Background The ketogenic diet, being high in fat and low in carbohydrates, has been suggested to reduce seizure frequency. It is currently used mainly for children who continue to have seizures despite treatment with antiepileptic drugs. Recently there has been interest in less restrictive ketogenic diets including the Atkins diet and the use of these diets has extended into adult practice. Objectives To review the evidence from randomised controlled trials regarding the effects of ketogenic and similar diets. Search methods We searched the Cochrane Epilepsy Group's Specialised Register (June 2011), the Cochrane Central Register of Controlled Trials (CENTRAL 2011, Issue 2 of 4), MEDLINE ( 1948 to May week 4, 2011) and EMBASE (1980 to March 2003). No language restrictions were imposed. We checked the reference lists of retrieved studies for additional reports of relevant studies. Selection criteria Studies of ketogenic diets and similar diets for people with epilepsy. Data collection and analysis Three review authors independently applied pre-defined criteria to extract data and also assessed study quality. Main results We identified four randomised controlled trials which generated five publications. These included Kossoff 2007, Bergqvist 2005, Seo 2007, Neal 2008 and Neal 2009. All trials applied the intention-to-treat analysis with varied randomisation method. The four studies recruited a total of 289 children and adolescents and no adults. Meta-analysis could not be conducted due to heterogeneity of the studies. Seven prospective studies and four retrospective studies were also identified. Authors' conclusions 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.
