Glossary of Terms
Antiepileptic drugs or AEDs are seizure medications used to suppress seizures in people with epilepsy. Read more about AEDs.
Brain surgery is a treatment option for epilepsy, which may be considered when seizures cannot be controlled with anti-epileptic medications. Although it can be effective in controlling seizures, not all patients are appropriate candidates. Learn more about brain surgery for epilepsy.
Carbohydrates are one of the 3 nutrients (along with fat and protein) which provide calories to the body. Carbohydrates are the main source of energy in a typical diet, contributing about 50-60% of the average American's calorie intake (Kossoff, 2011). The digestive system converts the carbohydrates we consume in food into glucose, which is used as energy by the body's cells, tissues and organs1. The brain almost exclusively uses glucose for energy, except during periods of starvation, when it can use ketone bodies instead.
Docosahexaenoic acid (DHA) and Arachidonic acid (ARA) are fatty acids found naturally in human milk. Because they are shown to support brain and eye development, these nutrients are often added to formulas for infants and young children.
An electroencephalogram, better known as an EEG, is a medical test used to monitor the electrical activity in the brain. An EEG is commonly used to detect seizure activity and diagnose epilepsy. Learn more about EEGs.
Epilepsy is a neurological disease
characterized by the tendency to have seizures2.
It may be diagnosed after 2 or more unprovoked seizures*. According to the Epilepsy Foundation of
America, "Epilepsy is the fourth most common neurological disorder in the U.S.
after migraine, stroke, and Alzheimer's disease. Its prevalence is greater than
autism spectrum disorder, cerebral palsy, multiple sclerosis and Parkinson's
disease combined." Read more about epilepsy.
*A provoked seizure is a seizure that is caused by a factor outside the brain. For example, a seizure might be triggered by a high fever or severe hypoglycemia (low blood sugar). These "provoked" seizures do not start in the brain and are not the same as epileptic seizures.
Epileptic syndromes describe groups of patients with epilepsy who share similar characteristics, such as seizure-type, EEG patterns, seizure-triggers, seizure severity and frequency, genetic factors, age of onset, co-morbidities, response to treatment, etc. Read more about epilepsy syndromes.
Fats are one of the 3 nutrients (along with protein and carbohydrates) that supply calories to the body. The majority of fat in the human diet is in the form of triglycerides, specifically long-chain triglycerides. Dietary fat can be classified as unsaturated, saturated or trans. Dietary fats are also sources of essential fatty acids, like linolenic acid and alpha-linolenic acid which the body cannot produce on its own. Essential fatty acids, include omega-3s, which have many functions in the body including anti-inflammatory properties.
Fiber is a type of carbohydrate which cannot be digested by our bodies. It is found naturally in plant foods, such as fruits, vegetables, and grains, and is an important part of a healthy diet. Fiber is classified into two main types: soluble and insoluble, each with unique health benefits. Soluble fiber is most known for its role in lowering cholesterol and insoluble fiber is most known for its role in managing constipation. With the ketogenic diet, fiber is usually subtracted from the total carbohydrate content since it is not digested and therefore does not affect blood glucose levels. Read more about fiber.
Glut-1 Deficiency Syndrome (Glut-1 DS):
Glut-1 DS, also known as Glucose Transporter Type 1 Deficiency Syndrome, Glut1 Deficiency, or DeVivo Disease, is a genetic disorder characterized by impaired brain metabolism. The human brain relies on glucose almost exclusively for energy. With Glut-1 DS, the transport of glucose from the blood into the brain is impaired, depriving the brain of energy and causing serious neurological consequences. The Ketogenic Diet produces ketone bodies, which can serve as an alternative fuel source for the brain. Learn more about Glut-1 DS.
Intractable or refractory
epilepsy is usually defined as epilepsy which cannot be
controlled with medication, as demonstrated by the failure of 2-3 different anti-epileptic drugs (AEDs)3.
Experts believe that around 30-40% of people with epilepsy have intractable forms4.
The ketogenic diet is a high fat, adequate protein, and low carbohydrate diet which is used as a dietary therapy for the management of intractable epilepsy and for the dietary management of rare disorders of carbohydrate metabolism. The body's main energy source is glucose, however, in the absence of glucose (such as during fasting, prolonged exercise, or when following a ketogenic diet), the liver metabolizes fat to produce ketone bodies, which can be used as an alternative energy source. The ketogenic diet is precisely calculated, strictly controlled and closely monitored. It should only be done under the supervision of a medical professional. The classical ketogenic diet is generally calculated at a 4:1 or 3:1 ketogenic ratio. Variations of the classical ketogenic diet include the MCT ketogenic diet, the modified Atkins diet and the low glycemic index diet. Read more about the ketogenic diet from the following sources: Epilepsy Foundation. The Charlie Foundation.
The ketogenic ratio refers to the ratio of the amount of fat to the combined amounts of protein and carbohydrate. The traditional ketogenic diet is typically a 4:1 or 3:1 ratio, where the 4 or 3 refers to the grams of fat and the 1 refers to the grams of combined protein and carbohydrate. The dietitian or other health care provider will determine the appropriate ketogenic ratio for each patient.
Ketone bodies or "ketones" are by-products of fat metabolism, which build up in the blood when the body is using fat, rather than carbohydrate, as the primary fuel (energy) source, such as during periods of fasting, prolonged exercise, or when consuming a high-fat, low carbohydrate (ketogenic) diet. Ketone bodies can be detected in the blood, urine, and breath of someone who is in "ketosis". There are 3 types of ketone bodies: beta -hydroxybutyric acid, acetoacetic acid, and acetone5. It is not known which of these ketone bodies, if any, contributes to seizure control. Many researchers believe that ketone bodies may just be an indicator that the body has made the metabolic shift to using fat for fuel, and that another factor of this metabolic change which has not yet been identified is responsible for seizure control (Kossoff, 2011).
The term "ketosis" describes the state of having large amounts of ketone bodies in the blood.
In the state of ketosis or having large amounts of ketone bodies in the blood.
Long chain triglycerides (LCTs) are the main form of fat provided by foods. The traditional ketogenic diet is based on LCTs.
Low Glycemic Index Diet or Low Glycemic Index Therapy (LGIT):
The Low Glycemic Index Therapy (LGIT) is a more liberal variation of the traditional ketogenic diet. The glycemic index classifies carbohydrates by their potential to raise blood glucose on a scale from 0-100. LGIT allows for a greater intake of carbohydrates but the carbohydrates are limited to those with a low glycemic index (typically considered a glycemic index ≤50)6. Unlike the traditional ketogenic diet, LGIT does not require hospitalization for initiation and meals are prepared using household measurements, rather than a gram scale. LGIT may be recommended for patients unable to tolerate or comply with a standard ketogenic diet. Like the traditional ketogenic diet, LGIT should only be used under medical supervision. Read more about the Low Glycemic Index Diet.
MCT Diet or MCT Ketogenic Diet (MCTKD):
The Medium Chain Triglyceride Ketogenic Diet (MCTKD) is a variation of the traditional Ketogenic Diet (KD), unique because a percentage (30-70%) of total daily calories comes from medium chain triglycerides (MCTs). Because MCTs produce more ketones than LCTs7, the MCTKD allows more protein and carbohydrate in comparison to the traditional KD, which is based on LCTs. Like the traditional KD, the MCTKD is initiated in the hospital and a gram scale is used to measure foods. High intake of MCTs can cause gastrointestinal side effects (discomfort, cramping, diarrhea, or vomiting) for some patients so the dietitian will introduce MCTs gradually and adjust the amounts as needed to find the best balance of ketosis and tolerance8.
MCTs are a type of fat found in a small number of foods, such as coconut oil and palm kernel oil, and also provided by special nutritional formulations, such as LiquigenÂ®. MCTs are absorbed and metabolized differently in the body, making them more "ketotic" (producing more ketones) than long-chain triglycerides. MCTs may be added to the traditional ketogenic diet to boost ketone production or used to implement the MCT ketogenic diet (MCTKD). High intake of MCTs can cause gastrointestinal side effects (discomfort, cramping, diarrhea, or vomiting) for some patients, so the dietitian will introduce MCTs gradually and adjust the amounts as needed to find the best balance of ketosis and tolerance.
The Modified Atkins Diet (MAD) is a more liberal variation of the traditional ketogenic diet. While the ketogenic diet is typically given at 4:1 or 3:1 ketogenic ratio, MAD is done at about a 1:1 ratio, which allows for more protein and carbohydrate intake, and requires less fat intake. MAD does not require hospitalization for initiation and meals are prepared using household measurements, rather than a gram scale. MAD may be recommended for patients unable to tolerate or comply with a standard ketogenic diet. Like the traditional ketogenic diet, MAD should only be done under medical supervision.
Protein is one of the 3 nutrients (along with carbohydrate and fat) which provide calories to the body. In addition to providing the body with energy, protein is required for growth, structure, and various body functions.
Pyruvate Dehydrogenase Deficiency (PDD):
PDD is a rare genetic disorder characterized by impaired metabolism of carbohydrates, the major energy source for the body and brain. Pyruvate dehydrogenase is an important enzyme involved in converting energy from the foods we eat into a form of energy which our bodies can use. When this enzyme is impaired, the body and brain are starved for energy and a substance called lactic acid accumulates to dangerous levels in the body. A ketogenic diet is often used in the management of PDD9 because carbohydrate restriction helps limit the accumulation of lactic acid and ketone bodies provide an alternative energy source for the brain and body.
Saturated fat is a type of fat found primarily in animal sources, such as meats and dairy. High saturated fat intake is known to contribute to the risk for atherosclerosis (heart disease)10.
A seizure is an episode of abnormal electrical activity in the brain which affects a person's consciousness, movements, and/or actions. There are many types of seizures but the two major classifications are primary generalized seizures and partial seizures.
The Epilepsy Foundation of America's Working Group on Status Epilepticus defines status epilepticus as "More than 30 minutes of continuous seizure activity or two or more sequential seizures without full recovery of consciousness between seizures.11" Read more about status epilepticus.
Trans fat is a man-made type of fat found primarily in processed, commercially-prepared foods, such as cookies, doughnuts, margarine, and some fried foods. High trans fat intake is known to contribute to the risk for atherosclerosis (heart disease)12.
Unsaturated fats are typically viewed as the "healthy fats" in the diet. These fats are found primarily in vegetable sources, like avocados, olives, nuts, and seeds.
Vagus Nerve Stimulation (VNS):
Vagus Nerve Stimulation or VNS is a treatment option for epilepsy, which may be considered when seizures cannot be controlled with anti-epileptic medications13. Read more about VNS.
1 Carbohydrates. US National Library of Medicine. Updated May 2013. Accessed May 2013. http://www.nlm.nih.gov/medlineplus/carbohydrates.html.
2 International League Against Epilepsy. Seizures [brochure]. 2012. http://www.ilae.org/Visitors/Centre/documents/Brochure-2012-Seizures.pdf
3 Kwan P, et al. Definition of drug resistant epilepsy: Consensus Proposal by the Ad Hoc Task Force of the ILAE Commission on Therapeutic Strategies. Epilepsia. 2010 Jun;51(6):1069-77.
4 Sinha S, Siddiqui KA. Definition of intractable epilepsy. Neurosciences (Riyadh). 2011 Jan;16(1):3-9. [PubMed].
5 Kossoff EH, et al. Ketogenic Diets: Treatments for Epilepsy and Other Disorders; Fifth Edition. Demos Health Publishing, NY, NY, 2011.
6 Pfeifer HH & Thiele EA. Low-glycemic-index treatment: a liberalized ketogenic diet for treatment of intractable epilepsy. Neurology 2005;65:1810–1812.
7 Liu YM & Wang HS. Medium-chain triglyceride ketogenic diet, an effective treatment for drug-resistant epilepsy and a comparison with other ketogenic diets. Biomed J. 2013 Jan-Feb;36(1):9-15.
8 Neal E. The medium-chain triglyceride ketogenic diet. In: Neal E. Dietary Treatment of Epilepsy: Practical Implementation of Ketogenic Therapy. West Sussex, UK: Wiley-Blackwell;2012:78-88.
9 Wexler ID, et al. Outcome of pyruvate dehydrogenase deficiency treated with ketogenic diets. Studies in patients with identical mutations. Neurology. 1997 Dec;49(6):1655-61.
10 Wilson, MG. Carbohydrates, Proteins, and Fats. Merck Sharp & Dohme Corp. Updated July 2008. Accessed May 2013.<http://www.merckmanuals.com/home/disorders_of_nutrition/overview_of_nutrition/carbohydrates_proteins_and_fats.html>.
11 Epilepsy Foundation of America. Treatment of convulsive status epilepticus. Recommendations of the Epilepsy Foundation of America's Working Group on Status Epilepticus. JAMA. Aug 18 1993;270(7):854-9. [Medline].
12 Wilson, MG. Carbohydrates, Proteins, and Fats. Merck Sharp & Dohme Corp. Updated July 2008. Accessed May 2013.<http://www.merckmanuals.com/home/disorders_of_nutrition/overview_of_nutrition/carbohydrates_proteins_and_fats.html>.
13 Boon P, et al. Vagus nerve stimulation for refractory epilepsy. Seizure. 2002 Apr;11 Suppl A:448-55.