L-carnitine, also referred to as simply carnitine, is a nutrient that your body makes naturally from substances called amino acids. It also comes from a range of food sources and is available in a variety of supplemental forms. L-carnitine helps your body produce energy by burning fat, but does not appear to help you lose weight.
Basics
Amino acids are the building blocks that your body uses to make its proteins. Through a natural internal process, your body also uses the amino acids lysine and methionine to make an internal supply of L-carnitine in your liver and kidneys. After it is formed, this nutrient accumulates in your skeletal muscles, brain and heart, as well as in male sperm. You also get dietary L-carnitine from foods such as beef, fish, poultry, pork, avocados, asparagus and milk and other dairy products. Supplemental L-carnitine is available in oral and intravenous forms, as well as in closely related forms called acetyl-L-carnitine and propionyl-L-carnitine.
Fat Burning
To get energy from the fats in your diet, your body must turn them into substances called fatty acids. Your heart and skeletal muscles, in particular, rely on fatty acid burning for the fuel that keeps them going. L-carnitine plays an essential role in this process by transporting fatty acids to structures in your cells called mitochondria, which perform the actual burning and produce energy. L-carnitine also removes potentially harmful waste products from the burning of fatty acid so they don't accumulate and cause cellular damage.
Weight Loss
Because of L-carnitine's role in the burning of fatty acids, supplemental forms of the nutrient are frequently marketed as weight loss aids. However, there is no scientific basis for these claims, according to the University of Maryland Medical Center. Unless you have a genetic inability to produce or use the nutrient, or have certain medical conditions -- including heart disease or an overactive thyroid gland -- your body makes enough L-carnitine to support its energy requirements. Still, there is some evidence that oral doses of L-carnitine can increase your muscle mass, lower your fat mass and lower your levels of fatigue. Each of these actions has the potential to produce a reduction in your weight.
Considerations
Before you consider taking an L-carnitine supplement, ask your doctor for advice. While the nutrient will not typically produce toxic effects, doses in excess of 5 grams per day may give you diarrhea, in addition to potentially giving your body a fish-like odor, abnormally increasing your appetite or giving you a rash. Medications that can potentially produce harmful or altered effects in combination with L-carnitine include valproic acid, doxorubicin, AZT and isotretinoin, better known as Accutane.
Member Comments