by Elaine Wirrell, MD

The ketogenic diet can be a highly effective therapy for epilepsy. On the ketogenic diet, the body burns fats rather than sugar, which results in the production of ketones.

In the early 20th century, reports emerged that described fasting as a seizure treatment for some children. While fasting controlled seizures in many cases, prolonged fasting was clearly not a viable long-term solution. In 1925, Dr. Peterman at the Mayo Clinic reported on the successful use of a “ketogenic diet,” which was designed to mimic the fasting state and provide adequate calories for growth and development. The ketogenic diet was used in only a few centers over most of the 20th century. However, in the last two decades, there has been a marked resurgence of interest in its use. The ketogenic diet is now available in most epilepsy centers. (See the list of centers at www.charliefoundation.org.)

Who Can Be Treated?

The ketogenic diet is used most often in children with epileptic encephalopathies such as Lennox-Gastaut syndrome, Dravet syndrome, Myoclonic-Atonic Epilepsy of Doose and West syndrome. These particular syndromes often result intractable seizures (seizures poorly responsive to currently available antiepileptic medications) and cognitive delays in the child. In the past, the ketogenic diet has been used only after several anti-epileptic medications have failed to control seizures. However, given its success in these syndromes, early use (possibly even first-line therapy) should be strongly considered.

The ketogenic diet is also the only proven effective therapy in patients with glucose transporter type 1 deficiency, a disorder classically resulting in intractable seizures, movement disorders and cognitive delay due to inability to transport glucose from the blood to the brain. The ketogenic diet may also be beneficial in cases of focal epilepsy although is less likely to result in effective seizure control than is epilepsy surgery, for those who are candidates for surgical resection.

While traditionally used predominantly in young children, recent findings suggest the ketogenic diet can be effective in adolescents and adults as well.

What Forms of Ketogenic Diet Exist?

1. Traditional ketogenic diet: This form of the diet is carefully calculated to provide a precise ratio of fat, carbohydrate and protein. The ketogenic ratio refers to the grams of fat divided by the grams of protein and carbohydrate combined. Typical ratios range from 2.5 to 4.0. Specific meal plans are obtained from a dietician, and all ingredients must be weighed and measured. The patient needs to finish every morsel of the meal to maintain the proper ratio. The traditional ketogenic diet is the most time-consuming to prepare. However, it is generally easier to maximize ketosis using this form of the diet, as the dietician knows precisely how much of each food is being given.
2. Modified Atkins diet: This form of the diet requires counting carbohydrates, but provides only rough guidance regarding the amounts of fat and protein. As such, meal preparation is less time-intensive. Additionally, the portion size can be adjusted for appetite changes. While the dietician provides guidance to the family, there are no specific meal plans, resulting in a bit more “guess work” at the beginning until the family becomes accustomed to the diet. This form of the diet may be more palatable and tolerable at the onset, as it contains less fat than the traditional form of the diet.
3. Low-Glycemic Index diet: This form of the diet is based on the South Beach diet. Total carbohydrates are limited, but to a lesser degree than the Modified Atkins diet. Only carbohydrates with a low glycemic index (those which are broken down very slowly to glucose) are allowed. Similar to the Modified Atkins diet, no specific meal plans are given to the family. Since this diet is less restrictive, it may be more palatable to teens and adults.

All forms of the ketogenic diet require supplementation with calcium and vitamins. For patients who are tube-fed, specific ketogenic formulas exist that make administration very easy.

How Successful Is It?

Approximately half of children experience a greater than 50% reduction in total seizures, and between 10-15% will become seizure-free. Seizure freedom is most commonly obtained in children with specific forms of epileptic encephalopathy such as Myoclonic-Atonic Epilepsy of Doose and West syndrome.

The less stringent forms of the diet (Modified Atkins and Low-Glycemic Index) may be as effective as the traditional diet in many cases. However, some children will achieve better response with the traditional form of the diet, which results in higher ketosis.

How Does It Work?

The exact mechanism by which the ketogenic diet works to control seizures is not understood. Research is ongoing in this area. It is possible that ketones may have direct antiepileptic activity or may act to stabilize the membranes of brain neurons. Also, certain types of fatty acids (polyunsaturated fatty acids) may have antiepileptic activity.

What Are The Side Effects?

Acute:

• Hypoglycemia
• Nausea and vomiting
• Excessive ketosis and acidosis
• Lethargy
• Worsening of rare metabolic disorders (all children starting on the diet should be screened for these disorders with blood and urine tests before starting on the diet)

Chronic:

• Constipation
• Kidney stones
• Cardiomyopathy
• High cholesterol levels
• Slower growth
• Vitamin or calcium deficiencies if not properly supplemented

Chronic side effects are usually manageable without needing to stop the diet. Most centers advocate regular urine and blood monitoring of the diet to screen for these problems. Side effects may be less problematic with the less stringent forms of the diet.

How is the Ketogenic Diet Started?

The method used to start the ketogenic diet varies by epilepsy center. Younger children are more commonly hospitalized to start the traditional form of the ketogenic diet, whereas older children and adults may be started gradually at home. If the traditional diet is started at home, careful monitoring for vomiting or food refusal is needed.

The Modified Atkins and Low Glycemic Index diet are started at home, without the need for hospitalization.

Medications, Lotions and Products

Most medication formulations for children contain large amounts of sugar, and cannot be used on the ketogenic diet. As a general rule, suspensions or chew tablets are contraindicated. Lotions, such as moisturizers and sunscreens, as well as certain toothpastes can also contain sugar and will prevent ketosis from being achieved. Ketogenic-friendly products should be used whenever possible. (See the list of products at www.charliefoundation.org.)

How long is it continued?

Initiating the diet generally lasts a minimum of one month to determine if it will be effective in reducing seizures. If no improvement is seen in seizure control at that time despite achieving good ketosis (moderate or high levels in the urine), continuing the ketogenic diet is unlikely to be beneficial.

If the diet is effective in improving seizure control, it is usually continued for a minimum of two years and then gradually weaned. Some patients are treated for substantially longer periods of time.

If the diet is effective, medications can often be weaned slowly. While most patients remain on a combination of medication and the diet, some children achieve excellent seizure control on the diet alone.

Further references:

www.charliefoundation.org

www.matthewsfriends.org

Elaine Wirrell, M.D.
Mayo Clinic
Last Reviewed: 5/15/11

Article from the May 2011 Epilepsy.com Spotlight Newsletter. Other articles in this issue inclue:

• On My Mind: What is Juvenile Myoclonic Epilepsy?
• What Happens When You Don't Take Your Medication in Children with Newly Diagnosed Epilepsy
• Long-term IQ Outcome after Temporal Lobe Surgery in Childhood
• Folic Acid Supplementation Prevents Phenytoin-induced Gingival Overgrowth in Children
• Seizures: The Next Level of Care: The Comprehensive Epilepsy Center
• Epilepsy Medication Mebaral to be Discontinued