Carnitine (Carnitor or Vitamin B13)

August 5, 2011

What is it?

Carnitine (vitamin B13) is a protein found in all tissues and is essential in mammalian energy metabolism. It facilitates the entry of long-chain fatty acids into the mitochondria of the cells, thereby delivering substrate. Enzymes act on this for oxidation and subsequent energy production.

Humans get carnitine from food, including red meat, milk and milk products. The body also produces it from the dietary amino acids, lysine and methionine. Most carnitine (90 to 98 per cent) is stored in skeletal and cardiac muscles at levels roughly 10 times higher than the levels found in the blood.

People with epilepsy often have lower levels of plasma carnitine. This carnitine deficiency may result from:

  • nutritional factors,
  • underlying metabolic disorders,
  • the effects of drugs and diseases or
  • any number of these in combination.

Plasma levels are usually lowest in people taking a combination of valproate with other anti-epileptic drugs (AEDs) such as phenobarbital, phenytoin or carbamazepine (valproate polypharmacy). Taking valproate or other AEDs alone may also sometimes cause a deficiency. Studies suggest young children and people with multiple disabilities are at greater risk for carnitine deficiency.

Who should use it?

Carnitine is used for:

  • a small percentage of people who are at risk of liver damage from AEDs
    • including emergency situations where there is liver damage caused by valproate
  • children with
    • multiple seizure types who are taking multiple AEDs
    • complex neurologic disorders who are taking multiple AEDs
  • persons with epilepsy whose
    • carnitine levels are low from taking valproate – strongly recommended
    • ammonia (hpyerammonemia) levels are high from taking valproate – strongly recommended
  • emergency cases of valproate overdose
  • people on the ketogenic diet (where it may promote ketosis) who have low plasma levels of carnitine
  • people on dialysis -prescribed
  • treating rare diseases involving problems of the transport of carnitine into the mitochondria

Side Effects

Adverse effects may include:

  • transient nausea,
  • vomiting,
  • abdominal cramps and
  • diarrhea.

Less frequent reactions may include body odour or gastrointestinal symptoms.

Although animal studies show no evidence of infertility or fetal harm due to carnitine, no valid data is available for human pregnancies. It is not known whether it is excreted in the mother’s milk.


In Canada, Carnitor (carnitine) is available in two forms, prescription drugs and non-prescription supplements. The prescription formula is more expensive, it is generally recommended because carnitine supplements are less regulated and are not always made purely with biologically active compounds, which may cause some side effects and interfere with medication.

The material offered at this site is to provide general information about epilepsy to the public. It is not intended to be taken as medical advice. Although all material presented at this site has been thoroughly researched and is believed to be correct, Epilepsy Ontario accepts no liability. Consult your physician and/or neurologist with any questions you have. People with epilepsy should never discontinue anti-epileptic medications or make changes in activities unless specifically advised to do so by an attending physician.

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