Larry Taylor's mysterious seizures, hives, headaches and blurred vision eluded medical explanation for nearly three years. He lost his job. He had to quit driving.
In 1986, at his doctor's suggestion, the Arlington, Texas, man stopped drinking his normal six diet soft drinks a day. "From that day forward I never had another visual disturbance, headache, seizure or anything again," he said.
Mr. Taylor blames his problems on aspartame, the decade-old artificial sweetener that Monsanto Co. markets under the brand names NutraSweet and Equal. NutraSweet is the sweetener in the Diet Cokes and Diet Dr Peppers that Mr. Taylor favored.
Mr. Taylor's experience is extreme, but he is not alone in his belief that aspartame can be harmful.
Of the 8,500 food-additive complaints received by the Food and Drug Administration since 1984 when monitoring began, 6,000 have been about aspartame.
Both the FDA and the manufacturer say the complaints are groundless, and even aspartame's worst critics concede that most users seem unaffected by the sweetener.
There are more than 4,000 aspartame-sweetened products, NutraSweet reminds Americans with the $25 million advertising campaign it launched last month in honor of its 10th anniversary.
The FDA describes NutraSweet "as one of the most thoroughly tested and studied additives ever approved." The vast majority of those studies and a 1987 congressional hearing concluded that the sweetener is harmless. And NutraSweet says it has never lost a lawsuit.
"It saddens us to the extent that people who may have legitimate medical concerns may associate their problems with the last thing they drank," said Richard Nelson, a spokesman for NutraSweet.
"We see it as our duty to make sure any questions raised about our safety are answered. That's why we test," Mr. Nelson said. "We feel we go above and beyond what's expected from us."
Dr. Linda Tollefson, who heads the FDA's Adverse Reaction Monitoring System, attributes the large number of complaints to the product's widespread availability. "We don't have any other food additive that's used as much as NutraSweet is," she said.
From sugar-free Certs to Carnation cocoa, Jell-O pudding, Metamucil, Bugs Bunny Children's Chewable Multivitamins and the 2.3 billion cases of diet soft drinks that Americans drink each year, NutraSweet can scarcely be avoided.
Sweetness minus calories has long equaled controversy.
Cyclamate, the artificial sweetener that dominated the diet markets in the 1960s, was banned in 1970 after being linked to tumors.
Saccharin, in use for more than 100 years, began to disappear from grocery stores in 1977, when the FDA linked it to bladder cancer.
Aspartame, approved by the FDA in 1981, came under fire almost immediately. Citing cases like Mr. Taylor's and a number of critical studies, CBS News questioned NutraSweet's safety in a three-part series in January 1984. Many other media reports have followed.
Searle patented its formula in 1970, but the road to FDA approval was a bumpy one. Aspartame was certified in 1974, but production stopped when complaints of sloppy research prompted an investigation into Searle's testing procedures.
In 1980, a scientific board selected by the FDA, NutraSweet and concerned consumer groups recommended that aspartame should not be approved without more research. The board feared the sweetener might cause brain tumors.
Nine months later, discounting the board's recommendation, then-FDA Commissioner Arthur Hull Hayes Jr. approved the use of aspartame in dry foods and as a granulated table-top sweetener. Approval of aspartame in carbonated beverages followed in July 1983.
Hundreds of aspartame studies have been performed. Dave Hattan, the FDA scientist charged with keeping track of them, has three 2-inch-thick volumes of studies from last year alone. An estimated 95 percent say NutraSweet is safe.
"Everyone says that's because they're funded by NutraSweet," bTC Dr. Tollefson said. "I sympathize with that, but nobody else out there has an interest in doing those multimillion-dollar studies."
All companies are required to pay for testing to prove their product's safety to the FDA.
"That's the Catch-22," said NutraSweet scientist Harriett Butchko. "We're damned if we do test, and damned if we don't."
Horror stories continue. Aspartame seems a particularly popular topic for aviation magazines.
Charles King, a part-time pilot who owns a grocery store in Brownwood, Texas, was enthusiastic about NutraSweet and Equal from the start. He drank about 10 aspartame-sweetened drinks a day. He began to feel their effect within months, he said.
"Earlier in my life, I would get out of bed at 6 a.m. and go flying before work," he said. "All of a sudden, I couldn't even get out of bed to fly the plane I'd spent three years of my life building. That's when I knew something was really wrong."
Mr. King said he began suffering headaches, muscle twitches and mental confusion. He had to give up precision flying.
When Mr. King suffered a seizure in 1986, he was restricted to flying only with another certified pilot. That same year, after watching a TV report on NutraSweet research, he quit using aspartame.
"Within a few months, I was getting back to normal," he said. "I just couldn't believe that this product that I thought was the greatest could have taken my flying away."