One of the most effective therapies for intractable seizures in children is the ketogenic diet. Introduced by Wilder in 1921, this diet has been shown to decrease the number and severity of seizures for more than two-thirds of children who have tried it. The diet consists of approximately 70% to 90% of energy from fat, with the remaining energy from protein and carbohydrate. There are two main types of the diet. The first is the classic ketogenic diet that produces ketosis by limiting intake of carbohydrate and protein to less than 10% of energy combined. The second type is a medium chain triglyceride diet (MCT), which uses medium-chain triglyceride fat to produce ketosis. The MCT diet allows for a greater percentage of intake from carbohydrate and protein (approximately 29% combined). While the benefits of the diet have been well established, little is known about the nutritional risks of the diet and potential impact upon growth.

The objective of a recent study was to use a prospective, nonrandomized study design to assess growth velocity and potential nutritional risks for children on both types of ketogenic diets. Admission criteria for the study included age between 1 and 16 years and at minimum two unsuccessful trials with different anticonvulsant medications. The subjects were assigned to one of the two diets based upon their individual and family preferences, the family’s financial situation, and the medical team’s assessment of which diet would likely achieve greater compliance and tolerance.

Sixteen subjects were placed into the classic ketogenic diet and 14 in the MCT ketogenic diet. Before starting either diet, the children fasted until their urine becomes strongly saturated with ketones. The children’s diets were supplemented with sugar-free multivitamin and mineral preparations, calcium tablets with magnesium and zinc, and iron tablets or liquid iron. The initial energy prescription was estimated to be 75% of estimated total energy expenditure from basal energy expenditure calculation plus an activity factor. Protein requirements were figured at 1 gm/kg body weight per day.