May 2 (HealthDay News) -- The "ketogenic" diet, which features high levels of fat, low levels of carbohydrates and controlled protein intake, helps control and prevent seizures in children with drug-resistant epilepsy, a new study finds.

The trial is the first randomized controlled study to confirm that the ketogenic diet -- widely used since the 1920s -- is effective against epilepsy, the British researchers said.

Experts believe that the regimen's high fat and restricted carbohydrate content mimics the biochemical response to starvation, when compounds called ketone bodies (rather than sugar) provide the main source of energy for the brain.

Ketone bodies are byproducts produced when fatty acids are broken down for energy in the liver and kidneys. They are used as energy sources in the heart and brain. In the brain, ketone bodies are a crucial source of energy when a person fasts.

This University College London study included 145 children, aged 2 to 16, who suffered seizures at least once a day or more than seven seizures per week. These patients hadn't responded to treatment with at least two epileptic drugs, and hadn't previously been placed on the ketogenic diet.

Baseline information about the children's seizures was first recorded. Seventy-three of the children started the ketogenic diet immediately, while the other 72 started it after a three-month delay. The delay group acted as a control group during the study. Complete data was obtained from 54 children in the diet group and 49 children in the control group.

The overall number of seizures in the diet group declined by more than 38 percent, while seizures in the control group increased by 36.9 percent, the researchers report. The study found that 28 of the 54 children who completed three months in the diet group had a greater than 50 percent reduction in seizures, compared to four of 49 children in the control group. Five children in the diet group had more than 90 percent fewer seizures. None of the children in the control group experienced that kind of improvement.

The study appears in the current online edition of The Lancet Neurology and will appear in the June print issue.

"We have shown that the diet has efficacy and should be included in the management of children who have drug-resistant epilepsy. However, the diet is not without possible side effects, which should be considered alongside the risk-benefit of other treatments when planning the management of such children," the study authors wrote.

More information is needed about the long-term effects of the ketogenic diet, such as changes in blood fat concentrations and ketosis, Dr. Max Wiznitzer, of Rainbow Babies and Children's Hospital in Cleveland, wrote in an accompanying comment article.

"Better identification of epilepsies that benefit from starting early on the ketogenic diet and comparisons between the choices of ketogenic diet are needed," he wrote.

SOURCE: The Lancet Neurology, news release, May 2, 2008