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.
The ketogenic diet in refractory childhood epilepsy.
To report the efficacy and tolerability of the ketogenic diet (KD) in refractory paediatric epilepsy.
                Twenty-six consecutive children were treated with the classical KD from 1996 to 2001. The epilepsy syndromes included symptomatic generalized epilepsy (15), idiopathic generalized epilepsy (4), symptomatic partial epilepsy (1) and unclassified epilepsy (6). One child was lost to follow up.
                Median age at initiation of the KD was 6.1 years. Median duration of the treatment was 9 months. Twelve children (48%) were treated for >12 months; one still remains on the KD. Four children (16%) became seizure-free. Five children (20%) had 50-99% reduction in seizures, seven (28%) had <50% reduction in seizures and eight (36%) had no improvement. Age, seizure-type and aetiology did not predict response. The medications were decreased in 33% of the children. The KD was discontinued in 64% of the children because of poor efficacy and in 12% because of side-effects. Problems during initiation of the KD included asymptomatic hypoglycaemia (24%) and vomiting (12%). Later complications included poor growth (20%), hyperlipidaemia (16%), hypercalcuria (8%), hypocarnitaemia (8%), constipation (8%), pancreatitis (4%) and decreased bone density (4%). There were no deaths. A 3-month trial of the KD costs A3879 dollars. The first 12 months cost A7275 dollars with a cost of A4528 dollars each year, thereafter.
                The KD is an effective treatment for some children with refractory epilepsy, being generally well tolerated and rarely associated with side-effects. Response is not necessarily predicted by age, syndrome or aetiology. A prospective study of the KD is presently underway.