The ketogenic diet is a relatively newly accepted way of treating intractable epilepsy in children. It is a high fat, adequate protein, low carbohydrate diet. Under these dietary conditions, the body is forced to break down fats for energy (rather than burning carbohydrates); among the by-products of this process are chemicals called ketones. High levels of these in the body reduce seizure occurrence, though exactly how this works is not yet understood.

Many of the studies carried out to date on the ketogenic diet involve only small numbers of children, and their results are mixed: some patients do extremely well on the diet, but many patients drop out, as the diet is rigid and hard to stick to. So is it effective or not? One way of finding out is by pooling the data from many trials (using stringent statistical and quality criteria) to see if a clearer picture then emerges. This sort of study is called a meta-analysis.

Dr Beth Henderson and her team at the University of Utah School of Medicine, Salt Lake City in Utah, USA, analysed the data from nineteen studies, which together treated 1084 patients. The average age of children starting the diet was just over five years and nine months. Successful treatment was measured in terms of whether or not the patient achieved a greater than 50% reduction in number of seizures.

Just over half of all patients dropped out of the study they were in before its end. The most common reasons for stopping the diet were not achieving a meaningful reduction in number of seizures (47%), the restrictiveness of the diet (16.4%) and experiencing an illness or side effects of the diet (13.2%). Despite this, patients who stuck to the diet did well, being over twice as likely to have achieved a greater than 50% reduction in seizures compared to those who dropped out. Twenty-four percent of patients who stuck to the diet became seizure-free, and 52% achieved a greater than 90% seizure reduction. Children with generalised seizures benefited more from the diet than children with other types of seizures. Younger children tended to stick to the diet better than did older children (possibly because of parental influence). Doing well on the diet after three months was a good indicator for continued successful treatment.

This study, published in the Journal of Child Neurology, concludes that the ketogenic diet is clearly an effective treatment for paediatric epilepsy with complete seizure control being achieved in some cases. Success appears to depend partly on the type of seizures the child has. The researchers said however that more studies were necessary, particularly to investigate the long-term effects of the diet, why patients drop out, and which seizure types the diet is most effective against.

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