It was designed to induce a similar metabolic response to starvation, with ketone bodies becoming the primary energy substrate for brain and other metabolically active tissues in the absence of adequate glucose supply. Worldwide scientific research on the ketogenic diet has expanded considerably over the past two decades and established it as a proven therapy, placed firmly alongside other treatment options for intractable childhood epilepsy.

Newer and more liberal variants of the diet, the low glycaemic index treatment and the modified Atkins diet, have also been used with success. Despite considerable international and UK-wide variation in the availability of these ketogenic therapies, their clinical use is continuing to expand to other age groups, with on-going research into the dietary treatment of epilepsy in young infants and adults with refractory seizures.

Ketogenic therapy should always be implemented with specialist medical and dietetic supervision to ensure it is an appropriate and safe treatment choice. This requires nutritional supplementation, regular clinical monitoring and on-going dietary adjustments; aiming to maximise efficacy and minimise side effects. If successful, the benefits can extend beyond seizure control; anticonvulsant medications can frequently be reduced or discontinued and improvements in behaviour, cognition and quality of life are commonly reported. The effects of the diets can be long lasting and some who have seen benefit can return to a normal diet without resumption of seizure activity.

The potential of ketogenic therapy to treat disorders beyond epilepsy is gaining recognition. Already established as a first-line treatment choice for the neurometabolic diseases glucose transporter type 1 deficiency syndrome and pyruvate dehydrogenase deficiency, emerging evidence suggests wider applications.

  • The preference of malignant cancer cells for glucose as an energy source suggests that this low-carbohydrate, high-fat dietary regime could be a way to specifically target tumours, especially those of neurological origin.
  • Evidence is mainly from animal studies but growing interest in using ketogenic therapy to treat brain cancers has led to development of clinical trials of the diet alongside conventional cancer treatments.
  • The enhancement of mitochondrial function induced by the ketotic state may also be beneficial in disorders of neuro-degeneration such as Parkinson’s disease, Alzheimer’s disease and Amyotrophic lateral sclerosis.
  • Limited evidence also suggests a protective role in trauma and ischaemia, with the injured brain preferring to use ketones as a fuel.

Future clinical use of ketogenic therapy in cancer and wider neurological conditions must be led by well designed research trials in order to clarify who would benefit from this type of treatment and how best it should be implemented. But at almost a century old, the outlook for the ketogenic diet remains very positive; it is clearly here to stay with an exciting future ahead of it.