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Researchers Differ Over Long-Range Effects of Sweetener

November 03, 1988|ROSE DOSTI | Times Staff Writer

NutraSweet--the trade name for aspartame, an artificial sweetener packaged under the name Equal--has recently been approved for use in six additional categories including frozen desserts, flavored milk beverages, fruit wine beverages and yogurt products, joining the 1,200 products already using aspartame.

Despite widespread use of aspartame, controversy over its safety has left a murky residue that may take time to settle, if at all.

"Aspartame took 17 years to petition successfully (for home use) to the Food and Drug Administration, and it is one of the most thoroughly tested food substances on the market, with more than 100 tests done to assure its safety," said Janet Klich, media representative for NutraSweet Center in Illinois. "We've even gotten a clean bill of health after we subjected anecdotal criticisms to scientific scrutiny."

Aspartame, the methyl ester of the amino acids phenylalanine and aspartic acid, is about 180 times sweeter than sugar. Because only a small amount of aspartame is required to provide the sweet taste of sugar, it has been used to successfully mimic the taste of sugar in numerous products while substantially lowering the caloric content of these products.

However, some of the major safety concerns voiced about aspartame in the past are still stirring. These concerns center on several health risks, primarily the inability of certain adults and children with phenylketonuria (PKU) to metabolize phenylalanine correctly, thus causing a brain dysfunction resulting in epileptic seizures and risks of retardation to offspring.

The potential for the phenylalanine component in NutraSweet to affect brain function has, according to the NutraSweet Co., been "thoroughly examined by medical and regulatory authorities in the United States and Europe."

But Dr. Richard Wurtman, mood and behavior specialist at the Massachusetts Institute of Technology, questions the FDA's wisdom in approving the sweetener in the preface to the recently published "Dietary Phenylalanine and Brain Function," edited by Wurtman and Eva Ritter-Walker (Birkhauser). In it he describes that sweetener as one that "beside being neurotoxic in high concentrations, can, in concentrations much lower than those associated with clinical PKU, affect production of neurotransmitters and thereby modify any of the numerous brain functions that depend on these compounds."

In the same publication, which contains manuscripts and papers presented at a conference on dietary phenylalanine and brain function in Washington in May, 1987, Louis Elsas of Atlanta's Emory University reported on aspartame-controlled studies on human volunteers showing changes in brain wave function. The scientific findings reported in the book include further evidence of epileptic seizures and brain damage in rats, human metabolic and electrophysiological changes as well as other studies showing no evidence of damage following ingestion of aspartame and phenylalanine.

In a letter to the editors of the New England Journal of Medicine (Volume 318, No. 19, 1988), Elsas called for a "more unbiased peer review of clinical research protocols, claiming that the NutraSweet Co., which supported this experimental design (showing that aspartame was safe), may have had an interest in protocols that would find that their product had no untoward effects."

According to Klich, there is a blood-to-brain selective barrier for substances entering the brain. "The likelihood of phenylalanine levels rising is not likely and has not been seen in studies," she said.

William M. Pardridge MD, of the UCLA School of Medicine, described in a letter to the editor of the Journal of American Medical Assn. (Nov. 21, 1986) how easy it is for children in particular to consume dangerous amounts of aspartame. Because of their lower body weight, children consuming adult-size quantities of the sweetener achieve far higher blood concentrations. In fact, as few as five servings of products containing NutraSweet can impair brain function in a 50-pound child, according to Pardridge.

Pardridge holds to the theory to this day. "That's still my theoretical argument based on basic research on animals," he said.

The Centers for Disease Control evaluated consumer reports on various symptoms, including seizures, and concluded that NutraSweet "was unlikely to act as a trigger for seizure activity," but they could not rule out the possibility of a relationship.

The FDA relied on CDC reports and said that they interviewed hundreds of individuals with PKU reactions before approving use of aspartame for general consumption. According to Gordon Scott, media spokesperson for the FDA in Los Angeles, persons with PKU (a disease diagonsed in infancy) "must markedly reduce consumption of protein foods containing phyenalaline." For this reason products containing asparatame must by law be labeled with the warning, "Phenylketonurics: Contains Phenylaline."

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