L-Carnitine is a nutrient that is derived from the amino acids lysine and methionine. Its name is derived from the fact that it was first isolated from meat (carnus). L-Carnitine is not considered a dietary essential because it is synthesized in the body. The body produces carnitine in the liver and kidneys and stores it in the skeletal muscles, heart, brain, and other tissues. But its production may not meet the needs under certain conditions such as increased energy demands and therefore it is considered a “conditionally essential nutrient”. There are two forms (isomers) of carnitine, viz. L-carnitine and D-carnitine, and only the L-isomer is biologically active.
What does L-carnitine do in the body?
L-Carnitine is responsible for the transport of fats (long-chain fatty acids) into the energy-producing centers of the cells known as the mitochondria. This is where fatty acids are oxidized to produce vital biological energy that is essential to run all cellular processes. In other words, carnitine helps the body convert fatty acids into energy that is necessary for muscular and all other activities throughout the body.
Factors affecting L-carnitine status in the body
L-Carnitine status in the body is affected by a number of factors. Vegetarians may not get an adequate supply of preformed L-carnitine or its precursors to synthesize carnitine and they run the risk of deficiency. Also, there are individuals who are unable to properly absorb carnitine from foods. Carnitine deficiencies may also be caused by genetic disorders, liver or kidney problems, high-fat diets, certain medications, and low dietary levels of the amino acids lysine and methionine (precursors of carnitine). Carnitine deficiencies are occasionally associated with other diseases such as diabetes and cirrhosis. Carnitine deficiency symptoms include fatigue, chest pain, muscle pain, weakness, low blood pressure, and/or confusion.
Uses of L-carnitine
Health benefits of L-carnitine supplementation, generally as an adjunct to standard medical therapy, have been reported in numerous conditions. These include, in addition to primary and secondary carnitine deficiencies, myocardial infarction, heart failure, angina pectoris, intermittent claudication, renal disease, diabetes, Alzheimer's disease, HIV infection, male infertility, and age related declines in memory. Because of its role in energy production, L-carnitine is also thought to enhance athletic performance.
Types of L-carnitine supplements available
Because L-carnitine (base) happens to be highly hygroscopic and unstable, dietary supplements of carnitine are based upon its esters and derivatives. These include L-carnitine fumarate, L-carnitine tartrate, acetyl-L-carnitine and propionyl-L-carnitine.
Safety of L-carnitine
L-Carnitine in large doses is well tolerated. No adverse side effects other than mild gastrointestinal symptoms have been reported. L-Carnitine supplements at more than 3,000 mg/day may cause a “fishy” body odor.
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