Triheptanoin (also known as C7 oil) is an investigational medical food or supplement. Triheptanoin is thought to have an anaplerotic role, meaning that it can replenish substances involved in the tricarbolic acid cycle, a pathway used by cells to produce energy, providing an alternative source of energy to the brain. It supplies the body with heptanoate which can either be oxidized to propionyl-CoA directly or is metabolized by the liver to the“C5 ketones”, β-ketopentanoate and/or β-hydroxypentanoate, which are released into the blood. After one month of triheptanoin use, the level of energy production in the brain during visual stimulation had become normal in Huntington’s patients. Triheptanoin was anticonvulsant in two chronic mouse models and increased levels of anaplerotic precursor metabolites in epileptic mouse brains. Despite the unknown mechanism of triheptanoin’s anticonvulsant action, the fact that triheptanoin has been used safely in several animals and for various metabolic diseases in children and adults should expedite the ethical and regulatory approval processes for a clinical trial in medically refractory patients with epilepsy. Triheptanoin is phase II clinical trial for the treatment of glycogen storage disease type V, Huntington's disease, Rett syndrome and amyotrophic lateral sclerosis.