The ketogenic diet is a special high-fat, adequate protein, low-carbohydrate diet that is primarily used in medicine to treat difficult-to-control, or refractory, epilepsy in children. Heavy cream, butter and vegetable oils provide the necessary fat and the diet eliminates sweets such as candies and cookies. Other foods rich in carbohydrates such as bread, potatoes, rice, cereals and pasta are not allowed on the strictest form of the diet, but are allowed in small amounts on more liberal forms of the diet. All foods must be carefully prepared and weighed on a precise food scale and each meal must be eaten in its entirety for the diet to be most effective.
No one is certain how the diet works, but some children do become seizure-free when put on the diet. However, the diet does not work for everyone and there is no way to predict whether it will be successful. In every decade since the 1920s, studies consistently show that 50 to 75 percent of children with difficult to control seizures of all types are helped by the diet.
The diet forces the body to burn fats rather than carbohydrates for energy. Normally, the carbohydrates contained in food are converted into glucose, which is then transported throughout the body and is particularly important in providing energy for brain function. However, if there is very little carbohydrates in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as the energy source. An elevated level of ketone bodies in the blood, a state known as ketosis, leads to a reduction in the frequency of epileptic seizures.
Starting the ketogenic diet
If your child's doctor determines your child is a good candidate for the diet, it is started under close medical supervision. Blood tests may first be completed to help determine if the diet is safe for your child. These include metabolic tests to rule out fatty acid disorders or a carnitine deficiency.
When the ketogenic diet is started, your child will be admitted to the hospital. It may take four to five days in the hospital to get the diet started and for you to learn how to plan the diet. During this time blood sugar and ketone levels are monitored. The dietitian will devise meal plans that provide the required fat, protein and carbohydrates for each meal. A typical meal includes a small amount of fruit or vegetable, a protein rich food, and a source of fat, such as heavy cream and butter or vegetable oil.
Special ketogenic diet formulas have been designed for children with feeding tubes. A dietitian will determine the type and amount of formula for your child.
Diet effectiveness
The diet may become effective immediately or it may take several months. Each child is unique and has different seizure patterns and frequency. There is usually improvement within the first three to five weeks on the ketogenic diet.
If the child is on more than one anti-seizure medication, one may be reduced as the child starts the ketogenic diet. The reduction of remaining seizure medication may be made if the child's seizures improve over time. Some children are able to have the medications discontinued completely. Medications may act stronger with the ketogenic diet, so close medical monitoring is necessary.
Possible adverse effects
The ketogenic diet is not a harmless, holistic or natural treatment for epilepsy; as with any serious medical therapy, there may be complications.
The most common adverse effect of the ketogenic diet is constipation. There are dietary options to prevent this problem including eating high fiber vegetables that are allowed on the diet and drinking enough water. A less common adverse effect is kidney stones. This problem can be prevented by making sure the child drinks adequate water. There are two anti-seizure medications that can cause acidosis and kidney stones that should be monitored very closely when used with the ketogenic diet (Zonegran and Topamax).
A short-lived increase in seizure frequency may occur during illness or if ketones levels fluctuate.
If a child develops high cholesterol or lipids, the diet can be modified to lower these. Lipid levels are drawn prior to starting the diet and at regular intervals throughout the course of the diet.
Ketogenic diet maintenance
After initiation, the child regularly visits the outpatient clinic, where the dietician and epileptologist will perform various tests and examinations. Infants under 1 year old are seen more frequently. Urinary ketone levels are checked daily using ketone test strips to detect whether ketosis has been achieved and to confirm that the patient is following the diet.
The diet is generally used for a period of up to three years if it is helpful in reducing or eliminating seizures. If the diet is not helpful, it will be stopped within a few months. The diet is calculated at a specific calorie level for each child. The dietician will determine if a change in calories is needed to ensure normal growth.
The diet alone does not contain enough vitamins or minerals, thus a nutritional deficiency could develop without supplements. Special vitamin and mineral supplements are prescribed for each child while on the ketogenic diet.
If a child eats or drinks something that was not part of his/her diet, they could experience a seizure within a short period of time.
Discontinuation of ketogenic diet
Commonly, at around two to three years on the diet, or after six months of being seizure-free, the diet may be gradually discontinued over two or three months. This is done by lowering the ketogenic ratio until urinary ketosis is no longer detected, and then lifting all calorie restrictions. Children who discontinue the diet after achieving seizure freedom have about a 20 percent risk of seizures returning.