Like cyclamate, aspartame was discovered accidentally - in 1965 during
research for ulcer drugs. Aspartame has been described by FDA and its
manufacturer, G.D. Searle & Co., of Skokie, Ill., as one of the most
thoroughly tested and studied additives ever approved by the agency.
Searle first sought FDA approval of aspartame in dry foods and as a table-top
sweetener in March 1973. FDA approved that petition in July 1974, but challenges
over the substance's safety and the validity of the company's data kept
aspartame from being marketed. To resolve the safety issues, the contesting
parties agreed to put the matter in the hands of a scientific board of inquiry.
Before the board could meet, however, FDA had to resolve the challenge to the
validity of various studies conducted for Searle. Their validity was affirmed by
an outside panel of pathologists in a December 1978 report to FDA.
The board of inquiry held its hearings in early 1980. In a report to FDA the
following October, the board concluded that the evidence did not support charges
that aspartame consumption posed an increased risk of brain damage that could
result in mental retardation or endocrine dysfunction. However, the board did
recommend that aspartame's approval be withheld until more long-term animal
tests were conducted on the possibility that aspartame might cause brain tumors.
With that, final action on the Searle petition rested with then FDA
commissioner Arthur Hull Hayes Jr. On July 24, 1981, Hayes approved the use of
aspartame in dry foods. Stating that Searle had "met its burden of proving that
aspartame is safe," as required by law, Hayes said that aspartame consumption at
even the "maximum projected" levels of daily consumption would "not pose a risk
of brain damage resulting in mental retardation, endocrine dysfunction, or
both." Hayes also noted that both he and the FDA's Center for Food Safety and
Applied Nutrition disagreed with the inquiry board's recommendation for further
safety studies on the risk of brain tumors. In effect, Hayes ruled that both he
and the center's food experts were satisfied that the data submitted
demonstrated the safety of aspartame on that issue, as well. To ensure that
public consumption levels of aspartame products remained below what might be
considered toxic to humans, the decision required Searle to monitor and report
consumption levels to FDA.
Approval of aspartame for use in carbonated beverages followed in July 1983.
The following December it also was proposed as an "inactive ingredient" in human
drug products. FDA currently is reviewing petitions for other food uses for
Foods and beverages containing aspartame are required by FDA to include a
warning to individuals suffering from a rare genetic disease called
phenylketonuria (PKU). The warning notes that phenylalanine, an amino acid whose
intake must be restricted by PKU victims, is present in the product.
Phenylalanine is an essential nutrient for humans. However, when it increases to
very high levels in body fluids, those who cannot metabolize it normally can
suffer brain damage and mental retardation. Those most susceptible to brain
damage from PKU are infants, and all states require newborn children to be
screened for the disease. A person not born with PKU does not develop it later.
Following the 1983 approval for carbonated beverage use, some scientists and
consumer groups charged that aspartame was a health hazard because it broke down
and exposed consumers to excessive levels of methanol. At high enough levels,
methanol is a poison and can cause blindness. It also is metabolized into
formaldehyde, a "known carcinogen," the critics charged. (Some inhalation tests
in animals show that formaldehyde produces nasal tumors.)
The critics maintained that decomposition of aspartame could occur - and
expose consumers to possibly high levels of methanol and formaldehyde - if a
beverage containing the sweetener was stored for long periods at high
temperatures. FDA evaluated the charges and concluded "that the levels of
methanol resulting from the use of aspartame in carbonated beverages did not
pose any safety issues because they were well below levels of exposure expected
to produce toxicity." It was also noted that other foods - including juices,
fruits and vegetables - exposed consumers to higher amounts of methanol without
Aspartame's widely publicized approval for use in carbonated drinks also was
accompanied by an increasing number of complaints from consumers about
headaches, dizziness and a wide variety of other symptoms they attributed to
consuming aspartame-containing products.
In February of 1984, FDA asked the Centers for Disease Control in Atlanta to
evaluate the consumer complaints received by the agency, Searle and others. FDA
furnished CDC with the results of interviews conducted by its investigators with
517 of the 592 people who had reported complaints up to mid-April 1984.
After evaluating the complaints, CDC reported in November of 1984 that,
although some individuals may have an "unusual sensitivity" to aspartame
products, the data obtained "do not provide evidence for the existence of
serious, widespread, adverse health consequences attendant to the use of
aspartame." Although a wide variety of symptoms were reported, CDC said most
were mild and the kind that would be "common to the general populace." Few
complainants, the report said, went to a doctor with their symptoms.
CDC noted that investigations of this type are "unlikely to establish any
cause-and-effect relationship" between the consumption of aspartame and the
occurrence of symptoms. It acknowledged that some segments of the population
might be sensitive to the sweetener but this could only be clearly established
with additional clinical studies.