Ketogenic (or 'keto') diets are all over the news these days. Yet despite all the hype and large number of recently published, glossy cookbooks, the ketogenic diet has actually been around for a long time. It was initially developed in 1921, as a treatment for epileptic patients.
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Almost 100 years ago, Dr. Wilder at the Mayo Clinic suggested that the observed benefits of fasting for epileptic patients could be obtained if ketonemia was produced by other means. He proposed that a ketogenic diet should be as effective, and could be maintained for a much longer period of time. Wilder subsequently began to treat epileptic patients with a ketone‐producing diet at the Mayo Clinic, and coined the term “ketogenic diet.”
So what is a ketogenic diet? To put it simply, it's a carbohydrate-free (or extremely low carbohydrate) diet that causes the body to release ketones into the bloodstream. In the absence of circulating glucose from carbohydrate, we start start using free fatty acids from stored fat to produce molecules called ketone bodies (the process is called ketosis). These somewhat mysterious-sounding ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) can produce a characteristic odour similar to nail polish remover - this can often be smelled on the breath of a ketotic person.
Foods that are included as part of a traditional ketogenic diet include fatty meats and seafood, eggs, high fat dairy products, fats like butter, coconut oil and olive oil, and vegetables "that grow above the ground".
Most fruits, pasta, bread, other grains, most drinks, rice, sweets and starchy vegetables are definitely out.
There is substantial evidence demonstrating that a traditional ketogenic diet can reduce seizures in children with several forms of childhood epilepsy. Other ketogenic diets, some with improved palatability and tolerability, have been developed. These include the modified Atkins diet, medium-chain triglyceride (MCT) ketogenic diet, low-glycaemic-index treatment and diets that involve intermittent caloric restriction.
The MCT ketogenic diet is of particular interest; it also includes a large amount of dietary fat, with at least 30% (and up to 60%) of calories from MCTs. Neal et al. (2009) demonstrated that, in children, both the traditional and MCT ketogenic diet protocols were comparable in efficacy and tolerability. A lot of research has focused on the trying to determine how MCTs help to reduce seizure frequency. MCTs are more ketogenic than long-chain triglycerides, however Chang et al. (2016) demonstrated that direct inhibition of excitatory neurotransmission by decanoic acid in the brain may contribute to the anti-convulsant effect of the medium chain triglyceride ketogenic diet.
Not surprisingly, there has been recent interest in the use of an MCT-supplemented diet as a treatment for dogs with idiopathic epilepsy. In 2015, a paper by Law et al. was published, entitled "A randomised trial of a medium-chain TAG diet as treatment for dogs with idiopathic epilepsy". The authors conducted a 6-month prospective, randomised, double-blinded, placebo-controlled cross-over dietary trial designed to compare a MCT-supplemented diet with a standardised placebo diet, in dogs with idiopathic epilepsy. The authors found that seizure frequency was significantly lower when dogs were fed the MCT-supplemented diet, and this study subsequently led to the development of Purina NC NeuroCare™, which contains approximately 10% of calories from MCTs, similar to the Law study.
Purina NeuroCare™ is not a ketogenic diet, as it contains a substantial amount of carbohydrate. It's not currently available in New Zealand.