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In a previous blog post, we looked at how the ketogenic diet could be used as a treatment option for both children and adults with refractory epilepsy.
When we look at the practical use of the ketogenic diet, there are more than one option that can be followed. All the forms of ketogenic diets for epilepsy have different pros and cons and practical implications to consider.
1. The Classical Ketogenic Diet
The Classical Ketogenic Diet was the original form of diet developed to mimic the ketosis which was observed with fasting. It is the strictest form of the ketogenic diet available with a macronutrient ratio of 4:1 or 3:1 being employed.
What Is the 4:1 and 3:1 Ketogenic Diet?
The ratio is based on fat: carbohydrate + protein. What this means in practical terms is that for every 5 grams of food you eat, 4 grams comes from fat and 1 gram comes from protein and carbohydrates combined. This means that people are eating around 90% of their calories from fat and 10% from protein and carbohydrates combined on a 4:1 approach.
On a 3:1 approach it is around 87% from fat and 13% from protein and carbohydrates added together.
The exact make up of this type of ketogenic diet is calculated out for each individual person to make sure all the nutritional needs are met, including energy intake (calorie level).
Why is it Difficult to Follow the Classical Ketogenic Diet?
Foods need to be weighed and measured out to ensure 100% accuracy of the diet. The exact ratios of the diet can be adjusted depending on the severity of seizure control needed and tolerability. It is normally started in an in-patient setting meaning that the individual is required to stay in hospital for a set period.
Due to the severe restrictive nature of this form of ketogenic diet and the adverse side effects that have been noted ( 1), the classical ketogenic diet does not suit everyone with refractory epilepsy.
Many epileptic centres around the world would begin a ketogenic diet with an initial fasting period. This would vary between 12-72 hours and is done to get someone into ketosis as quickly as possible.
Once a high level of ketosis is achieved, the classical ketogenic diet is initiated, generally at a 1/3 of the calorie requirements, then increased until the full calorie needs are met and tolerated.
Over recent years, new studies have shown that an initial fasting period may not actually be necessary. One randomised controlled trial looked to compare a ketogenic diet with a fasting period and a gradual type of ketogenic diet ( 2).
Those in the fasting group, fasted for around 48 hours and then were placed onto a 4:1 classical ketogenic diet. The other group was started on a 1:1 (fat: carbohydrate + protein) ratio then gradually titrated to a 2:1, 3:1 and finally up to a 4:1 level.
The authors of this study found that the gradual group was equally effective at reducing seizures at 3 months as the classical ketogenic approach. This is important because it can make implementing this 4:1 or 3:1 type of ketogenic diet much simpler and resulting in shorter hospital stays.
Classical Ketogenic Diet (4:1 or 3:1)
- Fat content makes up around 90% of the diet with the rest coming from carbs and proteins combined
- Strictest form of KD
- Generally started in a hospital environment
Can be achieved using food and tube feeds
Best suited for:
- Children or young adolescents
- Those with severe forms of epilepsy requiring rapid improvement
- Families who need close supervision on meal planning
Cons:
- Very strict
- Cumbersome
- Time consuming
- Precise food weighing required
- Requires in patient stay
Sample Meals for the Classical Ketogenic Diet
Based on a 400 kcal meal a 4:1 plate would consist of:
25 g (0.9 oz) green beans, 65 ml (2.2 fl oz) of double cream, 25 g (0.9 oz) chicken breast, 15 g butter (0.5 oz)
Based on a 400 kcal meal a 3:1 plate would consist of:
30 g (1.1 oz) of green beans, 50 ml (1.7 fl oz) double cream, 25 g (0.9 oz) chicken breast, 10 g (0.4 oz) butter
Other meals suitable for 4:1 Classical Ketogenic Diet
4:1= 90% fat (40 g); 4% Carbs (4 g) 6% protein (6 g)
Other meals suitable for 3:1 Classical Ketogenic Diet
3:1= 87% fat (39 g); 5% Carbs (5 g); 7% protein (7 g)
2. Medium Chain Triglyceride Ketogenic Diet
Since the classical ketogenic is a lot harder to initiate and stick to, over the recent years, researchers have been looking at other dietary methods to get people into ketosis.
The Medium Chain Triglyceride (MCT) Diet was first introduced in the 1970s. In our diets, most of the fat sources come from that of long chain triglycerides (LCTs) such as saturated, monounsaturated and polyunsaturated fats. MCTs are found in limited places in the diet and generally come from sources such as coconut and palm oil.
What are MCTs?
MCTs are processed differently in the body in that they are more efficiently digested, absorbed and facilitates faster metabolism to acetyl CoA (3). Ketone production in the body is heavily dependent on the generation of Acetyl CoA. Therefore, it has been shown that MCTs are more ketogenic than that of LCTs.
What are the Advantages of the MCT Diet?
Unlike the classical ketogenic diet, the MCT ketogenic diet is not specifically based on ratios. Instead it is more based on the percentage of energy that is coming from the MCTs to create ketone bodies.
The MCT percentage usually falls between 40-70% depending on the goals of the seizure control. The percentage initially calculated is around 50% of MCT, 19% carbohydrate, 10% protein and 21% LCTs. On a diet providing 1600 kcal this would equate to: 89 grams of MCT, 76 grams of Carbohydrate, 40 grams of protein and 37g LCTs.
This form of ketogenic diet is much more flexible than the classical ketogenic diet, with the carbohydrate content being much more liberal. This form of diet does still require healthcare supervision and initiation would generally be carried out in a hospital environment. One may argue that this level of carbohydrate may not be low enough to invoke good seizure control.
However, a randomised controlled trial carried out in 2009 ( 4), compared the classical ketogenic diet to the MCT diet. At 3, 6 and 12 months, there were no significant differences found between the 2 groups. They established that 29% of the MCT group had over a 50% seizure reduction at 3 months.
What are the Drawbacks of the MCT Diet?
One potential drawback of the MCT diet, is the perceived gastrointestinal side effects ( 5). To help prevent this from happening, the MCTs should be given to people in a slow and progressive way. Ideally the MCT dosage would be spread across three meals and three snacks to make sure no stomach upsets happen. The diet, like the classical approach still needs to be weighed out precisely for every meal time.
MCT Ketogenic Diet
- Between 40-70% of energy needs comes from MCT
- Allows a higher carbohydrate content - around 19%
- Rest comes from LCTs and protein
- MCT needs to be included in every meal and snack
Best suited for:
- Those who struggle with the carbohydrate restriction
- Those who need a strict eating structure
Cons:
- Can cause GI disturbances
- Precise food weighing required
- Requires in patient stay
Sample Meals for the MCT Diet
50% MCT (22 g - this would usually come in the form of MCT oil); 19% carbs (19 g); 10% protein (10 g); 21% LCTs (9 g)
3. The Modified Atkins Diet (MAD)
The Modified Atkins Diet first came into effect in 2003 when the first case report was published form the John Hopkins hospital ( 6). In this study, 6 patients were placed on the Atkins diet, of which 3 of them reported a 90% reduction in their seizure activity. This study paved the way for centres around the world to begin using and studying this diet for the use in epilepsy.
Atkins Diet vs Modified Atkins Diet
In 2006, it was eventually named as the Modified Atkins Diet to distinguish between the actual Atkins diet. From the authors that coined the diet, they elicit three reasons as to why it is different from the Atkins diet (7):
- The “induction phase” of the Atkins diet is maintained indefinitely on the Modified Atkins Diet, i.e. there is no gradual increase in carbohydrate levels
- High fat foods are mandatory not just accepted
- Weight loss is not the goal of the MAD and unless overweight, it is actively discouraged.
People on the Modified Atkins Diet generally receive a ratio of 1-2:1 (fat: carbohydrates + protein), but the need to hit the ratio is not as important as with the classical ketogenic diet.
The major emphasis on this form of ketogenic diet is to do with the carbohydrate content. In children, the carbohydrate content is limited to 10 g/day, 15-20 g/day for adolescents and 20 g/day for adults.
There are no set restrictions put on the protein or the calorie level, but guidance is given to maintain what the standard requirement for that individual would be i.e. the right level of calories prescribed to ensure no weight loss or gain etc.
If percentages were to be estimated then they would be based on: 65% from fat, 5% from carbohydrates and 30% from protein.
What are the Benefits of the Modified Atkins Diet?
Dissimilar to the other 2 approaches, this form of ketogenic diet does not need to be initiated in a hospital setting. Standard household measurements can also be used (cups, grams etc.) instead of weighing of food.
The Modified Atkins Diet has been used more within adults, presumably due to the freedom that it can provide. People often report that this form of ketogenic diet is easier to stick with as it gives more social independence.
In 2013, a review paper was published which looked at the last 10 years’ worth of research carried out on the efficacy of the Modified Atkins Diet (7). In it they report that 53% of children reported a 50% seizure reduction, with 15% achieving seizure freedom. In adults around 30% reported a similar reduction and only 3% became seizure free.
Modified Atkins Diet
- Follows more of a 1-2:1 ratio
- Fat provides around 65% of energy needs
- Calories and protein are allowed “freely”
- Weight loss is not the goal
- Carbohydrates must still sit around 5% of energy needs
Best suited for:
- Adolescents and adults who require a little more food freedom
- Those who struggle to comply with the strict form of carbohydrate counting
- Those with less severe forms of epilepsy i.e. less seizures per day
Cons:
- Still stricter on the carbohydrate level
- May not be strict enough for some people to invoke seizure control
Sample Meals for the Modified Atkins Diet
1-2:1 = 65% fat (29 g); 5% Carbs (5 g); 30% protein (30 g)
4. Low Glycemic Index Diet
The final diet that is gaining in popularity for use in epileptic patients is that of the Low Glycemic Index Diet. The Glycemic Index (GI) is a measure of the effect of carbohydrate on blood sugar levels. Slower absorbing foods in the digestive tract have a lower glycemic level.
Other factors that can affect the glycemic response include the fibre content, cooking methods and processing of foods. Likewise, adding in protein and fat to carbohydrate sources can also effect its glycemic response.
What is the Glycemic Index?
The index ranges from 0 to 100 with a food scoring 100 having the highest glycemic value. Foods ranging from 0-50 are classed as having a low glycemic value and are the ones included for this dietary approach.
The first study looking at the low glycemic diet was published in 2005 ( 8) which was later updated to include more patients in 2009 (9).Both studies found that more than half of the patients reported a 50% reduction in seizures. These are similar figures that are seen in the more stricter form of ketogenic diets including the classical ketogenic diet.
How Many Carbs on the Low GI Diet?
The major difference with this form of diet is the range of carbohydrate level. The above study (9) found that patients had a carbohydrate content ranging from 15-150 g per day.
Whilst some could cope with the higher intake, others had to stay at the lower level to achieve seizure control. The importance for seizure control with the diet also had to do with maintaining carbohydrate sources that have a GI of 50 or less.
Overall, 10% of the total energy from the diet will come from carbohydrates but the emphasis must be on the lower glycemic forms. Examples of low GI carbohydrates include:
- Low starchy veggies
- Sweet potatoes
- Yams
- Plums
- Berries
- Cherries
- Certain whole grains- oats, buckwheat
- Brown rice
- Nuts
- Raisins
- Dairy
Approximately 30% of energy comes from protein and 60% comes from fat. The carbohydrate should be spaced throughout the day and they should be eaten with some fat and/or protein to help reduce the GI.
Low Glycemic Index Diet
- Emphasis is on an intake of carbohydrates with a glycemic level of 50 or less
- 10% of energy needs can come from carbohydrates
- Foods don’t need to be weighed and based on normal household portion sizes
- Carbohydrate intake must be evenly spread throughout the day
Best suited for:
- Suited for those who cannot cope with any strict form of carbohydrate restriction
Cons:
- May be too liberal in carbohydrate level to invoke good seizure control
- Requires understanding of the glycemic index
Sample Meals for the Low Glycemic Index Diet
*60% fat (27 g); 10% carbs (10 g); 30% protein (30 g).
*
Which Diet to Choose?
The exact ketogenic diet to follow that will be right for you will come down to a variety of different factors. Things such as lifestyle, age, food preferences and feeding methods will all come into play.
The summary overviews listed in each of the four approaches will help you choose the best suited diet for you. It is important to note that before placing yourself on any form of ketogenic diet for epilepsy, to consult with your health care provider.
Practical Considerations
When following any of the ketogenic diets for epilepsy there are certain considerations that must be taken on board before starting and throughout:
- All contraindications to the stricter forms of the ketogenic diet (classical and MCT) need to be considered
- Baseline biochemistry (especially for children) must be checked before starting i.e. liver enzymes, kidney function
- Vitamin and mineral supplementation may need to be started
- Adequate guidance and training needs to be given on the diet before starting to ensure full understanding
- Ketone levels generally should be checked twice a day as good ketosis is believed to be correlated with seizure control
- Clinical monitoring and regular follow ups (especially in children) are needed to asses seizures, tolerance and any other benefits or adverse events noted
- A hospital stay may be required (for the stricter forms of ketogenic diets)
- For both the classical and MCT based diets, all food needs to be weighed out and calculated specifically
- Significant understanding of what carbohydrates are and where they come from
- Growth and bone health in children needs to be closely monitored
- Eating out and in social situations must be considered- you can’t just stop and start the diet
- Flexibility between the diets, if one is not bringing the desired results then it may need to be changed
- One approach won’t work for all
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