L-Carnitine Deficiencies

L-carnitine is an amino acid-like molecule which is synthesized in your liver and kidneys from two other amino acids, lysine and methionine. Although it is found in high concentrations in red meats, carnitine is also present in fish, poultry, tempeh, milk, wheat and avocados. L-carnitine is stored primarily in your skeletal muscles and heart, where it participates in the generation of energy for these highly metabolic tissues. Because humans can manufacture L-carnitine, deficiencies are uncommon, but your needs for carnitine can outstrip your ability to make this important molecule.

Carnitine Deficiency

The Office of Dietary Supplements states that carnitine's primary function is to transport fatty acids into your mitochondria so they can be oxidized for energy. It then carries the toxic products of fatty acid metabolism back out of the mitochondria to prevent their accumulation. Since L-carnitine plays such a crucial role in energy production, deficiency can cause a variety of symptoms including fatigue, low blood sugar, muscle weakness, confusion and heart failure.

Inadequate Intake Causes Deficiency

Inadequate dietary intake of L-carnitine can lead to deficiency. This might occur during fad diets, prolonged intravenous feeding or extended periods of poor access to animal-based foods. In some situations, such as a serious medical illness, your requirements for L-carnitine can actually increase when you are least able to consume it.

Enzymatic Defects Prevent Normal Carnitine Function

Prior to their transfer into your mitochondria for oxidation, fatty acids must be hooked to carnitine by an enzyme; they are then unhooked from carnitine by a different enzyme once they are inside the mitochondria. Genetic defects can cause abnormalities in either of these two enzymes, called carnitine palmitoyltransferase I and II, respectively. This enzymatic failure creates a "relative deficiency" of carnitine by preventing it from functioning as a carrier molecule.

Genetic Disorder Results in Defective Carnitine Transporter

Carnitine transporters are molecules that carry L-carnitine into cells or prevent its loss from your body via your kidneys. Systemic primary carnitine deficiency is a rare genetic disorder that causes the production of defective transporter molecules, thereby preventing carnitine from entering your cells or allowing it to escape from your body. This disease can occur in children as a full-blown syndrome of weakness, brain disorders and heart failure, but "carriers" may not have any symptoms until they are adults and experience significant stress, such as pregnancy or strenuous exertion.

Systemic Illness Causes Carnitine Deficiency

Severe liver disease, such as cirrhosis, can interfere with the production of carnitine. Hemodialysis removes carnitine from your circulation. A prolonged bout of diarrhea or excessive loss of urine due to diuretics can deplete your body's stores of carnitine. Vitamin C deficiency can contribute to carnitine deficiency because vitamin C is needed for carnitine synthesis. Some of these conditions are temporary and you might not suffer any ill effects from a transient fall in carnitine levels.

Considerations

L-carnitine is an essential molecule which is usually manufactured in your body. Although deficiency is unusual, poor dietary intake, illness and genetic disorders can lead to carnitine deficiency. L-carnitine appears to be useful in some medical conditions, such as heart disease or lipid abnormalities. In these situations it is administered in daily doses of 1,800 to 3,600 mg. Because L-carnitine hastens the metabolism of fatty acids, it has become popular among individuals who are attempting to lose weight, and athletes consume L-carnitine to improve muscle performance. However, the evidence to support these uses is controversial. If you have liver or kidney disease, or if you suffer from diabetes, consult your physician before taking L-carnitine.