vegetables and their juices. The body handles components from aspartame in the same way it handles them when derived from other foods.

The FDA has determined that the tolerable upper limit for aspartame is 50 mg/kg body weight (for adults). A 12 oz. can of diet soda has ~ 220 mg. When used in moderation (as with all foods) aspartame can be a part of a healthy eating plan.

Resources: Liz Marr, MS, RD
Katherine Holden, MS, RD