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Epilepsy

Ketogenic diet: Frequently asked questions

What is the Ketogenic diet?

The Ketogenic diet is a high fat, low carbohydrate and low protein diet used in the treatment of epilepsy. The diet was first developed in the early part of the last century when it was discovered that fasting could alleviate seizures. But its popularity declined in later years with the introduction of modern anti-convulsant drugs.

Over the years different versions of the diet have been used predominantly in America and the UK. The initial diet was based on the 'Classical' Ketogenic diet - based on a ratio of fat to carbohydrate in the diet. In the early seventies a new form of giving the diet was developed called the medium chain triglyceride (MCT) diet - where MCT is used as one source of fat in the diet.

How does the diet work?

The diet appears to be effective in a significant proportion of children, but not every child. It works by mimicking the effects of starvation. When fasting or starving your body first uses up glucose and glycogen before burning up stored body fat. In the absence of glucose it produces chemicals called ketones, which provide energy. The diet alters the body's metabolism by replacing glucose with fats as a major energy source. The broken down fat produces ketone bodies that help to alleviate seizures in some people. However, the exact mechanism by which the diet works is not yet known.

What does the UK study of the diet hope to establish?

As well as already demonstrating that the diet does actually work in reducing seizures, the UK clinical trials aim to establish the exact mechanism by which the diet works. The research is being undertaken by Great Ormond Street Hospital (GOSH) together with the Institute of Child Health (ICH), the National Centre for Young People with Epilepsy (NCYPE) and the Central Middlesex Hospital. GOSH experts also believe it is not known which of the two ways of giving the diet are better. Up to 120 children (aged two to sixteen) will be recruited on the study. The study will examine if there is actually any difference between the diets by randomising half of the children to each diet. Click onto www.gosh.nhs.uk for further details of the study

What are the benefits of the diet?

Already the UK clinical trials have demonstrated that the diet can work as a dietary alternative to drugs in dramatically reducing or ending seizures in children with challenging and resistant epilepsy. While only a percentage of children become seizure free, many show a significant improvement in alertness, awareness and responsiveness. It is worth noting that in some cases the diet has not proved an effective means of reducing seizures.

Who would the Ketogenic diet be suitable for?

The diet is a recognised alternative treatment for any child with challenging or drug-resistant epilepsy. This would usually include children who experience a minimum of two seizures a week despite anticonvulsant medications. Parents of children with drug resistant epilepsy interested in taking part in the ketogenic diet trial will need to seek a medical referral from their local paediatrician. The paediatrician will assess the appropriateness of the Ketogenic diet for their child's seizure disorder. Please note that the diet should only be undertaken with the full support of a paediatrician and experienced dietician.

How is the diet calculated and applied?

The diet is often regarded as difficult to implement, as every child's intake is different. To ensure that it is safe and nutritionally adequate for the child it must therefore be individually calculated by a skilled and experienced paediatric dietician. However, with the right level of support, basic understanding and specialist advice the diet will quickly become routine.

Can a child have other medication on the diet?

Yes, but the sugar and calorie content needs to be checked. Low calorie, carbohydrate-free medicines are best, however sugar-free does not necessarily mean carbohydrate free. If in doubt parents need to ask their pharmacist or paediatrician.

How is the diet monitored?

Every family is given a diary to complete to record the number of each seizure type each day including changes in the child's mood, alertness and overall behaviour. Each child will have regular follow-ups in outpatients with the dietician and paediatrician, who will monitor the child's growth (height and weight), health, the epilepsy and the need for change in medication.

Typically what type of food is eaten on the diet?

Although high in fat, meals on the ketogenic diet can be extremely tasty if well prepared and some parents have conjured up some very inventive recipes to make the diet as palatable as possible. The exact dietary composition will depend on which type of ketogenic diet a child is following, and on their individual prescription. A typical breakfast on the classical diet might include double cream, egg, butter and a small portion of fruit or vegetable, whereas more starchy carbohydrate would be allowed on the MCT diet, for example a small serving of cereal or bread. However, the special MCT supplement is needed with each meal on the MCT diet - this can be mixed into milk or food. Lunch and dinner might include a protein source, such as meat, fish or cheese, a serving of vegetable or fruit, and fat in the form of butter, double cream, oil or mayonnaise, or the MCT supplement if on the MCT diet. Snacks can be included if these suited a child's eating pattern. The portion sizes will be individualised for each child, however do tend to look smaller than normal, as fat provides more calories per gram than carbohydrate or protein.

Can extra snacks and sweets be introduced on the diet?

Only snacks that have been calculated into the diet are allowed, extra snacks and all sweets are not allowed. A skilled and experienced paediatric dietician must calculate the diet to ensure that it is safe and nutritionally adequate. Recipes cannot be exchanged as the diet is calculated individually for the child alone.

What if a child cheats on the diet?

If this occurs ketones will be lost and seizures may recur. In order for the diet to work properly it needs to be strictly followed.

What are the side effects of the diet?

In general the diet has very few side effects, as the paediatric team carefully monitors every child. When starting on the diet the most common symptoms may include nausea or constipation. In extremely rare cases where children do not drink enough, kidney stones have been reported. Sometimes growth can be a problem but most children on the diet will grow normally.

Can it increase the risk of heart disease?

Whilst the diet is high in fat it works by transforming the fat into ketones, which are used by the brain for energy. It therefore should not increase the risk of heart disease. Cholesterol levels are also closely monitored on the diet.

Does the diet encourage weight gain?

The calories on the diet are carefully controlled. Weight gain can sometimes be a problem if the prescribed amounts are exceeded, or if the child is very physically inactive. However, in most cases this does not happen as the child's weight is carefully monitored by the paediatric team, and the dietary prescription altered as necessary.

How quickly does the diet work?

Whilst some children improve within a week others may take up to three months to respond. If, after this time sufficient levels of ketones are being maintained and there are no beneficial changes, the diet should be stopped.

In the beginning when adjusting to the diet children may feel sleepy and miserable. With time, signs that a child is improving on the diet can include improved alertness and activity.

How long is a child expected to stay on the diet?

This will depend on the extent to which the child is benefiting from the diet and how difficult the child and family are finding maintaining the diet. If the child is seizure-free for two years, most doctors would suggest a trial of going slowly back to a more normal diet.

Is the diet suitable for children who are allergic to dairy products?

It is possible for children with allergies to dairy products to do the diet, however it makes it much more difficult to implement due to the limitations in food choice.

Does adjusting to the diet involve an initial spell in hospital?

This will depend on the unit where the child is treated and the child's condition. Sometimes the diet can be started as an outpatient; in other cases the child may need to be admitted. Each child will need to be assessed individually.

Will anti-epileptic drugs be stopped after a child goes on the diet?

This really depends on the child's individual circumstances. In most cases anti-epileptic medications can be reduced or even withdrawn, and this may take some time. No attempt should be made to change the child's dose of medication unless recommended by the child's paediatric team.

Does the diet benefit adults?

Although there have been a few case reports of benefits in adults with epilepsy, the diet is only generally thought to be of significant benefit in children.

How can parents find out more?

There are only a very limited number of centres in the UK that offer the ketogenic diet and GOSH is the only centre in the UK with a full-time nurse and dietician dedicated to the diet. Parents are advised to consult with their local paediatrician who will decide whether their child is a suitable candidate.

Matthew's Friends website aids and supports parents through their own experiences in managing the ketogenic diet.

This page was last updated on 29 August, 2008

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