Ketogenic diet · Grey Matter

The ketogenic diet is a medically supervised diet very high in fat and very low in carbohydrate that shifts the body to burning fat and ketone bodies, and it is used to reduce seizures in epilepsy that drugs have failed to control, mostly in children.

Ketogenic diet. The ketogenic diet is a medically supervised diet very high in fat and very low in carbohydrate that shifts the body to burning fat and ketone bodies, and it is used to reduce seizures in epilepsy that drugs have failed to control, mostly in children.

It has been used for epilepsy since 1921. The classic version gives four grams of fat for every gram of protein and carbohydrate combined, which keeps blood glucose low and lets the liver turn fatty acids into ketone bodies (beta-hydroxybutyrate and acetoacetate) that the brain then uses as fuel instead of part of its glucose. In a randomised trial in children with drug-resistant epilepsy, 38 % on the diet had their seizures more than halved after three months against 6 % of controls, and 7 % had a reduction of more than 90 %.

How it works is still a set of hypotheses. Ketone bodies themselves, changes in how neurons produce ATP, more adenosine, opening of ATP-sensitive potassium channels, and decanoic acid (a fatty acid in the medium-chain version of the diet that directly blocks AMPA receptors) are the main candidates; acidosis and low blood sugar were tested and rejected.

It is a treatment, with costs. Constipation, raised cholesterol, kidney stones and slowed growth in children are among the side effects, and it is started and followed by a specialist team.

It is the first choice for a few metabolic disorders. In GLUT1 deficiency, where glucose cannot cross into the brain, ketones supply the fuel the brain is missing.

Gentler versions exist. The modified Atkins and low glycaemic index diets are easier to follow and are used especially in adolescents and adults.

Questions: How can a diet reduce seizures, and how well does it work? A diet very high in fat and very low in carbohydrate makes the liver produce ketone bodies that partly replace glucose as the brain's fuel, and it changes how excitable neurons are by routes still being worked out (ketone bodies themselves, adenosine, ATP-sensitive potassium channels, and decanoic acid, which blocks AMPA receptors directly). In a randomised trial in children whose epilepsy resisted drugs, 38 % on the diet had their seizures more than halved after three months against 6 % of controls. It is a medical treatment with real side effects, started and followed by a specialist team.