Although the main dietary source of carnitine is meat,[1][2] people who follow a strict plant-based diet typically do not have a higher risk of carnitine deficiency because sufficient amounts of carnitine can be synthesized in the body from other amino acids (e.g., lysine and methionine).[3][4]
In rare cases, carnitine deficiency can occur in children with inborn errors of metabolism (i.e., genetic defects affecting metabolic function) in carnitine biosynthetic or carnitine transport pathways.[5][6] Carnitine deficiency can also be caused by some drugs, including pivalic-acid-containing antibiotics and valproic acid, and it can occur in response to dialysis in people with chronic kidney disease.[5][6] In such cases, supplementation with carnitine is sometimes used to help treat the symptoms, but high-quality randomized controlled trials are needed to confirm its efficacy.[7][5][6]