Tuesday, May 15, 2007

Although the ketogenic diet has been used for over 80 years, there has been an increased interest in other, perhaps less restrictive diets. One such diet is the modified Atkins diet, discussed in previous issues of Ketogenic News, including last month’s update. This month we are introducing the low glycemic index treatment, another alternative dietary treatment for epilepsy, which has been pioneered by Dr. Elizabeth Thiele and Heidi Pfeifer, RD, LDN from the Massachusetts General Hospital in Boston. Initial findings indicate that it is an effective treatment for children with either generalized or partial onset seizures. We have asked Heidi Pfeifer, RD, from Massachusetts General Hospital, to prepare for us the questions and answers that follow. Eric Kossoff, MD

Low Glycemic Index Treatment

By Heidi H. Pfeifer, RD, LDN

What is the Low Glycemic Index treatment (LGIT)?

The LGIT for epilepsy was developed in 2002 as an alternative medical nutrition therapy to the ketogenic diet (KD) as a treatment for intractable epilepsy. Although the ketogenic diet is a very effective method of treatment for seizures, compliance with the KD can be difficult. This is due both to the rigid procedures for weighing and measuring foods that are high in fat and very low in carbohydrates as well as to the restrictiveness of the diet. The LGIT monitors not only the total amount of carbohydrates consumed daily, but focuses on carbohydrates that have a low Glycemic Index.

What is Glycemic Index?

The Glycemic Index of a food refers to how high that food raises your blood glucose after ingestion compared to a reference food such as sugar. There are different features of foods that affect glycemic index. For example, dietary fiber reduces glycemic index. The rate at which a food is digested and absorbed also affects its glycemic index – so buttering a piece of bread can actually reduce its glycemic index.

How is it different from the ketogenic diet?

The LGIT allows for an increased intake of carbohydrates, with a typical goal of 40-60 grams per day. Food quantities are not weighed out to the gram, but are based on portion sizes. Because it is based on portion instead of exact measurement, patients are able to live a more flexible lifestyle that includes eating at restaurants. Foods that are the basis for the ketogenic diet and are high in fat, such as heavy cream and high fat meats (bacon, sausage, hot dogs and eggs) are also included in the LGIT. However, on the LGIT the percentage of calories from fat is approximately 60%, compared with up to 90% on the ketogenic diet.

How is the diet initiated?

The LGIT is initiated as an outpatient following education from a registered dietitian. Individualized diet goals are provided based on a person’s current diet intake and growth history.

Whom will it help?

Initial findings indicate that it is an effective treatment for individuals with either generalized or partial onset seizures. Seizures were reduced in a majority of patients using the LGIT. Some of these individuals achieved seizure freedom, and many were able to reduce their use of anticonvulsant medications.

What is it like?

The LGIT is flexible as long as carbohydrate intake is restricted to target levels and the overall diet meets caloric needs. We recommend that all carbohydrates be consumed together with fats and protein to further reduce glycemic index. Due to the dietary changes, multivitamin and mineral supplementation as well as calcium supplementation is required while on the LGIT to reduce the risk of deficiencies.

If you would like to hear a personal experience with the use of the LGIT, click on Rose at http://www.massgeneral.org/childhoodepilepsy/

Are there side effects?

Some children have demonstrated positive weight reduction while on the LGIT. There has also been an increase in risk of acidosis while initiating the LGIT. Acidosis is a blood condition in which the bicarbonate concentration is below normal; symptoms include lethargy, nausea, vomiting and headache and acidosis is diagnosed with a simple blood test. This can be treated with supplementation of a bicarbonate solution without affecting treatment efficacy of the LGIT.

How is the patient monitored over time?

To ensure that no untoward side effects are seen while on the treatment, follow up visits are scheduled one month after initiation and then every three months thereafter. During these visits, height and weight as well as blood tests are obtained to carefully monitor each individual.

A registered dietitian with experience in treating patients with intractable epilepsy assesses individuals to make sure all nutrition requirements are met while on the treatment.

How does it work?

Similarly to the ketogenic diet, the mechanism of action of the LGIT remains unknown. It is thought that the metabolic changes, such as the reduction in blood glucose levels and production of ketones that occur when the primary energy source in the diet is changed from carbohydrates to fats, may have a therapeutic effect on the brain.

Can the treatment ever be stopped?

Like with any anticonvulsant treatment, if seizure freedom is achieved, physicians and patients can discuss the pros and cons of weaning off of the treatment.

Authored by: Heidi H. Pfeifer, RD, LDN on 5/2007
Reviewed by: Steven C. Schachter, MD on 5/2007