MAUI, HAWAII – A high-fat ketogenic diet is effective in helping epilepsy patients control their seizures, but it is underused because it is misunderstood, said Dr. Eileen P.G. Vining.
The diet is not difficult. It can be palatable, adaptable, and inexpensive, she explained at a meeting sponsored by the University Childrens Medical Group and the American Academy of Pediatrics.
It has been estimated that the diet is initiated in only about 2,500 patients each year, based on a rough calculation of published data, while approximately 100 million people worldwide have epilepsy, according to the World Health Organization, she said.
The ketogenic diet is a high-fat, low-carbohydrate diet that provides adequate protein (1 g/kg per day), but greatly restricts carbohydrate intake, Dr. Vining said at the meeting, also sponsored by California Chapter 2 of the AAP. The effect of the diet is to mimic ketosis. The ketogenic diet's fat-to-carbohydrate and protein ratio may range from 2:1 (less strict) to 4:1 (very strict), with an average of 3:1. At a 3:1 ratio, fat intake accounts for 80%-90% of calories.
“We know the diet is effective for a wide variety of seizures,” said Dr. Vining, director of the John M. Freeman Pediatric Epilepsy Center at the Johns Hopkins Hospital, Baltimore.
She admitted, however, that “we don't understand the biology of the ketogenic diet.”
About 46% of patients on the diet have greater than 90% control of seizures at 12 months, she said. For those using the diet, medications often can be decreased, although for patients helped by just two or three medications, it may make sense to continue them.
But a study on more “aggressive” discontinuation of medications found good results even within 1 month (Epilepsy Behav. 2004;5:499–502). “There are some 'superresponders' who become seizure free within the first 2 weeks,” added Dr. Vining, who is also professor of neurology and pediatrics at Johns Hopkins University.
The diet emerged in the 1920s, when it was discovered that a person who is fasting becomes ketotic, she explained.
Researchers at the Mayo Clinic developed the idea that changing the nutrient structure of a diet would mimic fasting. By using the ketogenic diet, a person is put in a constant state of ketosis. The diet was popular until phenytoin came on the market and was seen as easier to use than maintaining the diet, she said. But the diet has had a resurgence since the mid-1990s. It is comparable to the popular Atkins diet for weight loss (Epilepsia 2006;47:421–4).
Prior to beginning the diet at Johns Hopkins' clinic, children fast for 24 hours and are seen in the clinic on Monday morning. They are then admitted to the clinic for 4 days (Monday-Thursday), where they are given eggnog to increase the fat in their diet from one-third to two-thirds of the full calories, and finally to a full percentage of calories using regular food. Individual adjustments are made to maintain 80–160 mmol urinary ketosis and to avoid significant weight gain or loss.
Dr. Vining cited several studies in support of the effectiveness of the diet.
A large prospective study that was conducted at Johns Hopkins enrolled 150 children with a mean age of 5.3 years and a mean monthly seizure rate of 410. The children used a mean of 6.2 antiepileptic drugs prior to initiating the diet. At 3 months, 83% remained on the diet, and 34% experienced greater than 90% reduction in seizures. At 12 months, 55% of the children remained on the diet, and 27% had greater than 90% reduction in seizures. The diet appeared to work across a wide spectrum of ages and seizure types.
Another study found that after 1 year of being on the diet, 74% of pediatric patients were able to reduce their medications, with the number on two medications was reduced from 79% to 23%. No medications were needed by 48%. There was a 67% reduction in medication costs, resulting in an average savings of about $1,000 per child per year (J. Child. Neurol. 1999;14:469–71).
A downside to the diet is impaired growth. A study conducted by Dr. Vining of 237 children ranging in age from 2 months to 9 years and 10 months found at 1 year that weight had not substantially increased and linear growth had also been reduced (Dev. Med. Child. Neurol. 2002;44:796–802).
Another study by Dr. Vining and her associates found that use of the diet for as long as 2 years resulted in elevated triglycerides, total cholesterol, and LDL cholesterol levels but no rise in HDL cholesterol levels (JAMA 2003;290:912–20). Also, acidosis is seen routinely.