'Yes, Aspartame Is a Carcinogen'
The Italian scientist Morando
Soffritti has revived the debate about the safety
of aspartame, an artificial sweetener used in many
popular products, including diet softdrinks made
by Coca-Cola and Pepsi Co. After studying 1,800
rats over eight years, his research team concluded
that aspartame could have carcinogenic effects.
The results, first released in July 2005 and published
in March in the U.S. Department of Health's journal,
"Environmental Health Perspectives", contradict
other studies financed by the company that created
the sweetner, G.D. Searle & Company, which assures
aspartame poses no risks to human health.
For the past 25 years, the product has been authorised
by the U.S. Food and Drug Administration (FDA) for
The sale of aspartame, with only four calories per
gram and 200 times sweeter than sugar, is sold under
the trademarks NutraSweet and Equal, bringing in
570 million dollars a year. It is estimated that
some 350 million people around the world, many in
hopes of losing weight, consume aspartame daily
through 6,000 kinds of foods and beverages. In Europe
alone, 2,000 tonnes of the sweetener are sold annually.
Soffritti's investigation was conducted at the Cesare
Maltoni Cancer Research Centre, of the European
Ramazzini Foundation in Bologna, which he heads.
This institution, founded in 1971, won international
credibility when it uncovered the cancer-causing
properties of the gasoline additive MTBE (methyl
tertiary butyl ether), which led to its ban in 21
Tierramérica spoke with Soffritti in Italy. Following
are excerpts from that dialogue:
Q: What are the results of your investigations conducted
between 1997 and 2005 about the effect of aspartame?
A: The results indicate that aspartame is a multi-potential
carcinogen, even consumed daily at 20 milligrams
per kilogram of body weight. That is a lower quantity
than the maximum recommended by the FDA (50 mg/kg
of body weight) and the European Union (40 mg/kg).
Q: What kind of cancer does it produce?
A: Our study showed for the first time that aspartame
increases the incidence of malignant tumours in
rats. In the females it increases leukaemia and
lymphomas, as well as cancerous cells in the pelvis
and urethra. In the males, it especially increases
the incidence of malignant tumours in peripheral
Q: How many rats were studied and what method was
A: We studied 1,800 rats (Sprague-Dawley) that were
raised for this purpose. We gave them, by groups,
doses similar to those ingested daily by people,
of 5,000, 2,500, 500, 100, 20, 4 or 0 mg/kg of body
weight. Aspartame was added to the standard diet
(seven doses in the food).
The experiment began when the animals were eight
months old and lasted until their natural death,
at 159 weeks. When the rats died we conducted histopathological
studies of their organs and tissues. We analysed
more than 30,000 samples.
Q: Can it be assumed that what happened in the rats
could also happen in human beings?
A: According to an investigation of cancer by the
World Heath Organisation, the experimental study
of carcinogenic agents in rats is very important
for humans. One-third of the cancer-causing agents
in man have been discovered with experiments conducted
Q: Aspartame is sold mainly as a means for people
to control their weight. In your experiment, did
the animals lose weight?
A: No. We saw that those consuming aspartame ate
less, but their body weight remained the same. We
don't have an explanation for that, not in our field.
Q: Aspartame is also consumed by children and by
pregnant women. What effects could it have on them?
A: The study of the doses correlated between the
milligrams that were consumed and body weight. This
tells us that the carcinogenic effect in children
could be greater (because of their lower weight).
The carcinogenic agents have a stronger effect on
the embryo, which is why pregnant women are at greater
Q: Are people who consume aspartame condemned to
A: Cancer is related to many factors and to genetics.
We can't say that a consumer of aspartame will develop
cancer. There are people who smoke cigarettes their
entire lives and never develop lung cancer.
Q: There are several studies that assure aspartame
is harmless to human health. What is the difference
between those and the study that you led?
A: First, those studies about the cancerous effect
in rats and mice were done in the 1970s, before
the commercialisation of aspartame began, and were
paid for by the companies that produced [the sweetener].
The results of those studies did not show that aspartame
was carcinogenic. But some members of the scientific
community doubt the quality of of those experiments
because some animals that consumed aspartame presented
with brain tumours, while the control animals didn't
have any problems.
Second, those studies utilised fewer animals (280
and 688 rats) and were not conducted according to
the standards of "Good Laboratory Practices", so
one cannot conclude with certainty that aspartame
is not a carcinogen. Our research centre is independent.
It doesn't receive any financing from the industry
producing the product.
Q: Are new scientific studies about the potential
cancer-causing effects of aspartame necessary?
A: Yes, more studies are needed in order to obtain
greater precision in quantifying the risk. The current
results already demand -- by the competent bodies
-- an urgent review of the norms regulating the
use and consumption of aspartame in order to protect
public health, especially children's health.
Q: Your study is being reviewed by the European
Commission's Food Safety Authority, which will issue
a statement in May. Do you think it will validate
your study, and do you think government agencies
in Europe and elsewhere should ban aspartame?
A: I hope they revise their current regulations.