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 randomized trial of classical and medium-chain triglyceride ketogenic diets in the treatment of childhood epilepsy.
To conduct the first randomized trial on classical and medium-chain triglyceride (MCT) versions of the ketogenic diet, examining efficacy and tolerability after 3, 6, and 12 months.
                One hundred forty-five children with intractable epilepsy were randomized to receive a classical or an MCT diet. Seizure frequency was assessed after 3, 6, and 12 months. Treatment withdrawals were documented. Tolerability was assessed by questionnaire, and blood ketone levels were measured.
                Of the 61 children who started a classical diet and the 64 who started an MCT diet, data from 94 were available for analysis: 45 classical and 49 MCT. After 3, 6, and 12 months there were no statistically significant differences in mean percentage of baseline seizures between the two groups (3 months: classical 66.5%, MCT 68.9%; 6 months: classical 48.5%, MCT 67.6%; 12 months: classical 40.8%, MCT 53.2%; all p > 0.05). There were no significant differences between groups in numbers achieving greater than 50% or 90% seizure reduction. Serum acetoacetate and beta-hydroxybutyrate levels at 3 and 6 months were significantly higher in children on the classical diet (p < 0.01); this was the case at 12 months for acetoacetate. There were no significant differences in tolerability except increased reports in the classical group of lack of energy after 3 months and vomiting after 12 months.
                This study has shown classical and MCT ketogenic diet protocols to be comparable in efficacy and tolerability; both ways of implementing the diet have their place in the treatment of childhood epilepsy.