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Background
It has been known for centuries that fasting can suppress seizure activity in patients with epilepsy.1 In 1921, it was suggested that a ketogenic diet, designed to induce and sustain the metabolic effects of fasting, might have the same beneficial effects.2 This diet, high in fat and low in carbohydrates and proteins, was popular until the introduction of anticonvulsants such as phenytoin.3 In the 1990s, interest in the diet was renewed, following its successful use to treat a child with drug-resistant epilepsy, and the establishment of an awareness raising support group by the father of the child.3
This article provides a brief overview of ketogenic diets and then focuses on the issues relating to the use of medicines in patients on these diets.
When is dietary therapy suitable?
Approximately 25% of children with epilepsy have an inadequate response to antiepileptic drugs.4 Consideration of ketogenic diet use has been recommended under the following circumstances:
In children who have failed 2–3 anticonvulsant therapies, regardless of age and gender, and particularly in those with symptomatic generalised epilepsies (International Ketogenic Diet Study Group (IKDSG), 2008).5
In children and young people with epilepsy whose seizures have not responded to appropriate antiepileptic drugs (AEDs) and who have been referred to a tertiary paediatric epilepsy specialist (National Institute for Health and Care Excellence guidance, 2012).6
Contraindications to the ketogenic diet include pyruvate carboxylase deficiency, β-oxidation defects, primary carnitine deficiency and porphyria.3
What are the different types of ketogenic therapy and how do they differ?
Currently, four types of ketogenic therapy are in use: the classical ketogenic diet, the medium-chain triglyceride (MCT) diet, the modified Atkins diet (MAD) and the low glycaemic index (LGI) treatment. For the classical ketogenic diet, the ratio of fat to carbohydrate and protein ranges from 2:1 to 4:1 and it is predominantly long-chain fat sources that are used. As the name suggests, the …
Footnotes
Contributors RM planned this article and was involved with editing and finalising it. AB performed the literature searches and undertook much of the writing and final editing. HC provided valuable dietetic input.
Competing interests None declared.
Provenance and peer review Commissioned; externally peer reviewed.