A substance made by the body when it uses fat as fuel could provide a new way of treating epilepsy, experts hope.

Researchers in London who have been carrying out preliminary tests of the fatty acid treatment, report their findings in Neuropharmacology journal.

They came up with the idea because of a special diet used by some children with severe, drug resistant epilepsy to help manage their condition.

The ketogenic diet is high in fat and low in carbohydrate.

The high fat, low carbohydrate diet is thought to mimic aspects of starvation by forcing the body to burn fats rather than carbohydrates.

Although often effective, the diet has attracted criticism, as side-effects can be significant and potentially lead to constipation, hypoglycaemia, retarded growth and bone fractures.

By pinpointing fatty acids in the ketogenic diet that are effective in controlling epilepsy, researchers hope they can develop a pill for children and adults that could provide similar epilepsy control without the side-effects.

In early trials, the scientists, from Royal Holloway and University College London, say they have identified fatty acids that look like good candidates for the job.

They found that not only did some of the fatty acids outperform a regular epilepsy medication called valproate in controlling seizures in animals, they also had fewer side-effects.

But many more tests are needed to determine if the treatment would be safe and effective in humans.

Prof. Matthew Walker, from the Institute of Neurology, University College London, said: “Epilepsy affects over 50 million people worldwide and approximately a third of these people have epilepsy that is not adequately controlled by our present treatments.

“This discovery offers a whole new approach to the treatment of drug-resistant epilepsies in children and adults.”

Simon Wigglesworth, deputy chief executive at Epilepsy Action, said: “We know the ketogenic diet can be a highly effective treatment for children with difficult to control epilepsy and it is starting to be used for adults.

“The diet is high in fats and low in carbohydrates and the balance of the diet needs to be carefully worked out for each child. Although some children manage the diet very well, others find the diet unpleasant and difficult to follow. Children can also experience side-effects including constipation and weight loss.

“The identification of these fatty acids is an exciting breakthrough. The research means that children and adults with epilepsy could potentially benefit from the science behind the ketogenic diet without dramatically altering their eating habits or experiencing unpleasant side-effects.

“We look forward to seeing how this research progresses.”