What Is In A Ketogenic Diet?

Patient Presentation
A 9-month-old female came to clinic for her 9-month health maintenance examination.

The past medical history was significant for a history of hypoxic-ischemic encephalopathy at birth but she had been doing well overall. She was followed by the neonatal intensive care follow-up team as well as receiving physical therapy services for some gross motor delays. She was also followed by neurology for seizures and had been on Keppra® since birth. Her mother was overall happy with her progress but had noted increased numbers of seizures that lasted from several seconds up to one minute and were generalized tonic-clonic in activity. She had been having 3-4 a day but now was having 8-10 per day that the family was aware of. The mother asked what the general pediatrician thought about starting a ketogenic diet. The family history was positive for a paternal uncle with seizures as a child but “grew out of them” as he got older.

The pertinent physical exam had normal growth parameters around the 50%. She was a smiling infant who would say consonants and vowels, would sit by herself once placed into a seated position but wouldn’t consistent roll into that position nor get into a crawling position. Her tone was good as was her strength. Deep tendon reflexes were +2/+2 and cranial nerves were intact.

The diagnosis of a 9-month old with a significant past medical history and increasing seizures was made. The pediatrician didn’t feel comfortable offering an opinion about the ketogenic diet as he knew this was a specialized treatment and decisions needed to made by the neurologist and dietician. “I do know that it can be helpful for some children but I don’t know enough to give you an informed opinion. I can tell you that if you start the diet that usually this is done in a hospital to monitor people closely, and people stay on the diet for a while. I am happy to continue to follow her for her well child appointments and to help her when she gets sick. I can work with you and the neurologist together,” he explained.

The patient’s clinical course at her next neurology appointment, she was switched to another anti-epileptic medication. She continued to have more seizures and around 18 months of age, she began a ketogenic diet. At 24 months of age, her seizures had decreased to 1-2 per day.

Epilepsy is a common problem for the general pediatrician. Its incidence is estimated at 41-87/100,000 children. While many children are controlled with medication, it is also estimated that up to 1/3 will develop drug-resistant epilepsy. Some children may have an identifiable seizure focus that may be amenable to surgery, but many others do not. One option for potential control is a ketogenic diet (KD).

Indications for KD usually are for drug-resistant epilepsy including partial and complex seizure patterns as well as some metabolic disorders such as glucose transport 1 deficiency syndrome. It has also found to be useful for some epileptic encephalopathies such as Doose, Dravet, Lennox-Gastaut, Ohthahara and West syndromes. KD is contraindicated in other conditions such as primary carnitine deficiency and other carnitine disorders, beta-oxidation defects, pyruvate carboxylase deficiency and porphyria.

The exact mechanism for the KD efficacy is not known but ketone bodies, mainly beta-hydroxybutyrate, cross the blood brain barrier. They become the main energy source for the brain and regulate various neurotransmission processes including accelerated re-uptake of neurotransmitters and neuronal inhibition. KD can be effective with up to 50% reduction in seizures for patients with drug-resistant epilepsy within 6 months. The diet is used usually for a minimum of 2 years.

Learning Point
A KD needs to have dieticians and neurologists with expertise to oversee them.
A KD consists mainly of calories from fat and a low percentage from proteins and carbohydrates. The classic diet is 80-90% fat and 10-20% proteins and carbohydrates. However other variations, which have a lower fat content, are used and can be effective. Most diets are 4:1 (fat: protein/carbohydrate) or 3:1. Basically the diet is mainly fat such as butter, whipping cream, mayonnaise, oils and protein such as eggs, meat, cheese and ground nuts. There is a lower concentration of fruits and vegetables and those chosen need to have other high quality nutrition such as vitamins and minerals associated with them such as such as avocado, broccoli, green beans, etc. Ground nuts and egg whites are often substituted for carbohydrates such as creating pizza dough or pancakes. Sugar free substitutes can be used but the type of substitute and amount needs to be scrutinized. This includes innocuous looking products such as gum or mints. Beverages usually are water, whipping cream or similar. Patients on a KD also need to have medications with the lowest sugar or carbohydrates in them.

Similar to other health conditions such as diabetes that need to be managed closely when a child is ill; children on a KD have special needs when they are ill. Breaking the KD when the child is ill may cause seizure frequency to increase. Oral rehydration solutions have low amounts of glucose but this still needs to be accounted for as part of the total day’s carbohydrates. Common medications such as acetaminophen, ibuprofen etc. may also have sugar or other carbohydrates in them and again need to be accounted for. Over the counter medications are a common reason that KD is broken. A child coming into the emergency room needs to have their fluids evaluated and replaced as necessary, but 0.9 NS and/or 0.45 NS should be used without glucose similar to a patient with diabetes. Close monitoring is very important.

Usually a KD diet is initiated in the hospital so the initial laboratory evaluations can be completed and monitored as the diet is initiated. The diet can be started by fasting, but also can be done by changing the content of the diet over from normal to 1:1, 2:1, and eventually 3:1 or 4:1. Metabolic problems associated with the diet include hypoglycemia, metabolic acidosis, excessive ketosis, electrolyte imbalances and dehydration. KD is associated with constipation because it is a low food and fiber diet. It is also associated with kidney stones especially if used for longer periods of time. Low Vitamin D, calcium, selenium and carnitine are also associated with the diet. Long-term effects on lipid profile are not clear.

Questions for Further Discussion
1. What are the various classifications of seizures? A review can be found here
2. What causes spells? A review can be found here
3. What are indications for a clinical dietician consultation?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Epilepsy and Seizures.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Martin K, Jackson CF, Levy RG, Cooper PN. Ketogenic diet and other dietary treatments for epilepsy. Cochrane Database Syst Rev. 2016;2:CD001903. doi:10.1002/14651858.CD001903.pub3

van der Louw E, van den Hurk D, Neal E, et al. Ketogenic diet guidelines for infants with refractory epilepsy. Eur J Paediatr Neurol. 2016;20(6):798-809. doi:10.1016/j.ejpn.2016.07.009

Luat AF, Coyle L, Kamat D. The Ketogenic Diet: A Practical Guide for Pediatricians. Pediatr Ann. 2016;45(12):e446-e450. doi:10.3928/19382359-20161109-01

Barry D, Ellul S, Watters L, Lee D, Haluska R, White R. The ketogenic diet in disease and development. Int J Dev Neurosci. 2018;68:53-58. doi:10.1016/j.ijdevneu.2018.04.005

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa