Aspartame is widely used in many food products
Scientists are to assess whether the artificial sweetener aspartame causes health problems in people unusually sensitive to it.
Expert advice is that aspartame - found in more than 4,000 products - is safe to consume.
However, a number of people have reported sensitivity to the product including headaches, dizziness, vomiting, diarrhoea and fatigue.
The University of Hull study is funded by the Food Standards Agency (FSA).
Aspartame, 150 times sweeter than sugar, is found in products such as diet soft drinks, cereal bars, yogurts and chewing gum.
There have long been concerns that the sweetener is linked to a raft of health problems, including a greater risk of cancer, fertility issues, nausea, double vision and an effect on appetite.
However, after reviewing the available scientific literature, both the FSA and the European Food Safety Authority decided there was no firm evidence of any impact on health, and ruled that aspartame was safe to consume.
Professor Stephen Atkin, who will lead the new research, said: "This study is not to determine whether aspartame can be consumed safely; this has already been established, but rather to see whether certain people are sensitive to it."
The Hull team hope their work will lead to a larger international study to pin down the issue once and for all.
Professor Atkin also hopes to secure funding to analyse the chemical breakdown of aspartame in the body.
The sweetener can be broken down to produce methanol and formaldehyde, both of which have been previously linked to cancer.
However, it is not clear whether this process takes place in the body, or, if it does, whether the metabolites are absorbed into the blood in sufficient quantity to produce any biological effect.
Andrew Wadge, Chief Scientist at the Food Standards Agency said: "The study will address consumer concerns, including anecdotal reports that have linked a range of conditions to aspartame.
'The Agency's view remains that aspartame can be consumed safely and we are not recommending any changes to its current use.
"However, we know that some people consider that they react badly to consuming this sweetener so we think it is important to increase our knowledge about what is happening."
One hundred people will take part in the Hull study, half of who have complained of side effects from aspartame.
The study is expected to take 18 months.
At present the Acceptable Daily Intake (ADI) for aspartame is set by the European Commission's Scientific Committee on Food (SCF) at 40 milligrams per kilogram of body weight.
An adult would have to drink about 14 cans a day of diet soft drink, or consume about 80 sachets of sweetener to reach this amount.