Understanding the core principles of a 'modified ketogenic diet': a UK and Ireland perspective

Many centres across the UK and Ireland anecdotally report using a 'modified ketogenic diet' (MKD) as a treatment for refractory epilepsy. Although a MKD is within the spectrum of ketogenic diets (KDs), there is little literature reporting upon its definition, use or clinical effectiveness. We aimed to understand the core principles of MKD practice and to assess whether and how the MKD differs from other KD protocols.

An online survey, designed by a consensus group of ketogenic dietitians, was circulated to 39 KD centres across the UK and Ireland. It consisted of 35 questions regarding dietetic practice when providing MKD.

Eighteen centres completed the questionnaire: 13 paediatric, three adult and two combined centres. All dietitians based MKD 'prescriptions' on estimated total energy requirements. The average macronutrient profile was 75% fat and 5% carbohydrate, with protein ad libitum. Carbohydrate and fat targets were implemented via weighed portions (carbohydrate lists n = 18; fat lists n = 13) and 'household measures' (carbohydrate lists n = 2; fat lists n = 3). Of the centres, 94% (n = 17) adjusted macronutrients over time; these decisions were based on ketone levels and seizures in most cases (83%; n = 14). Ketogenic nutritional products available on prescription were used by 10 centres (56%) when initiating and by all centres when 'fine-tuning' the MKD.

A modified ketogenic diet in the UK and Ireland is a hybrid KD, adopting principles from other established KD protocols and defining new elements unique to the MKD. Further research into the clinical and cost-effectiveness of MKD would be of benefit.