The artificial sweetener aspartame could cause allergic reactions in some people, Food Safety Authority officials have admitted to MPs.

Wellingtonian Abby Cormack, who blames the serious health problems she suffered on her habit of eating four packs a day of sugar-free chewing gum, asked Parliament's health select committee yesterday to recommend banning aspartame.

"I don't believe this should be in the food chains," she told MPs.

The previously fit and healthy 25-year-old said she suffered debilitating physical and psychological symptoms for more than four months this year.

She was tested for diabetes, lupus, multiple sclerosis, electrolyte imbalances and mineral deficiencies before chancing on the link with aspartame on the Internet.

"Within 48 hours of removing aspartame from my diet, my excruciating limb discomfort starting subsiding," she told the committee.

"One change to my lifestyle, and within the following two weeks, every single one of both my physical and psychological symptoms disappeared."

There needed to be more education for doctors on the subject to avoid more misdiagnoses.

"Many people don't know what they are suffering from."

Ten other people gave written testimony to the committee about the effects of aspartame on their health.

Woodrow Monte, formerly director of the nutrition laboratory at Arizona State University, told MPs aspartame was "a proven grade one carcinogen" and there was no safe level of it.

It broke down into methanol, which was metabolised by the body into formaldehyde, he said.

"Why are we allowing multinational companies to give this poison to our children?"

The Food Safety Authority's principal adviser on toxicology, John Reeve, agreed it was not possible to rule out aspartame as the cause of Ms Cormack's symptoms.

"Some people could be more sen-sitive than we would otherwise expect."

It was equally possible, however, that she reacted to other substances she had removed from her diet, such as caffeine, which had a proven effect on the nervous system.

While aspartame was metabolised into methanol, formaldehyde and formic acid, it also occurred naturally in many other foods, including fruit and vegetables, he said.

Consumption many times higher than the authority's standard daily maximum of 40 milligrams of aspartame per kilogram of body weight was likely to be well within safety limits.

Health Ministry spokesman Chris Laurenson said international research showed aspartame was a safe and useful product for those wanting to cut down on sugar.

While the ministry was "not unmoved" by Ms Cormack's description of her ordeal, it could not rely on anecdotal evidence.

There was no scientific evidence to back the claim that aspartame was a carcinogen or neurotoxin.