'Antiepileptic drugs cause vitamin D deficiency through induction of hepatic microsomal enzymes that metabolise vitamin D.'
I believe this is one of the main causes of lethargy and break through seizures for individuals with epilepsy but neurologists will often dismiss this suggestion in my experience and tell you to increase medication instead. They do not study nutrition in enough depth at medical school so usually they don't know this.
You can get a free vitamin D test from your GP. If vitamin D is low you will need to supplement with vitamin D3. The type of vitamin D you get through diet is D2 which is not adequate. It is very difficult to get enough vitamin D3 from the sun to reach optimal levels in the blood (typically 100-150mmol/l).
Vitamin D is a fat soluble vitamin so you will also want to eat plenty of quality fats with enough vitamin A which works together with vitamin D. We typically already get enough calcium, magnesium and phosphorus in our diets so this consideration is less important.
I hope this information helps people to control seizures better and to have more energy, less muscle weakness, better moods, etc. contact me if you have any questions. :)
This is the best vitamin D3 supplement I know of. It is completely natural and contains no corn, soy, gluten, sugar, starch, or any nasty ingredients to fill it up.