Fasting as a treatment for epilepsy has been known since biblical times. In the 1920ties the principle of the ketogenic diet was established as a systematic approach to treat intractable childhood epilepsy. It was an established therapy until the discovery of anticonvulsants led to decreased use of the diet. Recent years have seen a resurgence of the interest in the ketogenic diet, in particular as novel indications such as GLUT1 deficiency syndrome emerged.
intractable childhood epilepsy
The ketogenic diet is a normocaloric, high-fat, low-carbohydrate diet for the treatment of intractable childhood epilepsy and specific defects of brain energy metabolism (see Principle).
The ketogenic diet simulates the body’s response to starvation by shifting the metabolism from carbohydrate to fat utilization for fuel. In starvation, ketones are formed from the breakdown of body fat. They readily pass the blood-brain barrier and provide the brain with energy.
Applying a ketogenic diet follows the same principle but prevents weight loss by providing nutritional fat to maintain ketosis.
Application of the diet
The application of the ketogenic diet follows these steps:
- Starting the dietc
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2. Starting the diet
For the initiation of the ketogenic diet the patient should be hospitalized for roughly 5 days.
Patients are fasted initially (except for Pyruvat-Carboxylase-desease) and metabolic parameters such as blood glucose are monitored closely. Water or sugar-free beverages are allowed.
When ketosis is achieved, the ketogenic diet is initiated.
After establishing the maintenance of the diet and the dietary education the patient can be discharged once he and his caretakers feel confident to prepare and monitor the diet at home.
Zunächst wird gefastet (Ausnahme: Pyruvat-Dehydrogenase-Mangel), bis der Körper Ketone produziert.
Dies kann je nach Alter des Kindes 1-3 Tage dauern. The ketogenic diet is started usually after 72 hours.
Blood pressure, pulse, respiration, blood sugar and the rise of ketones in the blood and urine are closely monitored.
Occasional vomiting, due to high levels of ketosis, can be well resolved by a small sip of orange juice and continued fasting.
When evidence of a clear ketosis is started in stages with food intake.
If the diet is tolerated without complications and the patient / family is familiar with the calculation of the diet, it can be discharged into the outpatient care.
After discharge the patient needs to be followed up closely at outpatient clinics.
Frequent phonecalls and initial appointments at weekly intervals can gradually be extended to regular follow-up appointments every 3-6 months.
Maintaining the diet in kindergarten and at school often takes some getting used to for the child and carers.
For this purpose, it is advisable to involve the caregivers and to take the "fear" of the diet and disease.
The ketogenic diet is only a balanced diet, if daily carbohydrate-free multivitamins, trace elements and minerals, especially calcium are taken. Biannual controls of blood counts are required.
Control of ketosis:
The development of ketosis is during the fasting phase every 4-6 hours by the direct measurement
of the ketone β-hydroxybutyrate (target range> 2 mmol / L) and
glucose (target range> 40 mg / dl) in the blood.
The effectiveness of the diet, or the required ketone ß-hydroxybutyrate concentration can be very individual.
After successful conversion to the ketogenic diet, daily, then weekly, measurements of the β-hydroxybutyrate in the blood make sense. In the course of this, the monitoring of ketosis in the urine can then be carried out by means of test strips (target range: 80-160 mg / dl).
In special situations (eg, seizures, infections, dietary errors, etc.) the measurement of ß-hydroxybutyrate in the blood should be carried out again - this indicates the current metabolic situation and gives the supervising physician important information for the further course of action.
To be able to assess the ketogenic diet, you must consistently perform it for at least three months.
If it shows no effect despite detectable constant ketosis, it can be stopped again within a short time.
If the diet is successful in patients with epilepsy and the child is seizure-free, consider stopping the ketogenic diet after two to three years.
This should be done over a year by gradually changing the ratio of fat: non-fat (from 4: 1 to 3: 1 over 2: 1 to normal diet) so as not to provoke seizures.
For pyruvate dehydrogenase deficiency, the ketogenic diet is likely to be life-long.
The duration of the diet is currently unclear for glucose transporter (GLUT1) deficiency - due to the increased energy expenditure in the brain of the child, the ketogenic diet should definitely be maintained until puberty.
Contraindications and adverse effects
The ketogenic diet must not be used in defects of fatty acid oxidation nor in defectsof ketone body production or ketolysis. These diseases are rare but need to be excluded before starting the ketogenic diet to avoid severe hypoglycemia andmetabolic decompensation in the fasting situation.
An acylcarnitine profile in blood and an organic acid profile in urine should be determined, but do not generally rule out these diseases. For this reason children should be admitted for the initial fast. A further contraindication is pyruvate carboxylase deficiency. Of note, expected non-compliance of patients and/or caretakers also is a contraindication to the ketogenic diet. Glycogen storage diseases are discussed controversially.
Potential side effects associated with the ketogenic diet are change in bowel habits, renal stones, and potentially hyperlipidemia. Because patients on the ketogenic diet are in a chronic acidotic state, bone-demineralization is a risk and supplements need to be strictly adhered to. Sporadic complications of the ketogenic diet have been reported in single patients.
The ketogenic diet is an individually calculated restricting diet that should only be administered under the care of physicians experienced with the diet. The amount of fat to non-fat (in gram, not in calories) is expressed as a ratio, e.g. 3:1 :
3 : 1
3 gram fat : 1 gram (protein + carbohydrates)
The ratio should be strictly adhered to in every meal. Adequate protein needs to be provided for sufficient growth. Every food item needs to be weighed and calculated into the meal plan. The dieticians will help to select and calculate the ketogenic meals.