Carnitine is not an amino acid in the strictest sense; it's actually related to the B vitamins. But because it has a chemical structure similar to that of amino acids, it is usually grouped with them. It helps transport fatty acids into the mitochondria, part of the cell that contains enzymes responsible for the conversion of food into usable energy.

Carnitine deficiency is not uncommon in patients with epilepsy. Research has found carnitine levels to be lowest in patients taking sodium valproate (epilim), but levels may be low in those taking other anticonvulsants, too. This can be a cause of concern because more than one hundred people have died from valproate-induced hepatic (liver) failure.*

About 90% of total body carnitine is in muscle tissue, much higher than in the blood, so a normal blood carnitine level reading may be misleading. Symptoms of carnitine deficiency include listlessness, hypoglycemia (low blood sugar), heart failure, and muscle weakness. People low in carnitine benefit from supplementation. Many nutritionalists believe that acetyl-carnitine has better brain penetration than L-carnitine and also enhances brain levels of acetylcholine.

*Konig, S., et al. (1994) "Severe Hepatoxity During Valproate Therapy: An Update and Report of Eight New Fatalities," Epilepsia (35) 1005-1015.