Ketogenic diet therapy is a recognized and effective treatment for epilepsy in children and is offered by many epilepsy care centres. It is usually tried in children for whom surgery is not an option, if two or more anti-epileptic medications have failed to control seizures or if the medications cause very severe side effects. Although it does not work for every child, it can produce dramatic results in controlling epilepsy for some children.
What is ketogenic diet therapy?
All forms of ketogenic diet therapy for epilepsy involve restricting carbohydrates and increasing fat in the diet. The classic ketogenic diet, which usually provides 85 to 90 per cent of the calories in the diet from fat, is the traditional diet and has been used to treat epilepsy since the 1920s with significant success. More recently, less restrictive diets have been developed. Not all ketogenic diets are available at all epilepsy care centres.
- The traditional, or classic, ketogenic diet is calculated as a ratio, usually providing 3 to 4 grams (g) of fat to every 1 g of protein and carbohydrates. Children treated with the ketogenic diet need to eat mostly fatty foods, such as oils, butter and cream. They cannot eat starchy foods such as bread and pasta.
- The medium-chain triglyceride (MCT) diet includes an oil that supplements fatty acids called medium-chain triglycerides. Children can eat more protein and carbohydrates with this diet than with the classic ketogenic diet. However, the MCT diet is less widely available than the classic ketogenic diet. It is as effective as the classic ketogenic diet in controlling seizures.
- The modified Atkins diet, as its name suggests, is a modification of the Atkins diet for weight loss. Children taking this diet can usually not eat more than 10 to 15 g of carbohydrates per day and get about 65 per cent of their calories from fat. The modified Atkins diet was first described as a treatment for epilepsy in 2003.
- The low glycemic index treatment (LGIT) allows more carbohydrates than the other three diets. However, all the carbohydrates the child eats must have a low glycemic index. Low glycemic (GI) index foods include small amounts of high fibre and unrefined grains; fruits such as apples, strawberries, peaches, pears, and kiwis; and vegetables such as tomatoes, carrots, broccoli, cauliflower, celery, and zucchini. The LGIT was first described as a treatment for epilepsy in 2005.
Each of these treatment options must be strictly followed to give it the best chance of working. The treatment must be carefully monitored by a specially trained team, including a neurologist and a dietitian.
Ketogenic diet therapy for epilepsy should not be regarded as safer or more natural than medications for treating epilepsy. Just like medications, dietary therapies have side effects and are not right for all children. Like medications, dietary therapies are not a "miracle cure". As with any other treatment, some children will have complete seizure control, some children will still have some seizures and some children will see no effect.
Ketogenic diet therapy requires a high degree of collaboration between the child, parents, dietitian and doctor. The parents are ultimately the main implementers of this treatment; it is the parents who must manage the specific foods and the feedings.
Ketogenic diet therapy can be used on its own or along with anti-epileptic medication. There is no maximum amount of time that the ketogenic diet can be used to treat epilepsy. The length of time a child is treated with this therapy is a decision made between the child, parents and the Ketogenic Diet team. If one diet is working well to control seizures but the family finds the diet difficult to follow, it is sometimes possible to switch from one form of ketogenic diet therapy to another.
How does ketogenic diet therapy work?
The body usually burns glucose (carbohydrates) for energy. When the body does not have carbohydrates available for fuel, it will use fats instead. When the body uses fat as fuel it produces ketones, a situation called ketosis. The brain can use these ketones instead of glucose as a source of energy.
Doctors and researchers do not know exactly why diets that produce ketosis are effective for controlling seizures. Studies have not found a consistent relationship between ketone levels in the blood and seizure control. Controlling blood sugar levels may also be a factor in controlling seizures. Despite not understanding how the ketogenic diet therapy works, studies show that it is effective in controlling seizures.
Who should use ketogenic diet therapy?
Ketogenic diet therapy is usually tried in children for whom surgery is not an option, after two or more anti-epileptic medications have failed to control seizures or in cases where the medications cause very severe side effects. For ketogenic diet therapy to have a chance of working, the child and family must be highly motivated to learn how to use it correctly. Ketogenic diet therapy requires consistent effort by the parents to make it work. It also requires the child's co-operation.
Ketogenic dietary therapy has been found to be effective for all seizure types and is the recommended treatment for some metabolic conditions such as glucose transporter type 1 deficiency syndrome and pyruvate dehydrogenase deficiency. It has shown success in treating "drop" type seizures and epileptic encephalopathies such as Dravet syndrome, myoclonic-astatic epilepsy and Lennox-Gastaut syndrome. It is sometimes used to treat infantile spasms when medications do not work.
Ketogenic diet therapy has been used successfully in infants, children and teenagers. This therapy is now being used by adults who require this treatment for seizure control. Children who are fed by a feeding tube, such as a gastrostomy tube (G-tube) , can use the ketogenic diet. If safe to do so, infants are offered the ketogenic diet by bottle. It is given as a liquid formula when offered through feeding tube or bottle.
Who should not use the ketogenic diet therapy?
Ketogenic diet therapy is not a safe treatment for everyone. Children who are unable to metabolize fat or need a high carbohydrate diet cannot safely start the ketogenic diet. This is assessed by the health-care team before any child is started on this dietary treatment. Children must be able to safely take all of their nutrition and fluids to support healthy growth and hydration. If this is difficult for a child, further work may be needed before the ketogenic diet can be started.
The ketogenic diet can be very expensive, and some families may not be able to afford this medical treatment. Support from the health-care teams is offered to ensure that as many children as possible may have access to this treatment where necessary.