This past month saw the publication online of two articles that looked at the ketogenic diet in a new way. Both evaluated the effect of the classic ketogenic diet on how blood vessels distend: more distensibility (moving more with blood flow) being better. Although studies over the past few decades have demonstrated that there is an initial rise in “bad” cholesterol, and a later (after 6 to 12 months) decline back to normal, the long-term effects of this have not been shown. A study from our group determined that there were no reports from parents (or patients) about long-term heart disease, but that is not scientific proof it doesn’t exist.
The first study from Drs. Kapetanakis, Liuba, Odermarsky, Lundgren, and Hallbook from Lund, Sweden, was published in European Journal of Pediatric Neurology. Dr. Kapetanakis is now practicing in Greece; Dr. Hallbook had presented some of this research several years ago in the form of posters and oral presentations, so the published data is now available. In this study, 43 children ages 2 to 15 years were put mostly on a 4:1 ketogenic diet. They then had ultrasounds of their carotid (neck) arteries to look at the intima (wall) thickness, distensibility, compliance and stiffness at 3, 12 and 24 months on the diet. They found that yes; the carotid arteries did become stiffer at 12 months…but similar to cholesterol and triglycerides, by 24 months this had returned to normal. The intima wall thickness never changed.
The second study from Dr. Coppola and his colleagues from Italy also attempted to evaluate how blood vessels react to the diet; it was published in Seizure. This study included 46 patients, some who were adults, and also had a control group of children with epilepsy not on the ketogenic diet. They looked at one time point of patients, including some who had stopped the diet. Their results were very similar to the study from Sweden: distensibility was less common (vessels were more stiff) in the ketogenic diet group compared to controls, but the thickness of the walls was not different. They found that the patients who were more recently on the diet had higher signs of vessel changes.
What should we take from these two similar studies? Both provide evidence that patients on ketogenic diets may have early signs of blood vessel injury as evident by less distensibility on ultrasound. The walls of the blood vessels do not seem to get thicker (at least right away), but something in the diet may be having an effect. Only the study from Italy found a relationship between arterial wall distensibility and cholesterol values, so it may not be completely related to cholesterol or triglycerides (even though that seems logical) and thus discoverable by serum labs. On a good note, both studies found that either over time (after 12 months of diet use in the Swedish study) or after the diet was stopped (the Italian study), these changes seemed to revert back to normal. Neither study reported any clinical changes in these children – none had any described cardiac symptoms.
This is obviously preliminary data and the beginning of considerations of possible cardiac risks that aren’t immediately obvious when examining a child. Both studies appropriately highlighted how well these children did in regards to seizure control and stated that any risks have to be weighed in terms of benefit. We also do not know what the true risks to heart health are from a likely temporary change in how the arterial blood vessels move. This should not dissuade you from trying the ketogenic diet for you or your child.
But can we use this information wisely and try to prevent later cardiac risk? One method may be to use lower ketogenic diet ratios and more “healthy” fats to prevent high total cholesterol and triglycerides – if there is a link between abnormal serum lipids and changes to the blood vessels, then this would be wise. Perhaps children who require ketogenic diets long-term could be transitioned to the modified Atkins diet, not just for ease of use, but also for health purposes. In addition, doctors and patients should always consider just how long to keep children on the diet for – 2 years? 1 year? Shorter? More studies are needed, and, as better technologies allow us to examine the blood vessels, heart (and of course brain!), the bad (and good) potential effects of the diet will continue to be clearer.
Coppola G, Natale F, Torino A, et al. The impact of the ketogenic diet on arterial morphology and endothelial function in children and young adults with epilepsy: A case-control study. Seizure 2014;23:260-265.
Kapetanakis M, Liuba P, Odermarsky M, et al. Effects of ketogenic diet on vascular function. Eur J Pediatr Neurology 2014, on line early.