The artificial sweetener aspartame has been controversial for decades. The FDA approved it as a replacement for sugar in 1974. However, its public board of inquiry revoked the approval in October 1980, calling for more studies on the compound’s safety. In July 1981, the manufacturer convinced the FDA that aspartame was safe enough to be included in dry foods, and in July 1983, the agency approved it for use in carbonated beverages.
The FDA announced when it approved aspartame,
“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.”
That’s their story and they’re sticking to it.
Just How Safe Is Aspartame?
Over the years, frightening tales of aspartame toxicity have circulated on the Internet.
One reader wrote:
“I know from first-hand experience that there are very serious problems with aspartame. In 1996 I was diagnosed with epilepsy. At that time I was trying to lose weight and eating a lot of products with aspartame.
“I became suspicious and stopped eating aspartame-laced products. Even though my neurologist was skeptical, I was able to discontinue my seizure medicine and have not had further seizures.
Others have blamed aspartame for a wide variety of health problems including headaches, dizziness, confusion, memory loss, depression, blindness, ADD, ALS, lupus and multiple sclerosis.
With dozens of symptoms attributed to aspartame, it is easy to discount the diatribes. We have been skeptical about the more exaggerated claims, especially regarding links to cancer.
Research on Ramazzini Rats Raises Questions:
Research by a European Foundation has forced us to look at aspartame in a new light, however. A study published online in the journal Environmental Health Perspectives (March 2006) involved 1800 rats and 6 dosage levels of aspartame in their chow. Some of the dosage levels were comparable to levels of aspartame in the human diet.
The rats in this study were not sacrificed but lived out their natural lives and were examined upon death. The authors report an excess of leukemias, lymphomas and malignant tumors among rats fed aspartame at several dosage levels.
Critics charge that the researchers did not follow standard protocols for this type of study. The investigators responded, “the findings speak for themselves.” All these years later, there are still important disagreements, as you will learn below.
Boston Scientists Entered the Brawl and Wished They Hadn’t:
The controversy continued, however. More than a decade ago, the public relations people at Brigham and Women’s Hospital, an affiliate of Harvard University, issued an apology. They had put out a news release with the headline “The truth isn’t sweet when it comes to artificial sweeteners.” The PR people didn’t exactly retract their announcement, but they backed away from the attention-grabbing headline and apologized to reporters for wasting their time.
Here is the statement from Erin McDonough, senior vice president of communication and public affairs:
“It has come to our attention that the scientific leaders at Brigham and Women’s Hospital did not have an opportunity, prior to today, to review the findings of the paper entitled “Consumption of Artificial Sweetener and Sugar Containing Soda and the Risk of Lymphoma and Leukemia in Men and Women”, to be published in today’s Journal of Clinical Nutrition. Upon review of the findings, the consensus of our scientific leaders is that the data is weak, and that BWH Media Relations was premature in the promotion of this work. We apologize for the time you have invested in this story.”
This is highly unusual. Was the apology warranted?
Let’s dig a little deeper into this story.
The study was published in The American Journal of Clinical Nutrition, online October 24, 2012. The investigators followed roughly 77,000 women nurses and almost 48,000 male health professionals for many years.
The epidemiologists concluded:
“In the most comprehensive long-term epidemiologic study, to our knowledge, to evaluate the association between aspartame intake and cancer risk in humans, we observed a positive association between diet soda and total aspartame intake and risks of NHL [non-Hodgkin lymphoma] and multiple myeloma in men and leukemia in both men and women.”
One of the co-authors and arguably one of the world’s leading nutrition experts and epidemiologists, Dr. Walter Willett, told NPR, “I do think this finding is strong enough to justify further study on aspartame and cancer risk.”
In fact, the final version of their conclusion (American Journal of Clinical Nutrition, Dec. 2012) is far more cautious:
“Although our findings preserve the possibility of a detrimental effect of a constituent of diet soda, such as aspartame, on select cancers, the inconsistent sex effects and occurrence of an apparent cancer risk in individuals who consume regular soda do not permit the ruling out of chance as an explanation.”
So, to sum up this controversial issue:
1) Long-term rodent research from Italy suggests that aspartame is associated with a range of cancers including lymphomas, leukemias, liver, kidney and lung tumors. Shorter-term studies in the U.S. have not detected such a signal.
2) The longest and largest epidemiological study of aspartame in humans was inconclusive, but it suggested that further human research is needed.
3) The biological plausibility of a carcinogenic effect is described thoughtfully in the article by the Harvard researchers. They point out that aspartame has three breakdown products: phenylalanine, aspartic acid and methanol. Methanol is converted into formaldehyde in the body by an enzyme called ADH (alcohol dehydrogenase). This enzyme is more active in men than in women, which might possibly explain why the researchers found an association between diet soda consumption and a higher risk of lymphoma and multiple myeloma in men but not in women. Formaldehyde is a known carcinogen.
The controversy over this research is still bubbling. Scientists have questioned whether the tumor rates detected in the trials are truly higher than might be considered normal (Critical Reviews in Toxicology, March 2024). Ramazzini Institute lead investigator, Dr. Morando Soffritti, is sticking to earlier conclusions (Expert Review of Anticancer Therapy, Sep. 2024).
He writes:
“These studies have shown that aspartame is a carcinogenic agent in experimental animals, inducing a significant dose-related increased incidence of several types of malignant tumors and, among them, hematological neoplasia, and liver cancer.”
People’s Pharmacy readers have their own experiences with aspartame. One of the most intriguing recently landed in our email inbox.
Does Aspartame Contribute to Erectile Dysfunction?
Q. I have experienced ED problems, even with Viagra. I have long enjoyed diet tonic water containing aspartame sold by one particular company. When it was no longer available, I switched to tonic water containing saccharin instead of aspartame. My erectile dysfunction is no longer a problem. Connection?
A. We could find no scientific studies to confirm an association between aspartame and ED. However, research on mice suggests that aspartame may be harmful for the male reproductive system (Environmental Toxicology, Feb. 2021).
Switching to regular sugar-sweetened beverages is not an appropriate solution, though. We did find a link between sweetened soft drinks and erectile dysfunction (Central European Journal of Urology, Sep. 6, 2011).
