Thursday, 23 June 2011

How do ketogenic diets work?

Perhaps I have said it before and please excuse me if I am repeating myself, the influence of diet on both our physical and mental health is a bit of an interest of mine.

When I say interest, please don't infer that I have any dietetic training on the various components of our diet and the details of what we should or shouldn't eat outside what research in the public domain tells us. No, my interest and comfort zone is more about measuring and analysing the final outcomes from diet, particularly the psychological and behavioural endpoints.

Although the gluten- and casein-free diets lie at the centre of my interest, I have found myself drawn to other kinds of diet and their various uses in medicine down the years. Phenylketonuria (PKU) is one example; how a diet low in phenylalanine (combined with tyrosine supplements?) can so completely transform a person's life, indeed even save a life. Another type of diet has also been on my radar for a while now, the ketogenic diet.

My interest in the ketogenic diet has been piqued recently by a few things. Emily Deans over at Evolutionary Psychiatry has posted a few entries mentioning the ketogenic diet which make for some very interesting reading (see here). I also had the good fortune to attend a conference recently where dietitian Sue Wood presented some of her findings on the use of the ketogenic diet in practice. Both provide some tantalising suggestions about the ketogenic diet including much of what this post details. I might add that both Emily and Sue are trained healthcare professionals; this is not some dietary 'fad' being touted as alternative medicine.

If I had summarise a ketogenic diet in as few words as possible it would be something like this: high fat, low carbohydrate. Most people will probably have heard about the ketogenic diet or at least something related, under a pseudonym - the Atkins diet - and its proposals for weight loss. A ketogenic diet has been suggested as being a possible management option for quite a few conditions including Rett syndrome, Tuberous Sclerosis and other conditions. It is with certain types of epilepsy and seizure disorders in mind that the diet has found its primary function.

The precise theory behind the ketogenic diet and why it seems to be able to reduce/eliminate seizures in certain cases is... well, I dunno. Current thinking suggests that by using the diet to invoke the production of ketones, compounds normally produced when the body is in starvation mode, said compounds might have an anti-seizure effect. There is quite a bit of research to support this suggestion and who am I to argue. I have for quite a while, thought quite a bit about the whole ketone story and whether there may be other explanations for the results suggested in reducing seizures.

One of the interesting things for me is the overlap between a ketogenic diet and a gluten-free diet. Both diets are generally associated with the removal/reduction of carbohydrates although perhaps for different reasons. Yes, I know that gluten-free foods will often contain carbohydrates but there is some evidence to suggest that overall carbohydrate intake is reduced on a gluten-free diet whether due to the taste of the alternative foods or general nutritional preference. Granted also, that the ketogenic diet replaces said carbs with fat as an alternative energy source (adding fat to the diet is considered almost heresy in some circles today) but the overlap between the two diets is carbohydrate reduction. There are then a few lines of evidence that lead me to think that the ketogenic diet might be doing more than just putting the body into ketosis; the primary evidence coming from some results from the various trials on gluten- (and casein-) free dietary intervention for autism amongst other things.

It was Prof. Ann-Mari Knivsberg and colleagues who first reported on the effect of the GFCF outside of just core autistic symptoms. It was almost a secondary finding when they said that there was a reduction in the number of seizures experienced by some of their autistic participant group (pp230-231). Indeed in our own 1999 paper on examining the gluten-free diet for autism, we reported the experiences of one child who, coincidentally when coming off the gluten-free diet back on to a gluten-load diet, experienced a seizure at the same time as gluten reintroduction (pp50-51). I remember that at the time my colleagues and I thought such an individual observation was purely coincidental knowing about the association between autism and epilepsy. Combined with the Knivsberg results and a few years thought in-between, I do wonder if this was not just a chance finding.

On the basis of such preliminary evidence, the question posed is whether carbohydrate or a gluten reduction-removal might be an active anti-epileptic component working alone or in union with ketones? At this point I will remind readers that I am not offering medical advice or opinion on such 'strategies', merely exploring possibilities based on the research evidence available. Please speak to your medical physician and dietitian before making any changes to diet or medication particularly where epilepsy or seizure disorder is indicated. Don't mess with epilepsy.

Gluten has been linked to epilepsy on quite a few occasions (here and here for example). Of course being linked to a condition does not necessarily imply direct involvement in that condition; that is aside from the case studies like this one and this one which reported in cases of epilepsy and co-morbid coeliac disease, that a gluten-free diet improved both sets of symptoms. Precisely why a gluten-free diet had such an effect is unclear and beyond the limits of my competence. Trying also to find research which can disentangle an effect from gluten reduction or carbohydrate reduction is difficult.

I will perhaps leave things there. I could go on and talk about how those pesky gluten exorphins might play a role or how the ketogenic diet has shown some effectiveness in ameliorating autistic symptoms or how a gluten-free in some cases might put the body into starvation mode given the significant drop in calories expected at least in the early days of the diet or even the various discussions on the specific carbohydrate diet. But I won't. Instead I will stay here in my comfort zone.

To finish, Weird Al and a nice food link.. Eat It!