The MCT Ketogenic Diet

The ketogenic diet is a high-fat diet that causes the body to switch from glucose metabolism to ketone body metabolism. On the standard version of the diet, carbohydrates are restricted to 15 to 20 g a day and protein is restricted to 1 g per kilo body mass. Most fats enter the liver slowly from the lymph system. MCT fats, or medium chain triglycerides, enter the liver directly. As the liver produces the ketone bodies essential to the ketogenic diet, MCT fats are a more efficient source of ketone bodies. So, a ketogenic diet high in MCT fats allows for a higher intake of carbohydrate and protein.

A quart of coconut milk on the kitchen counter with vegetables. (Image: AtnoYdur/iStock/Getty Images)

The Ketogenic Diet

The ketogenic diet was invented by Mayo Clinic's R.M. Wilders, M.D., in the 1920s as a way of alleviating seizures in children. Few anti-seizure medications were available at the time. So the diet was one of the few ways to alleviate the symptoms of epilepsy. When anti-seizure medications became more readily available, the diet received less attention from the public. In recent years, the diet has received renewed attention as an alternative treatment form when standard medications have adverse effects. Johns Hopkins Hospital continues to prescribe the diet to patients responding less than optimally to conventional medicine.

How it Works

The body can use carbohydrates, fat and protein as energy sources, but it has a strong preference for glucose when readily available. The body only reluctantly converts protein into glucose, as it needs protein for maintenance of protein-rich tissue. When carbohydrates are severely restricted, then the body turns to fat metabolism. The brain can only use a byproduct of fat metabolism, called ketone bodies, as a fuel. Ketone bodies are a compact energy source, requiring more cell engines, or mitochondria, to metabolize. The increase of mitochondria stabilizes neurons, which prevents them from entering into a seizure-triggering mode.

MCT Fats

Whereas carbohydrates and fat turn into components that can enter the bloodstream directly from the digestive system, most dietary fat converts to water soluble molecules that enter the liver via the lymph system. The liver then converts these molecules to fatty acids and ketone bodies. MCT fats are medium chain triglycerides and are present in relatively small amount in most sources of dietary fat. Unlike their longer cousins, they can enter the liver directly without having to go through the lymph system. So, consuming MCT fats gives the body an opportunity quickly to produce ketone bodies as an energy source for the brain.

MCT Ketogenic Diet

The MCT ketogenic diet recommends that 30 to 60 percent of the fat intake in the diet comes from MCT fats. Good sources include MCT oil, coconut oil and coconut products, such as coconut milk and cream. Because MCT fats quickly convert into ketone bodies, without having to take the detour through the lymph system, an MCT ketogenic diet allows for a greater intake of carbohydrates and protein, potentially making it easier to follow the diet.