There is "no credible evidence" that the artificial sweetener aspartame fuels cancer, triggers behaviour problems or causes any other serious illnesses in humans, according to a study released this week.
The new research, carried out by experts from 10 universities around the world, is based on a review of more than 500 scientific papers dating as far back as the 1970s.
"This is as well studied as you are ever going to get for a compound. And there is no evidence there are any safety issues," said the lead scientist, Bernadene Magnuson of the University of Maryland.
The study was financed by Ajinomoto Co. Inc., a maker of aspartame, in part because the low-calorie sweetener has been dogged by controversy for many years.
Despite the industry funding, Prof. Magnuson said "we had a complete free hand to come up with our results." The panel's findings were published in the journal Critical Reviews in Toxicology.
But a consumer organization, Center for Science in the Public Interest, was quick to denounce the study. Michael Jacobson, executive director of the advocacy group, accused the scientists of playing down studies that found problems with aspartame.
"I disagree with his assessment," said Prof. Magnuson. "We seriously looked at all studies with equal weight." She added that studies that cast a cloud over aspartame were "methodologically flawed." For instance, some studies added pure aspartame directly to cell cultures. She said that would not happen in real life because aspartame is partly broken down in the stomach. "Aspartame never actually enters the body as a complete compound."
However, there was one potential side effect the experts could not rule out completely - headaches. "Some people do appear to feel they have a headache" when they consume aspartame, said Prof. Magnuson. "If that is their true feeling and belief ... I cannot prove them wrong."