The ketogenic diet contains a high ratio of fat to carbohydrate and protein. Most of the calories are provided as fats, using butter and heavy cream. Seizure control is greatest when the diet contains a ratio of fat calories to protein/carbohydrate calories of 3 or 4:1. A typical meal might consist of a very small portion of meat, fish, poultry or cheese, a slightly larger portion of fruit, additional fat served as butter or mayonnaise, and a serving of heavy (whipping type) cream. It doesn't sound very palatable, does it? It is this perception of the diet as unappealing that has interfered with its more frequent use.
When your child is severely handicapped by seizures and massive amounts of medication, what do you have to lose by trying the diet? Not much! What do you have to gain? If it works, a lot. If it doesn't, you've lost very little other than the time invested in learning how to prepare the diet. If your child is seizure free and less drugged, then the rigours of the diet are worthwhile. If the child's seizures continue after one to three months on the diet or if the diet is poorly tolerated, then the diet can be discontinued and the child returned to medication.
The diet is initiated with several days of starvation and limited fluid intake. The child should be carefully observed during this time for signs of hypoglycaemia (low blood sugar) – paleness, sweatiness, unresponsiveness, or seizures. When the child is very ketotic (has a lot of ketones in the urine) and has lost about 10 percent of his body weight, one third of the diet is begun. The diet is increased over the first three days. We usually do this in the hospital since this allows us to instruct the parents in diet preparation. Menus can be selected to fit the child's food preferences. It is surprising how much variety an innovative parent can introduce into this restricted diet.
WARNING: The diet should not be attempted on your own. The diet will only work when it, and you, are carefully supervised by a dietician familiar with using the diet. The diet may be dangerous if not done properly.
WARNING: The diet is deficient in vitamins B and C as well as in calcium and these must be given as supplements in a sugar-free form.
Also, remember that today many things like toothpaste, vitamins, and children's antibiotics and cough syrups have added glucose. If your child is on the ketogenic diet, you must read every label carefully and, if in doubt about added sugar, check with your physician, the dietician or the manufacturer.
Small deviations in the diet can result in a seizure. Indeed, if a child has been well controlled on the diet and has a seizure, you can almost be sure that the child has eaten a cookie, a piece of candy, or a bit of dog food. (Yes, small children can get into the dog food!) Should this happen, a day of starvation followed by reinstitution of the diet usually will re-achieve control.
The diet is not for all children with epilepsy. Indeed, for most children it is far easier to take a few pills each day. Most children will have their seizures easily controlled with medication. However, in situations where anticonvulsants are ineffective, or where their side effects are overwhelming, the ketogenic diet can often control the seizures with few if any adverse effects on behaviour or learning. But the diet is cumbersome, particularly at first. It requires careful weighing and measuring of food. It also requires strict compliance: sometimes a few extra nuts or a piece of a cookie can allow seizures to break through. For older children, teens in particular, this may be a very difficult diet to adhere to. There is little experience with the diet in adults. We rarely prescribe the diet for children under the age of one year, because it is difficult to obtain and maintain ketosis in children that young.
At the present time we are willing to try the diet in children who are older than one year of age and who have difficult to control seizures that have not responded to at least two anticonvulsant drugs. We have even successfully used the diet in children who would appear to be candidates for focal epilepsy surgery. We do not know what limitations might be put on use of the diet in future, but these are our current restrictions.
Our success rates in patients who are chosen using these restrictions remain about the same as has been reported from many centres over the past sixty years:
- Roughly 20 to 30 percent of children with difficult to control seizures have their seizures well controlled by this diet. Many are also able to decrease or stop medications.
- Roughly 30 to 40 percent of the children have a greater than 50 percent decrease in the number of seizures, but they don't achieve complete seizure control. Many of these children are also able to decrease their medications and thereby experience less toxicity.
- Roughly 30 to 40 percent of patients find that, after giving the diet a good try for one month or more, it is not sufficiently effective to continue, and they return to trying medications or surgery. However, even unsuccessful patients are glad that they made the effort.
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