[The ketogenic diet and its variants: state of the art]

The ketogenic diet is a high-fat, low-protein, low-carbohydrate diet that has been employed as a nonpharmacologic therapy for intractable epilepsy. Several multicenter or randomized studies have demonstrated the anticonvulsive properties of the ketogenic diet. The reports on the clinical efficacy have described a greater than 50% reduction in seizure frequency for about 60% of patients on a ketogenic diet. Efficacy has been reported both for child-teenager and adult patients. Patients who were responders to the ketogenic diet exhibited a decrease in seizure frequency within two months of treatment onset. Underlying mechanisms remain unknown. The current hypotheses are: anticonvulsive properties of ketone bodies, variation in excitatory or inhibitory brain neurotransmissions, modulation of cell excitability or implication of polyunsaturated fatty acids. Ketogenic diet is a fastidious and restrictive therapy. Moreover, side effects have been reported. In order to facilitate patient tolerability and palatability, the diet protocols are gradually modified including changes in ratios of the fat versus non fat components, initiation of the diet with or without fasting, fatty acids composition. A modified Atkins diet seems to be a possible alternative diet with a comparable efficacy on intractable epilepsy. This diet induces ketosis without fluid, calorie or protein restriction, nor the requirement for fasting and food weighing. Furthermore, 10 to 20 grams carbohydrates are allowed per day to increase patient tolerability and palatability. New data suggest that ketogenic diet and its variants should not be considered like a "last chance" treatment.