Our review update included data from four new randomised studies of the ketogenic diet. Although none were blinded, some were of good quality. These studies suggest that in children, the ketogenic diet results in short to medium term benefits in seizure control, the effects of which are comparable to modern antiepileptic drugs. However, one study of long term outcome reports a high attrition rate for the diet. This would suggest that many children find the diet difficult to tolerate. The main reasons for drop-outs in the included studies included gastrointestinal side effects and dislike for the diet.
We found just three studies on the use of the diet in adults and none of these were randomised. There has been less research involving other diets. We found one randomised study of reasonable quality of the Atkins diet. This study showed similar benefits in seizure control with a less restrictive diet.
For those with medically intractable epilepsy or those in whom surgery is unsuitable, a ketogenic diet could improve seizure control, but tolerability is poor. One observational study suggested that the Atkins diet may have a similar effect on seizure control, but this requires more investigation.
A multicenter study of the efficacy of the ketogenic diet.
To determine the efficacy of the ketogenic diet in multiple centers.
                A prospective study of the change in frequency of seizures in 51 children with intractable seizures who were treated with the ketogenic diet.
                Patients were enrolled from the clinical practices of 7 sites. The diet was initiated in-hospital and the patients were followed up for at least 6 months.
                Fifty-one children, aged 1 to 8 years, with more than 10 seizures per week, whose electroencephalogram showed generalized epileptiform abnormalities or multifocal spikes, and who had failed results when taking at least 2 appropriate anti-epileptic drugs.
                The children were hospitalized, fasted, and a 4:1 ketogenic diet was initiated and maintained.
                Frequency of seizures was documented from parental calendars and efficacy was compared with prediet baseline after 3, 6, and 12 months. The children were categorized as free of seizures, greater than 90% reduction, 50% to 90% reduction, or lower than 50% reduction in frequency of seizures.
                Eighty-eight percent of all children initiating the diet remained on it at 3 months, 69% remained on it at 6 months, and 47% remained on it at 1 year. Three months after initiating the diet, frequency of seizures was decreased to greater than 50% in 54%. At 6 months, 28 (55%) of the 51 initiating the diet had at least a 50% decrease from baseline, and at 1 year, 40% of those starting the diet had a greater than 50% decrease in seizures. Five patients (10%) were free of seizures at 1 year. Age, sex, principal seizure type, and electroencephalogram were not statistically related to outcome.
                The ketogenic diet is effective in substantially decreasing difficult-to-control seizures and can successfully be administered in a wide variety of settings.