By Laura Dolson | Medically reviewed by Claudia Chaves, MD 
Updated on January 14, 2020

The ketogenic diet for epilepsy (KDE) is a special diet that has helped many children and some adults achieve better (or even full) control of their seizures. It's a first-line treatment for a few specific epilepsy syndromes, such as epilepsy due to mutations in GLUT-1 or pyruvate dehydrogenase deficiency.1

Background

The ketogenic diet for epilepsy was developed in the 1920s by a Michigan doctor named Hugh Conklin. However, once effective medications were developed, the diet was used less and less frequently.2

It has regained recognition and has become a standard backup plan for children whose epilepsy symptoms are difficult to control with medication.1 With more than 470,000 children living with seizure disorders in the United States (according to Centers for Disease Control and Prevention statistics), it's an important addition to the arsenal of treatments for epilepsy.

Researchers are also beginning to see how it might help adults with epilepsy and people with a variety of neurologic disorders.

What It Entails

The ketogenic diet for epilepsy is a very high-fat diet with just enough protein for body maintenance and growth, and very low amounts of carbohydrate.

When fats are broken down for energy, the body goes into what's called a ketogenic state, in which the body generates molecules called ketones. The goal of the KDE is for the brain to use ketones for energy rather than glucose (sugar) as much as possible.

Ketones are (largely) water-soluble, so they are easily transported to the brain. The brain cannot use fatty acids for energy, but it can use ketones for a large portion of its energy requirements.
The KDE is usually begun in a hospital setting and often begins with a one- to two-day fasting period, though there may be a trend away from both of these requirements.3

After determining the proper amount of protein (depending on age, etc.), the diet is structured as a ratio of fat grams to protein grams, plus carb grams. It usually begins with a 4 to 1 ratio and can be fine-tuned from there. The diet is often calorie and fluid-limited.4 Additionally, no packaged low-carb foods (shakes, bars, etc.) are allowed for at least the first month.

Because a gram of fat has more than twice the calories of a gram of protein or carbohydrate, this equation means that at least 75% of the calories in the diet come from fat. This is a very strict diet, and it takes time to learn how to put together meals that fit the formula. All food must be weighed and recorded.

Weaning off the diet is often attempted after two years, though some children are kept on it for longer.1

Why It Works

Researchers are beginning to understand why the ketogenic diet works to lower seizure frequency. According to a 2017 review of studies, it appears that several mechanisms may be at work, including the following.

  • The diet appears to alter ketone metabolism in the brain in a way that enhances the brain's ability to produce the neurotransmitter GABA, which has a calming effect on the brain.1
  • The diet has significant anti-inflammatory and anti-oxidative impacts, which appear to alter the way some genes involved in epilepsy are expressed.
  • Certain fatty acids featured in the diet have anticonvulsant effects and have even been shown to boost the effects of valproic acid—a common anti-seizure medication.
  • Polyunsaturated fatty acids in the diet may prevent brain cells from becoming overexcited.
  • Decanoic acid, which is part of the diet as well, appears to have a direct inhibitory reaction on the AMPA receptors in the brain. These receptors are believed to play a role in epilepsy and are the target of some epilepsy medications.
  • Effects on a key sensor of cellular energy appear to help prevent excessive firing of brain cells.
  • The diet may impact circadian activities and the expression of a growth factor in the brain in a beneficial way.5

Effectiveness

Studies generally show that about a third of children with epilepsy who follow the ketogenic diet will have at least a 90% reduction in seizures, and another third will experience a reduction of between 50% and 90%.

This is remarkable, considering that these patients are generally those whose seizures are not well-controlled with medications.