L-carnitine is a lysine derivative. Almost all cells in the body contain l-carnitine. This nutrient, produced by the kidneys and liver and stored in the heart, sperm, muscles and brain, helps turn fat into energy, according to the University of Maryland Medical Center. The body typically produces all of this nutrient that it needs, but some people take supplements. Before taking any form of l-carnitine, it is important to talk to your doctor.
Weight Loss
No scientific evidence exists to show this nutrient promotes weight loss, but some research points to oral l-carnitine increasing muscle mass, decreasing fat mass and lowering fatigue, according to the University of Maryland Medical Center. All of these effects may help to promote weight loss. This nutrient is also purported to improve exercise performance, but no concrete evidence backs this claim.
Forms
As a supplement, l-carnitine is found in a variety of forms. Propionyl-l-carnitine is most often used in peripheral vascular disease and heart disease studies. Acetyl-l-carnitine is commonly used in brain disorder and Alzheimer's disease studies. D-carnitine supplements should be avoided due to their interference with l-carnitine in its natural form and adverse side effects, according to the University of Maryland Medical Center. This nutrient may be administered intravenously by a doctor or taken by prescription in some cases.
Dosage
In most cases, 1 to 3 g per day of l-carnitine is recommended for therapeutic use, according to the University of Michigan Health System. However, 500 mg to 1,000 mg a day, three times per day, is recommended by the University of Pittsburgh Medical Center. Those taking l-carnitine for weight loss should talk to a medical doctor to determine the safest dose for them.
Warnings
In most cases, the side effects associated with l-carnitine are mild and related to high doses of 5 g or more daily, according to the University of Maryland Medical Center. Though rare, body odor, increased appetite, diarrhea and rash may occur. Taking l-carnitine supplements is contraindicated for those with peripheral vascular disease, cirrhosis, kidney disease, high blood pressure and diabetes. Individuals should avoid certain medications when taking l-carnitine supplements, such as doxorubicin, valproic acid, isotretinoin and the HIV/AIDS medication known as AZT.
References
- Office of Dietary Supplements National Institutes of Health: Carnitine
- Hilary Spruytenburg of Vanderbilt University: L-Carnitine: Powerful Endurance Enhancer, or Unnecessary Ergogenic
- University of Maryland Medical Center: Carnitine (L-Carnitine)
- Oregon State University Linus Pauling Institute: L-Carnitine
- University of Michigan Health System: L-Carnitine
- University of Pittsburgh Medical Center: Carnitine
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